A 120 year history of ecosystem structure and maturity of Great South Bay, New York
Nuttall, M.A, A. Jordaan, R.M. Cerrato, M.G. Frisk
Mass balanced models yield valuable information regarding ecological function and delivery of ecosystem services, but often rely on data collected well before many species were reduced to fractions of their original abundance. Lagoonal systems, such as Great South Bay (GSB), NY, sit on the interface of terrestrial and marine ecosystems and are prone to anthropogenic stressors but proximity to land also makes the presence of data regarding historic populations and structure more likely. To quantify over a century of ecosystem change, Ecopath models were developed for GSB at each of four time periods where commercial and scientific data exist: 1880s, 1930s, 1980s and 2000s. The results indicate that the GSB has experienced a declining ecosystem maturity, loss of top keystone predators, declines in the contribution of migratory species and hence connectivity with other systems, and increasing dominance of low trophic level organisms. These changes undermine the delivery of ecosystem services, increase conflicts over limited resources and suggest that present-day restoration targets fail to recognize appropriate baselines. Further, maintenance of lagoonal physical structure by shoreline modification and dredging of inlets has removed an important characteristic in the periodic renewal and reworking of physical dynamics through storm induced breaches of barrier islands.
Flow diagrams of the Great South Bay for the 1880s and 2000s where the node size indicates biomass, curved lines show food web connectivity and vertical lines show trophic levels. Sand tiger sharks and the top keystone species Atlantic menhaden were functionally extirpated from GSB by the turn of the century. Not represented in the figure is that system biomass has significantly declineed from the 1880s to the 2000s.