Trawling Surveys at ANERR

ANERR’s long-term trawling program is designed to look at juvenile fish and macroinvertebrate distribute in the bay and link changes in distribution to water quality and other physical parameters. This study was begun in 2000 with the following goals: 

1. Describe the major trends in the spatial and temporal distribution of major fish and invertebrate species within the Apalachicola Bay System.
2. Relate the occurrence, abundance and seasonality of fish and invertebrate species to natural environmental variation such as temperature and salinity regimes and periodic events such as storms or changes in river flow.

From 2000-2013, sampling was conducted monthly at 12 sites within the boundaries of ANERR, including St. George Sound, East Bay and St. Vincent Sound respresenting a variety of water quality and habitat regimes and duplicating some sites from a prior study in the 1970s. The program was resumed 2015 – present with sampling conducted each winter, spring, summer, and fall at 9 stations in the Apalachicola Bay area. Sampling is performed over a two-day period and five 2-minute tows are performed at each site with a 16ft (4.8m) otter trawl. Fish and benthic macroinvertebrates are identified to species, the first 20 are measured and all are counted. Physical and chemical water parameters are measured at each station in conjunction with biological data. 

Reserve scientists (Garwood et al. 2023) analyzed the first two decades of study data and found that spatial variation in species was driven by differences in salinity, while seasonal changes were driven by temperature. Additional collaboration with graduate students have used this dataset to look at effects of stressors on the bay’s food web and how changes in Apalachicola River flow will affect fish populations. These studies can be found at:

• Garwood, J.A., Allen, K., Lamb, M.S. et al. (2023). Using long-term ecological monitoring to evaluate how climate and human-induced disturbances impact nekton communities in a Northern Gulf of Mexico estuary. Hydrobiologia 850,4479–4496.https://doi.org/10.1007/s10750-023-05206-6
• Allen K., Garwood J.A., Hu K., Meselhe E.A. and Lewis K.A. (2023) Simulating synergistic impacts of climate change and human induced stressors on a northern Gulf of Mexico estuarine food web. Front. Mar. Sci 10:1213949. https://doi:10.3389/fmars.2023.1213949
• Allen K. and Lewis, K. (2024). Future impacts of reduced freshwater inflow and sea level rise on forage fish and their predators in Apalachicola Bay, Florida. Food Webs 41, e00372. https://doi.org/10.1016/j.fooweb.2024.e0037

Studies like these answer critical research questions linking Apalachicola River and Bay physical parameters to food webs, and highlight the importance of long-term research and monitoring.