Abstract
Animal tissues incorporate the stable nitrogen isotopic composition from underlying resources into their biomass, but with an additional fractionation effect. The stable isotopic composition of nitrogen within these tissues therefore reflects both the baseline isotope values supporting primary producers and the animal’s position within the food web, reflecting trophic structure. Within a long-lived tissue such as bone, collagen remains well preserved after death, allowing investigating long term ecosystem states through collection and analysis of bones of known provenance. Here, collagen from 170 stranded harbor porpoise was sourced from a museum archive and the tissue bank of the Dutch Stranding Network. The samples from both archives were analyzed for stable nitrogen isotope ratios of bulk material and amino acids across historical (1950-2001) and recent (2009-2021) time periods. These results allow for: 1) identification of the modern trophic position of harbor porpoise in the North Sea food web, 2) comparison between the modern and historical trophic position of harbor porpoise, and 3) to infer ecosystem impacts that have led to changes in baseline N and trophic structure in the North Sea. Previously, Christensen et al. (2008) identified lowered δ15N values starting in the 1960’s from analysis of bulk collagen but were unable to conclusively tie this change to a shift in baseline N isotopic composition supporting primary producers or a shift in food web trophic structure or feeding status of porpoise in the North Sea. Baseline integrated analysis of trophic position using source and trophic amino acids will provide further context for this historical data set and provide a valuable multi-decadal baseline for comparison against the more recent archive (2009-2021). The long history of industrial overfishing in the North Sea confounds interpretation of the multi decadal impacts from climate change. We anticipate that the increased resolution and integration of baseline changes across the 75-year period will provide an opportunity to resolve the multiple anthropogenic impacts changing the harbor porpoise’s place in the food web structure in the North Sea.
Originalsprog | Engelsk |
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Publikationsdato | 21 feb. 2024 |
Status | Udgivet - 21 feb. 2024 |
Begivenhed | 2024 Ocean Sciences Meeting - New Orleans, USA Varighed: 18 feb. 2024 → 23 feb. 2024 https://www.agu.org/Ocean-Sciences-Meeting |
Konference
Konference | 2024 Ocean Sciences Meeting |
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Land/Område | USA |
By | New Orleans |
Periode | 18/02/2024 → 23/02/2024 |
Internetadresse |
Emneord
- stable isotope analysis