Marc H Hanke

Structurally complex biogenic habitats provide foraging grounds and predation refuges for a myriad of decapod crustaceans. Many of these habitats, such as reefs formed by the eastern oyster (Crassostrea virginica Gmelin, 1791), have been lost due to natural and anthropogenic reasons, leading to the construction of artificial reefs for habitat restoration. Previous studies have investigated the impacts of oyster reef restoration efforts on abundance patterns of decapod crustaceans, such as those of panopeid crabs, but largely ignored the influence of artificial, or created, habitat on other population characteristics such as reproductive output. We sampled five artificial reefs (constructed during 2014 or 2015) in Sweetwater Lake, Galveston Bay, Texas, USA in July-August 2016 to study the population characteristics of female panopeid mud crab Panopeus simpsoniRathbun, 1930. We quantified carapace width, counted eggs and measured dry egg mass to estimate reproductive output and determine how reef-age treatment, live-oyster abundance, and live-oyster size predicted female P. simpsoni abundance and egg production. Oyster size varied significantly (P < 0.001) by age treatment, and oyster abundance and size varied significantly (P < 0.001) between the reefs within each age treatment. The abundance of female P. simpsoni varied significantly (P < 0.001) between the two age treatments and was positively correlated with oyster size and reef age. The percentage of gravid females, which varied significantly (P = 0.027) among the reefs, was positively correlated with oyster abundance, and egg production was positively correlated with body size. These results suggest that oyster development on artificial reefs may influence the abundance and reproductive output of associated crustaceans such as P. simpsoni. We demonstrate that monitoring programs should not only consider population characteristics of reef-building organisms, but also the development of complex habitat structure and its impact on associated crustacean populations when determining the success of artificial habitats.