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

Sediment samples were collected at 105 sites throughout the Gulf of Carpentaria, Australia, in November-December 1990. Highest concentrations of chlorophyll a in the sediment occurred in 3 regions: the southeast, the northeast and the western Gulf. Fucoxanthin, the pigment indicative of diatoms and prymnesiophytes, was present at most sites. Astaxanthin, present in microcrustaceans, was most highly concentrated in the 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 analyses of pigments, environmental parameters and macrobenthos indicated relationships between individual pigments, and between pigments, molluscs, polychaetes, crustaceans and depth. When the variation due to sediment grain size was statistically controlled for, organic carbon was found to be a poor indicator of biological factors in the sediment.