Estuarine Fish Communities along a Spatial Urbanization Gradient

Valenti, J.L.; Grothues, T.M., and Able, K.W., 2017. Estuarine fish communities along a spatial urbanization gradient. In: Buchanan, G.A.; Belton, T.J., and Paudel, B. (eds.), A Comprehensive Assessment of Barnegat Bay–Little Egg Harbor, New Jersey. Journal of Coastal Research, Special Issue No. 78, pp. 254–268. Coconut Creek (Florida), ISSN 0749-0208. The human population surrounding Barnegat Bay, New Jersey, has increased dramatically in recent decades. Consequently, urbanization (anthropogenic development) of the watershed has occurred, resulting in shoreline hardening and habitat destruction. A resulting gradient of urbanization increases from the southern to the northern portion of the bay’s watershed. The objective of this study was to investigate cumulative impacts of urbanization in Barnegat Bay by assessing species composition, abundance, and diversity of fish communities in relation to the largescale urbanization gradient in the watershed. Otter trawl surveys occurred in April, June, August, and October for 3 years (2012–2014) at 40 sampling sites stratified along the urbanization gradient. The sampling sites included four different representative, subtidal subhabitats: open bay (soft bottom), submerged aquatic vegetation beds, upper marsh creek, and marsh creek mouth. Analyses did not reveal strong differences in fish communities among strata that could be solely attributed to the urbanization gradient. Fish species composition was similar among strata, whereas species abundances and diversity differed among strata. Many of the observed differences in abundance and diversity were attributed to ecological variables unassociated with the urbanization gradient. Further study on potential urbanization effects should include investigations at the species level and at smaller scales. ADDITIONAL INDEX WORDS: Barnegat Bay, estuary, urban watershed, anthropogenic effects, human development, fish assemblages. INTRODUCTION Humans rely on the marine ecosystem for many resources and services, such as food, climate regulation, and recreation (Costanza et al., 1997) but have altered that ecosystem directly through resource overexploitation, habitat alteration, and nutrient loading (Reid et al., 2005). In the United States, more than 50% of the population resides within coastal counties (Crossett et al., 2004), which endangers the continued provision of ecosystem services (Agardy et al., 2005) and makes coastal ecosystems particularly vulnerable to human perturbations (Hinrichsen, 1998). The east coast of the United States is an area highly affected by humans (Gittman et al., 2015; Halpern et al., 2008). New Jersey, in particular, is the most densely populated state within the United States (464 persons/km [1202 persons/mile]) with most of the population living along the coastline (Crossett et al., 2004). Within New Jersey, the Barnegat Bay watershed has become increasingly urbanized (developed). From 2000 to 2010, the population in the watershed increased by 11.7% (59,992 people) (Kauffman and Cruz-Ortiz, 2012). However, the urbanization (anthropogenic development) in the watershed is not evenly distributed. The northern portion of the watershed is highly urbanized in comparison to the southern portion, creating a gradient of urbanization within the watershed. The continued human population growth in the Barnegat Bay watershed and resultant construction of impervious surfaces increased the volume of nonpoint source pollution entering the estuary, which subsequently caused water quality degradation through eutrophication (Kennish, 2001c; Kennish and Fertig, 2012). In addition to water quality degradation, essential marsh habitat has been destroyed by marsh infilling, dredging, bulk-heading, and lagoon construction (Kennish, 2001c). The response of fish communities to urbanization varies. Several studies have documented effects of urbanization on species composition, abundance, and diversity within fish communities (Able, Manderson, and Studholme, 1998; Bilkovic and Roggero, 2008; Davis, Levin, and Walther, 2002; Hendon, Peterson, and Comyns, 2000; Partyka and Peterson, 2008; Peterson et al., 2000). For instance, Balouskus and Targett (2016) demonstrated fish were more abundant along natural marsh shorelines compared with altered rip-rap shorelines. In addition, urbanization may affect fishes physiologically or bioenergetically (Luther et al., 2004; Wedge, Anderson, and DeVries, 2015). In the lower Hudson River estuary, juvenile tautog (Tautoga onitis) and winter flounder (Pseudopleuronectes americanus) had decreased growth rates under piers when compared with open-water and pile field subhabitats (Able, Manderson, and Studholme, 1999). Furthermore, over longer periods, Hall-Scharf, Switzer, and Stallings (2016) found diet shifts in spotted seatrout (Cynoscion nebulosus) could be attributed to the loss of seagrass habitat from urbanization. DOI: 10.2112/SI78-017.1 received 8 December 2016; accepted in revision 7 July 2017; corrected proofs received 2 November 2017. *Corresponding author: [email protected] Coastal Education and Research Foundation, Inc. 2017 Coconut Creek, Florida 2017 Journal of Coastal Research SI 78 254–268