Dynamic trophic linkages in a large estuarine system — support for supply-driven dietary changes using delta generalized additive mixed models

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Buchheister, Andre, Latour, Robert J.
• Other Authors: Ramcharan, Charles
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2016
• Subjects: Northwest Atlantic
• Online Access: http://dx.doi.org/10.1139/cjfas-2014-0441; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjfas-2014-0441; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjfas-2014-0441

Trophic dynamics within aquatic systems are a predominant regulator of fish production and an important consideration for implementing ecosystem approaches to fisheries management. We analyzed 10 years of fish diet data from Chesapeake Bay, USA, to (1) evaluate the effects of environmental variables on trophic interactions of 12 common predatory fishes, (2) infer dynamics of four key prey groups (mysids, bay anchovy, bivalves, and polychaetes), and (3) evaluate whether interannual dietary trends were coherent among predators and regulated by prey availability. Based on delta generalized additive mixed models (delta-GAMMs), predator length was the most important covariate in modeling prey consumption. When latitude, temperature, and depth effects were statistically significant, the effects of each variable were largely similar across predators for a given prey. Annual patterns of mysid and bivalve consumption each showed a single, dramatic peak shared by multiple predators with varied feeding preferences and distributional characteristics, but annual trends were not correlated with available survey-based measures of prey availability, likely due to methodological differences. Overall, the coherence in consumption patterns across predators was consistent with supply-driven dynamics controlled by regional and annual changes in prey availability. Also, the novel application of delta-GAMMs to fish diet data was useful in characterizing the dynamics of poorly sampled prey groups and the trophic interactions for ubiquitous species from the Northwest Atlantic Ocean.