Colonisation of a lobster stock enhancement artificial reef
Supervisor: Ken Collins (National Oceanographic Centre, Southampton)
Artificial reefs (ARs) are increasingly being used to enhance stock of commercially important species. In the case of the Lobster AR in Weymouth, UK, the reef was deployed enhance lobsters stock in the surrounding area. Deployed in March 2012, it is made up of 6 separate reef units made up of piles of stone. The stones were used to provide structural complexity at the site and to provide shelter for juvenile lobster burrows in the sediment. The purpose of this study was to report the epifaunal colonization of the AR 1 year after deployment; to compare this data with previous studies and a nearby comparison reef to examine differences in communities present. Communities were also compared for rock surface orientation (horizontal vs. vertical) and location (edge vs. not edge). A temporal comparison was made of the Lobster AR from May to August to observe any seasonal change in epifauna; as well as a long term comparison with data from reefs of differing ages. Shannon Weiner species diversity index was also used to compare the diversity of the Lobster AR. Photographs of the reef were taken using divers from the National Oceanography Centre Southampton (NOCS) and quantified using Coral Point Count with Excel extensions (CPCe). The resulting data was analysed using PRIMER 6 software to perform an analysis of similarities (ANOSIM) on communities form different comparison groups, followed by a SIMPER test to determine what was causing these similarities and differences. Divers were also asked to record species name and abundance to use for the Shannon Weiner index calculation. The resulting data showed that the dominant groups present on the Lobster AR were polychaetes (serpulid worms), barnacles and red algae. The communities differed significantly to the natural reef (NR) control at the same depth. Shannon Weiner index results, showed the diversity differed significantly However, there was no significant difference in surface orientation and location on the surface to the communities present. The temporal studies showed a significant yearly variation in communities on reefs studied. However, there was no significant seasonal change in communities observed. The results of this study show that the Lobster AR is being dominated by primary settler species and differs to reefs in different locations and of different ages. The results of this study are important in monitoring the progression of Lobster AR to add to understanding of short and long term colonization of ARs. As well, understanding the variation in the AR, which could be coupled with juvenile lobster releases to maximise efficiency of the reef and survivability of lobsters.