Infaunal benthic community structure and function in the Gulf of Carpentaria, northern Australia

1994 ◽  
Vol 45 (3) ◽  
pp. 293 ◽  
Author(s):  
BG Long ◽  
IR Poiner
Keyword(s):  
Species Richness ◽  
Species Density ◽  
Physical Factors ◽  
Suspension Feeding ◽  
Sediment Texture ◽  
Surface Deposit ◽  
Feeding Mode ◽  
Sediment Grain Size ◽  
South Eastern ◽  
Deposit Feeders

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.

scholarly journals Historical Shifts in Benthic Infaunal Diversity in the Northern Gulf of Mexico since the Appearance of Seasonally Severe Hypoxia

Diversity ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 49
Author(s):  
Nancy N. Rabalais ◽  
Melissa M. Baustian
Keyword(s):  
Species Richness ◽  
Dissolved Oxygen ◽  
Bottom Water ◽  
Benthic Communities ◽  
Penaeid Shrimp ◽  
Severe Hypoxia ◽  
Low Oxygen ◽  
Large Area ◽  
Surface Deposit ◽  
Deposit Feeders

Severe and persistent bottom-water hypoxia (≤2 mg O2 L−1) occurs on the Louisiana/Texas continental shelf from mid-May through mid-September over a large area (up to 23,000 km2 in mid-summer). Benthic infauna are less mobile than demersal organisms and become stressed by the low dissolved oxygen; benthic community composition, abundance, diversity, and biomass become altered. From the 1950s to the early 1970s, when sediment core indicators identified the initiation and subsequent worsening of dissolved oxygen conditions, there were no hydrographic data or benthic infaunal studies within the current area of frequent bottom-water hypoxia. This study highlights the impacts of severe hypoxia on benthic macroinfaunal communities and how they may have changed from less-hypoxic periods. Polychaetes were and are the dominant taxa in the available studies, but polychaete species richness in summer is now curtailed severely beginning with our 1985–1986 data. Species richness of polychaetes in summer hypoxia (1985–1986 and 1990–1991) was about 60% less than comparable taxa in 1972–1973. Abundance of polychaetes was much less in summer than spring, and recent infaunal biomass in summer was only 15% of what was found in spring. The result is less prey for demersal penaeid shrimp and fishes. Over the period of our comparison, infaunal feeding modes shifted from subsurface deposit feeders and surface deposit feeders to primarily surface deposit feeders (i.e., 95.5% of all polychaetes). Most were opportunistic, hypoxia tolerant, and recruited in high numbers following hypoxia abatement, some in fall and winter but most in spring. As benthic communities succumb to the stress of severe and continued seasonal low oxygen, they occupy the few upper centimeters of the sediment profile above the redox discontinuity layer with negative feedbacks to the water column by way of altered biogeochemical processes.

The first 2 million years after the Cretaceous-Tertiary boundary in east Texas: rate and paleoecology of the molluscan recovery

Paleobiology ◽  
1993 ◽  
Vol 19 (2) ◽  
pp. 251-265 ◽  
Author(s):  
Thor A. Hansen ◽  
Benjamin R. Farrell ◽  
Banks Upshaw
Keyword(s):  
Species Richness ◽  
Primary Production ◽  
Relative Abundance ◽  
Species Turnover ◽  
Suspension Feeding ◽  
East Texas ◽  
Number Of Species ◽  
Deposit Feeders ◽  
Depletion Curve ◽  
Study Interval

Analysis of molluscan collections from a 3+ m.y. interval around the Cretaceous–Tertiary (K–T) interval in east Texas suggests that molluscs suffered an extinction at or near the K–T boundary, followed by a prolonged period of stress which lasted through the P0 and P1a planktic foraminiferal zones. The stressed period was characterized by low species richness, low abundances of individuals, high species turnover and a dominance of deposit feeders. Species richness and the relative abundance of deposit feeders generally track the 13C depletion curve suggesting that the stress was caused by a lack of primary production. A stable, relatively diverse, suspension feeding molluscan community was reestablished less than two million years after the K–T boundary. The total number of species within the habitat did not recover to Cretaceous levels within the study interval.

Species richness, distribution pattern, and conservation status of amphibians in Cross River National Park, south‐eastern Nigeria

Biologia ◽  
2021 ◽  
Author(s):  
Lotanna Micah Nneji ◽  
Adeniyi C. Adeola ◽  
Babatunde E. Adedeji ◽  
Omotoso Olatunde ◽  
Abiodun B. Onadeko ◽  
...  
Keyword(s):  
Species Richness ◽  
Distribution Pattern ◽  
National Park ◽  
Conservation Status ◽  
Cross River ◽  
South Eastern

scholarly journals Polymorphy and extinction of the Late Cretaceous burrowing shrimp Protocallianassa faujasi and first record of the genera Corallianassa and Calliax (Crustacea, Decapoda, Thalassinoidea) from the Cretaceous

2001 ◽  
Vol 70 (2) ◽  
pp. 85-98 ◽  
Author(s):  
Krista Swen ◽  
René H.B. Fraaije ◽  
Gijsbert J. van der Zwaan
Keyword(s):  
New Species ◽  
First Record ◽  
Suspension Feeding ◽  
Feeding Mode ◽  
Male And Female ◽  
Immature Male ◽  
Type Area ◽  
Mode Of Life ◽  
Burrow Morphology

A biometric study of chelae of the burrowing shrimp Protocallianassa faujasi ( Desmarest, 1822), from the late Maastrichtian of the Maastrichtian type area, The Netherlands, has revealed three morphotypes. These types are interpreted as sexual dimorphs (male and female) and earliest ecdysis stages (immature male). Among the studied material are fifteen specimens of a new Cretaceous callianassid, Corallianassa acucurvata new species, one specimen provisionally assigned to the genus Calliax and a callianassid from the Danian. Burrows preserving callianassid chelae in situ are discussed. Based on burrow morphology a suspension feeding mode of life for P.faujasi is inferred, whereas C. acucurvata n. sp. probably was an active omnivorous analogue of its closest Recent relatives. The extinction of P. faujasi in the Meerssen Member appears to correspond to the increase in seagrass vegetation. The Protocallianassa-Corallianassa faunal changeover took place about 100,000 yrs before the K/T boundary in this region.

The effects of forest fragmentation on species richness on the Obudu Plateau, south-eastern Nigeria

2012 ◽  
Vol 51 (1) ◽  
pp. 32-36 ◽  
Author(s):  
Filibus Danjuma Dami ◽  
Georgina Samuel Mwansat ◽  
Shiiwa A. Manu
Keyword(s):  
Species Richness ◽  
Forest Fragmentation ◽  
South Eastern

scholarly journals Diversity and distribution of crustaceans from 13 sheltered sandy beaches along São Sebastião Channel, south-eastern Brazil

2001 ◽  
Vol 81 (3) ◽  
pp. 475-484 ◽  
Author(s):  
P.R. Nucci ◽  
A. Turra ◽  
E.H. Morgado
Keyword(s):  
Organic Matter ◽  
Organic Matter Content ◽  
Clay Content ◽  
Fine Sand ◽  
Sandy Beaches ◽  
Matter Content ◽  
Sediment Grain Size ◽  
Crustacean Species ◽  
South Eastern ◽  
Eastern Brazil

The crustacean species composition in the intertidal zones of 13 sheltered unconsolidated marine beaches in south-eastern Brazil is described. Fifty-three crustacean species were collected, adding 46 species to the total reported by previous studies in the same region. Decapods dominated the community, in contrast to exposed sandy beaches where peracarids normally predominate. The species were distributed irregularly among the beaches. Richness varied markedly among sites, and was positively related to a combination of factors such as fine sand grains, high organic matter content, and relatively low silt–clay content. The presence of rock fragments enabled both rocky shore and sandy beach crustaceans to occur on the same beaches. Richness and abundance of crustaceans showed no clear relationship to sediment grain size and slope, in contrast to the norm for exposed sandy beaches. The dominance of the tanaid Kalliapseudes schubarti in some areas may be a result of organic matter pollution in the region. These beaches showed higher species richness than typical sheltered and exposed sandy beaches, indicating that this sheltered, highly heterogeneous seascape is an important area for conservation.

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