Mangrove Habitat Use by Resident versus Migrant Sport Fishes in the Coastal Everglades (Extended Abstract)
Jennifer S. Rehage, Ross E. Boucek, and Jessica A. Lee
Mangroves are well known for providing valuable nursery habitat for a myriad of estuarine and marine fishes (Faunce and Serafy 2006; Murchie and Daneshgar 2015). Yet, their role as refuge habitats across the freshwater–estuarine interface is understudied. We refer to refuge habitats as those that provide resistance (survival) and/or resilience (recovery time) to populations from the effects of disturbance, such as drying events (Parkos et al. 2011).
In the Florida Everglades, the recurrent pattern of seasonal drying of freshwater marshes strongly structures fish communities, limiting abundance and affecting distribution across the landscape (Parkos et al. 2011; Boucek and Rehage 2013). This marked seasonality is magnified by drainage and impoundment over the past 100 years (McVoy et al. 2011). Freshwater inflows into the southern Everglades have been greatly reduced, resulting in a higher frequency of drying in upstream marshes and higher salinity conditions in downstream mangroves. In response to these drier conditions, freshwater fishes move from marshes to deeper refuge habitats, including mangrove areas (Boucek and Rehage 2013); however, how these migrant fishes use mangroves relative to resident estuarine taxa remains poorly understood.
We compared the use of mangrove habitats by migrant Florida Largemouth Bass Micropterus salmoides floridanus to that of resident Common Snook Centropomus undecimalis. Both species are important sport fishes, but Florida Largemouth Bass are primarily freshwater migrants and highly abundant in mangroves only in the dry season, whereas Common Snook reside in mangroves year-around (leaving to spawn at sea, Boucek and Rehage 2013). We compared their movements and seasonal patterns of distribution in meso to oligohaline mangrove reaches. We expected more pronounced seasonality in distribution in the migrant species because of their immigration in and out of the system in relation to marsh drying. Since Florida Largemouth Bass are intolerant of high salinities and not highly mobile, we hypothesized a more limited distribution and lower movement relative to the euryhaline Common Snook.