Identifying 120 Years of Decline in Ecosystem Structure and Maturity of Great South Bay, New York Using the Ecopath Modelling Approach

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 indicated

that the GSB has experienced a decline in ecosystem maturity, loss of top keystone predators,

a decline in connectivity to the ocean though the reduction of migratory species 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. We discuss the role of stochastic events, which result in state changes that

could be defined as regime shifts, and ecosystem connectivity to the long-term stability of lagoonal

systems.