Variation in the size and abundance of the dictyocerid sponge, Coscinoderma matthewsi, at different spatial scales in central and eastern Torres Strait, Australia (MTSRF Project 1.3.2)

Abundance and size of the sponge Coscinoderma matthewsi was surveyed at 5 island groups in November 2006: Ugar (Stephen Island) and Erub (Darnley Island) in eastern Torres Strait; and Masig (Yorke Island), Poruma (Coconut Island) and Warraber (Sue Island) in central Torres Strait. These island groups are on average, 66 km apart.Surveys were carried out at 7 or 8 randomly selected locations in each island group with each location at least 2 km apart, averaging 8 km. Each location was divided into 2 sites, approximately 200 m apart. At each site, three 30 x 1 m strip transects, separated by at least 20 m in depths between 7-12 m were quantitatively surveyed for Coscinoderma matthewsi. The greatest dimension of every Coscinoderma matthewsi was measured with a ruler to examine size frequency distribution patterns. For any diseased sponge, the percent of infected or necrotic pinacoderm was noted. Environmental factors were also recorded: angle of the reef slope and percentage benthic cover of rock, rubble and sand. This research was undertaken to:1. assess the abundance and size of a commercial bath sponge species, Coscinoderma matthewsi, at different spatial scales in Torres Strait. 2. identify elements of environmental risk (evidence of disease, sedimentation, invasives).