Change search
Refine search result
1 - 35 of 35
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Alonso Aller, Elisa
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gullström, Martin
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Kloiber, Ulrike
    Linderholm, Hans W.
    Nordlund, Lina M.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Monitoring of a protected multi-specific tropical seagrass meadow reveals a pattern of decline and recoveryManuscript (preprint) (Other academic)
    Abstract [en]

    In a changing environment, there is an increasing interest to monitor ecosystems to understand their responses to environmental change. Seagrass meadows are highly important ecosystems, but at the same time they are under a constant threat from human activities, as well as climate impacts, and marked declines have been observed worldwide. Despite increasing efforts, monitoring of multi-specific tropical seagrass meadows is scarce, particularly in developing regions. Here we analysed data from the first 10 years of a monitoring programme in a marine protected area in Zanzibar (Tanzania) to assess temporal changes in seagrass cover and species composition and to detect potential drivers of change. The seagrass meadow experienced a strong gradual decline in seagrass cover and changes in species composition, followed by a period of recovery. However, the timing and length of these temporal patterns varied in space (between transects). Of the climate variables considered, cloud cover, temperature, storm occurrence, sunspot activity and the height of the diurnal low tide seemed to influence seagrass cover, although only to a small extent, suggesting that the monitored seagrass meadow may be influenced by other unmeasured factors. Considering our results, seagrass meadows seem to be highly dynamic at small spatial scales even in the absence of major local anthropogenic impacts. Further monitoring programmes should be developed in the region to gain a better understanding of seagrass temporal variability and causes of change.

  • 2.
    Alonso Aller, Elisa
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gullström, Martin
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eveleens Maarse, Floriaan K. J.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gren, Michaela
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Nordlund, Lina Mtwana
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. WIO CARE, Zanzibar, Tanzania.
    Jiddawi, Narriman
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Single and joint effects of regional- and local-scale variables on tropical seagrass fish assemblages2014In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 161, no 10, p. 2395-2405Article in journal (Refereed)
    Abstract [en]

    Seagrass beds are highly important for tropical ecosystems by supporting abundant and diverse fish assemblages that form the basis for artisanal fisheries. Although a number of local- and regional-scale variables are known to influence the abundance, diversity and assemblage structure of seagrass-associated fish assemblages, few studies have evaluated the relative and joint (interacting) influences of variables, especially those acting at different scales. Here, we examined the relative importance of local- and regional-scale factors structuring seagrass-associated fish assemblages, using a field survey in six seagrass (Thalassodendron ciliatum) areas around Unguja Island (Zanzibar, Tanzania). Fish density and assemblage structure were mostly affected by two regional-scale variables; distance to coral reefs, which positively affected fish density, and level of human development, which negatively affected fish density. On the local scale, seagrass biomass had a positive (but weaker) influence on fish density. However, the positive effect of seagrass biomass decreased with increasing level of human development. In summary, our results highlight the importance of assessing how multiple local and regional variables, alone and together, influence fish communities, in order to improve management of seagrass ecosystems and their services.

  • 3.
    Alonso Aller, Elisa
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Jiddawi, Narriman S.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Fishing weakens a positive link between herbivore abundance and plant growth in tropical seagrass bedsManuscript (preprint) (Other academic)
    Abstract [en]

    Herbivory is a key process influencing the structure and function of both terrestrial and aquatic systems. In seagrass ecosystems, moderate levels of herbivory may stimulate plant growth, compensating for the loss of eaten tissue. However, the relationship between herbivory and seagrass growth can be influenced by an array of factors, such as seasonality, herbivore abundance, and presence of epiphytes, many of which can be directly or indirectly affected by human activities like fishing. Here, we used data from a multi-season field survey in fished and protected seagrass beds to assess how fishing and seasonality affect the link between herbivores, herbivory, and plant growth in seagrasses. Path analyses revealed an interactive effect of seasonality and protection. In protected seagrass beds, seasonally high herbivore abundance positively affected herbivory rates, which in turn enhanced seagrass growth. This link was however not apparent in seagrass beds subjected to fishing activities. At the same time, seasonality effects seemed stronger in fished areas, suggesting that in addition to weakening a positive herbivory-plant growth interaction, fishing increases temporal instability of ecosystems. Our results highlight the need for evaluating not only the direct effects of fisheries exploitation on fish populations, but also the potential indirect effects on ecosystems, to improve fisheries management.

  • 4.
    Alonso Aller, Elisa
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Jiddawi, Narriman S.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Marine protected areas increase temporal stability of community structure, but not density or diversity, of tropical seagrass fish communities2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 8, article id e0183999Article in journal (Refereed)
    Abstract [en]

    Marine protected areas (MPAs) have been shown to increase long-term temporal stability of fish communities and enhance ecosystem resilience to anthropogenic disturbance. Yet, the potential ability of MPAs to buffer effects of environmental variability at shorter time scales remains widely unknown. In the tropics, the yearly monsoon cycle is a major natural force affecting marine organisms in tropical regions, and its timing and severity are predicted to change over the coming century, with potentially severe effects on marine organisms, ecosystems and ecosystem services. Here, we assessed the ability of MPAs to buffer effects of monsoon seasonality on seagrass-associated fish communities, using a field survey in two MPAs (no-take zones) and two unprotected (open-access) sites around Zanzibar (Tanzania). We assessed the temporal stability of fish density and community structure within and outside MPAs during three monsoon seasons in 2014-2015, and investigated several possible mechanisms that could regulate temporal stability. Our results show that MPAs did not affect fish density and diversity, but that juvenile fish densities were temporally more stable within MPAs. Second, fish community structure was more stable within MPAs for juvenile and adult fish, but not for subadult fish or the total fish community. Third, the observed effects may be due to a combination of direct and indirect (seagrass-mediated) effects of seasonality and, potentially, fluctuating fishing pressure outside MPAs. In summary, these MPAs may not have the ability to enhance fish density and diversity and to buffer effects of monsoon seasonality on the whole fish community. However, they may increase the temporal stability of certain groups, such as juvenile fish. Consequently, our results question whether MPAs play a general role in the maintenance of biodiversity and ecosystem functioning under changing environmental conditions in tropical seagrass fish communities.

  • 5.
    Chirico, Angelica A. D.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Alonso Aller, Elisa
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Additive effects of marine protected areas and land-use on inter- and intraspecific trait variability in tropical seagrass assemblagesManuscript (preprint) (Other academic)
    Abstract [en]

    Marine ecosystems are under increasing human pressure and therefore in need of effective management. Marine protected areas (MPAs) can reduce effects of local disturbances (e.g. fishing), but their ability to buffer stressors originating outside MPA borders (e.g. runoff) is more unclear. Moreover, while MPAs are well-known to affect species composition, we know much less about their effects on organisms’ traits (physiological, morphological, and/or behavioural characteristics), which in turn dictate how organisms respond to stressors and influence ecosystem processes and services. Here, we conducted a field survey in southern Kenya to assess the single and joint (interactive) effects of MPAs and land-use on species and trait composition of seagrass assemblages; a key group of habitat-forming plants in shallow coastal areas. We measured five morphological traits on multispecies seagrass assemblages (leaf length and width, number of leaves per shoot, and above- and below-ground biomass) within three types of sites: government-managed MPAs, community-managed MPAs, and unprotected areas. Using single- and multi-trait statistical analyses, we found that both MPAs and land-use influence seagrass species and trait composition. Changes in community-level traits were mostly explained by species turnover. However, management and land-use also had a direct influence on trait composition, with MPAs promoting wider leaves and higher above-ground biomass, while land-use mostly influenced seagrass leaf length and below-ground biomass. Moreover, even though there was an interactive effect of management and land-use, the largest and oldest MPAs did not seem to buffer effects of intense land-use. In conclusion, it appears that MPAs influence seagrass assemblages by reducing local disturbances, but do not buffer spatially distant land-use effects. Consequently, to sustain seagrass ecosystems and the important services they support, there is a need for a more integrated coastal zone management that regulates resource use and human impacts in both the marine and the terrestrial parts of tropical coastal zones.

  • 6.
    Chirico, Angelica A. D.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    McClanahan, Timothy R.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Community- and government-managed marine protected areas increase fish size, biomass and potential value2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 8, article id e0182342Article in journal (Refereed)
    Abstract [en]

    Government-managed marine protected areas (MPAs) can restore small fish stocks, but have been heavily criticized for excluding resource users and creating conflicts. A promising but less studied alternative are community-managed MPAs, where resource users are more involved in MPA design, implementation and enforcement. Here we evaluated effects of government-and community-managed MPAs on the density, size and biomass of seagrass- and coral reef-associated fish, using field surveys in Kenyan coastal lagoons. We also assessed protection effects on the potential monetary value of fish; a variable that increases non-linearly with fish body mass and is particularly important from a fishery perspective. We found that two recently established community MPAs (< 1 km(2) in size, <= 5 years of protection) harbored larger fish and greater total fish biomass than two fished (open access) areas, in both seagrass beds and coral reefs. As expected, protection effects were considerably stronger in the older and larger government MPAs. Importantly, across management and habitat types, the protection effect on the potential monetary value of the fish was much stronger than the effects on fish biomass and size (6.7 vs. 2.6 and 1.3 times higher value in community MPAs than in fished areas, respectively). This strong effect on potential value was partly explained by presence of larger (and therefore more valuable) individual fish, and partly by higher densities of high-value taxa (e.g. rabbitfish). In summary, we show that i) small and recently established community-managed MPAs can, just like larger and older government-managed MPAs, play an important role for local conservation of high-value fish, and that ii) these effects are equally strong in coral reefs as in seagrass beds; an important habitat too rarely included in formal management. Consequently, community-managed MPAs could benefit both coral reef and seagrass ecosystems and provide spillover of valuable fish to nearby fisheries.

  • 7.
    De La Torre-Castro, Maricela
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Rönnbäck, Patrik
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Björk, Mats
    Stockholm University, Faculty of Science, Department of Botany.
    Seagrass importance in food provisioning services: fish stomach content as a link between seagrass meadows and local fisheries2008In: Western Indian Ocean journal of marine science, ISSN 0856-860X, Vol. 7, no 1, p. 95-110Article in journal (Refereed)
    Abstract [en]

    The links between ecosystem processes and functions and ecosystem services (i.e. the humanbenefits from those) are elusive. In this paper, the food provisioning service of seagrass meadows isoperationalized through the study of the stomach contents of 13 important commercial fish species inChwaka Bay, Zanzibar. Using local fishers’ knowledge on bait, scientific knowledge about the structureof the meadows (associated flora and fauna), stomach content analysis and multivariate statistics, the foodprovisioning service associated with seagrasses and its importance for fish (as important diet component)and for humans (in small-scale artisanal fisheries) are described. The study presents the food items for 13commercial fish species identified at the lowest possible taxonomical level and compares with previousliterature findings. In addition, differences in stomach contents of Siganus sutor and Leptoscarus vaigiensiscaught with both drag-nets and dema basket traps are investigated in order to explore bait presence andindirectly evaluate fishers’ knowledge on bait preference. The results show that most of the items consumedby commercial fishes are associated with seagrass beds and that there are clear indicators that the baittraditionally used seems to be effective. The paper elaborates on the consideration of seagrass ecosystemsin a holistic perspective, the difficulties in valuation of ecosystem services and finally the crucial importanceof these aspects for human well-being and sustainability in coastal communities of the Western IndianOcean.

  • 8.
    Donadi, Serena
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre. Swedish University of Agricultural Sciences (SLU), Sweden.
    Austin, Åsa N.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Bergström, U.
    Eriksson, B. K.
    Hansen, Joakim P.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Jacobson, P.
    Sundblad, G.
    van Regteren, M.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    A cross-scale trophic cascade from large predatory fish to algae in coastal ecosystems2017In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 284, no 1859, article id 20170045Article in journal (Refereed)
    Abstract [en]

    Trophic cascades occur in many ecosystems, but the factors regulating them are still elusive. We suggest that an overlooked factor is that trophic interactions (TIs) are often scale-dependent and possibly interact across spatial scales. To explore the role of spatial scale for trophic cascades, and particularly the occurrence of cross-scale interactions (CSIs), we collected and analysed food-web data from 139 stations across 32 bays in the Baltic Sea. We found evidence of a four-level trophic cascade linking TIs across two spatial scales: at bay scale, piscivores (perch and pike) controlled mesopredators (three-spined stickleback), which in turn negatively affected epifaunal grazers. At station scale (within bays), grazers on average suppressed epiphytic algae, and indirectly benefitted habitat-forming vegetation. Moreover, the direction and strength of the grazer-algae relationship at station scale depended on the piscivore biomass at bay scale, indicating a cross-scale interaction effect, potentially caused by a shift in grazer assemblage composition. In summary, the trophic cascade from piscivores to algae appears to involve TIs that occur at, but also interact across, different spatial scales. Considering scale-dependence in general, and CSIs in particular, could therefore enhance our understanding of trophic cascades.

  • 9.
    Donadi, Serena
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Swedish University of Agricultural Sciences, Sweden; University of Groningen, The Netherlands.
    Nilsson Austin, Åsa
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Svartgren, Evira
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eriksson, Britas Klemens
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Hansen, J. P.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Density-dependent positive feedbacks buffer aquatic plants from interactive effects of eutrophication and predator loss2018In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 99, no 11, p. 2515-2524Article in journal (Refereed)
    Abstract [en]

    Self-facilitation allows populations to persist under disturbance by ameliorating experienced stress. In coastal ecosystems, eutrophication and declines of large predatory fish are two common disturbances that can synergistically impact habitat-forming plants by benefitting ephemeral algae. In theory, density-dependent intraspecific plant facilitation could weaken such effects by ameliorating the amount of experienced stress. Here, we tested whether and how shoot density of a common aquatic plant (Myriophyllum spicatum) alters the response of individual plants to eutrophication and exclusion of large predatory fish, using a 12-week cage experiment in the field. Results showed that high plant density benefitted individual plant performance, but only when the two stressors were combined. Epiphytic algal biomass per plant more than doubled in cages that excluded large predatory fish, indicative of a trophic cascade. Moreover, in this treatment, individual shoot biomass, as well as number of branches, increased with density when nutrients were added, but decreased with density at ambient nutrient levels. In contrast, in open cages that large predatory fish could access, epiphytic algal biomass was low and individual plant biomass and number of branches were unaffected by plant density and eutrophication. Plant performance generally decreased under fertilization, suggesting stressful conditions. Together, these results suggest that intraspecific plant facilitation occurred only when large fish exclusion (causing high epiphyte load) was accompanied by fertilization, and that intraspecific competition instead prevailed when no nutrients were added. As coastal ecosystems are increasingly exposed to multiple and often interacting stressors such as eutrophication and declines of large predatory fish, maintaining high plant density is important for ecosystem-based management.

  • 10. Donadi, Serena
    et al.
    van der Heide, Tjisse
    van der Zee, Els M.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Systems Ecology. University of Gothenburg, Sweden; University of Groningen, The Netherlands.
    van de Koppel, Johan
    Weerman, Ellen J.
    Piersma, Theunis
    Olff, Han
    Eriksson, Britas Klemens
    Cross-habitat interactions among bivalve species control community structure on intertidal flats2013In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 94, no 2, p. 489-498Article in journal (Refereed)
    Abstract [en]

    Increasing evidence shows that spatial interactions between sedentary organisms can structure communities and promote landscape complexity in many ecosystems. Here we tested the hypothesis that reef-forming mussels (Mytilus edulis L.), a dominant intertidal ecosystem engineer in the Wadden Sea, promote abundances of the burrowing bivalve Cerastoderma edule L. (cockle) in neighboring habitats at relatively long distances coastward from mussel beds. Field surveys within and around three mussel beds showed a peak in cockle densities at 50-100 m toward the coast from the mussel bed, while cockle abundances elsewhere in the study area were very low. Field transplantation of cockles showed higher survival of young cockles (2-3 years old) and increased spat fall coastward of the mussel bed compared to within the bed and to areas without mussels, whereas growth decreased within and coastward of the mussel bed. Our measurements suggest that the observed spatial patterns in cockle numbers resulted from (1) inhibition effects by the mussels close to the beds due to preemptive algal depletion and deteriorated sediment conditions and (2) facilitation effects by the mussels farther away from the beds due to reduction of wave energy. Our results imply that these spatial, scale-dependent interactions between reef-forming ecosystem engineers and surrounding communities of sedentary benthic organisms can be an important determinant of the large-scale community structure in intertidal ecosystems. Understanding this interplay between neighboring communities of sedentary species is therefore essential for effective conservation and restoration of soft-bottom intertidal communities.

  • 11. Duffy, J. Emmett
    et al.
    Reynolds, Pamela L.
    Boström, Christoffer
    Coyer, James A.
    Cusson, Mathieu
    Donadi, Serena
    Douglass, James G.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Engelen, Aschwin H.
    Eriksson, Britas Klemens
    Fredriksen, Stein
    Gamfeldt, Lars
    Gustafsson, Camilla
    Hoarau, Galice
    Hori, Masakazu
    Hovel, Kevin
    Iken, Katrin
    Lefcheck, Jonathan S.
    Moksnes, Per-Olav
    Nakaoka, Masahiro
    O'Connor, Mary I.
    Olsen, Jeanine L.
    Richardson, J. Paul
    Ruesink, Jennifer L.
    Sotka, Erik E.
    Thormar, Jonas
    Whalen, Matthew A.
    Stachowicz, John J.
    Biodiversity mediates top-down control in eelgrass ecosystems: a global comparative-experimental approach2015In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 18, no 7, p. 696-705Article in journal (Refereed)
    Abstract [en]

    Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top-down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale patterns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top-down control strongly influence functioning of threatened seagrass ecosystems, and suggest that biodiversity is comparably important to global change stressors.

  • 12.
    Eklöf, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Austin, Åsa
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Bergström, Ulf
    Donadi, Serena
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Eriksson, Britas D. H. K.
    Hansen, Joakim
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Sundblad, Göran
    Size matters: relationships between body size and body mass of common coastal, aquatic invertebrates in the Baltic Sea2017In: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, Vol. 5Article in journal (Refereed)
    Abstract [en]

    Background. Organism biomass is one of the most important variables in ecological studies, making biomass estimations one of the most common laboratory tasks. Biomass of small macroinvertebrates is usually estimated as dry mass or ash-free dry mass (hereafter `DM' vs. 'AFDM') per sample; a laborious and time consuming process, that often can be speeded up using easily measured and reliable proxy variables like body size or wet (fresh) mass. Another common way of estimating AFDM (one of the most accurate but also time-consuming estimates of biologically active tissue mass) is the use of AFDM/DM ratios as conversion factors. So far, however, these ratios typically ignore the possibility that the relative mass of biologically active vs. non-active support tissue (e.g., protective exoskeleton or shell)-and therefore, also AFDM/DM ratios-may change with body size, as previously shown for taxa like spiders, vertebrates and trees. Methods. We collected aquatic, epibenthic macroinvertebrates (>1 mm) in 32 shallow bays along a 360 km stretch of the Swedish coast along the Baltic Sea; one of the largest brackish water bodies on Earth. We then estimated statistical relationships between the body size (length or height in mm), body dry mass and ash-free dry mass for 14 of the most common taxa; five gastropods, three bivalves, three crustaceans and three insect larvae. Finally, we statistically estimated the potential influence of body size on the AFDM/DM ratio per taxon. Results. For most taxa, non-linear regression models describing the power relationship between body size and (i)DM and (ii) AFDM fit the data well (as indicated by low SE and high R-2). Moreover, for more than half of the taxa studied (including the vast majority of the shelled molluscs), body size had a negative influence on organism AFDM/DM ratios. Discussion. The good fit of the modelled power relationships suggests that the constants reported here can be used to quickly estimate organism dry-and ash-free dry mass based on body size, thereby freeing up considerable work resources. However, the considerable differences in constants between taxa emphasize the need for tax on specific relationships, and the potential dangers associated with ignoring body size. The negative influence of body size on the AFDM/DM ratio found in a majority of the molluscs could be caused by increasingly thicker shells with organism age, and/or spawning-induced loss of biologically active tissue in adults. Consequently, future studies utilizing AFDM/DM (and presumably also AFDM/wet mass) ratios should carefully assess the potential influence of body size to ensure more reliable estimates of organism body mass.

  • 13.
    Eklöf, Johan S.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Alsterberg, Christian
    Havenhand, Jonathan N.
    Sundbäck, Kristina
    Wood, Hannah L.
    Gamfeldt, Lars
    Experimental climate change weakens the insurance effect of biodiversity2012In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 15, no 8, p. 864-872Article in journal (Refereed)
    Abstract [en]

    Ecosystems are simultaneously affected by biodiversity loss and climate change, but we know little about how these factors interact. We predicted that climate warming and CO 2-enrichment should strengthen trophic cascades by reducing the relative efficiency of predation-resistant herbivores, if herbivore consumption rate trades off with predation resistance. This weakens the insurance effect of herbivore diversity. We tested this prediction using experimental ocean warming and acidification in seagrass mesocosms. Meta-analyses of published experiments first indicated that consumption rate trades off with predation resistance. The experiment then showed that three common herbivores together controlled macroalgae and facilitated seagrass dominance, regardless of climate change. When the predation-vulnerable herbivore was excluded in normal conditions, the two resistant herbivores maintained top-down control. Under warming, however, increased algal growth outstripped control by herbivores and the system became algal-dominated. Consequently, climate change can reduce the relative efficiency of resistant herbivores and weaken the insurance effect of biodiversity.

  • 14.
    Eklöf, Johan S.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Havenhand, Jonathan N.
    Alsterberg, Christian
    Gamfeldt, Lars
    Community-level effects of rapid experimental warming and consumer loss outweigh effects of rapid ocean acidification2015In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 124, no 8, p. 1040-1049Article in journal (Refereed)
    Abstract [en]

    Climate change and consumer loss simultaneously affect marine ecosystems, but we have limited understanding of the relative importance of these factors and the interactions between them. Moreover, effects of environmental change are mediated by organism traits or life histories, which determine their sensitivity. Yet, trait-based analyses have rarely been used to understand the effects of climate change, especially in the marine environment. Here we used a five-week mesocosm experiment to assess the single and interactive effects of 1) rapid ocean warming, 2) rapid ocean acidification, and 3) simulated consumer loss, on the diversity and composition of macrofauna communities in eelgrass Zostera marina beds. Experimental warming (ambient versus + 3.2 degrees C) and loss of a key consumer (the omnivorous crustacean, Gammarus locusta) both increased macrofauna richness and abundance, and altered overall species trait distributions and life history composition. Warming and consumer-loss favored poorly defended epifaunal crustaceans (tube-building amphipods), and species that brood their off spring. We suggest these organisms were favored because warming and consumer-loss caused increased metabolism, food supply and, potentially, settling substrate, and lowered predation pressure from the omnivorous G. locusta. Importantly, we found no single, or interactive, effects of the rapid ocean acidification (ambient versus -0.35 pH units). We suggest this result reflects natural variability in the native habitat and, potentially, the short duration of the experiment: organisms in these communities routinely experience rapid diurnal pH fluctuations that exceed the mean ocean acidification predicted for the coming century (and used in our experiments). In summary, our study indicates that macrofauna in shallow vegetated ecosystems will be significantly more affected by rapid warming and consumer diversity loss than by rapid ocean acidification.

  • 15.
    Eklöf, Johan
    et al.
    Groningen University, The Netherlands.
    van der Heide, Tjisse
    Donadi, Serena
    van der Zee, Els
    O´Hara, Robert
    Eriksson, Britas Klemens
    Habitat-Mediated Facilitation and Counteracting Ecosystem Engineering Interactively Influence Ecosystem Responses to Disturbance2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, article id e42060Article in journal (Refereed)
    Abstract [en]

    Recovery of an ecosystem following disturbance can be severely hampered or even shift altogether when a point disturbance exceeds a certain spatial threshold. Such scale-dependent dynamics may be caused by preemptive competition, but may also result from diminished self-facilitation due to weakened ecosystem engineering. Moreover, disturbance can facilitate colonization by engineering species that alter abiotic conditions in ways that exacerbate stress on the original species. Consequently, establishment of such counteracting engineers might reduce the spatial threshold for the disturbance, by effectively slowing recovery and increasing the risk for ecosystem shifts to alternative states. We tested these predictions in an intertidal mudflat characterized by a two-state mosaic of hummocks (humps exposed during low tide) dominated by the sediment-stabilizing seagrass Zostera noltii) and hollows (low-tide waterlogged depressions dominated by the bioturbating lugworm Arenicola marina). In contrast to expectations, seagrass recolonized both natural and experimental clearings via lateral expansion and seemed unaffected by both clearing size and lugworm addition. Near the end of the growth season, however, an additional disturbance (most likely waterfowl grazing and/or strong hydrodynamics) selectively impacted recolonizing seagrass in the largest (1 m2) clearings (regardless of lugworm addition), and in those medium (0.25 m2) clearings where lugworms had been added nearly five months earlier. Further analyses showed that the risk for the disturbance increased with hollow size, with a threshold of 0.24 m2. Hollows of that size were caused by seagrass removal alone in the largest clearings, and by a weaker seagrass removal effect exacerbated by lugworm bioturbation in the medium clearings. Consequently, a sufficiently large disturbance increased the vulnerability of recolonizing seagrass to additional disturbance by weakening seagrass engineering effects (sediment stabilization). Meanwhile, the counteracting ecosystem engineering (lugworm bioturbation) reduced that threshold size. Therefore, scale-dependent interactions between habitat-mediated facilitation, competition and disturbance seem to maintain the spatial two-state mosaic in this ecosystem.

  • 16. Eriksson, Britas Klemens
    et al.
    Sieben, Katrin
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Ljunggren, Lars
    Olsson, Jens
    Casini, Michele
    Bergström, Ulf
    Effects of Altered Offshore Food Webs on Coastal Ecosystems Emphasize the Need for Cross-Ecosystem Management2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 7, p. 786-797Article, review/survey (Refereed)
    Abstract [en]

    By mainly targeting larger predatory fish, commercial fisheries have indirectly promoted rapid increases in densities of their prey; smaller predatory fish like sprat, stickleback and gobies. This process, known as mesopredator release, has effectively transformed many marine offshore basins into mesopredator-dominated ecosystems. In this article, we discuss recent indications of trophic cascades on the Atlantic and Baltic coasts of Sweden, where increased abundances of mesopredatory fish are linked to increased nearshore production and biomass of ephemeral algae. Based on synthesis of monitoring data, we suggest that offshore exploitation of larger predatory fish has contributed to the increase in mesopredator fish also along the coasts, with indirect negative effects on important benthic habitats and coastal water quality. The results emphasize the need to rebuild offshore and coastal populations of larger predatory fish to levels where they regain their control over lower trophic levels and important links between offshore and coastal systems are restored.

  • 17.
    Eriksson, Hampus
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Jiddawi, Narriman
    Institute of Marine Science, University of Dar es Salaam, Mizingani Rd., PO Box 668, Zanzibar .
    Resource degradation of the sea cucumber fishery in Zanzibar, Tanzania: a need for management reform2010In: Aquatic Living Resources, ISSN 0990-7440, E-ISSN 1765-2952, Vol. 23, p. 387-398Article in journal (Refereed)
    Abstract [en]

    This study assessed the Zanzibar sea cucumber fishery using a multidisciplinary approach. Data was collected by (i) interviewing various groups of actors in the fishery and reviewing management documentation and legislation, (ii) by monitoring catches and (iii) through a visual census of coastal sea cucumber populations in areas open and closed to fishing. The fishery showed clear signs of being unsustainable with high fishing effort, and weak formal and informal management institutions. The fishery operation was characterised by an intricate cross-scale structure with both fishers and sea cucumber products being transported across national borders. The visual census of commercial sea cucumber stocks at three sites open to fishing around Zanzibar showed low densities across the range of sea cucumber value groups including low value species. Furthermore, the diversity of commercial sea cucumber species was lower in fished reefs than on a protected reef. The poor status of the sea cucumber populations was confirmed by the perception of an overfished resource by the interviewed actors active in the fishery. This was also depicted by the paucity of high value species, and high representation of low value and newly commercialised species in fishers catch. We conclude that the current state of Zanzibar’s sea cucumber populations is compromising the fisheries self-replenishment and existence and that the fishery is in urgent need of a complete management reform. 

  • 18.
    Gullström, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Lyimo, Thomas J.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Björk, Mats
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Semesi, I. Sware
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Seagrass Meadows in Chwaka Bay: Socio-ecological and Management Aspects2012In: People, Nature and Research in Chwaka Bay, Zanzibar, Tanzania / [ed] Maricela de la Torre-Castro, Thomas J. Lyimo, Zanzibar: Western Indian Ocean Marine Science Associoation (WIOMSA) , 2012, p. 89-110Chapter in book (Refereed)
    Abstract [en]

    The shallow-water seascape of Chwaka Bay consists of diverse habitats including coral reefs, sand/mud flats, algal belts and mangrove forests, but the embayment is primarily characterized by its widespread and highly productive seagrass beds. The Bay is a unique seagrass diversity “hotspot”, with eleven species observed, from small, fast-growing and thin-leaved “pioneer” species like Halophila ovalis and H. stipulacea to large, slower-growing “climax species” with thick and long leaves like Thalassodendron ciliatum and Enhalus acoroides. Consequently, it is not surprising that the small-scale subsistence fishery of Chwaka Bay can be seen as a seagrass fishery, with catches consisting primarily of species intimately associated with the seagrass meadows (de la Torre-Castro and Rönnbäck 2004; de la Torre-Castro 2006).Seagrasses are a polyphyletic group of marine vascular, rhizomal plants (den Hartog 1970, 12-13), which form stands of varying sizes usually called “beds” or “meadows” in intertidal and subtidal coastal waters across the globe. Seagrass meadows typically occur on nearshore soft bottoms (although some species are found on rocky bottoms) in single- or mixed-species assemblages, with the typical wide range from tropical to boreal margins of coastal waters (Green and Short 2003, 21-22). They form one of the most productive aquatic ecosystems on Earth (Duarte and Chiscano 1999) and in most areas occur intermixed with other large primary producers like macroalgae. Seagrass ecosystems support multiple ecological functions, including nursery grounds, food and refuge for many benthic,

  • 19.
    Hansen, Joakim P.
    et al.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Sundblad, Göran
    Bergström, Ulf
    N. Austin, Åsa
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Donadi, Serena
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Swedish University of Agricultural Sciences (SLU), Sweden.
    Eriksson, Britas Klemens
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Recreational boating degrades vegetation important for fish recruitment2019In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 48, no 6, p. 539-551Article in journal (Refereed)
    Abstract [en]

    Recreational boating increases globally and associated moorings are often placed in vegetated habitats important for fish recruitment. Meanwhile, assessments of the effects of boating on vegetation, and potential effects on associated fish assemblages are rare. Here, we analysed (i) the effect of small-boat marinas on vegetation structure, and (ii) juvenile fish abundance in relation to vegetation cover in shallow wave-sheltered coastal inlets. We found marinas to have lower vegetation cover and height, and a different species composition, compared to control inlets. This effect became stronger with increasing berth density. Moreover, there was a clear positive relationship between vegetation cover and fish abundance. We conclude that recreational boating and related moorings are associated with reduced cover of aquatic vegetation constituting important habitats for juvenile fish. We therefore recommend that coastal constructions and associated boating should be allocated to more disturbance tolerant environments (e.g. naturally wave-exposed shores), thereby minimizing negative environmental impacts.

  • 20. Jakubavičiūtė, Eglė
    et al.
    Bergström, Ulf
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Haenel, Quiterie
    Bourlat, Sarah J.
    DNA metabarcoding reveals diverse diet of the three-spined stickleback in a coastal ecosystem2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 10, article id e0186929Article in journal (Refereed)
    Abstract [en]

    The three-spined stickleback (Gasterosteus aculeatus L., hereafter 'stickleback') is a common mesopredatory fish in marine, coastal and freshwater areas. In large parts of the Baltic Sea, stickleback densities have increased > 10-fold during the last decades, and it is now one of the dominating fish species both in terms of biomass and effects on lower trophic levels. Still, relatively little is known about its diet-knowledge which is essential to understand the increasing role sticklebacks play in the ecosystem. Fish diet analyses typically rely on visual identification of stomach contents, a labour-intensive method that is made difficult by prey digestion and requires expert taxonomic knowledge. However, advances in DNA-based metabarcoding methods promise a simultaneous identification of most prey items, even from semi-digested tissue. Here, we studied the diet of stickleback from the western Baltic Sea coast using both DNA metabarcoding and visual analysis of stomach contents. Using the cytochrome oxidase (CO1) marker we identified 120 prey taxa in the diet, belonging to 15 phyla, 83 genera and 84 species. Compared to previous studies, this is an unusually high prey diversity. Chironomids, cladocerans and harpacticoids were dominating prey items. Large sticklebacks were found to feed more on benthic prey, such as amphipods, gastropods and isopods. DNA metabarcoding gave much higher taxonomic resolution (median rank genus) than visual analysis (median rank order), and many taxa identified using barcoding could not have been identified visually. However, a few taxa identified by visual inspection were not revealed by barcoding. In summary, our results suggest that the three-spined stickleback feeds on a wide variety of both pelagic and benthic organisms, indicating that the strong increase in stickleback populations may affect many parts of the Baltic Sea coastal ecosystem.

  • 21. Kollars, Nicole M.
    et al.
    Henry, Amy K.
    Whalen, Matthew A.
    Boyer, Katharyn E.
    Cusson, Mathieu
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hereu, Clara M.
    Jorgensen, Pablo
    Kiriakopolos, Stephanie L.
    Reynolds, Pamela L.
    Tomas, Fiona
    Turner, Mo S.
    Ruesink, Jennifer L.
    Meta-Analysis of Reciprocal Linkages between Temperate Seagrasses and Waterfowl with Implications for Conservation2017In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 8, article id 2119Article, review/survey (Refereed)
    Abstract [en]

    Multi-trophic conservation and management strategies may be necessary if reciprocal linkages between primary producers and their consumers are strong. While herbivory on aquatic plants is well-studied, direct top-down control of seagrass populations has received comparatively little attention, particularly in temperate regions. Herein, we used qualitative and meta-analytic approaches to assess the scope and consequences of avian (primarily waterfowl) herbivory on temperate seagrasses of the genus Zostera. Meta-analyses revealed widespread evidence of spatio-temporal correlations between Zostera and waterfowl abundances as well as strong top-down effects of grazing on Zostera. We also documented the identity and diversity of avian species reported to consume Zostera and qualitatively assessed their potential to exert top-down control. Our results demonstrate that Zostera and their avian herbivores are ecologically linked and we suggest that bird herbivory may influence the spatial structure, composition, and functioning of the seagrass ecosystem. Therefore, the consequences of avian herbivory should be considered in the management of seagrass populations. Of particular concern are instances of seagrass overgrazing by waterfowl which result in long-term reductions in seagrass biomass or coverage, with subsequent impacts on local populations of waterfowl and other seagrass-affiliated species. While our results showed that bird density and type may affect the magnitude of the top-down effects of avian herbivory, empirical research on the strength, context-dependency, and indirect effects of waterfowl-Zostera interactions remains limited. For example, increased efforts that explicitly measure the effects of different functional groups of birds on seagrass abundance and/or document how climate change-driven shifts in waterfowl migratory patterns impact seagrass phenology and population structure will advance research programs for both ecologists and managers concerned with the joint conservation of both seagrasses and their avian herbivores.

  • 22. Maxwell, Paul S.
    et al.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    van Katwijk, Marieke M.
    O'Brien, Katherine R.
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Boström, Christoffer
    Bouma, Tjeerd J.
    Krause-Jensen, Dorte
    Unsworth, Richard K. F.
    van Tussenbroek, Brigitta I.
    van der Heide, Tjisse
    The fundamental role of ecological feedback mechanisms for the adaptive management of seagrass ecosystems - a review2017In: Biological Reviews, ISSN 1464-7931, E-ISSN 1469-185X, Vol. 92, no 3, p. 1521-1538Article, review/survey (Refereed)
    Abstract [en]

    Seagrass meadows are vital ecosystems in coastal zones worldwide, but are also under global threat. One of the major hurdles restricting the success of seagrass conservation and restoration is our limited understanding of ecological feedback mechanisms. In these ecosystems, multiple, self-reinforcing feedbacks can undermine conservation efforts by masking environmental impacts until the decline is precipitous, or alternatively they can inhibit seagrass recovery in spite of restoration efforts. However, no clear framework yet exists for identifying or dealing with feedbacks to improve the management of seagrass ecosystems. Here we review the causes and consequences of multiple feedbacks between seagrass and biotic and/or abiotic processes. We demonstrate how feedbacks have the potential to impose or reinforce regimes of either seagrass dominance or unvegetated substrate, and how the strength and importance of these feedbacks vary across environmental gradients. Although a myriad of feedbacks have now been identified, the co-occurrence and likely interaction among feedbacks has largely been overlooked to date due to difficulties in analysis and detection. Here we take a fundamental step forward by modelling the interactions among two distinct above-and belowground feedbacks to demonstrate that interacting feedbacks are likely to be important for ecosystem resilience. On this basis, we propose a five-step adaptive management plan to address feedback dynamics for effective conservation and restoration strategies. The management plan provides guidance to aid in the identification and prioritisation of likely feedbacks in different seagrass ecosystems.

  • 23.
    Nilsson Austin, Åsa
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hansen, Joakim P.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Donadi, Serena
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Relationships between aquatic vegetation and water turbidity: A field survey across seasons and spatial scales2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 8, article id e0181419Article in journal (Refereed)
    Abstract [en]

    Field surveys often show that high water turbidity limits cover of aquatic vegetation, while many small-scale experiments show that vegetation can reduce turbidity by decreasing water flow, stabilizing sediments, and competing with phytoplankton for nutrients. Here we bridged these two views by exploring the direction and strength of causal relationships between aquatic vegetation and turbidity across seasons (spring and late summer) and spatial scales (local and regional), using causal modeling based on data from a field survey along the central Swedish Baltic Sea coast. The two best-fitting regional-scale models both suggested that in spring, high cover of vegetation reduces water turbidity. In summer, the relationships differed between the two models; in the first model high vegetation cover reduced turbidity; while in the second model reduction of summer turbidity by high vegetation cover in spring had a positive effect on summer vegetation which suggests a positive feedback of vegetation on itself. Nitrogen load had a positive effect on turbidity in both seasons, which was comparable in strength to the effect of vegetation on turbidity. To assess whether the effect of vegetation was primarily caused by sediment stabilization or a reduction of phytoplankton, we also tested models where turbidity was replaced by phytoplankton fluorescence or sediment-driven turbidity. The best-fitting regional-scale models suggested that high sediment-driven turbidity in spring reduces vegetation cover in summer, which in turn has a negative effect on sediment-driven turbidity in summer, indicating a potential positive feedback of sediment-driven turbidity on itself. Using data at the local scale, few relationships were significant, likely due to the influence of unmeasured variables and/or spatial heterogeneity. In summary, causal modeling based on data from a large-scale field survey suggested that aquatic vegetation can reduce turbidity at regional scales, and that high vegetation cover vs. high sediment-driven turbidity may represent two self-enhancing, alternative states of shallow bay ecosystems.

  • 24.
    Norling, Pia
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Kautsky, Nils
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Rönnbäck, Patrik
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Troell, Max
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    The role of the blue mussel (Mytilus sp.) for ecosystem functioning, generation of ecosystem services and ecological resilience in the Baltic SeaManuscript (Other academic)
  • 25.
    Nyström, Magnus
    et al.
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Norström, Albert V.
    Blenckner, Thorsten
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Folke, Carl
    Österblom, Henrik
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Steneck, Robert S.
    Thyresson, Matilda
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Troell, Max
    Confronting Feedbacks of Degraded Marine Ecosystems2012In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 15, no 5, p. 695-710Article in journal (Refereed)
    Abstract [en]

    In many coastal areas, marine ecosystems have shifted into contrasting states having reduced ecosystem services (hereafter called degraded). Such degraded ecosystems may be slow to revert to their original state due to new ecological feedbacks that reinforce the degraded state. A better understanding of the way human actions influence the strength and direction of feedbacks, how different feedbacks could interact, and at what scales they operate, may be necessary in some cases for successful management of marine ecosystems. Here we synthesize interactions of critical feedbacks of the degraded states from six globally distinct biomes: coral reefs, kelp forests, seagrass beds, shallow soft sediments, oyster reefs, and coastal pelagic food webs. We explore to what extent current management captures these feedbacks and propose strategies for how and when (that is, windows of opportunity) to influence feedbacks in ways to break the resilience of the degraded ecosystem states. We conclude by proposing some challenges for future research that could improve our understanding of these issues and emphasize that management of degraded marine states will require a broad social-ecological approach to succeed.

  • 26. Reynolds, Pamela L.
    et al.
    Stachowicz, John J.
    Hovel, Kevin
    Boström, Christoffer
    Boyer, Katharyn
    Cusson, Mathieu
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Engel, Friederike G.
    Engelen, Aschwin H.
    Eriksson, Britas Klemens
    Fodrie, F. Joel
    Griffin, John N.
    Hereu, Clara M.
    Hori, Masakazu
    Hanley, Torrance C.
    Ivanov, Mikhail
    Jorgensen, Pablo
    Kruschel, Claudia
    Lee, Kun-Seop
    McGlathery, Karen
    Moksnes, Per-Olav
    Nakaoka, Masahiro
    O'Connor, Mary I.
    O'Connor, Nessa E.
    Orth, Robert J.
    Rossi, Francesca
    Ruesink, Jennifer
    Sotka, Erik E.
    Thormar, Jonas
    Tomas, Fiona
    Unsworth, Richard K. F.
    Whalen, Matthew A.
    Duffy, J. Emmett
    Latitude, temperature, and habitat complexity predict predation pressure in eelgrass beds across the Northern Hemisphere2018In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 99, no 1, p. 29-35Article in journal (Refereed)
    Abstract [en]

    Latitudinal gradients in species interactions are widely cited as potential causes or consequences of global patterns of biodiversity. However, mechanistic studies documenting changes in interactions across broad geographic ranges are limited. We surveyed predation intensity on common prey (live amphipods and gastropods) in communities of eelgrass (Zostera marina) at 48 sites across its Northern Hemisphere range, encompassing over 37 degrees of latitude and four continental coastlines. Predation on amphipods declined with latitude on all coasts but declined more strongly along western ocean margins where temperature gradients are steeper. Whereas insitu water temperature at the time of the experiments was uncorrelated with predation, mean annual temperature strongly positively predicted predation, suggesting a more complex mechanism than simply increased metabolic activity at the time of predation. This large-scale biogeographic pattern was modified by local habitat characteristics; predation declined with higher shoot density both among and within sites. Predation rates on gastropods, by contrast, were uniformly low and varied little among sites. The high replication and geographic extent of our study not only provides additional evidence to support biogeographic variation in predation intensity, but also insight into the mechanisms that relate temperature and biogeographic gradients in species interactions.

  • 27. Ruesink, Jennifer L.
    et al.
    Stachowicz, John J.
    Reynolds, Pamela L.
    Boström, Christoffer
    Cusson, Mathieu
    Douglass, James
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Engelen, Aschwin H.
    Hori, Masakazu
    Hovel, Kevin
    Iken, Katrin
    Moksnes, Per-Olav
    Nakaoka, Masahiro
    O'Connor, Mary I.
    Olsen, Jeanine L.
    Sotka, Erik E.
    Whalen, Matthew A.
    Duffy, J. Emmett
    Form-function relationships in a marine foundation species depend on scale: a shoot to global perspective from a distributed ecological experiment2018In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 127, no 3, p. 364-374Article in journal (Refereed)
    Abstract [en]

    Form-function relationships in plants underlie their ecosystem roles in supporting higher trophic levels through primary production, detrital pathways, and habitat provision. For widespread, phenotypically-variable plants, productivity may differ not only across abiotic conditions, but also from distinct morphological or demographic traits. A single foundation species, eelgrass Zostera marina, typically dominates north temperate seagrass meadows, which we studied across 14 sites spanning 32-61 degrees N latitude and two ocean basins. Body size varied by nearly two orders of magnitude through this range, and was largest at mid-latitudes and in the Pacific Ocean. At the global scale, neither latitude, site-level environmental conditions, nor body size helped predict productivity (relative growth rate 1-2% day(-1) at most sites), suggesting a remarkable capacity of Z. marina to achieve similar productivity in summer. Furthermore, among a suite of stressors applied within sites, only ambient leaf damage reduced productivity; grazer reduction and nutrient addition had no effect on eelgrass size or growth. Scale-dependence was evident in different allometric relationships within and across sites for productivity and for modules (leaf count) relative to size. Zostera marina provides a range of ecosystem functions related to both body size (habitat provision, water flow) and growth rates (food, carbon dynamics). Our observed decoupling of body size and maximum production suggests that geographic variation in these ecosystem functions may be independent, with a future need to resolve how local adaptation or plasticity of body size might actually enable more consistent peak productivity across disparate environmental conditions.

  • 28. Röhr, Maria Emilia
    et al.
    Holmer, Marianne
    Baum, Julia K.
    Björk, Mats
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Chin, Diana
    Chalifour, Lia
    Cimon, Stephanie
    Cusson, Mathieu
    Dahl, Martin
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Deyanova, Diana
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Bulgarian Academy of Sciences, Bulgaria.
    Duffy, J. Emmet
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Geyer, Julie K.
    Griffin, John N.
    Gullström, Martin
    Hereu, Clara M.
    Hori, Masakazu
    Hovel, Kevin A.
    Hughes, A. Randall
    Jorgensen, Pablo
    Kiriakopolos, Stephanie
    Moksnes, Per-Olav
    Nakaoka, Masahiro
    O'Connor, Mary I.
    Peterson, Bradley
    Reiss, Katrin
    Reynolds, Pamela L.
    Rossi, Francesca
    Ruesink, Jennifer
    Santos, Rui
    Stachowicz, John J.
    Tomas, Fiona
    Lee, Kun-Seop
    Unsworth, Richard K. F.
    Boström, Christoffer
    Blue Carbon Storage Capacity of Temperate Eelgrass (Zostera marina) Meadows2018In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 32, no 10, p. 1457-1475Article in journal (Refereed)
    Abstract [en]

    Despite the importance of coastal ecosystems for the global carbon budgets, knowledge of their carbon storage capacity and the factors driving variability in storage capacity is still limited. Here we provide an estimate on the magnitude and variability of carbon stocks within a widely distributed marine foundation species throughout its distribution area in temperate Northern Hemisphere. We sampled 54 eelgrass (Zostera marina) meadows, spread across eight ocean margins and 36 degrees of latitude, to determine abiotic and biotic factors influencing organic carbon (C-org) stocks in Zostera marina sediments. The C-org stocks (integrated over 25-cm depth) showed a large variability and ranged from 318 to 26,523gC/m(2) with an average of 2,721gC/m(2). The projected C-org stocks obtained by extrapolating over the top 1m of sediment ranged between 23.1 and 351.7MgC/ha, which is in line with estimates for other seagrasses and other blue carbon ecosystems. Most of the variation in C-org stocks was explained by five environmental variables (sediment mud content, dry density and degree of sorting, and salinity and water depth), while plant attributes such as biomass and shoot density were less important to C-org stocks. Carbon isotopic signatures indicated that at most sites <50% of the sediment carbon is derived from seagrass, which is lower than reported previously for seagrass meadows. The high spatial carbon storage variability urges caution in extrapolating carbon storage capacity between geographical areas as well as within and between seagrass species.

  • 29.
    Svensson, Filip
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Karlsson, Erik
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gårdmark, Anna
    Olsson, Jens
    Adill, Anders
    Zie, Jenny
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Snoeijs, Pauline
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    In situ warming increases top-down control in a coastal food webManuscript (preprint) (Other academic)
  • 30.
    Svensson, Filip
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Swedish University of Agricultural Sciences, Sweden.
    Karlsson, Erik
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Institute of Coastal Research, Sweden.
    Gårdmark, Anna
    Olsson, Jens
    Adill, Anders
    Zie, Jenny
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Snoeijs-Leijonmalm, Pauline
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    In situ warming strengthens trophic cascades in a coastal food web2017In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 126, no 8, p. 1150-1161Article in journal (Refereed)
    Abstract [en]

    Global warming may affect most organisms and their interactions. Theory and simple mesocosm experiments suggest that consumer top-down control over primary producer biomass should strengthen with warming, since consumer respiration increases faster with warming than plant photosynthesis. However, these predictions have so far not been tested on natural communities that have experienced warming over many generations. Natural systems display a higher diversity, heterogeneity and complexity than mesocosms, which could alter predicted effects of warming. Here we used an artificially heated part of the northern Baltic Sea (the Forsmark Biotest basin) to test how warming influences trophic interactions in a shallow coastal food web with four trophic levels: omnivorous fish, invertivorous fish, herbivorous invertebrates, and filamentous macroalgae. Monitoring of fish assemblages over six years showed that small invertivorous fish (gobiids, sticklebacks and minnows) were much less abundant in the heated basin than in unheated references areas. Stomach content analyses of the dominating omnivorous fish - Eurasian perch Perca fluviatilis - revealed a strikingly different diet within and outside the Biotest basin; gammarid crustaceans were the dominating prey at heated sites, whereas invertivorous fish (e.g. gobiids) dominated at unheated sites. A 45-day cage experiment showed that fish exclusion did not affect the biomass of algal herbivores (gastropods and gammarids), but reduced algal biomass in heated sites (but not unheated). This suggests that warming induced a trophic cascade from fish to algae, and that this effect was mediated by predator-induced changes in herbivore behavior, rather than number. Overall, our study suggests that warming has effectively compressed the food chain from four to three trophic levels (algae, gammarids and perch), which have benefitted the primary producers by reducing grazing pressure. Consequently, warming appears to have restructured this coastal food web through a combination of direct (physiological) and indirect (species interactions) effects.

  • 31. Unsworth, Richard K. F.
    et al.
    McKenzie, Len J.
    Collier, Catherine J.
    Cullen-Unsworth, Leanne C.
    Duarte, Carlos M.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Jarvis, Jessie C.
    Jones, Benjamin L.
    Nordlund, Linda M.
    Global challenges for seagrass conservation2019In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 48, no 8, p. 801-815Article in journal (Refereed)
    Abstract [en]

    Seagrasses, flowering marine plants that form underwater meadows, play a significant global role in supporting food security, mitigating climate change and supporting biodiversity. Although progress is being made to conserve seagrass meadows in select areas, most meadows remain under significant pressure resulting in a decline in meadow condition and loss of function. Effective management strategies need to be implemented to reverse seagrass loss and enhance their fundamental role in coastal ocean habitats. Here we propose that seagrass meadows globally face a series of significant common challenges that must be addressed from a multifaceted and interdisciplinary perspective in order to achieve global conservation of seagrass meadows. The six main global challenges to seagrass conservation are (1) a lack of awareness of what seagrasses are and a limited societal recognition of the importance of seagrasses in coastal systems; (2) the status of many seagrass meadows are unknown, and up-to-date information on status and condition is essential; (3) understanding threatening activities at local scales is required to target management actions accordingly; (4) expanding our understanding of interactions between the socio-economic and ecological elements of seagrass systems is essential to balance the needs of people and the planet; (5) seagrass research should be expanded to generate scientific inquiries that support conservation actions; (6) increased understanding of the linkages between seagrass and climate change is required to adapt conservation accordingly. We also explicitly outline a series of proposed policy actions that will enable the scientific and conservation community to rise to these challenges. We urge the seagrass conservation community to engage stakeholders from local resource users to international policy-makers to address the challenges outlined here, in order to secure the future of the world’s seagrass ecosystems and maintain the vital services which they supply.

  • 32. van der Heide, Tjisse
    et al.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Systems Ecology. University of Groningen, The Netherlands; University of Gothenburg, Sweden.
    van Nes, Egbert H.
    van der Zee, Els M.
    Donadi, Serena
    Weerman, Ellen J.
    Olff, Han
    Eriksson, Britas Klemens
    Ecosystem Engineering by Seagrasses Interacts with Grazing to Shape an Intertidal Landscape2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 8, article id e42060Article in journal (Refereed)
    Abstract [en]

    Self-facilitation through ecosystem engineering (i.e., organism modification of the abiotic environment) and consumer-resource interactions are both major determinants of spatial patchiness in ecosystems. However, interactive effects of these two mechanisms on spatial complexity have not been extensively studied. We investigated the mechanisms underlying a spatial mosaic of low-tide exposed hummocks and waterlogged hollows on an intertidal mudflat in the Wadden Sea dominated by the seagrass Zostera noltii. A combination of field measurements, an experiment and a spatially explicit model indicated that the mosaic resulted from localized sediment accretion by seagrass followed by selective waterfowl grazing. Hollows were bare in winter, but were rapidly colonized by seagrass during the growth season. Colonized hollows were heavily grazed by brent geese and widgeon in autumn, converting these patches to a bare state again and disrupting sediment accretion by seagrass. In contrast, hummocks were covered by seagrass throughout the year and were rarely grazed, most likely because the waterfowl were not able to employ their preferred but water requiring feeding strategy ('dabbling') here. Our study exemplifies that interactions between ecosystem engineering by a foundation species (seagrass) and consumption (waterfowl grazing) can increase spatial complexity at the landscape level.

  • 33.
    Wallner-Hahn, Sieglind
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gullström, Martin
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Muthiga, Nyawira A.
    Uku, Jacqueline
    Cascade effects and sea-urchin overgrazing: An analysis of drivers behind the exploitation of sea-urchin predators for management improvement2015In: Ocean and Coastal Management, ISSN 0964-5691, E-ISSN 1873-524X, Vol. 107, p. 16-27Article in journal (Refereed)
    Abstract [en]

    Marine ecosystems generate a wide variety of goods and services, but are globally deteriorating due to multiple drivers associated with anthropogenic activities. Intense fishing pressure can lead to changes in structure and function of marine food webs. Particularly overfishing of predatory species at high trophic levels can cause cascading effects leading to ecosystem degradation, affecting both marine organisms and people dependent on them. In the Western Indian Ocean region, intensive fishing takes place and degradation of coral reefs and seagrass beds has been documented. One reason behind this degradation is overgrazing by increasing numbers of sea urchins. An essential step towards better management is to thoroughly understand the drivers leading to such changes in ecosystems. Against this background, the general aim of this study was to gain understanding about whether sea urchin predators in the WIO region are fished, and to identify the drivers behind the fishing of these species. The study had four objectives: (i) to document if and how predatory fish eating sea urchins are caught in smallscale fisheries, (ii) to assess if, and if so why, sea urchin predators are targeted species, (iii) to assess if and to what degree local ecological knowledge (LEK) on ecological complexity involving sea urchins and their predators (e.g. trophic cascades) is present among local fishers, and (iv) to identify fishers' suggestions for management that can reduce problems linked to sea urchin overgrazing. The results show that all investigated species of sea urchin predators are fished by local small-scale fishers. Most sea urchin predators are not actively targeted, are not popular local food fish, and have minor use and economic importance for fishers. This stands in sharp contrast to their ecological keystone role by controlling sea urchin populations. The fishers' awareness and LEK were weak and partly lacking. Management suggestions targeted mostly the symptoms of food web changes rather than the drivers behind them.

    Based on the results we suggest that management of degraded ecosystems, as a result of food web changes, should encompass a wide variety of strategies and scales. Specific suggestions for sea urchin predator management are education of local stakeholders on destructive gear effects and food web complexity, further investigations of catch- and release fishing as well as the use of selective gears.

  • 34.
    Wallner-Hahn, Sieglind
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Molander, Fia
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gallardo, Gloria
    Villasante, Sebastian
    Eklöf, Johan S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Jiddawi, Narriman S.
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Destructive gear use in a tropical fishery: Institutional factors influencing the willingness-and capacity to change2016In: Marine Policy, ISSN 0308-597X, E-ISSN 1872-9460, Vol. 72, p. 199-210Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to empirically assess institutional aspects shaping fishers' behavior leading to unsustainable resource use, by using the example of destructive drag-net fishing in Zanzibar, Tanzania. A broad institutional approach was used to specifically assess institutional factors influencing the fishers' reasons for the current use of destructive drag-nets as well as their willingness- and economic capacity to change to less destructive gears. Different regulative, normative, cultural-cognitive and economic factors (tradition, group-belonging, social acceptance, common practice, identity of drag-net users and weak economic capacity) were identified as critical elements influencing the current use of destructive gears, as well as obstructing changes to other gears. Hence, the importance of addressing all of these factors, matching to the different contexts, rather than focusing on fast-moving regulative measures, is emphasized to increase chances of management success. More promising approaches would be resource allocations to more sustainable fishing gears, well-managed gear exchange programs, as well as alterations of slow-moving normative and cultural factors, e.g. awareness raising on the advantages of more sustainable fishing gears, their traditional and cultural values, information on the actual income they generate, as well as education and an exchange of traditional knowledge on how to use them.

  • 35. Östman, Örjan
    et al.
    Eklöf, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eriksson, Britas Klemens
    Olsson, Jens
    Moksnes, Per-Olav
    Bergström, Ulf
    Top-down control as important as nutrient enrichment for eutrophication effects in North Atlantic coastal ecosystems2016In: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 53, no 4, p. 1138-1147Article, review/survey (Refereed)
    Abstract [en]

    Seagrass and seaweed habitats constitute hotspots for diversity and ecosystem services in coastal ecosystems. These habitats are subject to anthropogenic pressures, of which eutrophication is one major stressor. Eutrophication favours fast-growing ephemeral algae over perennial macroalgae and seagrasses, causing habitat degradation. However, changes in top-down control, caused by, for example, overfishing, may also have negative impacts on such habitats by decreasing grazer control of ephemeral algae. Meanwhile, systematic analyses estimating top-down effects of predator manipulations across a wide range of studies are missing, limiting the potential use of top-down control measures in coastal management. Here, we review the literature on experiments that test top-down and bottom-up controls in seagrass Zostera marina and seaweed Fucus spp. food webs in the North Atlantic. Using meta-analysis and meta-regression, we compare effect sizes of consumer and nutrient manipulations on primary producers, grazers and mesopredators. Presence of mesopredators on average doubled the biomass of ephemeral algae through trophic cascades, mainly mediated via negative effects on amphipods and isopods. Of the grazers, gastropods had twice as strong a negative effect on ephemeral algae as amphipods/isopods, but responded weakly to both predators and fertilization. In accordance with theory, top-down effects became stronger with eutrophication. Across studies, top-down effects on ephemeral algae at all trophic levels are on par with eutrophication effects. However, the few studies manipulating piscivorous fish make estimates of their top-down effects uncertain.Synthesis and applications. Consistently strong top-down effects in coastal ecosystems call for an integrated ecosystem perspective. Management should consider measures to improve stocks of predatory fish and reduce mesopredators for restoration and conservation of essential seagrass and seaweed habitats, thereby increasing the long-term viability of ecosystem services from coastal habitats.

1 - 35 of 35
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf