Severe storms and anthropogenic activity can cause habitat loss, reduced patch size, increased fragmentation, and isolation, which are strongly associated with loss in species persistence and abundance. Isolated habitat patches are more likely to become “sink” habitats where individuals are less likely to contribute to the spawning stock. Within the Mid-Atlantic Bight, habitat structures are highly fragmented and isolated, where patch size and complexity are highly variable. Corridor implementation between patches is common within terrestrial settings, however there is little implementation within marine habitats. The purpose of this research is to determine if increasing connectivity between two established patches via an artificial reef (AR) “corridor” will facilitate movement and increase fish abundance on the patch-reefs. Research was conducted at two sites: control and experimental. Both sites consisted of two established patches separated by sandy bottom, 31 and 240 m apart, respectively. One year prior to AR construction, a 30-minute fish abundance video survey was conducted in early and mid-summer, and fall. Recordings were completed on both patches and open bottom at both sites. AR construction occurred in December 2016 where 24 oyster-castle pyramids of various height at 6 m intervals in a mosaic stepping-stone fashion. Monitoring continued as previously mentioned.
Results/Conclusions
Prior to AR construction, fish were not observed in video surveys or utilizing open bottom between patches at either site. This suggests that if movement between patches exists it is not continuous, and possibly minimal. However, seven months after AR construction, schools of various fish species are observed swimming throughout the mosaic corridor while other fish remained at the pyramids for duration of the survey. Fish were observed on pyramids in all video surveys in 2017 despite the lack of biofouling (e.g. corals). Preliminary video data showed no evidence of a decline fish abundance at the two established patches of the experimental or control sites in the 2017 surveys suggesting an overall increase in fish abundance at the experimental site. Surveys at the control open bottom site continued to capture no movement between patches. Monitoring will continue throughout 2018 to determine the persistence of the increase in fish abundance at the experimental site. These preliminary data demonstrate that increasing connectivity via a mosaic stepping-stone corridor between two established reef patches can increase fish abundance in a relatively short time period. This can be an effective method to help increase local fish populations and to maintain sustainable and productive marine ecosystems.