Benthic Species Diversity Research Articles

Scales of coastal heterogeneity and benthic intertidal species richness, diversity and abundance

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 136:111-121 (1996) - doi:10.3354/meps136111 Scales of coastal heterogeneity and benthic intertidal species richness, diversity and abundance Archambault P, Bourget E Species richness, diversity, total biomass of the benthic macrofauna and macroflora, and the biomass of the 2 dominant taxa (Fucus spp. and Mytilusedulis) were examined in relation to coastal heterogeneity at different scales in the intertidal zone. The sampling design included randomness at all scales and replication of treatments. A 103 km portion of the south shore of the St. Lawrence Estuary, Canada, was divided into 1 km stretches of shore (stations)-the large scale-which were classified using a shore heterogeneity index (SHI) into 3 categories (low, medium and high). Species richness was qualitatively evaluated for each station and substratum heterogeneity on a 100 m (medium scale) was measured as covariate. At the smallest scale 4 types of surface (smooth, crevices of 1, 10 and 20 cm) were quantitatively sampled. Species richness tended to increase with SHI category but this tendency was not statistically significant. A multiple regression analysis was carried out to find which scale of heterogeneity was the most significant for defining species richness. Diversity in types of surface did not vary significantly among SHI categories. Our results show that large-scale heterogeneity explained a higher proportion of the variance in species richness than substratum heterogeneity on a 100 m scale. No statistically significant difference was found in total biomass, M. edulis and Fucus spp. biomass or percent cover among the SHI categories. At the small scale (types of surface), the abundance increased significantly from smooth surfaces to 20 cm crevices except for mussels, where abundance was higher in 10 cm crevices. The types of surface explained 42% of the variation in total biomass and 21% of that in Fucus spp. biomass. Variation in percent cover was explained by the types of surface (40%) and to a lesser extent by the SHI (7%). The present study showed that the scales which influenced abundance were smaller than 20 cm in the intertidal zone. Thus, our results indicated that 2 distinct spatial scales explained the variability within the same marine intertidal community, i.e. variability in species richness (scale of 1 km) and in abundance (types of surface; scale of &LT=20 cm). Shore heterogeneity . Topographical heterogeneity . Small- and large-scale heterogeneity . Species richness . Diversity . Abundance . Benthos . Sampling design Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 136. Publication date: June 06, 1996 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1996 Inter-Research.

Benthic foraminiferal fauna during the time of the Indian-Asian contact, in southern Balochistan, Pakistan

Cretaceous and early Paleocene benthic foraminifera were studied from one section along the western Gaj River, southern Balochistan, Pakistan, to reconstruct the paleoenvironment of the Tethys Sea during the Indian-Asian contact. We recognize three lithostratigraphic units in ascending order: the Mughal Kot Formation, the Pab Sandstone, and the Jamburo Group. Both the Maastrichtian Mughal Kot Formation, which consists of shale with grey marly limestone, and the Maastrichtian Pab Sandstone, which consists of quartzose sandstone, indicate an open ocean environment as they have diversified planktic and benthic foraminiferal assemblages. The Maastrichtian-Paleocene Jamburo Group, consisting of dark grey, calcareous shale and marlstone with some sulfide grains, is characterized by low diversities of benthic assemblages. The change to the lower diversities may be associated with the development of poor circulation of deeper water that was caused by narrowing of the Tethys Sea. The Trochammina spp. Assemblage from the Jamburo Group, which can be correlated with flysch-type agglutinated foraminiferal assemblages, has a low benthic species diversity, indicating an unfavorable condition for calcareous foraminifera because of the development of oxygen-depleted water. The absolute abundance of agglutinated specimens shows a remarkable change from low numbers in the Maastrichtian to high ones in the Paleocene. The benthic foraminiferal evidence supports the hypothesis that the collision of the Asian and Indian plates occurred near the end of the Cretaceous.

Time-Based Correlation of Biogenic, Lithogenic and Authigenic Sediment Components with Anthropogenic Inputs in the Gulf of Mexico NECOP Study Area

Hypotheses related to variability in seasonal hypoxic conditions, coastal nutrient enhancement, and off-shelf transport of carbon on the Louisiana continental shelf were tested by characterization of biogenic, lithogenic, and authigenic components from two shelf and one Mississippi Canyon sediment cores. The authigenic-phase glauconite occurs above detection limits only in the core from the hypoxic area. A major increase in glauconite concentration was coincident with the onset (≈1940) of the increased use of commercial fertilizers in the United States. In the same hypoxic-area core, benthic foraminifera species diversity decreases upcore from approximately the turn of the century to the present in a manner concurrent with glauconite and fertilizer increases. A subset of opportunistic benthic foraminifera species, known to become more prominent in stressed environments (i.e., hypoxic), increased upcore from ∼52% of the total population at core bottom to ≈90% at core top. These benthic foraminifera population and diversity changes were not apparent in a “control” core outside the area of documented hypoxia. Seaward of the shelf, in the Mississippi Canyon, coincident increases in sediment accumulation rate, percentages of coarse fraction and of organic carbon at core top indicate increased offshelf transport of carbon and other components. Quartz percentages indicate that episodic down-canyon transport has been active to core bottom (prior to the mid 1800s).

Recent deep-sea benthic foraminiferal distributions in the South China and Sulu Seas

Thirty-nine surface sediment samples collected from the South China and Sulu Seas were examined to determine the bathymetric distribution of benthic foraminifera in these two basins and the factors responsible for these distributions. The benthic foraminiferal faunas of both basins are highly diverse but have low absolute abundances; benthic number and species diversity systematically decrease with increasing water depth. Four faunal assemblages were identified for each basin by Q-mode principal component analysis. The Globocassidulina subglobosa/Uvigerina assemblage (< 1500 m) and the Uvigerina assemblage (< 1400 m) represent the shallowest assemblages in the South China Sea and Sulu Sea, respectively, and are found within the oxygen minimum zone of each basin where the sedimentary organic carbon content is highest and the pore water oxygen penetration depth (Z o) is shallowest. The Bulimina aculeata assemblage occurs at water depths between 1700 and 2000 m in the southeastern South China Sea and is also associated with relatively high sedimentary organic carbon content. The Astrononion pusillum assemblage is found in South China Sea at the depths between 1500 and 3200 m. Below the lysocline (∼ 3200 m) in the South China Sea, this assemblage is replaced by the agglutinated Rhabdammina abyssorum assemblage. This assemblage reflects the presence of a water mass that is highly undersaturated with respect to calcite. In the Sulu Sea, the Pyrgo murrhina assemblage occupies water depths from 1400 to 2200 m. Below 2200 m, two deep water assemblages are present that are both dominated by Oridorsalis umbonatus. A correlation between various environmental and benthic foraminiferal variables indicates that salinity, temperature, sediment grain size, water depth, and bottom water oxygen concentration are not key factors controlling the benthic foraminiferal distribution in either the South China Sea or the Sulu Sea. Rather, organic carbon content and oxygen penetration depth in sediments appear to play important roles in determining the distribution of benthic foraminifera in both basins.

Community structure of macroinvertebrates inhabiting the rocky subtidal zone in the Gulf of Maine: seasonal and bathymetric distribution

Community structure of the macroinvertebrate fauna inhabiting a rocky subtidal habitat at Pemaquid Point, Maine, USA, was studied, using qualitative and quantitative descriptions of the distribution, diversity and abundance of benthic species, as well as their spatial (bathymetric) and temporal (seasonal) changes. A total of 60 species of macroinvertebrates representing 9 phyla were found in the 133 (0.25 m2) disruptive benthic samplings obtained by SCUBA between August 1984 and October 1986. Crustaceans, mollusks and polychaetes were best represented accounting for ca 77 % of the total number of species identified. Green sea urchln Strongylocentrotus droebachiensis and horse mussel Modiolus modiolus were consistently the most important (in biomass and density) assemblage components. Bathymetrically, there were clear patterns in the composition and abundance of macroinvertebrates. Sea urchins decreased in abundance with depth (from 5 to 18 m), while the opposlte was obsemed in horse mussels. Distribution and abundance patterns of remaining benthic macroinvertebrates were strongly influenced by the spatial distrlbuhons of sea urchins (at 5 and 10 m depth) and horse mussels (at 18 m). Species richness was higher In the deepest zone (18 m; 41 species) than In the shallower zones (5 and 10 m; 34 and 31 species respectively), due to the presence of clumps of A4. modiolus Comparative analysis at 18 m depth showed that the invertebrate fauna within I ~ o ~ ~ o ~ u s beds i significantly more abundant, dense, and dlverse than that outside pointing out the functional importance of Modolus beds in providing spatial refuges from predators, and suitable and stable mlcrohabitats for numerous invertebrates. No significant temporal changes were observed in the biomass and density of the invertebrate community. Number of species, however, showed marked seasonal vanations. Maximum values occurred during summer, intermediate values in fall and spring, and mlnimum values in winter, probably related to migration or changes in activlty of some species. Results of this and other studies indicate that coralline communities, despite their low primary productivity, are ecological systems with relatively high species diversity and secondary productivity, sometimes comparable to systems dominated by kelps.

Biogenic sedimentation in McMurdo Sound, Antarctica

Surface sediments from eastern McMurdo Sound and fjord basins of the Victoria Land Coast are enriched in organic carbon and opal. At depths below 600 m, opal contents commonly exceed 30%; organic carbon contents average 1.5% and are as high as 3.5%. Opal and organic carbon are supplied by local production within and below sea ice and by advection from open water areas of the southwestern Ross Sea. The distribution of organic carbon and opal at the sea floor is consistent with cyclonic (clockwise) water circulation in McMurdo Sound. Advective transport from the Ross Sea supplies biogenic sediment to eastern and northern McMurdo Sound; the southwestern shelf is bathed by waters derived in part from beneath the Ross Ice Shelf which transport very little allochthonous carbon. The supply of biogenic debris in southwestern McMurdo Sound is further curtailed by sea-ice conditions, e.g., more prevalent multi-year sea ice which reduces photosynthesis, and the absence of summer basal melting and ice breakout which restricts the flux of sea ice and open-water production to the sea floor. Consistent with this hypothesis, organic carbon fluxes measured via sediment trapping beneath fast ice are one to two orders of magnitude higher in eastern versus western McMurdo Sound. Pronounced cross-sound gradients in shallow water benthic biomass and species diversity have previously been attributed to east-west variations in productivity. Our surface sediment data suggest that similar or even more dramatic contrasts in benthic community structure may exist in the deeper water areas of McMurdo Sound. Pervasive resuspension is documented by pronounced near-bottom flux increases measured by sediment trapping. Resuspension events, which may be more common during the austral winter, act to winnow and transport biogenic debris and fine terrigenous sediment from shallow regions (< 400 m) to protected shelf basins. Despite oxidative loss within the water column, the accumulation rate of organic carbon in the deep basins of McMurdo Sound averages 45 mg C m −2 day −1, more than an order of magnitude higher than the world average organic carbon flux to continental margins and equivalent to accumulation rates observed in many anoxic settings. Preservation efficiency of opal during transport and deposition appears anomalously high and the most opal-rich sediments of McMurdo Sound are depleted in organic carbon relative to mid- and low-latitude siliceous deposits. Despite this observation, if similar patterns of biogenic sedimentation exist on many other parts of the shelf, the Antarctic continental margin is an important sink for sedimentary organic carbon, as has been previously suggested for the silica system.

Composition and Productivity of the Benthic Macroinvertebrate Community of a Subtropical Reservoir

AbstractPhysical‐chemical conditions, phytoplankton productivity, community structure and productivity of the macroinvertebrate benthic community were determined during 1976–77 in a subtropical reservoir. Physical‐chemical results revealed high nitrate and phosphate concentrations with highest values in the riverine segment. Large phytoplankton populations were present during most of the year. Phytoplankton productivity was high, producing an annual mean of 87 mg C · m−3 · h−1 (12 hours light day). High turbidity in the riverine segment limited phytoplankton productivity during winter and spring. Macrobenthos was dominated by chironomids (Chironomus, Procladius, Coelotanypus and Tanypus) and oligochaetes (Limnodrilus). The annual mean benthic population was estimated at 1,626 · m−2 with a mean dry weight of 0.66 g · m−2. Mean benthic species diversity was 1.80. A lacustrine‐riverine community gradient was revealed. Benthic productivity was 6.8 g · m−2 · yr−1 (dry weight) with a P: B ratio of 10. A low correlation was observed between benthic and phytoplankton productivity, and between phytoplankton standing crop and benthic macroinvertebrate numbers throughout the reservoir. Algal food supplies had little impact on the benthic community which was composed predominately of species which fed mostly on organic detritus. Stressful conditions caused by low dissolved oxygen concentrations probably inhibited development of the benthic community throughout the reservoir during summer months, while high sedimentation rates limited development in the head waters.

Neutral modelanalysis of patterns of marine benthic species diversity

Neutral modelanalysis of patterns of marine benthic species diversity

Effects of dredging on the macrobenthic infauna of Botany Bay

The macrobenthic. infauna of dredged and undredged areas in Botany Bay were sampled. Data were analysed using tests of significance and computer classification. While dredging has not significantly affected average species density per sample, the benthic fauna of dredged areas differs from that of nearby undredged areas with respect to species composition and richness. both of which appear to be strongly associated with sediment type. Species richness. in particular. is generally higher in areas characterized by sand than in those characterized by, mud. Thus, where dredging has brought about a change in sediment type from sand to mud, species richness has decreased. This has occurred in the dredged areas near the Kingsford-Smith Airport extension and Port Botany revetment. However, in the region of the entrance to the bay, where harsh conditions of high swell and current exposure apparently normally limit benthos. the deeply dredged entrance channel supports a particularly diverse and abundant fauna. It is concluded that the major influence of dredging on the macrobenthos in Botany Bay has been indirect, through permanent modification of its physical environment. Extension of the present facilities at Port Botany are expected to lead to a significant decrease in the benthic species diversity of this area.

Effects of dredging operations on estuarine benthic macrofauna

Dredging operations in a Swedish estuary reduced the number and diversity of benthic species. The larval recruitment in the vicinity of the dredged area was strongly affected. An overall increase in concentrations of Hg, Cd, Zn, Cu, Pb and Ni were recorded in benthic fauna. One and a half years after termination of dredging, the benthic community structure was nearly restored and the high concentrations of heavy metals had decreased considerably.

Benthic fauna species diversity in six central Florida lakes in summer

The summer macroinvertebrate fauna was studied in six central Florida monomictic lakes during July, 1973. No direct relationships were found between physiochemical conditions and species diversity. Of the 22 species of benthic organisms recorded, only four species were found in all the lakes. Mean species diversity (d) values for the lakes ranged from 0.735 to 1.731.