Seagrass surveys of Exmouth Gulf

A preliminary survey of seagrass communities in Exmouth Gulf, Western Australia, found very low abundances of seagrasses. This seems surprising given the abundance of seagrass beds elsewhere in northern and western Australia, and the highly productive prawn fishery in the gulf; prawn fisheries are usually associated with seagrass systems. Quantitative and qualitative survey of 64 sites, mainly in the inaccessible south and east of the gulf, in September 1994, indicated that seagrasses were neither extensive nor abundant. Percent covers were rarely over 5-10%. Predominant seagrasses were species of Cymodocea Konig, at depths of 0-5 m, and Halodule Endlicher in intertidal areas. Species recorded were largely in accordance with published distribution ranges. Subjective assessments indicate that epiphytic and epilithic ephemeral macroalgae contribute significant amounts of production, compared to seagrasses. The lack of extensive seagrass beds is considered in terms of the physical environment of the gulf, and in terms of the carbon source for the highly productive prawn fishery. Despite the ecological and economic importance of seagrasses, this survey is only the second published account of seagrasses for the coast between Shark Bay, Western Australia, and the Gulf of Carpentaria.