The infaunal benthos (>20 m) of the Gulf of Carpentaria was surveyed during November and
December 1990. In all, 684 taxa were collected from 105 stations, each with three replicate 0.1-m2
grab samples (Smith-McIntyre grab). Trends in abundance and species richness were correlated with
gulf-wide trends in sediment texture and depth. Highest abundance (20-153 individuals per 0.1 m2),
wet-weight biomass (X=7.6 g per 0.1 m2) and species density (X=25.8 taxa per 0.1 m2) occurred in
the sands and muddy sands along the eastern and south-eastern margins of the gulf. Lowest abundance
(3.3-20.0 individuals per 0.1 m2), biomass (X=3.0 g per 0.1 m2) and species density (X=9.5 taxa
per 0.1 m2) occurred in the muds and sandy muds in the centra, western and north-western gulf.
Infaunal abundance and biomass were similar to those of other tropical continental shelves but were
lower than those of some temperate-region shelves and upwelling areas. Species richness was also lower
than in temperate areas of upwelling or high production.
Scavengers/carnivores (44%) and deposit feeders (43%) numerically dominated throughout the gulf.
Suspension feeding was less prevalent (13%), and few herbivores were found (< 1%). There was a trend
in the proportion of deposit and suspension feeders that was related to sediment texture. Suspension
feeding was highest in the muddy sands of the eastern and south-eastern gulf and lowest in the muds
of the north-west. The proportion of deposit feeders was highest in muddy sediments and lowest in
sandy sediments. Small (<5 mm) surface deposit feeders numerically dominated within this feeding
mode.
The 15 numerically dominant taxa were comprised mainly of opportunistic or second-stage colonizing
taxa. Most had gulf-wide distribution patterns, but levels of abundance were correlated with sediment
and depth.
The infaunal benthic communities in the Gulf of Carpentaria appear to be regulated by physical
factors of the environment that correlate with sediment grain size and depth.
The Gulf of Carpentaria is a large embayment less than 70 m deep on Australia's remote northern
coastline. This paper, which describes aspects of its hydrology and variation in sediment types, is part
of a larger study of the size and distribution of commercial fish resources of the gulf. Much of the
data on the hydrology and sediments were collected during a gulf-wide survey in November and
December 1990.
Waters in the central part of the gulf were found to be vertically stratified, with bottom temperatures
just below 25°C and surface temperatures around 30°C. The waters to the north of the gulf
remained well mixed, presumably because of greater tidal mixing through the Torres Strait. In contrast
to water temperature, salinity was relatively uniform throughout the water column: between 35
and 36.
In depths below 20 m, there was a clear trend in sediment grain size, from sediments of >80%
>63 pm (sandy) in the south-eastern gulf to sediments of > 80% < 63�m (muddy) in the north-west.
A second muddy zone was also evident in the coastal zone (<20 m) in sheltered embayments or
adjacent to rivers.
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 pryrnnesiophytes, 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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.