Baited remote underwater video survey of macro-invertebrate distribution and abundance across False Bay, South Africa
Bachelor Thesis
2014
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University of Cape Town
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Abstract
Assessing invertebrate species diversity and distribution based on environmental predictors is essential for conservation planning. South Africa need to understand ecological patterns to better plan for species conservation. South Africa’s unique coastline requires additional protection, but the design of areas is reliant on evidence based research. South Africa has a distinctive marine environment and is host to tropical, subtropical and temperate invertebrate species. False Bay in the Western Cape province of South Africa is a biodiversity hotspot with high species richness due to the overlap of two bioregions. This project reports on the first comprehensive camera survey of False Bay’s invertebrate population and assesses diversity across more habitat types and a greater depth range than previous dredge studies. 154 sites were sampled across summer and winter, reef and sand and three depth categories: shallow (5-15 m), intermediate (16-30 m) and deep (31-50 m). A total of 67 species from 8 phyla were recorded in this study. Winter samples showed a greater diversity than those sampled in summer (p=0.004). Intermediate depths (Shannon-H=1.184) and reef substrate (Shannon-H=1.403) support a greater diversity of invertebrate species. Habitat emerged as the most significant predictor of species distribution in the bay (p=0.01). Depth (p=0.01) and season (p=0.03) were also of influence, but to a lesser extent. Reef sites were separated from sand sites by the presence of Jasus lalandii and Comanthus wahlbergi on the former and Bullia laevissima, Marthasterias glacialis and Ovalipes trimaculates on the latter. Reef species J. lalandii and Tropiometra carinata and sand species B. laevissima and M. glacialis had the greatest contribution to dissimilarity between winter and summer samples. Complex granite reefs should be a main priority in invertebrate conservation as they host the greatest species diversity and abundance of all habitats sampled. BRUVs have provided a non-invasive, non-destructive method of sampling invertebrate species on all habitat types and are recommended for use in future studies of invertebrate species composition.
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Includes bibliographical references.
Reference:
Carr, I. 2014. Baited remote underwater video survey of macro-invertebrate distribution and abundance across False Bay, South Africa. University of Cape Town.