Effects of an Inshore Artificial Reef on the Trophic Dynamics of Three Species of Estuarine Fish

Estuarine habitats are important in the life history of many fish species, yet are being degraded at an alarming rate. Habitat loss is often mitigated by the addition of artificial reefs. Understanding how artificial habitat affects the trophic dynamics of associated fish communities is important to understanding their role in estuarine environments. This study compared the trophic dynamics of spotted seatrout, Cynoscion nebulosus (Cuvier, 1830), Atlantic croaker, Micropogonias undulatus (Linnaeus, 1766) , and bay anchovy, Anchoa mitchilli (Valenciennes, 1848), at an inshore artificial reef and a nearby mud-bottom site. Trophic dynamics were assessed using a combination of gut content analysis and stable isotopes for spotted seatrout and Atlantic croaker, and stable isotopes alone for bay anchovy. No significant differences were found in the either the diets or mean values of δ13C, δ15 N, or δ34S of spotted seatrout between habitats. Differences were seen in both the centroid distance and total area of the δ 13 C-δ15N biplot for spotted seatrout indicating greater trophic niche breath at the artificial reef. Diets of Atlantic croaker differed significantly between habitats and specimens were more enriched in δ15N at the artificial reef; however, no differences in trophic niche breadth were observed. Bay anchovy were more depleted in both δ13C and δ34S over the artificial reef and differences in the trophic niche breadth were observed. Results suggest that habitat alterations can affect trophic dynamics of estuarine species in different ways. Therefore, foraging strategy should be considered when evaluating estuarine artificial reefs.