Depth is a consistently powerful explanatory variable in benthic studies (Gray 2001) due to its association with a range of other factors directly affecting abundance, biomass, and biodiversity (e.g. pressure, primary productivity, temperature). Shallow, eutrophic systems tend to have high biomass and low species richness due to high productivity but potentially stressful environmental conditions (Edgar 2001). As depth increases, these systems give way to moderate biomass and species richness on most coastal shelves (Snelgrove 2001), followed by an increase in richness and decrease in biomass and abundance in the deep sea (Levin et al. 2001). Peak benthic species richness values have been recorded seaward of the continental rise, excluding the deep sea (Snelgrove 2001). While the lower slope and abyssal plains become comparatively depauperate, species turnover tends to be high. The deep sea may house greater diversity than coastal shelf systems (Levin et al. 2001), although genetic differentiation within given populations decrease in abyssal environments (Etter et al. 2005). Because deep-sea richness occurs at far lower abundances than on coastal shelves, deep-sea habitats require greater sampling effort to reliably account for diversity, as shown by a survey to the western Australian continental margin (Williams et al. 2010, Poore et al. 2015).

Use the interactive map below to explore how depth varies around Australia's coastline.

How to use the map

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Edgar, G. 2001. Australian Marine Habitats in Temperate Waters. REed New Holand Publishers Australia Pty Ltd, Sydney.

Etter, R. J., M. A. Rex, M. R. Chase, and J. M. Quattro. 2005. Population differentiation decreases with depth in deep-sea bivalves. Evolution 59:1479-1491.

Gray, J. S. 2001. Marine diversity: the paradigms in patterns of species richness examined. Scientia Marina 65:41-56.

Levin, L. A., R. J. Etter, M. A. Rex, A. J. Gooday, C. R. Smith, J. Pineda, C. T. Stuart, R. R. Hessler, and D. Pawson. 2001. Environmental influences on regional deep-sea species diversity. Annual Review of Ecology and Systematics 32:51-93.

Poore, G. B., L. Avery, M. Błażewicz-Paszkowycz, J. Browne, N. Bruce, S. Gerken, C. Glasby, E. Greaves, A. McCallum, D. Staples, A. Syme, J. Taylor, G. Walker-Smith, M. Warne, C. Watson, A. Williams, R. Wilson, and S. Woolley. 2015. Invertebrate diversity of the unexplored marine western margin of Australia: taxonomy and implications for global biodiversity. Marine Biodiversity 45:271-286.

Snelgrove, P. V. R. 2001. Diversity of marine species. Pages 748-757 in J. Steele, S. Thorpe, and K. Turekian, editors. Encyclopedia of Ocean Sciences. Academic Press, Oxford.

Williams, A., F. Althaus, P. Dunstan, G. C. B. Poore, N. J. Bax, R. J. Kloser, and F. R. McEnnulty. 2010. Scales of habitat heterogeneity and megabenthos biodiversity on an extensive Australian continental margin (100 - 1100 m depths). Marine Ecology: An Evolutionary Perspective 31:222-236.