An ecosystem model of food web and fisheries interactions in the Baltic Sea

Harvey, Chris J.; Cox, Sean P.; Essington, Timothy E.; Hansson, Sture; Kitchell, James F.

doi:10.1016/s1054-3139(03)00098-5

Cited by 121 publications

(79 citation statements)

References 29 publications

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“…For example, both the RTI and the Ecosim model sensitivity analysis (steps 3 and 4) imply that cod is the most important food-web structuring group in the Baltic Proper. In contrast to some previous studies (Harvey 2003;Casini et al 2009;Möllmann et al 2009), however, our results do not readily support the hypothesis that changes in the adult cod biomass directly act as the foremost pelagic ecosystem structuring mechanism. Most of our models, including the original, indicate bottom-up control between sprat and adult cod (Fig.…”

Section: Food-web Functioncontrasting

confidence: 99%

Uncertainties in a Baltic Sea Food-Web Model Reveal Challenges for Future Projections

Niiranen

Blenckner

Hjerne

et al. 2012

AMBIO

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Models that can project ecosystem dynamics under changing environmental conditions are in high demand. The application of such models, however, requires model validation together with analyses of model uncertainties, which are both often overlooked. We carried out a simplified model uncertainty and sensitivity analysis on an Ecopath with Ecosim food-web model of the Baltic Proper (BaltProWeb) and found the model sensitive to both variations in the input data of pre-identified key groups and environmental forcing. Model uncertainties grew particularly high in future climate change scenarios. For example, cod fishery recommendations that resulted in viable stocks in the original model failed after data uncertainties were introduced. In addition, addressing the trophic control dynamics produced by the food-web model proved as a useful tool for both model validation, and for studying the food-web function. These results indicate that presenting model uncertainties is necessary to alleviate ecological surprises in marine ecosystem management.

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Section: Food-web Functioncontrasting

confidence: 99%

Uncertainties in a Baltic Sea Food-Web Model Reveal Challenges for Future Projections

Niiranen

Blenckner

Hjerne

et al. 2012

AMBIO

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“…Cod, herring and sprat dominate fisheries in the Baltic Sea (Sparholt 1991;Heikinheimo 2011) and are key components of Baltic Sea food web models (Harvey et al 2003). These food web models are highly sensitive to changes in cod and sprat abundances , suggesting that the effects of ocean acidification on these species may have more far-reaching consequences than for other components of the Baltic Sea food web.…”

Section: Fishmentioning

confidence: 99%

How will Ocean Acidification Affect Baltic Sea Ecosystems? An Assessment of Plausible Impacts on Key Functional Groups

Havenhand

2012

AMBIO

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Increasing partial pressure of atmospheric CO 2 is causing ocean pH to fall-a process known as 'ocean acidification'. Scenario modeling suggests that ocean acidification in the Baltic Sea may cause a B3 times increase in acidity (reduction of 0.2-0.4 pH units) by the year 2100. The responses of most Baltic Sea organisms to ocean acidification are poorly understood. Available data suggest that most species and ecologically important groups in the Baltic Sea food web (phytoplankton, zooplankton, macrozoobenthos, cod and sprat) will be robust to the expected changes in pH. These conclusions come from (mostly) single-species and single-factor studies. Determining the emergent effects of ocean acidification on the ecosystem from such studies is problematic, yet very few studies have used multiple stressors and/or multiple trophic levels. There is an urgent need for more data from Baltic Sea populations, particularly from environmentally diverse regions and from controlled mesocosm experiments. In the absence of such information it is difficult to envision the likely effects of future ocean acidification on Baltic Sea species and ecosystems.

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“…Recent correlative analyses have demonstrated that overfishing of top predators may have resulted in changes to food web structure in the Northwest Atlantic (Frank et al 2005) and Baltic pelagic ecosystems (Harvey et al 2003, Österblom et al 2007, Casini et al 2008, which may partly explain the general increase in primary production observed in these systems. Similar to the NW Atlantic and Baltic situations, large-scale declines in the abundance of top predatory gadoid species have also been documented on the Swedish west coast bordering the Skagerrak and Kattegat Sea, presumably as a result of overfishing (Svedäng & Bardon 2003).…”

Section: Introductionmentioning

confidence: 99%

Shift in seagrass food web structure over decades is linked to overfishing

Baden¹,

Emanuelsson²,

Pihl³

et al. 2012

Mar. Ecol. Prog. Ser.

114

129

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Empirical field studies in seagrass have revealed that overgrowth by filamentous algae which reduces seagrass growth can be explained by a top-down cascading effect caused by declines in top predators, which is enforced by eutrophication. On the Swedish west coast, 60% of the seagrass has disappeared since the 1980s. We hypothesised that overfishing, responsible for a > 90% decline in the cod stock, and the 4 to 8 times increase in nutrient load since the 1930s have altered the seagrass structure and function during recent decades. We used quantitative samples from the 1980s and 2000s and analysed the trends in abundance of the 4 feeding guilds: top predatory fish, intermediate predatory fish, crustacean omnivores and mesoherbivores. Since the 1980s, the commercial catch of gadoids on the Swedish west coast has decreased by > 90%, and here we found that the biomass of top predators (gadoids and trout) that forage in seagrass has decreased by approximately 80%. In contrast, the biomass of intermediate predatory fish (gobids and sticklebacks) has increased 8 times during summer and 11 times during autumn, while mesoherbivores (idoteids and gammarids > 7 mm) have more or less disappeared from the seagrass bed. We thus found clear evidence that a shift in seagrass food web structure has taken place over the last 3 decades. Combining these findings with our recent empirical results from field cage experiments in the Skagerrak seagrass, where we manipulate top-down and bottom-up regulation, we conclude that lack of grazers in concert with eutrophication most likely contributed to the overgrowth by filamentous algae and disappearance of the seagrass on the Swedish west coast. KEY WORDS: Food web structure · Overfishing · Eutrophication · SeagrassResale or republication not permitted without written consent of the publisher

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An ecosystem model of food web and fisheries interactions in the Baltic Sea

Cited by 121 publications

References 29 publications

Uncertainties in a Baltic Sea Food-Web Model Reveal Challenges for Future Projections

Uncertainties in a Baltic Sea Food-Web Model Reveal Challenges for Future Projections

How will Ocean Acidification Affect Baltic Sea Ecosystems? An Assessment of Plausible Impacts on Key Functional Groups

Shift in seagrass food web structure over decades is linked to overfishing

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