Short term monitoring of biotic change in Tasmanian marine reserves

Fishes, large invertebrates and macroalgae inside four marine reserves and at associated external reference sites off the eastern Tasmanian coast were censused between 1992 and 1993 shortly after the declaration of the reserves. Changes in several population parameters during the first year of protection in the largest Maria Island Marine Reserve were examined using two different ANOVA designs. The densities of rock lobsters and sea urchins and the mean sizes of wrasse, leatherjackets, abalone and rock lobsters all increased within the reserve relative to outside over the first year; however, only the increases in density of sea urchins and mean abalone size were statistically significant at the 5% level. The census methodology and statistical techniques nevertheless were considered sufficiently sensitive to reveal any long term change following future censuses. A doubling in population numbers of most large fishes and invertebrates, or a 10% increase in the mean size of animals, is required to indicate that significant change has occurred.