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The importance of biodiversity for ecosystem processes in sediments: experimental examples from the Baltic Sea
Stockholm University, Faculty of Science, Department of Systems Ecology. (Marin Ekotoxikologi)
2010 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Betydelsen av biologisk mångfald för ekosystemprocesser i sediment : experimentella exempel från Östersjön (Swedish)
Abstract [en]

Aquatic sediments are, by surface, the largest habitat on Earth. A wide diversity of organisms inhabit these sediments and by their actions they have a large influence on and also mediate many ecosystem processes. Several of these processes, such as decomposition and remineralisation of organic matter are important on a global scale and are essential to sustain life on Earth. The main aim of this thesis was to use an experimental ecosystem ecology approach in order to study some of these ecosystem processes in marine sediments and how they are linked to biodiversity.

Paper I and II found that an increased species richness of sediment deposit feeders increases the processing of organic matter from phytoplankton settled on the sea-floor, and that species-rich communities have a more efficient resource utilization of deposited organic matter. The results in paper IV and V also suggest that there is a link between microbial diversity in sediments and the degradation of organic contaminants. Paper V also shows that antibiotic pollution is a potential threat to natural microbial diversity and microbially mediated ecosystem services. The introduction of invasive species to ecosystems is another major threat to biodiversity and was studied in Paper II and III, by investigating the ecology of Marenzelleria arctia, a polychaete worm recently introduced in the Baltic Sea. Paper II suggests that M. arctia mainly utilize food resources not used by native deposit feeders, thus potentially increasing the benthic production in the Baltic Sea by increasing resource use efficiency. Paper III, however, show that M. arctia is protected from predation by the native benthic invertebrate predators, due to its ability to burrow deep in the sediment, suggesting that predation on M. arctia by higher trophic levels is restricted, thereby limiting trophic transfer.

In conclusion, this thesis gives some examples of the importance of marine biodiversity for the generation of a few key ecosystem processes, such as organic matter processing and the degradation of harmful contaminants.

Place, publisher, year, edition, pages
Stockholm: Department of Systems Ecology, Stockholm University , 2010. , 37 p.
Keyword [en]
Biodiversity, Soft-bottom sediment, Ecosystem processes, Ecosystem function, Benthic-pelagic coupling, Baltic Sea, Trophic interactions, Pollutant biodegradation, Organic matter mineralization, Deposit feeder, Detritivore, Invasive species
National Category
Ecology
Research subject
Marine Ecotoxicology
Identifiers
URN: urn:nbn:se:su:diva-38893ISBN: 978-91-7447-087-1 (print)OAI: oai:DiVA.org:su-38893DiVA: diva2:317367
Public defence
2010-06-04, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: In press. Available from: 2010-05-11 Created: 2010-05-03 Last updated: 2010-05-05Bibliographically approved
List of papers
1. Higher diversity of deposit-feeding macrofauna enhances phytodetritus processing
Open this publication in new window or tab >>Higher diversity of deposit-feeding macrofauna enhances phytodetritus processing
2010 (English)In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 91, no 5, 1414-1423 p.Article in journal (Refereed) Published
Abstract [en]

The link between biodiversity and ecosystem functioning is an important question that remains unresolved, particularly in marine systems, in which cycling of organic matter by benthic organisms is of global significance. Direct observations of specific resource use by each species in single- and multispecies communities, as quantified by stable isotopes, facilitates a mechanistic understanding of the importance of each species for ecosystem functioning. We tested the effects of altered biodiversity (species richness) of deposit-feeding macrofauna on incorporation and burial of phytodetritus in combinations of three species representing natural communities found in the sediments of the species-poor Baltic Sea. The three species, two amphipods and a bivalve, had different rates of incorporation and burial and different needs for carbon (C) and nitrogen (N). The amphipods exhibited clear resource partitioning in sympatry, as a result of vertical separation in the sediment and consequent differential use of food. Communities of several species incorporated more C and N than expected from the respective single-species treatments, due to higher incorporation by surface feeders in multispecies treatments. Community incorporation of N in the most diverse treatment even exceeded N incorporation by a single-species treatment of the best-performing species, showing transgressive over-yielding. This over-yielding was primarily due to positive complementarity in all treatments. Diverse soft bottoms are also likely to be more productive in the long run, as species-specific traits (subsurface feeding) preserve fresh phytodetritus by burying it to depths in the sediment at which the mineralization rate is low. The more diverse sediment communities showed more efficient trophic transfer of phytodetritus, a finding of general significance for understanding biological processes driving the transformation of nutrients and energy in benthic ecosystems.

Keyword
Baltic Sea, benthic–pelagic coupling, biodiversity, complementarity, ecosystem function, functional diversity, Macoma balthica, Monoporeia affinis, Pontoporeia femorata, resource partitioning, species richness, transgressive over-yielding
National Category
Ecology
Identifiers
urn:nbn:se:su:diva-38888 (URN)10.1890/09-0660.1 (DOI)000277867600017 ()
Available from: 2010-05-03 Created: 2010-05-03 Last updated: 2017-12-12Bibliographically approved
2. Effects of a polychaete invader on soft-bottom ecosystem functions
Open this publication in new window or tab >>Effects of a polychaete invader on soft-bottom ecosystem functions
(English)Manuscript (preprint) (Other academic)
Keyword
biodiversity, ecosystem functioning, invasive species, benthic-pelagic coupling, complementarity, selection, dominance, competition, niche, Baltic Sea
Identifiers
urn:nbn:se:su:diva-32592 (URN)
Available from: 2009-12-14 Created: 2009-12-14 Last updated: 2010-05-05Bibliographically approved
3. The enemy release hypothesis may contribute to explain the invasion success of Marenzelleria arctia (Polychaeta) in the Baltic Sea
Open this publication in new window or tab >>The enemy release hypothesis may contribute to explain the invasion success of Marenzelleria arctia (Polychaeta) in the Baltic Sea
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The invasive genus Marenzelleria spp. was introduced into the Baltic Sea during the 1980’s, and currently, three species of Marenzelleria are present in the Baltic Sea. Since its introduction, the genus has become wide-spread and abundant across the whole Baltic Sea and in deeper soft-bottoms, the species Marenzelleria arctia has established itself very successfully. Several hypotheses for the success of this introduced species have been suggested, e.g. better tolerance to pollutants and poor oxygen conditions, superior competitive ability for resources and low predation pressure from native predators. A predation experiment with several species of Baltic Sea deposit feeders as prey, including the non-indigenous M. arctia, was performed. The three major invertebrate predators in the area were used in the experiment, the isopod Saduria entomon, the priapulid Halicryptus spinulosus and the polychaete Bylgides sarsi. The results show that due to its ability to bury deeper than native fauna, M. arctia is well protected from the native invertebrate predators. Thus, the enemy release hypothesis may help explain the invasion success of M. arctia in addition to its utilization of a previously empty niche. Furthermore, a conceptual model over the main community interactions in Baltic Sea soft-bottoms after the introduction of M. arctia is presented.

Keyword
Invasive species, Enemy release, Predation, Baltic Sea, Benthic food-web interactions, Sediment, Marenzelleria
Identifiers
urn:nbn:se:su:diva-38892 (URN)
Available from: 2010-05-03 Created: 2010-05-03 Last updated: 2010-05-05Bibliographically approved
4. Meiofauna reduces bacterial mineralization of naphthalene in marine sediment
Open this publication in new window or tab >>Meiofauna reduces bacterial mineralization of naphthalene in marine sediment
2010 (English)In: The ISME journal, ISSN 1751-7362, no 4, 1421-1430 p.Article in journal (Refereed) Published
Abstract [en]

The role of sediment-living meiofauna, benthic invertebrates smaller than 1000lm, such as nematodes and ostracods, on the mineralization of naphthalene, a common polycyclic aromatic hydrocarbon (PAH), in marine sediment was studied in microcosms using radiorespirometry. A method to extract live meiofauna was developed and used in order to experimentally manipulate meiofauna abundance and group diversity. Higher abundances of meiofauna were found to significantly decrease naphthalene mineralization. Furthermore, a change in the bacterial community composition (studied using terminal restriction fragment length polymorphism) was also observed in presence of higher meiofauna abundance, as well as a lower number of cultivable naphthalene-degrading bacteria. The reduced mineralization of naphthalene and the altered bacterial community composition in the presence of increased meiofauna abundance is likely the result of top-down control by meiofauna. This study shows that higher abundances of meiofauna can significantly decrease the microbial mineralization of PAHs such as naphthalene and also significantly modify the bacterial community composition in natural marine sediments.

Place, publisher, year, edition, pages
International Society for Microbial Ecology, 2010
Keyword
biodegradation; predation; polycyclic aromatic hydrocarbons; trophic interactions; top-down control; live meiofauna extraction; T
National Category
Ecology
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-38802 (URN)10.1038/ismej.2010.63 (DOI)
Available from: 2010-04-29 Created: 2010-04-29 Last updated: 2011-01-10Bibliographically approved
5. Effects of the antibiotic ciprofloxacin on the bacterial community structure and degradation of pyrene in marine sediment
Open this publication in new window or tab >>Effects of the antibiotic ciprofloxacin on the bacterial community structure and degradation of pyrene in marine sediment
2008 (English)In: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 90, no 3, 223-7 p.Article in journal (Refereed) Published
Abstract [en]

The ecological consequences of antibiotics in the aquatic environment have been an issue of concern over the past years due to the potential risk for negative effects on indigenous microorganisms. Microorganisms provide important ecosystem services, such as nutrient recycling, organic matter mineralization and degradation of pollutants. In this study, effects of exposure to the antibiotic ciprofloxacin on the bacterial diversity and pollutant degradation in natural marine sediments were studied using molecular methods (T-RFLP) in combination with radiorespirometry. In a microcosm experiment, sediment spiked with (14)C-labelled pyrene was exposed to five concentrations of ciprofloxacin (0, 20, 200, 1000 and 2000 microgL(-1)) in a single dose to the overlying water. The production of (14)CO(2) (i.e. complete mineralization of pyrene) was measured during 11 weeks. Sediment samples for bacterial community structure analysis were taken after 7 weeks. Results showed a significant dose-dependent inhibition of pyrene mineralization measured as the total (14)CO(2) production. The nominal EC(50) was calculated to 560 microgL(-1), corresponding to 0.4 microg/kg d.w. sediment. The lowest effect concentration on the bacterial community structure was 200 microgL(-1), which corresponds to 0.1 microg/kg d.w. sediment. Our results show that antibiotic pollution can be a potential threat to both bacterial diversity and an essential ecosystem service they perform in marine sediment.

Identifiers
urn:nbn:se:su:diva-38891 (URN)10.1016/j.aquatox.2008.09.002 (DOI)000261776000008 ()18930559 (PubMedID)
Available from: 2010-05-03 Created: 2010-05-03 Last updated: 2017-12-12Bibliographically approved

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