Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UNITED KINGDOM.
Baited underwater camera (BUC) systems are becoming popular in the shallow water environment to monitor the relative diversity and abundance of fish and invertebrate assemblages. This thesis describes methods developed to use BUCs in temperate, tropical and Antarctic environments and their application to questions concerning the factors controlling shallow water marine biodiversity and abundance. In Chapter 2 the design and development of a BUC system suitable for attracting, identifying and counting temperate shallow water (< 30 m) fish and crustacean species on the West coast of Scotland is described. The use of BUC systems has been limited in temperate waters and a cost- and – time efficient method could be valuable to monitor the before and after impact of the proposed Scottish Marine Protected Area network. As a test of the BUC, deployments were made in Lamlash Bay no-take zone (NTZ) and in two control open sites to provide baseline data early in the life of the NTZ against which future BUC studies can be compared. The tropical Gulf of Aqaba supports unique coral reef fish assemblages and it is important to perform a study specific in this distinct biogeographical region to understand whether BUC surveys could be useful in this sensitive environment. In Chapter 3 we therefore compared the predatory fish assemblages recorded in BUC deployments to the established method of Underwater Visual Census (UVC) surveys in the northern Gulf of Aqaba. Abundance metrics from the arrival pattern of fish at the BUC did not correlate with population abundance estimates from UVCs and it was concluded that until improved methods of interpreting BUC data are developed the deployment of BUCs could be used to assess predator species richness but is not able to indicate relative variation in population abundance. Chapter 4 demonstrates how BUC systems can be used to gather data on a complicated ecological question in extreme conditions. A BUC system was used to examine the distribution of scavenging fauna in relation to the spatial variation in exposure to iceberg impacts experienced at difference iceberg scouring conditions and depths within Marguerite Bay. The results indicate that different scavenger species are adapted to high and low iceberg scouring environments and that they are distributed in accordance with the recognised pattern of decreasing iceberg scouring frequency with depth. The above studies used relative measures of abundance such as recording the highest number of individuals observed at a single time (MaxN). Such measures are limited in their usefulness but there are no robust means of estimating absolute abundance, especially for complex shallow water systems. In Chapter 5 a modelling approach, using a stochastic simulation, was developed and used to estimate population abundance for species commonly observed in the above studies. Model abundance estimates were generally found to be comparable to those from corresponding UVC transects. This modelling approach has the potential to substantially improve the ability of BUC systems around the world to assess fish and invertebrate diversity and abundance.