Abstract
When establishing minimum flows and levels for tidal tributaries, it is important to develop quantitative criteria that provide some value in predicting the ecological responses of estuarine organisms downstream to reductions in flow. These criteria can also prove generally useful when managing estuarine resources. This study was conducted from January 2005 through December 2006 in an attempt to begin developing ecological criteria for proposing minimum flows for Estero Bay and to understand how the bay and its tidal tributaries are utilized as habitat by the early life stages of fishes and invertebrates. Because Estero Bay is influenced by freshwater inflow from five tidal tributaries and because inflow can vary dramatically between dry and wet seasons in Southwest Florida, sampling was designed to quantify zooplankton distribution and density at locations near the mouths of some of the bay’s tidal tributaries, as well as in the open waters of the bay proper and near passes to the Gulf of Mexico. The overall objectives of the project were to determine the role of open water and selected estuarine tributaries of Estero Bay as a habitat for larval fishes and decapods, to develop quantitative relationships between freshwater input (or its proxy, salinity) and habitat utilization, and to describe seasonal variation in the abundance and distribution of these organisms. Sampling targeted larval fishes, larval decapod crustaceans, and gelatinous zooplankton and was conducted monthly at sixteen stations using plankton nets that were towed to fish the entire water column. In addition to biological sampling, salinity, temperature, and dissolved oxygen concentration were recorded in association with each net deployment.