Showing papers on "Indicator species published in 1993"

Diatom assemblages from Adirondack lakes (New York, USA) and the development of inference models for retrospective environmental assessment

Abstract: Detrended canonical coreespondence analysis (DCCA) was used to examine the relationships between diatom species distributions and environmental variables from 62 drainage lakes in the Adirondack region, New York (USA). The contribution of lakewater pH, Alm (monomeric Al), NH4, maximum depth, Mg, and DOC (dissolved organic carbon) were statistically significant in explaining the patterns of variation in the diatom species composition. Twenty-three and sixteen diatom taxa were identified as potential indicator species for pH and Alm, respectively (i.e. a taxon with a strong statistical relationship to the environmental variable of interest, a well defined optimum, and a narrow tolerance to the variable of interest). Using weighted-averaging regression and calibration, predictive models were developed to infer lakewater pH (r2=0.91), Alm (r2=0.83), DOC (dissolved organic carbon) (r2=0.64), and ANC (acid neutralizing capacity; r2=0.90). These variables are of key importance in understanding watershed acidification processes. These predictive models have been used in the PIRLA-II (Paleoecological Investigation of Recent Lake Acidification-II) project to answer policy-related questions concerning acidification, recovery, and fisheries loss.

Tintinnid ciliates as indicator species of different water masses in the western North Pacific Polar Front

Abstract: Distributions of 10 dominant tintinnid taxa and groups in the western North Pacific Polar Frontal Zone or the Sanriku Waters were analysed on T-S-Plankton diagrams to estimate their values as indicator species of water masses. Because it is difficult to identify the origin of water by conventional T-S analysis in areas such as this where three currents such as the warm Kuroshio, the Tsugaru Warm Current and the cold Oyashio are converging, reliable indicator species can be of great help in identification of the water masses. Normal cells of tintinnids with a soft body together with empty loricae were plotted separately on T-S diagrams. Because empty loricae of most species were distributed over wider ranges of temperature and salinity, or empty loricae might remain suspended in a particular water mass for a fairly long time, tintinnid species including empty loricae were recognized as reliable indicator species. Because contrastingly different tintinnid faunas were derived from the Kuroshio and the Oyashio, water masses originating from both currents were clearly traced by the indicator species as would be expected. Furthermore, by employing the appropriate indicator species defined on the T-S-Plankton diagram, it was also possible to identify the most similar pair of water masses, i.e. the Tsugaru Warm Current and mixture of the Kuroshio and the Oyashio, which cannot be identified by conventional T-S analysis.

Patterns in the benthic communities on the shelf of the sub-Antarctic Prince Edward Islands

Abstract: Benthic communities at the sub-Antarctic Prince Edward Islands were sampled qualitatively with an epi-benthic sled at 57 stations over a five year period. Additional information on these communities was obtained from replicate underwater photographs. In total, 546 macrofaunal species were found. Despite the extreme isolation and geological youth of the islands, there seems to have been a diverse colonisation. A cluster-analysis based on species abundance aggregated most stations into 8 groups. Each of these groups had a unique depth and substratum combination. Thourella variabilis (Octocoralea), and Cabarea darwinii (Bryozoa) characterised deep rocky assemblages and Serpula vermicularis, Lanice conchilega (Polychaeta) and Magellania kerguelenensis (Brachiopoda) characterised soft substrata. Indicator species separating each of the 8 clusters are given. Trends in percentage cover and densities of major taxa with respect to depth and substratum, as shown by photographs, are described. Deep, rocky substrata were dominated by Porifera, Bryozoa and Cnidaria, while soft-substrata were dominated by Polychaeta, Bivalvia and Brachiopoda. Errant forms consisted predominantly of Echinodermata, with Crustacea being important in shallower habitats. Filter-feeders dominated the benthos of the islands in all habitats.

Trends in copepod species abundances across and along a Gulf Stream meander: evidence for entrainment and detrainment of fluid parcels from the Gulf Stream

Abstract: Abundances of zooplankton populations are hypothesized to change across and along Gulf Stream meanders in response to meander-associated physical processes. Upwelling and northward detrainment of Gulf Stream water occur upstream of the meander crest (trailing flank) while downwelling and entrainment of Slope Water into the Gulf Stream occur downstream of the meander crest (leading flank). Two mesoscale zooplankton surveys of a Gulf Stream meander were conducted in autumn 1988 as part of the BIOSYNOP program to identify cross-stream trends and meander-associated changes in species abundances. The abundances of eight selected copepod species (five Sargasso Sea species, two Slope Water species and one widespread species) were enumerated from samples taken along three transects at different locations along the meander. The integrated abundances (0–1000 m) of seven of the selected species support the hypothesized entrainment and detrainment. Sargasso Sea species were more abundant across the upwelling flank than across the downwelling flank, whereas the opposite was true for Slope Water species. Species abundances on a trailing flank transect (upstream of the upwelling region) demonstrate effective transport of Sargasso Sea/Gulf Stream species out of the current into the Slope Water. The relative proportions of two copepod species (Pleuromamma borealis and P. gracilis) were sensitive to the processes of entrainment and detrainment in the meander, suggesting that these two species are useful indicator species of their respective water masses. Gulf Stream meanders may be sites of cross-stream exchange of plankton populations between the Sargasso Sea and the Slope Water.

A Review on the Copepods in the South Sea of Korea

Abstract: Ecological and taxonomical studies on the copepods were reviewed in order to dake data bases on the species composition, abundance, distributional pattern, and seasonal variations of copepods in the South Sea of Korea. Total 179 species have been reported in this area. The dominant species in the coastal waters and embayments, such as Acartia clausi, Paracalanus parvus, Oithona similis, and Oithona nana, were different from those reported in the offshore waters around Cheju Island. Indicator species of the South Sea were also discussed in this paper. Copepod abundances were higher in the coastal waters, up to more than 390,000 individuals/(collected with a mesh net), than in the offshore waters. There were two types of temporal variations in copepod abundances in the coastal waters, i.e., bimodal abundance peaks in spring and fall, md unimodal peak during summer to early fall.

Vertebrate abundance and wildlife habitat suitability near the Palmerton zinc smelters, Pennsylvania

Abstract: Wild vertebrates associated with habitats affected by two zinc smelters near Palmerton, Pennsylvania, were surveyed in 1986 and 1987. The objectives were to estimate abundance and distribution of vertebrate fauna, and to determine habitat suitability for 10 species of vertebrates at locations adjacent to and up to 15 km from the smelters. Sixteen species of amphibians and 51 species of birds were identified during surveys in April–July. The highest diversity of amphibians and birds occurred at habitats more than 5 km upwind or 5 km downwind of the smelters, whereas only a few species were observed or captured in areas within 5 km of the smelters where vegetation was minimal or absent. White-footed mice (Peromyscus leucopus) and southern red-backed voles (Clethrionomys gapperi) were captured during August 19–29, 1986. Mean capture rates were markedly higher at upwind and downwind sites compared with sites close to the smelters. Habitat unit scores for 10 indicator species, based on standard habitat evaluation procedures, were lowest at sites closest to the smelters. The lack of plant cover and generally low quality habitat were associated with the depauperate vertebrate community within 5 km of the zinc smelters.

Stickstoff-Immissionen als neuer Standorfsfaktor in Waldgesellschaften: neue Entwicklungen am Beispiel südwestdeutscher Wälder

Abstract: Investigations into the rate of atmospheric nitrogen deposition, of nitrogen recycling by litter and of nitrogen concentration levels in seepage water under different coniferous and broad-leaved tree stands in South-West Germany prove that the nitrogen status (e.g. input, turnover, balance) of the studied ecosystems is quite different from each other. The evident differences, presumably caused to a great deal by recent increase in deposition rates, is expressed by indicator species of ground vegetation only with delay and at a restricted scale. The species involved are correlated with more persistent site factors (e.g. soil reaction, buffer state, humus type), that do change only in a longer term. Species will show adapted reactions as their physiological reaction pattern is much greater than the ecological range in which they are normally present in actual forest vegetation types

Douglas-fir/white spirea habitat type in central Idaho: Succession and management. Forest Service general technical report

Abstract: The report includes a taxonomic system for classifying plant succession in the Douglas-fir/Pinegrass habitat type in central Idaho. A total of 10 potential tree layer types, 32 shrub layer types, and 60 herbaceous layer types are categorized. Diagnostic keys based on indicator species provide for field identification of the types. The discussion of management implications includes pocket gopher populations, success of planted and natural tree seedlings, big-game and livestock forage preferences, and responses of major shrub and herb layer species to disturbance.

The environmental quality of the sewage discharge area of Qingdao Cove—A cladistic analysis

Abstract: This study on the environmental quality of the Qingdao Cove intertidal zone sewage discharge area is based on data obtained from the December of 1989 and 1990 macrobenthos investigations there, and uses pollution indicator species and computer aided cladistic analysis to divide the area into a polluted area and a semipolluted area. The study showed the environmental quality in 1990 improved over that in 1989.