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1.
The surface sediment, subsurface sediment, and hyporheos were sampled by freeze‐coring at three sites of contrasting geomorphology in a New Zealand gravel‐bed stream. No differences in size class composition were detected among the subsurface sediments of the three sites but the forced pool‐riffle (a stretch of stream where the sequence of pool and riffles is controlled by in‐channel bedrock outcrops) had significantly finer surface sediments than the other sites. The hyporheos of all sites was dominated numerically by insects, including nymphs of Deleatidium and Oniscigaster, and chironomid larvae. Of the non‐insect taxa, Isopoda, Oligochaeta, and Acari were most common. No significant differences existed between total invertebrate density or taxon richness at the sites. Aoteapsyche was found only in the plane bed site, whereas Nesameletus was found only in the forced pool‐riffle. Psilochorema and Nematoda occurred at significantly lower densities in the forced pool‐riffle than in the plane bed or floodplain sites. For most taxa, local variation within a site was greater than that between sites. Total invertebrate density was highest near the sediment surface but no significant differences were found between the three sites in this or any other depth layer. Significant site‐depth interactions were obtained for three taxa (Zelandobius, Ostracoda, and Oligochaeta) indicating that local geomorphology may result in differential depth distributions of hyporheic species. 相似文献
2.
Hyporheic invertebrates were sampled in six small headwater streams draining pine, pasture, and native forest catchments. Sites were sampled in autumn and spring using three different hyporheic sampling methods (colonisation pots, pump sampling, and freeze‐coring). Total invertebrate abundance and taxon richness differed significantly among sites on both sampling occasions for pump samples, whereas freeze‐coring did not discriminate among sites, and pot samples showed significant differences in autumn, but not in spring. Differences among sites with respect to community composition were not consistent between sampling methods. Community ordination indicated that samples from colonisation pots tended to group together, whereas pump and freeze core samples were widely separated. Differences across land uses were also apparent (native forest sites formed a distinct cluster separated from pine and pasture sites). Results suggest that colonisation pots may provide a pathway for the entry of epigean organisms into the hyporheic zone even when hydraulic connectivity between surface and hyporheic zones is low. Invertebrate abundance was very low in pump samples, and this method also captured the fewest taxa of the three methods. The size bias known to exist with pump sampling techniques may restrict the usefulness of the method when comparing streams of differing hydraulic conductivity. 相似文献
3.
ABSTRACT Understanding temporal patterns in restored environments is important for identifying potential barriers to recovery and improved management of degraded habitats. In this paper, we use temporal beta diversity analyses to compare invertebrate community recovery trajectories in three restored agricultural stream sites under different integrated catchment plans, a native forest reference site, and two unmodified pasture control stream sites over 24 years. The restored sites diverged from their initial community composition over time and became more similar to the reference site community, which was relatively stable over time. Variation partitioning showed that prior to restoration beta diversity was primarily associated with environmental and spatial drivers, whereas post-restoration beta diversity was more influenced by temporal and environmental drivers, including changes in substrate size, fine sediments, water clarity, and nutrients, as well as temperature and flow regime. Species’ contributions to beta diversity varied between sites and years, with sensitive EPT taxa contributing more in reference and control sites. However, contributions of some EPT species, particularly mayflies, increased in restored sites post-ICM. In summary, after nearly two decades of ICM, restored stream sites show recovery towards reference conditions, yet differences persist, indicating that rehabilitation may take longer, depending on the restoration goals. 相似文献
4.
E.L. Wenner D.M. Knott R.F. Van Dolah V.G. Burrell 《Estuarine, Coastal and Shelf Science》1983,17(2):143-158
Epibenthic invertebrates associated with nine hard bottom areas in the South Atlantic Bight between South Carolina and northern Florida were collected with dredge, trawl, suction and grab samplers to evaluate species composition, biomass, abundance, diversity, spatial distributions, and seasonality (winter and summer). Species composition changed noticeably with depth and season. Inner and outer shelf stations were least similar in species composition. Middle shelf areas were transitional and contained taxa characteristic of both inner and outer sites. Bryozoa (88 taxa), Cnidaria (85 taxa), Porifera (67 taxa), Annelida (261 taxa) and Mollusca (203 taxa) represented the richest taxonomic groups of the 1175 taxa collected. Both diversity (1175 total taxa) and biomass (1995 kg total) of invertebrates from hard bottom areas exceeded those reported in the literature for sand bottom communities. Sponges accounted for >60% of the total invertebrate biomass collected by dredge and trawl during both seasons. High diversity values were attributed primarily to habitat complexity and did not exhibit any discernible pattern with depth or latitude. 相似文献
5.
Johanna Mattila Glen Chaplin Michele R. Eilers Kenneth L. Heck Jr. Jonathan P. O'Neal John F. Valentine 《Journal of Sea Research》1999,41(4):209
Fish, epibenthos and macroinfauna were collected in a Zostera marina bed and nearby unvegetated sediments in the estuary of the Damariscotta River, on the mid-coast of Maine. Samples of epibenthic fauna and fish were collected at low tides both during day and night, and samples of infauna at low tides during the day. The mean density of Zostera shoots in the study area was 335 m−2. Abundance and species number of fish were greater at night than during the day and greater in eelgrass beds (Z. marina) than in unvegetated habitats. Daytime fish collections were dominated by Atlantic silversides (Medinia medinia), while juvenile winter flounder (Pseudopleuronectes americanus) dominated night collections. Also Zostera-associated epifaunal abundances and number of species were significantly higher at night than during the day. Mysis stenolepis, Idotea balthica and Littorina obtusata were dominant species in the epifauna samples. Of the total of 37 invertebrate species encountered, only five occurred both in the infaunal and epifaunal samples. Nineteen different taxa were collected from the benthic core samples. The most abundant invertebrate infaunal taxa were sipunculids, the polychaete Nereis virens, and oligochaetes. Infaunal invertebrate abundances and species diversity were significantly higher in eelgrass beds than in unvegetated sediments. The abundance and number of species of benthic invertebrates were also positively correlated to seagrass biomass. Community diversity values (H′) were relatively low but fit well in the general pattern of decreasing diversity towards northern latitudes. 相似文献
6.
Invasive fish eradication is a key management strategy in aquatic ecosystems, and is often accomplished using piscicides such as rotenone. However, the effects of piscicides on aquatic invertebrate communities are poorly understood, particularly over long time scales. We monitored invertebrate communities in two treatment and two reference streams prior to and for one year following the use of rotenone to eradicate trout in Zealandia wildlife sanctuary, Wellington. Immediately following treatment, invertebrate density and taxonomic richness declined significantly, and community composition diverged markedly relative to reference streams, with pollution sensitive taxa declining greater than more tolerant taxa. Treatment streams recovered to pre-treatment conditions within 4–12 months of rotenone application, indicating minor long-term impacts on invertebrate communities. Speed of recovery of individual taxa appeared to be associated with life history variables, e.g. generation times and dispersal ability. Untreated upstream reaches and nearby water bodies likely facilitated successful invertebrate community recovery. Our results demonstrate that rapid recovery of New Zealand stream invertebrate communities is possible within one year of rotenone application. 相似文献
7.
Aspects of sea-bed structure and benthic-macroinvertebrate species composition, distribution, richness and diversity in coastal waters off eastern Waiheke Island, Hauraki Gulf, are reported. In contrast to the sole historical account of sea-bed community structure from this same region, no widely distributed assemblages of species are recognised throughout it; no two sites share the exact same complement of species; and almost all sites are less than 80% similar in their taxonomic composition, most considerably so. Species richness and diversity are reported to vary with substratum type and depth, and spatially; species occurring within muds are the least diverse and species rich, followed by those of muddy gravels, and then gravels; many taxa prove common to the three substratum types; and dominance of taxa is recognised to decrease with an increase in substratum complexity, from muds to gravels, and species richness. With the exception of invasive marine species, apparent changes in the composition of assemblages throughout this region over the eight-decade period that data span are considered artefacts of the way in which such assemblages were historically defined. We recommend historical accounts of sea-bed community distributions throughout Hauraki Gulf be interpreted with caution, especially when attempting to use such schematic depictions to determine whether changes have occurred in assemblage composition. 相似文献
8.
Suzi M. Ribeiro Elianne P. Omena Guilherme Muricy 《Estuarine, Coastal and Shelf Science》2003,57(5-6):951-959
The macrofauna (endo- and epi-biotic) associated to the sponge Mycale (Carmia) microsigmatosa Arndt, 1927 was studied at three sites in Rio de Janeiro State, Brazil (Arraial do Cabo, Niterói, and Rio de Janeiro). A total of 2235 individuals (over 1 mm long) of 75 invertebrate species were found associated to 19 specimens of the sponge. The most abundant and diverse taxa were the crustaceans (83%, 31 spp.), polychetes (10%, 18 spp.), and molluscs (3.7%, 15 spp.). Cnidarians, platyhelminthes, ascidians, echinoderms, pycnogonids, bryozoans, and sponges were also represented. Amphipod crustaceans were the dominant group, comprising 61% of all individuals collected. Species richness and abundance of associated fauna were highly correlated with sponge volume, but diversity and evenness were not. The site of collection influenced the species composition of the fauna associated to M. microsigmatosa but did not change significantly its diversity, abundance, richness, and dominance patterns of higher taxa. Pregnant females and juvenile stages of 29% of the species associated, including crustaceans, molluscs, echinoderms, and pycnogonids were frequently found inside M. microsigmatosa. Although many of these organisms do occur and reproduce in other habitats outside the sponge as well, M. microsigmatosa is also important for their reproduction and survivorship, thus contributing for the maintenance of biodiversity in Southwestern Atlantic sublittoral rocky shores. 相似文献
9.
《African Journal of Marine Science》2013,35(3):341-347
Southern Africa supports a rich marine biota of 12 734 currently described marine species. Although the distribution and overall species-richness patterns of several component taxa are well documented, studies considering range sizes are absent. This study considers range size frequencies and distribution patterns of seven major marine invertebrate taxa. The most commonly observed pattern of size frequency distributions is bimodal, with a predominance of species with either small or large range sizes, and few taxa with intermediate-sized ranges. This pattern is displayed by prosobranch and opisthobranch molluscs, polychaetes and amphipods, and for all invertebrate taxa examined combined. Peaks in small range sizes are likely a reflection of the numerous poorly sampled and/or endemic species in the region, while the high number of species with large range sizes can be attributed to the large proportion of widespread tropical Indo-Pacific species within the regional fauna. Overall, the largest peaks of range-restricted endemic species occurred around False Bay, Port Elizabeth, Durban, St Lucia and Maputo Bay. These areas are all situated at or adjacent to recognised biogeographic breaks for invertebrate assemblages, but coincidentally also tend to also be areas of enhanced research and shipping activity. The Cape Point region supports the highest number of endemics, with 73 species restricted to ranges of <100 km and 28 species to ranges <200 km. 相似文献
10.
Microplankton communities of three coastal sites of Qingdao, Shandong Province, China were investigated using RAPD (random amplified polymorphic DNA) molecular markers and morphological observations. Eight RAPD-primers were selected to amplify the DNA polymorphy. The genetic distances inferred from the pairwise similari-ties were calculated for the phylogenetic tree construction. Meantime, the traditional microscopic determination, a way of visualizing the species composition, was performed to detect the major taxa of microplanktons from all samples. Results showed that: (1) the band sharing index values were in the range of 0. 504 2-0. 763 2 among samples from the same sampling site at different time scales, while 0.406 5-0.685 7 among the samples from different stations at the same time scales, indicating that spatial variations of microplankton communities were more pronounced than temporal ones; (2) samples from the same station basically clustered together, cor-responding to the geographic distribution of the sampling sites; (3) diversity derived from genetic and morpho-logical data did not correspond with each other well. 相似文献
11.
《Journal of Sea Research》2002,47(2):161-184
Benthic community data collected between 1938 and 1950 by N.S. Jones were compared with modern samples from seven sites in the Irish Sea. Multivariate and univariate methods were used to compare community change over time and examine the possible impact of scallop dredging over the 60 year time period. A conservative approach to data analysis ensured that observed differences in faunal composition between time periods were not due to differences in sampling methodologies or taxonomic identification. The community composition changed at all sites, though to different degrees. The amount of change was related to how long a site had been fished, rather than fishing intensity. Mobile, robust and scavenging taxa have increased in abundance, while slow-moving or sessile, fragile taxa have decreased. Differences between historical and modern samples were greater than could be accounted for by the natural variability of the system (as indicated by spatial and temporal replication at three sites) and indicate real long-term change. This study emphasises that, in the absence of good-quality data series and experiments, the use of ‘fuzzy’ historical data is often the only possible way to judge long-term change and can yield valuable results. 相似文献
12.
A field experiment was carried out in Hong Kong to study the patterns of recolonization and succession of subtidal macrobenthos in defaunated sediment contaminated with petroleum hydrocarbons and to determine the time required for benthic recovery from petroleum contamination. A total of 31 species was found and 83 animals/tray and 14 species/tray on an average were recorded after one month. Initial colonization was dominated by polychaetes in both abundance and species number (accounting for 69.1% and 64.5%, respectively). Abundance of macrobenthos came to a small crest (308 animals/tray) after three months, reached a sharp peak (1257 animals/tray) after six months, and then declined to a steady level. Abundance, species number and diversity in the petroleum-contaminated sediment were significantly lower than those in the control sediment in the early successional stages, indicating deleterious effects of petroleum hydrocarbons on recolonization and succession of macrobenthos. Petroleum hydrocarbons in sediment significantly altered species composition of macrobenthos in recolonization and succession. No significant differences in community parameters and species composition between the petroleum-contaminated and the control communities were found after 11 months, indicating that macrobenthic community had recovered from petroleum contamination. 相似文献
13.
The Diep River estuary, a small estuary in suburban Cape Town, South Africa, has been subject to disturbance for centuries. Several earlier studies have documented conditions in the system, providing baselines against which to measure more recent changes. This study: (i) describes major physical and hydrological changes that have occurred within this estuary; (ii) documents faunistic changes subsequent to earlier biological surveys; and (iii) provides an up-to-date faunal list. Salinity measurements and both invertebrate and fish samples were taken at five stations along the estuary in summer and winter 2014. A census of sandprawn Callichirus kraussi densities was also undertaken to compare with earlier surveys. Developments within the Diep River catchment and estuary have resulted in extensive changes in flow and salinity regimes, causing marked reductions in summer salinity levels, changes in frequency of mouth closure, and deteriorations in water quality. These have resulted in major changes in faunal composition and distribution, including an increase in numbers of non-indigenous species. Surveys in the early 1950s recorded 47 invertebrate species, whereas only 23 were found in 1974. A total of 23 species were again recorded in 2014, but these included several freshwater forms not previously reported, which had entered the system due to lowered salinity values, as well as new alien introductions. Only six of the 69 taxa recorded were reported by all three surveys. There have been substantial declines in sandprawn abundance, from 40 million in 1998 to just over 12 million in 2014. In all, 12 fish species were recorded in the 1950s, nine in 1974, but only five in 2014, including the newly detected invasive mosquito fish Gambusia affinis and the translocated tilapia Tilapia sparrmanii. Thus, only three of the original native fish species remain. Contrary to these losses, the present bird fauna appear to be more abundant and diverse than previously. Regular monitoring is recommended to obtain a clearer understanding of ongoing changes, and major management interventions will be needed if further degradation is to be prevented. 相似文献
14.
Diatom communities and assemblages are widely used as indicators of ecological change in aquatic environments and for reconstructing palaeo-environments. Good calibration data sets, directly linking changes in diatom composition to environmental factors, are needed for building reliable gradient models with high indicative value. Such models have a broad applicability because most diatom species have cosmopolitan distributions. This paper presents community analyses of brackish-water diatoms living on submerged stones in four areas of the Baltic Sea proper along the Swedish coast. The communities on the stones were composed of epilithic, epiphytic, epipelic, epipsammic and occasionally some pelagic species. Altogether, 158 quantitative samples were taken at 41 sites between 23 April and 11 May, 1990, and the data set contained 300 diatom taxa belonging to 75 genera. Species data were analysed with principal components analysis (PCA) and environmental factors were fitted passively by multiple regression analysis on the ordination results. Differences in community composition could be explained by variation in salinity (which was correlated with N:P and Si:P ratios and the occurrence of macroalgae on the stones), nutrient concentrations and variation in exposure to wave action (which was correlated to the occurrence of soft bottoms around the stones, water temperature and the occurrence of sand grains and macroalgae on the stones). Separate analyses for small taxa (cell biovolume <1000 μm3), for large taxa (cell biovolume ≥1000 μm3) and for small and large diatom taxa together showed that diatoms of different size classes respond differently to environmental variation. 相似文献
15.
In order to depict the distribution of diatom fossils in surface sediments and to establish a reliable reference data for further paleoenvironmental study in the Changjiang (Yangtze) River estuary and its adjacent waters, the diatom fossils from 34 surface sediment samples and their relationship with environmental variables were analyzed by principal component analysis and redundancy correspondence analysis. The diversity and abundance of diatom fossils were analyzed. Some annual average parameters of the overlying water (salinity, temperature, turbidity, dissolved oxygen, depth, dissolved inorganic nitrogen, dissolved inorganic phosphate and dissolved inorganic silicate) were measured at each sampling site. A total of 113 diatom taxa and one silicoflagellate species were identified in the investigation area. Diatom fossils were better preserved in fine sediments. The absolute abundance of diatom fossils did not significantly diff er between inshore and off shore areas, the species diversity decreased from inshore to off shore. This may be because high nutrients and low salinity promoted the growth of more brackish species in coastal waters. The diatom taxa were divided into three groups, on the basis of their response and indication to environmental changes. For example, Actinocyclus ehrenbergii and Cyclotella stylorum were dominant in coastal waters (Group 1 and Group 3) with high nutrients and low salinity;the relative abundances of Paralia sulcata and Podosira stelliger were significantly higher in off shore sites (Group 2, average 39.5%), which were characterized by high salinity and deep water. Four environmental variables (salinity, dissolved inorganic nitrogen, temperature and water depth) explained the composition and distribution of diatom taxa independently ( P< 0.05), this finding can be applied in further paleoenvironmental reconstruction research in this area. 相似文献
16.
Thomas B. Stringell Wesley V. Clerveaux Brendan J. Godley Flora E. A. Kent Emma D. G. Lewis Jessica E. Marsh Quinton Phillips Peter B. Richardson Amdeep Sanghera Annette C. Broderick 《Marine Ecology》2016,37(5):1036-1049
Marine turtles are considered keystone consumers in tropical coastal ecosystems and their decline through overexploitation has been implicated in the deterioration of reefs and seagrass pastures in the Caribbean. In the present study, we analysed stomach contents of green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) harvested in the legal turtle fishery of the Turks and Caicos Islands (Caribbean) during 2008–2010. Small juveniles to adult‐sized turtles were sampled. Together with data from habitat surveys, we assessed diet composition and the taxonomic distinctness (and other species diversity measures) in the diets of these sympatric marine turtle species. The diet of green turtles (n = 92) consisted of a total of 47 taxa: including three species of seagrass (present in 99% of individuals), 29 species of algae and eight sponge species. Hawksbill turtles (n = 45) consumed 73 taxa and were largely spongivorous (16 species; sponges present in 100% of individuals) but also foraged on 50 species of algae (present in 73% of individuals) and three species of seagrass. Plastics were found in trace amounts in 4% of green turtle and 9% of hawksbill turtle stomach samples. We expected to find changes in diet that might reflect ontogenetic shifts from small (oceanic‐pelagic) turtles to larger (coastal‐benthic) turtles. Dietary composition (abundance and biomass), however, did not change significantly with turtle size, although average taxonomic distinctness was lower in larger green turtles. There was little overlap in prey between the two turtle species, suggesting niche separation. Taxonomic distinctness routines indicated that green turtles had the most selective diet, whereas hawksbill turtles were less selective than expected when compared with the relative frequency and biomass of diet items. We discuss these findings in relation to the likely important trophic roles that these sympatric turtle species play in reef and seagrass habitats. 相似文献
17.
M. Hourston I.C. Potter R.M. Warwick F.J. Valesini K.R. Clarke 《Estuarine, Coastal and Shelf Science》2009
This study has determined the ways in which the density, number of species, species composition and trophic structure of free-living nematode assemblages in the subtidal waters of a large southern hemisphere microtidal estuary change spatially and seasonally, and has explored whether those four biotic characteristics are related to certain environmental factors. Based on data derived from samples collected seasonally at 12 sites throughout the estuary, the densities and number of species of nematodes decreased progressively with distance from estuary mouth, to reach a minimum at sites where salinities were most variable, and then increased slightly in the uppermost part of the estuary where salinities were least. Densities were also generally greatest in spring, due largely to increases in the abundance of epistrate-grazing species at this time and thus when the amount of primary food (microphytobenthos) peaked. The spatial distribution of the composition of the nematode assemblages was closely correlated with salinity and, to a lesser extent, grain-size composition and amount of particulate organic material (%POM) in the sediment. Although species composition changed sequentially along the estuary, the change was particularly pronounced between sites above and below the area where salinities started to decline markedly and become more variable and %POM increased markedly. This reflected, in particular, far greater abundances of Spirinia parasitifera at the six downstream sites and of Theristus sp. 1 at the six sites further upstream. Species composition underwent pronounced seasonal cyclical changes at all sites, presumably reflecting interspecific differences in the timing of peak reproduction and thus of recruitment. The trophic structure of the nematode assemblages changed both spatially and temporally in relation to the relative abundance of different food sources. Thus, for example, non-selective deposit feeders, such as Theristus sp. 1, dominated samples in the upper estuary, where %POM was by far the greatest, and was rare or absent at downstream sites. Conversely, epistrate grazers, such as species of the Chromadoridae, were most abundant at downstream sites in spring, when the density of the microphytobenthos reached its maximum. 相似文献
18.
GAO Shan HU Xiaozhong CHEN Zigui XU Henglong YI Zhenzhen LIN Xiaofeng LI Jiqiu 《海洋学报(英文版)》2009,28(1):55-61
Microplankton communities of three coastal sites of Qingdao, Shandong Province, China were investigated using RAPD (random amplified polymorphic DNA) molecular markers and morphological observations. Eight RAPDprimers were selected to amplify the DNA polymorphy. The genetic distances inferred from the pairwise similarities were calculated for the phylogenetic tree construction. Meantime, the traditional microscopic determination, a way of visualizing the species composition, was performed to detect the major taxa of microplanktons from all samples. Results showed that: (1) the band sharing index values were in the range of 0.504 2—0.763 2 among samples from the same sampling site at different time scales, while 0.406 5—0.685 7 among the samples from different stations at the same time scales, indicating that spatial variations of microplankton communities were more pronounced than temporal ones; (2) samples from the same station basically clustered together, corresponding to the geographic distribution of the sampling sites; (3) diversity derived from genetic and morphological data did not correspond with each other well. 相似文献
19.
Microcosms were used to assess the impact of copper mine tailings disposal on the littoral meiofaunal assemblages of the Atacama region of northern Chile. The specific purpose was to establish a cause and effect relationship between the elevated copper concentrations and altered meiofaunal assemblages observed at the study sites. Meiofaunal assemblages were exposed to a series of copper concentrations to assess general toxicity, both densities and taxa diversities decreased with increasing copper. Natural coarse sediments were mixed with a tailings substitute to assess the physical impact of the tailings dumping on meiofaunal assemblages. Meiofaunal assemblage densities increased with increasing amounts of tailings substitute, entirely due to an increase in surface utilising foraminiferans. However, taxa diversities decreased as the interstitial spaces became blocked. Finally, the microcosms were used to conduct bioassays of sediments and seawaters from the impacted sites. The sediments from the impacted sites proved to be toxic resulting in reduced meiofaunal densities and taxa diversities. Seawater samples did not prove to be significantly toxic. The use of microcosms has allowed the effects of the physical and chemical components of tailings to be assessed individually, which was not possible in the field. Additionally, it allowed a cause and effect relationship to be established between elevated concentrations of porewater copper observed in the field and the reduced densities and taxa diversities of the meiofaunal assemblages observed at the same sites. 相似文献
20.
To test if environmental contamination acts as a selection force affecting genetic diversity at the population level, two intertidal invertebrate species, Mytilus galloprovincialis and Balanus glandula, were collected from seven different bay sites in southern California. Collections were made at three relatively pristine 'clean' sites and four 'impacted' sites exposed to heavy industrial or boating activity, and which had previously been identified as having measurable levels of pollution. Genetic diversity at each site was assessed by comparing fragment polymorphisms generated from genomic DNA by randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). All populations retained a large amount of genetic diversity and were genetically similar to each other. However, several different measures of diversity indicated that, for most primers, the populations of both species from impacted sites had lower genetic diversity compared to those populations from clean sites. Individuals at impacted sites were more likely to share the same haplotypes than were those from clean sites. Few bands seen in the clean sites were absent from the impacted sites or vice versa, but a number of bands in the clean site populations were significantly less common in the impacted populations, while a few bands uncommon in clean site populations were more common at impacted sites. Together, these results suggest that pollution at the impacted sites may reduce genetic diversity among the resident invertebrate populations. 相似文献