Abstract
Tidal creek ecosystems along the northern Gulf of Mexico (GoM) are experiencing increasing development pressure as populations continue to grow in coastal counties. These creeks serve as important linkages between watersheds and coastal waters and include fringing salt marshes that are valuable habitats for economically important fish species. Because of urban growth along the GoM, there are concerns about altered watershed drainage and other impacts to tidal creek habitats. To better understand how coastal development impacts tidal creek ecosystems, 12 creeks (2nd-3rd order) were selected to represent a range of urban watershed development along the Alabama and west-Florida coast. Using salinity loggers (installed in each creek in June 2019), mean daily salinities have ranged from 5.5-14.1 ppt and salinity flashiness (modified Richard-Baker index) ranged from 0.19-2.62. Salinity was flashier in high development (1.72±0.39) streams than in medium (1.15±0.35) and low (0.64±0.45) development streams, though the difference was not significant (P=0.24). In October 2019 and August 2020, 12 minnow-traps were deployed along each creek to sample fish. Mean total abundance of Fundulus grandis (the most common marsh fish species) ranged from 0.1-19.3 per trap and increased with percent wetland land cover in the watershed. Diets of a subset of F. grandis from each creek (n=20-74) from 2019 were quantified and we found that diet composition did not differ with urban land use class. Interestingly, the frequency of fish in F. grandis stomachs was particularly high (52±6%) and the percentage of fish with empty stomachs was much lower (8±3%) than reported from other comparable studies. We continue to synthesize hydrologic, physiochemical, and biotic data from these creeks to characterize how watershed development may alter marsh fish assemblages and tidal creek habitats.
