Environmental, Spatial and Temporal Patterns in Chesapeake Bay Forage Population Distributions and P
- Published:
- October 24, 2017
- Originator:
- Ryan Woodland
- Associated with:
- Forage Action Team
The research focused on evaluating: 1) evidence of spatial and temporal structuring of forage populations and predator consumption along environmental gradients and, 2) the effects of variability in abundance of multiple forage taxa on predator consumption patterns. The project built upon previous research (Buchheister 2016). We evaluated patterns patterns of relative abundance of important invertebrate forage taxa at a highly aggregated, functional group level. Invertebrate forage groups included Macoma spp. bivalves, non-Macoma (other) bivalves, polychaetes, and small crustaceans (including amphipods and isopods). Species-level analyses focused on forage fish previously identified as important or potentially important forage taxa in Chesapeake Bay (Ihde et al. 2015), including bay anchovy, young-of-the-year (YOY) Atlantic menhaden, YOY weakfish, YOY spot, YOY Atlantic croaker, Atlantic silversides, mummichog and killifishes. The river herrings, alewife and blueback herring, were included where possible due to strong interest in their recovery in Chesapeake Bay and their historically significant abundances in the ecosystem. Our results indicate that the relative interannual abundance of many of the forage group covaried with the timing of spring time warming of the water, winter-spring flow volume, and the Atlantic Multidecadal Oscillation (AMO). Annual mean per capita consumption by dominant predators – including several size-classes of striped bass, summer flounder, Atlantic croaker, weakfish, white perch and spot – did not covary with forage density in the mainstem but did show significant non-linear relationships with several key environmental variables. Multivariate diet analysis suggested the diet of several predators was influenced by environmental variables (particularly AMO) and that predator diets differed between Maryland and Virginia portions of the mainstem, however these spatial differences were subtle. Overall, we found that there is evidence to suggest that years in which winter water temperatures warm slowly are conducive to higher summertime forage abundances. We failed to find evidence that per capita consumption was linked to relative abundance of individual forage taxa, but consumption did covary with environmental conditions in complex, generally non-linear ways.