SEDIMENTARY PIGMENTS AND ORGANIC-CARBON IN RELATION TO MICROALGAL ANDBENTHIC FAUNAL ABUNDANCE IN THE GULF-OF-CARPENTARIA

Sediment samples were collected at 105 sites throughout the Gulf of Ca rpentaria, Australia, in November-December 1990. Highest concentration s of chlorophyll a in the sediment occurred in 3 regions: the southeas t, the northeast and the western Gulf. Fucoxanthin, the pigment indica tive of diatoms and prymnesiophytes, was present at most sites. Astaxa nthin, present in microcrustaceans, was most highly concentrated in th e same areas as chlorophyll a. The concentration of organic carbon was highest in the northwest and decreased towards the southeast, and was correlated with an increase in sediment grain size. Correlation analy ses of pigments, environmental parameters and macrobenthos indicated r elationships between individual pigments, and between pigments, mollus cs, polychaetes, crustaceans and depth. When the variation due to sedi ment grain size was statistically controlled for, organic carbon was f ound to be a poor indicator of biological factors in the sediment.