Abundance Of Species In Habitats Research Articles

Ecological Survey of Aquatic Snails in Man-made and Natural Water bodies in Benue State.

The epidemiological implications of fresh water snails have continued to pose serious challenge to schistosomiasis control. A survey was conducted to ascertain the species diversity and abundance of aquatic snails in man-made and natural water bodies in Benue state, Nigeria. Eight sites were sampled for the presence of snails using the sweep net and handpicking method. Snails captured were carefully placed into pre- labelled specimen bottles and transported to Benue State University Zoology Laboratory for identification. Plants commonly known to be suitable for snail attachment were collected and brought to the Botany laboratory for identification. The physiochemical parameters of the water were also documented. Data was processed using Analysis of Variance (ANOVA). A total of 1038 snails belonging to 3 species were identified; Melanoides tuberculata, 468 (45.1%), Lanistes libycus 210 (20.2%), Bulinus species 360 (34.7%). Northbank dam harboured 2 (Bulinus and Melanoides) out of the 3 species recorded, making it the most favourable habitat sampled. Bulinus species was the most abundant in the natural habitats while it was replaced by Melanoides tuberculata in the man-made water bodies. ANOVA revealed a significant difference in relation to snail species encountered, and species abundance in habitats sampled (P< 0.05). The predominant aquatic flora encountered were Ipoemoea aquatic and Nelsonia species. The study revealed that natural and man-made water bodies in Makurdi and Ochobo support the breeding of snail species that have serious epidemiological implications.

Biological characteristics influence mammal road kill in an Atlantic Forest–Cerrado interface in south-western Brazil

Few studies have addressed mortality causes of neotropical mammals on roads, especially considering the extensive road system and biodiversity. The goal of this article was to examine the biological factors related to mortality of non-volant mammals on roads of an Atlantic Forest–Cerrado interface in Brazil. Mammals were recorded during a seven-year period and over 3900 km of roads, in order to estimate data for abundance of species in habitats (areas) and frequencies of species killed by cars on roads. Areas (n = 80) within two adjacent ecoregions (Atlantic Forest, n = 23; Cerrado, n = 57) were searched for records of mammals. Thirty-two species were surveyed, comprising 480 dead mammals on the roads and 503 records of the presence of species in adjacent habitats. Ten species that have been recorded in these habitats were never found dead on the roads, which could indicate road avoidance behaviour. Correlations and multiple regressions showed that abundance is the more important variable influencing road kill, followed by habit (nocturnal/diurnal) and threat category. Therefore, large-sized and threatened species tended not to be run over, as well as agile, mostly diurnal, or recent, advanced species (carnivorous or herbivorous). The data are discussed in the light of Road Impact Index (RII), with five species exhibiting high RII (Cerdocyon thous, Dasypus novemcinctus, Euphractus sexcinctus, Myrmecophaga tridactyla and Tamandua tetradactyla) being run over more than expected bases on their abundance, and dozens of species exhibiting lower RII, belonging to those avoiding or being isolated by roads.

Interseasonal Changes in Shorebird Habitat Specialisation in Moreton Bay, Australia

SummaryHabitat use by shorebirds in Moreton Bay was examined by monitoring 56 intertidal study sites during southward and northward migrations between 1988 and 1990. Sites were selected to include four areas in Moreton Bay that had distinct intertidal habitats (mainland, island, coral and sewage habitats). At each site, the relative abundance of species was recorded and habitat assessed using sediment particle size analysis and visual assessment of sea-grass coverage. Spatial and temporal patterns of habitat use were characterised by variation in the relative abundance of species in habitats. Spatial and temporal patterns were integrated by seeking patterns that could explain the variability in community structure between different times of year, and that could be attributed to temporal aspects of migration. Species diversity and measures of habitat specialisation supported the prediction that shorebirds are more concentrated within preferred habitat during the northward compared with the southward migration in Moreton Bay, and that the size of this change is related to the respective degree of specialisation of each species. The change between seasons may have been caused either by greater energy reserves of individual birds at the time of northward migration or an increase in the ability of first-year birds to locate suitable habitat by this time of year. The protection of all habitats in Moreton Bay is required to conserve the full range of shore-bird species using both the eastern and western portions of the Bay.