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Contrasting effects of food quality and quantity on a marine top predator
Stockholm University, Stockholm Resilience Centre.
Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
Stockholm University, Stockholm Resilience Centre.ORCID iD: 0000-0002-3201-9262
Stockholm University, Stockholm Resilience Centre.
2012 (English)In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 444, 239-249 p.Article in journal (Refereed) Published
Abstract [en]

Overfishing of predatory fish has contributed to an increase in forage-fish stocks. At the same time, a rising demand for forage fish to supply fishmeal markets, in combination with ­climate change, has put strong pressure on these stocks, and this, in turn, has had an impact on marine top predators. We examined how inter-annual variation in food quality (sprat Sprattus sprattus weight-at-age) and quantity (sprat abundance) influenced Baltic Sea common murres Uria aalge during chick-rearing. Fledging success, i.e. survival from hatching to fledging, showed a positive relationship with food quality, but we found no effect of food quantity. We found no relationship between food quality and parental behaviour or chick feeding parameters, but a negative relationship between food quantity and trip duration. Our data indicate that there was room for parental birds to increase their effort to compensate for reduced food quality, but we found no signs of such compensation. We analysed different types of fish and seabird life-history data to separate effects of food quantity and quality on a top predator. Understanding such effects can contribute to clarifying causes and consequences for observed changes in life-history parameters and population dynamics of top predators.

Place, publisher, year, edition, pages
2012. Vol. 444, 239-249 p.
Keyword [en]
Junk food, Trophic cascades, Ecosystem approach, Environmental change, Climate change, Alcidae, Common guillemot
National Category
Environmental Sciences
Research subject
Natural Resources Management
Identifiers
URN: urn:nbn:se:su:diva-70425DOI: 10.3354/meps09417ISI: 000298970900017OAI: oai:DiVA.org:su-70425DiVA: diva2:481193
Note

4

Available from: 2012-01-20 Created: 2012-01-20 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Man, murres and modern fisheries: A case study in the Baltic Sea
Open this publication in new window or tab >>Man, murres and modern fisheries: A case study in the Baltic Sea
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Overfishing and climate change put increasing pressure on marine systems, with effects on commercially targeted fish and top predators dependent on these resources. To achieve sustainable resource use, governance mechanisms need to incorporate knowledge about ecosystem dynamics. Another key for success is the perception among actors about the challenges oceans are facing. Seabirds have become well-known symbols of coasts and oceans and their struggles with the consequences of human actions provide an illustration of the need to properly govern marine resources. Seabirds can be useful indicators of states of marine systems, forming tools that can help informing ecosystem approaches to management. The thesis focuses on the piscivorous seabird the common murre Uria aalge in the Baltic Sea, investigating two different aspects of interactions between seabirds and fisheries. In paper I, the effects of food quality and quantity during the chick-rearing period were investigated. Food quality (sprat Sprattus sprattus weight-at-age), but not quantity (sprat abundance), was positively related to murre fledging success. The adjustments of parental effort in relation to quality and quantity showed the opposite pattern – no relationships between parental effort and sprat weight-at-age but a negative relationship between sprat abundance and the duration of foraging trips. Paper II uses a long-term ring recovery dataset to study murre bycatch in Baltic Sea fisheries. We found an increase in the proportion bycatch between 1972 and 2008, and a strong bimodal intraannual pattern in bycatches, with peaks in spring and autumn, similar in three investigated periods. Uncertain finding dates were common and could potentially affect conclusions about intraannual patterns. Reported bycatches were concentrated to waters around the Hel peninsula, Poland. In recent years, 2000-2008, an increase of reported bycatch could be observed in the southeastern parts of the Baltic Sea. The findings of this thesis can aid the selection and interpretation of indicators for ecosystem approaches to Baltic Sea fisheries management, and further be used to communicate the need for such approaches.

Place, publisher, year, edition, pages
Stockholm: Department of Systems Ecology, Stockholm University, 2012. 18 p.
Keyword
Seabirds, ecosystem dynamics, fisheries, indicators, ecosystem services, Baltic Sea, common murre, common guillemot, Uria aalge
National Category
Biological Sciences
Research subject
Natural Resources Management
Identifiers
urn:nbn:se:su:diva-68704 (URN)
Presentation
2012-01-30, Room 312, Stockholm Resilience Centre, Kräftriket 2 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the defence the following paper was unpublished and had a status as follows: Paper nr 2: Manuscript

Available from: 2012-11-30 Created: 2012-01-05 Last updated: 2012-12-14Bibliographically approved
2. Seabirds as food for thought: An integrative study on seabird ecology and ecosystem services in changing marine systems
Open this publication in new window or tab >>Seabirds as food for thought: An integrative study on seabird ecology and ecosystem services in changing marine systems
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The importance of the benefits that humans obtain from the oceans is increasingly recognized, along with the rapid decline in marine resources that threatens these benefits. Studying seabirds – top predators in marine ecosystems, can provide insights about multiple pressures and the state of the oceans. The thesis links studies of seabirds through the lens of ecosystem services with an ecological case study. Paper I reviews ecosystem services, finding that seabirds contribute to provisioning, regulating, supporting and cultural services. Seabirds serve as mobile links in marine and terrestrial ecosystems, through regulating and supporting services. Further, scientific knowledge and indicators based on seabirds can be seen as an ecosystem service as they facilitate management. Papers II-IV proceed to build such knowledge about the importance of food quality and quantity for breeding seabirds, in particular common murres Uria aalge in the Baltic Sea. Here, there is a negative relationship between quantity (sprat Sprattus sprattus abundance) and quality (sprat weight-at-age). Quality, but not quantity, was positively related to common murre fledging success while parental foraging trips had shorter duration when quantity was higher, but showed no relationship with food quality (paper II). Paper III describes foraging behaviour of adults and found indications of good foraging conditions at sea. Parents made efforts to adjust provisioning of food according to the needs of the chicks (paper IV), but the adjustments did not seem to be enough to counteract the impact of lower food quality. Paper V explores ecosystem services obtained from seabirds over time identifying a shift from provisioning to cultural services, where current cultural services are often connected. The integration of ecosystem services with seabird ecology shows that seabirds are illustrative of changes in marine resources and provide ways to help people reconnect with the health of marine systems.

Place, publisher, year, edition, pages
Stockholm: Stockholm Resilience Centre, Stockholm University, 2014. 44 p.
Keyword
seabirds, ecosystem services, social-ecological systems, marine systems, fisheries, foraging ecology, provisioning behaviour, common murre, common guillemot, Uria aalge, Stora Karlsö, Baltic Sea
National Category
Ecology Environmental Sciences
Research subject
Natural Resources Management
Identifiers
urn:nbn:se:su:diva-108420 (URN)978-91-7649-035-8 (ISBN)
Public defence
2014-11-28, 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 1: Manuscript. Paper 4: Submitted. Paper 5: Manuscript.

 

Available from: 2014-11-06 Created: 2014-10-23 Last updated: 2017-03-03Bibliographically approved

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