Examining underwater visual census techniques for the assessment of population structure and biodiveristy in temperate coastal marine protected areas

The Tasmanian Aquaculture and Fisheries Institute and the Victorian Department of Natural Resources and Environment conducted a two day joint workshop in October 1999 to examine underwater visual census techniques for the assessment of population structure and biodiversity in temperate coastal marine protected areas. The proposed outcome of the workshop was to establish a consensus on the most appropriate methodologies to use and to standardise methodologies across the temperate Australian states. The workshop goals included determining the types and magnitude of biotic change we want to detect, examining UVC techniques currently in use worldwide, and exploring alternative techniques. A clear outcome from the workshop was that as the current round of MPAs are being developed from a biodiversity perspective, most managers felt that monitoring should be related to this. Because biodiversity is such a broad concept, monitoring should also be broadly based, involving sampling at a range of scales from seascapes, through communities, to populations of individual species. Gary Davis outlined how such a broadly based monitoring program was developed in the Californian Channel Islands. The availability of funding was identified as a major limiting factor in establishing broadly based monitoring programs, and it was clear that funding will be predominantly a state responsibility and be related to individual MPA management. To give an indication of what can be achieved within the current Australian funding network, Hugh Sweatman discussed the types of monitoring being conducted on the GBR with moderate funding, and Graham Edgar discussed monitoring on a shoestring budget in Tasmanian MPAs. Managers will have to accept that existing resources are limited and monitoring programs need to be targetted and have clear and achievable goals. To achieve these goals we need good experimental design, and Mick Keough discussed ways of achieving this with MPAs. One of the most critical points in this design is in determining the effect size that we consider significant. The discussion on this subject, including the types of change as well as magnitude, ranged widely from habitats to individual species. Although there was no overall consensus, it was considered at the species level, a 100% change in abundance and a 20% change in mean size might be significant in many cases. Representatives from individual states and the Commonwealth indicated that monitoring in temperate MPAs was currently limited, with the exception of Tasmania and a program currently being developed in Victoria. This lack of monitoring is in part related to the lack of MPAs in many areas as yet, and partly due to funding restrictions. Current monitoring programs are focused on visual census of reef communities for practical purposes although many managers indicated that broader monitoring was desired, including other habitats, and species. A discussion aimed at developing a consensus on appropriate visual census methodology accepted that the current techniques in use in the Tasmanian and Victorian studies were valid, and that with sufficient replication of sites, would detect the types and magnitude of changes that were of interest to managers. This methodology is restricted to shallow reefs however, and many of the managers present were interested in exploring and developing methodologies over a wider range of habitat types and species, with some questioning the value of adopting a standard methodology between states. It was evident that if a standard and broadly based methodology is to be developed, a series of workshops will be needed, each examining clearly defined habitats, species and techniques.