The Distribution of Intertidal Crabs in the Brisbane River

Abstract

This paper records investigations made on the ecology of intertidal crabs of the Brisbane River.

Traverses were made at selected localities extending from the river mouth upstream to points beyond the limit of tidal influence. Twenty-three species of crabs were found, two of which extend 37 miles upstream. The population was found to fall into four clearly defined vertical zones: (1) sesarmine zone, H.W.N. upwards, (2) ooypodine zone, H.W.K. to M.S.L., (3) upper macrophthalmine zone, M.S.L. to L.W.X., and (4) lower macrophthalmine zone, L.W.N. to L.W.S.

After drought, species not usually found in the river were present in the lower reaches. Freshwater flooding caused disappearance of these from the river and reduced the upstream penetration of one species.

Comparisons with work in other parts of the world show that the estuarine crab distribution in the Brisbane River is similar to that in South Africa and Java. It is suggested that salinity is the most important factor controlling the distribution of estuarine crabs.