Assessment of faunal communities and habitat use within a shallow water system using non-invasive BRUVs methodology

Seagrass and mangrove habitats have long been established as critical for diverse species at various life-stages,particularly as nursery grounds.However,despite their intrinsic and environmental value,these ecosystems are increasingly threatened by anthropogenic activities.In Bimini,Bahamas,where ongoing development threatens ecosystem integrity,baited remote underwater video surveys(BRUVs)were used to examine faunal communities in both nearshore habitat and a shallow water central lagoon(average depth 1 m).The study assessed species abundances and spatial distribution in a currently unperturbed of the North Bimini Marine Reserve(NBMR).A total of 140 BRUVs,conducted over a 13-month period,recorded 62 species from 27 different families.MaxN was used to assess relative abundances and multivariate analyses(i.e.nMDS,PCA,PERMANOVA)investigated differences in community composition across discrete factors and environmental variables.Boosted Regression Trees(BRTs)were used to explore environmental variables for their uncorrelated influences on recorded species diversity.Findings evidenced the importance of habitat diversity and particularly mangroveadjacent habitat for teleost fishes in Bimini with species diversity and abundance being significantly greater in the mangrove-adjacentdge habitat.Further,the study highlighted differences in environmental conditions between habitat types and the association this had with species diversity,abundance and distribution.Despite the shallow water environment,BRUVs served as a scalable,non-invasive technique to assess community structures within the study site.Results from this study should inform ongoing decision-making processes regarding the protection of the Bimini Islands ecosystem.

Fish assemblages in protected seagrass habitats:Assessing fish abundance and diversity in no-take marine reserves and fished areas

Marine reserves are an important management tool for conserving local biodiversity and protecting fragile ecosystems such as seagrass that provide significant ecological functions and services to people and the marine environment.With humans placing ever-growing pressure on seagrass habitats,marine reserves also provide an important reference from which changes to seagrass and their ecological assemblages may be assessed.After eight years of protection of seagrass beds(Posidonia australis)in no-take marine reserves(Sanctuary Zones)within the Jervis Bay Marine Park(New South Wales,Australia;zoned in 2002),we aimed to assess what changes may have occurred and assess continuing change through time in fish assemblages within these seagrass meadows.Using baited remote underwater videos(BRUVs),we sampled seagrass fish assemblages at three locations in no-take zones and five locations in fished zones three times from 2010 to 2013.Overall,we observed a total of 2615 individuals from 40 fish species drawn from 24 families.We detected no differences in total fish abundance,diversity,or assemblage composition between management zones,although we observed a significant increase in Haletta semifasciata,a locally targeted fish species,in no-take marine reserves compared with fished areas.Fish assemblages in seagrass varied greatly amongst times and locations.Several species varied in relative abundance greatly over months and years,whilst others had consistently greater relative abundances at specific locations.We discuss the potential utility of marine reserves covering seagrass habitats and the value of baseline data from which future changes to seagrass fish populations may be measured.