Showing papers on "Indicator species published in 2002"

Selecting indicator species to monitor ecological integrity: a review.

Abstract: We review critical issues that must be considered when selecting indicator species for a monitoring program that aims to maintain or restore ecological integrity. First, we examine the pros and cons of different management approaches on which a conservation program can be based and conclude that ecosystem management is most appropriate. We then identify potential indicators of ecological integrity at various levels of the ecosystem, with a particular emphasis on the species level. We conclude that, although the use of indicator species remains contentious, it can be useful if (1) many species representing various taxa and life histories are included in the monitoring program, (2) their selection is primarily based on a sound quantitative database from the focal region, and (3) caution is applied when interpreting their population trends to distinguish actual signals from variations that may be unrelated to the deterioration of ecological integrity. Finally, we present and discuss different methods that have been used to select indicator species.

Benthic indicators to use in Ecological Quality classification of Mediterranean soft bottom marine ecosystems, including a new Biotic Index

Abstract: A general scheme for approaching the objective of Ecological Quality Status (EcoQ) classification of zoobenthic marine ecosystems is presented. A system based on soft bottom benthic indicator species and related habitat types is suggested to be used for testing the typological definition of a given water body in the Mediterranean. Benthic indices including the Shannon-Wiener diversity index and the species richness are re-evaluated for use in classification. Ranges of values and of ecological quality categories are given for the diversity and species richness in different habitat types. A new biotic index (BENTIX) is proposed based on the relative percentages of three ecological groups of species grouped according to their sensitivity or tolerance to disturbance factors and weighted proportionately to obtain a formula rendering a five step numerical scale of ecological quality classification. Its advantage against former biotic indices lies in the fact that it reduces the number of the ecological groups involved which makes it simpler and easier in its use. The Bentix index proposed is tested and validated with data from Greek and western Mediterranean ecosystems and examples are presented. Indicator species associated with specific habitat types and pollution indicator species, scored according to their degree of tolerance to pollution, are listed in a table. The Bentix index is compared and evaluated against the indices of diversity and species richness for use in classification. The advantages of the BENTIX index as a classification tool for ECoQ include independence from habitat type, sample size and taxonomic effort, high discriminative power and simplicity in its use which make it a robust, simple and effective tool for application in the Mediterranean Sea.

The verification and application of bioindicators: a case study of dung beetles in a savanna ecosystem

Abstract: Summary 1 Bioindicators of habitat quality and environmental change must be identified quantitatively and tested independently to confirm their usefulness. We used the indicator value (IndVal) method, which combines measures of habitat fidelity and specificity, to assess the indicator responses of dung beetles (Coleoptera: Scarabaeidae) in Tembe Elephant Park, South Africa. The indicator responses were verified by sampling in different areas of the Park, 2 years after the responses were originally quantified. 2 We postulated that terrestrial insect indicators with different combinations of habitat specificity and fidelity might fulfil different indicator roles. Indicator species with strong habitat specificity (characteristic species) are unlikely to provide information on the direction of ecological change despite high vulnerability. Rather, detector species that span a range of ecological states are likely to be better in this role. We used IndVal for selecting such detector species that indicate the direction of ecological change. 3 Sets of species were found to be robust bioindicators, i.e. reliably characteristic across the habitat of which they were indicative. The suite of indicators was refined by discarding those with IndVals that varied significantly across years, thus improving the confidence in the final suite of species selected. By clearly responding to a change in habitat between two ecological states, detector species provided information complementary to that provided by characteristic species. 4 The IndVal method enabled both the identification and testing of indicator (characteristic and detector) species. Because of its resilience to changes in abundance, IndVal is a particularly effective tool for ecological bioindication. 5 We conclude that both characteristic and detector species are useful bioindicators of habitat quality and conversion. We propose that bioindicators that are categorized and verified in this way will have valuable application in the monitoring of habitat integrity.

Spider assemblage structure and stability in a heterogeneous coastal dune system (belgium)

Abstract: An analysis of the spider assemblage structure and the presence of indicator species in the Flemish coastal dunes are presented. The analysis is based on data from more than 170 year-round pitfall sampling campaigns from the 1970s onwards. We were able to find indicator species for all identified habitats. The assemblages are determined by variation in vegetation structure (succession), atmospheric and soil humidity and the occurrence of both natural of anthropogenic disturbance. In the fragmented habitats (grasslands and grey dunes), a clear relationship was found between the mean habitat size and the stability of the assemblage composition. In moss dominated dunes and short grasslands total species numbers do not increase with patch size. Due to microhabitat variation and the possibility of attaining viable population sizes the total number of typical species is, however, higher in larger patches. In small patches, edge effects are more important and the number of observed species is enlarged by the intrusion of species from nearby habitats.

Phylogenetic diversity: a quantitative framework for measurement of priority and achievement in biodiversity conservation

Abstract: The value of biodiversity lies in its option value for the future, the greater the complement of contemporary biodiversity conserved today, the greater the possibilities for future biodiversity because of the diverse genetic resource needed to ensure continued evolution in a changing and uncertain world. From this perspective, biodiversity option value can be equated with richness in the different features expressed by species. An individual species of greater value is one contributing more novel features to a given subset. The feature diversity of species and communities is difficult to estimate directly, but can be predicted by the phylogenetic relationships among the species. The ‘Phylogenetic Diversity’ measure (PD) (Faith, 1992a) estimates the relative feature diversity of any nominated set of species by the sum of the lengths of all those branches spanned by the set. These branch lengths reflect patristic or path-length distances. This study first reviews and expands on some of the properties of PD, and develops simple modifications of the measure (δnPD and enPD) to enable capture of both the phylogenetic relatedness of species and their abundances in each sample. Then the application of PD, δnPD and enPD to a wide range of conservation and resource management issues is demonstrated using avian case studies. Supertree construction procedures (matrix representation using parsimony analysis; average consensus) were used to combine the extensive DNA-DNA hybridization tree of Sibley & Ahlquist (1990) with numerous, recently published phylogenetic reconstructions to derive a phylogenetic tree for the global avian fauna. Using this supertree as a systematic framework, the utility of PD was demonstrated in four case studies: (i) state of the environment reporting, with changes in avian faunas resulting from extinctions quantified as indicators of the state of biodiversity at Global, New Zealand and Waikato region scales, and changes in available habitat quantified as indicators of pressures on biodiversity in the Waikato region; (ii) setting priorities for threatened species management, with PD as a measure of option value integrated with information on survivorship expectations to develop a ranking among threatened New Zealand forest bird species; (iii) monitoring biotic response to management, with data from 5-minute counts used to analyse changes in forest bird communities under three management regimes in New Zealand; and (iv) selection of indicator species, with PD used to objectively identify subsets of species in the Global, New Zealand and Waikato avian faunas that comprise a high proportion of the option value in those faunas.

A comparison of three methods to survey saproxylic beetles in hollow oaks

Abstract: One of the most endangered assemblages of species in Europe is insectsassociated with old trees. For that reason there is a need of developing methodsto survey this fauna. This study aims at comparing three methods – windowtrapping, pitfall trapping and wood mould sampling – to assess speciesrichness and composition of the saproxylic beetle fauna in living, hollow oaks.We have used these methods at the same site, and to a large extent in the sametrees. Useful information was obtained from all methods, but they partiallytarget different assemblages of species. Window trapping collected the highestnumber of species. Pitfall trapping collected beetles associated with treehollows which rarely are collected by window traps and therefore it isprofitable to combine these two methods. As wood mould sampling is the cheapestmethod to use, indicator species should preferably be chosen among specieswhich are efficiently collected with this method.

Aerial colonization of high Arctic islands by invertebrates: the diamondback moth Plutella xylostella (Lepidoptera: Yponomeutidae) as a potential indicator species

Abstract: . The restricted animal communities of the high Arctic islands are due, in part, to extreme geographical isolation. Migration via wind currents is one mechanism by which invasion of new species may occur. Here, we describe immigration of the non-resident migratory moth, Plutella xylostella, into Svalbard during 2000. This was associated with a warm south-easterly air mass that crossed from W. Russia: moths appear to have covered the 800 km to Svalbard in under 48 h, flying at an altitude between 500 and 1500 m. These events thus provide a case study for wind-dispersed movements of invertebrates to high Arctic regions. Climate change scenarios predict increased frequency of such air masses and also of the warm dry weather associated with increased aerial insect transport. The general factors determining successful colonization of the high Arctic by wind-dispersed animals are discussed, using P. xylostella as a model species whose important life history and physiological attributes are well known.

Cephalopod assemblages caught by trawling along the Iberian Peninsula mediterranean coast

Abstract: The cephalopod fauna collected in five MEDITS-ES trawl surveys carried out on the Iberian Mediterranean coast was analysed. Hauls, which were carried out in spring between 1994 and 1998, numbered 480. A total of 34 cephalopod species, grouped in 11 families, was found at depths of between 25 and 786 m. Species and samples assemblages were analysed with the Bray-Curtis similarity index. From the physical parameters studied (depth, temperature and bottom type) only depth showed a positive correlation with cephalopod distribution. Three main cephalopod communities were defined: the shelf community ( 480 m) and a group of cephalopods which were widely distributed more abundantly on the lower continental shelf-upper slope (150-480 m). SIMPER analysis revealed that Loligo (Alloteuthis) media was the main indicator species of the shelf group, Eledone cirrhosa was the indicator species of the lower shelf upper slope group and Todarodes sagittatus of the middle slope community. The 150-480 m stratum was considered a transitional zone, representing an overlapping region for shelf and slope faunas.

Effects of Camponotus punctulatus ants on plant community composition and soil properties across land-use histories

Abstract: Populations of the ant Camponotus punctulatusundergo demographic explosions after agricultural activities, buildingconspicuous, vegetation-covered soil mounds. We investigated the effects ofC. punctulatus on floristic composition and soilpropertiesalong a gradient of agricultural disturbance in Northeastern Argentina. Wesampled vegetation and soil “on” and “off” anthills in,at least, three replicate plots of each of the following situations thatrepresent an increasing gradient of soil disturbance: natural grasslands, sownpastures of Digitaria decumbens, sown pastures ofSetaria sphacelata, and recently abandoned rice fields.Sets of characteristic plant species for each of the land use histories, for“on” and “off” anthills as well as for anthills ofdifferent sizes were identified through Indicator Species Analysis. 64% of thevariation in plant community composition was mainly explained by land-usehistory which was associated to the first 2 axes of a Correspondence Analysisbased on the frequency of 126 species across all sites. At the replicate scale,Correspondence Analyses revealed patterns of plant species composition relatedto the presence and size of anthills. Larger mounds became enriched in species,especially herb weeds, in comparison to smaller mounds or samples gatheredoutside the anthills. A Principal Component Analysis of soil data revealed that71% of the variation in soil properties was explained by the presence ofanthills. Soils from “on” anthills were more fertile than soilsfrom“off” anthills, independent of land-use history. The fertilityeffect of C. punctulatus mounds in addition with thevegetation patterns observed along the gradient of anthill-sizes highlights theimportance of these ants at the landscape and local scales.

The use of ground beetles (Coleoptera: Carabidae) in conservation assessments of exposed riverine sediment habitats in Scotland and northern England

Abstract: Exposed riverine sediments (ERS) are an important invertebrate habitat. Ground beetle data from pitfall trap surveys of 165 sites in the catchments of the Rivers Carron, Nith, Spey, Tweed and Eden and from 48 sites in the catchments of the Rivers Blyth, Breamish, Coquet, Glen, Pont, South Tyne, Till, Tweed and Tyne were used to produce ERS habitat classifications in Scotland and northern England respectively. Within each habitat type the quality of sites were assessed using indices based on rarity and fidelity values and using species richness as a measure of diversity. Considerable variation in these indices was seen within and between habitat types, showing potential for their use in assessing site quality and for ranking sites within habitats. The use of standardised invertebrate survey and distribution data, together with species assemblage information, for the conservation of invertebrate habitat types as an alternative to the use of selected ‘indicator species’, is discussed.

Indicator species analysis as a test of non-random distribution of species in the context of marine protected areas

Abstract: Species are identified as bioindicators when their presence or abundance within sites of a particular habitat or a conservation area are high. Dufrene and Legendre (1997), Ecological Monographs 67: 345–366, proposed the use of a flexible asymmetrical approach to detect indicator species and species assemblages characterizing groups of sites, the indicator value for each species being subsequently tested by randomization. Although the advantages of these methods in comparison to other multivariate or two-way indicator species analyses have been demonstrated, relatively few ecological studies have made use of them. The aim of the present study was to demonstrate the advantages of the indicator species test using a data set generated by traditional fisheries activities at four areas in the Bonifacio Strait Marine Reserve, Corsica, France. ANOVA, Kruskal-Wallis and another randomization test were also performed on the same data set. Of the 54 species caught in the fishing nets, the indicator species analyses identified 19 species for which the indicator value was significant for a given area, whereas the a posteriori Tukey test for ANOVA detected only 12 species for which the mass capture per unit effort was significantly greater for a given area. The efficiency of this new approach within the framework of conservation and marine reserve studies is demonstrated by focusing on three species (Sciaena umbra, Palinurus elephas and Maja verrucosa).

Ground Beetle (Coleoptera: Carabidae) Species Assemblage as an Indicator of Forest Condition in Northern Arizona Ponderosa Pine Forests

Abstract: Reintroduction of fire and thinning have been suggested as the main practices to regain forest health in northern Arizona ponderosa pine (Pinus ponderosa Dougl. ex Lawson) forests. Criteria for assessing the impact of such management practices in the forest are based on benchmark reconstructed conditions resembling pre-European forest stand structure and on the enhancement of tree vigor. A range of forest conditions currently exists including stands that have been unmanaged, thinned only, thinned plus prescribed burned and burned by wildfire. A surrogate taxon was used to assess forest condition under criteria of maintaining habitat for native species operating at the soil level. We assessed changes occurring in ground beetle assemblages at the stand scale as related to changes that had occurred in forest stands previously treated with the above treatments. A pitfall-trapping scheme was deployed during the summer months of 1998, 1999, and 2000. A total of 4,452 specimens was caught representing 15 genera and 20 species of ground beetles. We found that species diversity increased as the level of disturbance increased. The indicator species assemblage found on the wildfire treatment was represented by species in the genera Amara and Harpalus that are characteristic of dry-open habitats. Unmanaged stands generally had the lowest diversity and the assemblage was dominated by the species Synuchus dubius (Leconte). The thinned only stands did not significantly vary from unmanaged stands in species assemblage. Cyclotrachelus constrictus (Say) was indicative of the thinning plus broadcast burned stands. Stands that were thinned plus burned were richer than both unmanaged and thinned only stands without a shift toward an open-area dominant assemblage as occurred in the stands burned by wildfire.

Constraints of Seed Bank Species Composition and Water Depth for Restoring Vegetation in the Florida Everglades, U.S.A.

Abstract: The Rotenberger Wildlife Management Area (RWMA) is a northern Everglades marsh, in Florida, U.S.A., that will undergo hydrologic restoration to remedy an artificially shortened hydroperiod. In an effort to predict vegetation responses to the impending changes in hydrology, plant community development from the resident seed bank was observed in response to three different moisture regimes in March and September 1998. Percent cover, species densities, total seedling densities, and percentages of facultative, facultative-upland, and upland indicator species were significantly higher in moist than in saturated soils. Flooding inhibited the germination of all species except Typha domingensis (cattail), which emerged in the highest numbers from saturated soils in both assays. Lythrum alatum (purple loosestrife) was abundant in both saturated and moist conditions. The season of assay affected species densities and the communities. Percent facultative-wetland species increased in saturated soils in the March assay but not in September. In contrast, percent obligate hydrophytes were higher in saturated conditions only in the September assay. In general the assay communities bore little resemblance to vegetation in currently undisturbed or historic wetlands of the northern Everglades. Consequently the RWMA seed bank will contribute little to the development of a restored community. Moreover, rehydration may encourage the spread of undesirable hydrophytes such as T. domingensis. This study supports the contention that hydrologic restoration must be accompanied by some level of active vegetation management and that the reference condition cannot be attained passively.

Phytoplankton in 63 limed lakes in comparison with the distribution in 500 untreated lakes with varying pH

Abstract: As a result of the different weathering of lime in soils and varying acid deposition, the pH of Swedish oligotrophic lake waters has a broad range from ca 4 to 85 Phytoplankton species occur in all lakes, but the composition and species richness varies in relation to pH The maximum number of taxa was recorded within the pH-range 70–76, while the number decreased at higher pH and especially at pH below 56 During 1975–1985, thousands of lakes in Sweden were limed with the intention to restore biotic diversity and production In order to find out whether there are differences in quality between limed and unacidified waters, the distribution of 57 selected phytoplankton taxa in 63 limed lakes was compared with that in 500 unlimed lakes with varying pH The study shows that most common species in unacidified lakes also occur in the limed ones However, several species of Cyanophyceae and Conjugatophyceae were missing especially in lakes that were strongly acidified before liming On the other hand, some taxa were more frequent in the limed lakes

Using “indicator” species to model species richness: model development and predictions

Abstract: Reliable indicators of species richness (e.g., particular species), if they can be found, offer potentially significant benefits for management planning. Few efficient and statistically valid methods for identifying potential indicators of species richness currently exist. We used Bayesian-based Poisson modeling to explore whether species richness of butterflies in the Great Basin could be modeled as a function of the occurrence (presence or absence) of certain species of butterflies. We used an extensive data set on the occurrence of butterflies of the Toquima Range (Nevada, USA) to build the models. Poisson models based on the occurrence of five and four indicator species explained 88% and 77% of the deviance of observed species richness of resident and montane-resident butterfly assemblages, respectively. We then developed a test framework, including formally defined “rejection criteria,” for validating and refining the models. The sensitivity of the models to inventory intensity (number of years of da...

Chironomid pupal exuviae as indicators of lake status

Abstract: Thirty lakes in England and Wales were characterised by the distribution and abundance of chironomid species, collected as pupal exuviae, in correlation with chemical and physical measurements. Alkalinity and lake volume were the best predictors of chironomid species assemblage among lakes. Conductivity, lake volume and altitude were the best variables discriminating lake classes based on species distribution. A biological classification, constrained by conductivity, was used to calculate indicator species scores. A conductivity gradient of indicator species assemblages was produced to demonstrate how temporal or spatial reference conditions could be inferred. Conductivity, lake area and catchment area were the best predictors of profundal species distribution. Potential lake anoxia increased in explanatory importance after exclusion of littoral species. Alkalinity, catchment area and lake area significantly explained distribution of genera. Compared with a classification derived from 208 littoral and profundal species, discriminant analysis of best subsets of indicator taxa found 97 % of lakes were correctly classified using 15 profundal species and 73 % were correct using 7 genera. It was concluded that the pupal exuvial technique was an easy and effective method for characterising large lakes, as required for implementation of the European Water Framework Directive.

Comparison of Deep-River and Adjacent Sandy-Beach Fish Assemblages in the Napo River Basin, Eastern Ecuador

Abstract: We sampled fishes with a small trawl in the deep midchannel and with beach seines on nearby sandy beaches at five sites along two parallel headwater tributaries of the upper Amazon in Eastern Ecuador. We quantified ecological distance between fish assemblages of deep-river and beach habitats and compared assemblage composition, species richness, and diversity. Results of detrended correspondence analyses (DCA) and two-way indicator species analyses (TWINSPAN) clearly revealed the presence of a striking faunal change (i.e., about 92% dissimilarity) between beach-zone and off-shore fishes. The boundary between these assemblages occurred at about 2 m depth. Beach samples collected as far apart as 325 km were more similar to each other than to trawl samples taken only 10s of meters away. The beach-zone fish assemblage was strongly dominated by small characins, whereas the deep-river habitat was dominated by catfishes and weakly electric gymnotiforms. Apparent adaptations to deep-water habitats includ...

A comparison of crop and non-crop plants as sensitive indicator species for regulatory testing.

Abstract: The effectiveness of regulatory non-target plant testing using crop species to predict the phytotoxicicity of herbicides to non-crop species was evaluated for eleven herbicides. These herbicides were representative of eight chemical classes and six modes of action. Data for non-crop plants from pre-emergence and post-emergence efficacy screening studies were compared with those for the most sensitive crop species defined by regulatory tests conducted to meet US EPA requirements. Testing under pre-emergence conditions for ten compounds indicated that for five of the compounds (K-815910, trifluralin, pyridyloxy A, pyridyloxy B and cyanazine), the most sensitive crop species was more sensitive than all the non-crop species evaluated. For metsulfuron-methyl, chlorimuron-ethyl, hexazinone and bromacil, only one of the non-crop species evaluated was more sensitive than the most sensitive crop species from regulatory tests. Data for the tenth compound, chloroacetamide, showed that four of 32 non-crop species tested in efficacy screens had at least one rate at which greater visual effects were observed than were observed for the most sensitive crop response in a regulatory test. The results of post-emergence exposure comparisons for five of the compounds (pyridyloxy A, cloransulam-methyl, chlorimuron-ethyl, cyanazine and hexazinone) indicated that the most sensitive crop species were more sensitive than all the non-crop species evaluated. Data for pyridyloxy B, metsulfuron-methyl and bromacil indicated that only one of the non-crop species evaluated was more sensitive than the most sensitive crop species. For trifluralin, three of the eight non-crop species were more sensitive than the most sensitive crop species. Data for K-815910 indicated that four of the fourteen non-crop species tested were marginally more sensitive than the most sensitive crop, but were within the same range of sensitivity. These results indicate that the current regulatory test batteries and methods using crop species effectively provide suitable sensitive indicator plants for the eleven diverse herbicides evaluated. This comparison indicates that crop species sensitivity to test substances is likely to be representative of non-crop herbaceous species response, regardless of chemical class, mode of action and magnitude or route of exposure.

Application of two indices of benthic community condition in Chesapeake Bay

Abstract: SUMMARY The Chesapeake Bay Benthic Index of Biotic Integrity (B-IBI) and the Environmental Monitoring and Assessment Program’s Virginian Province Benthic Index (EMAP-VP BI) were applied to 294 sampling events in Chesapeake Bay and the results were compared. These estuarine benthic indices are intended to identify benthic invertebrate assemblages that have been degraded by low dissolved oxygen concentrations or high concentrations of chemical contaminants. The B-IBI includes several community measures and weights them equally using a simple scoring system that compares them against values expected for undegraded sites. It includes 11 measures of species diversity, productivity, indicator species and trophic composition. The EMAP-VP BI uses discriminant function coefficients to weight contributions of species diversity and the abundances of two indicator families. The two indices agreed on degraded or undegraded classifications for benthos at 81.3% of the sites. This level of agreement is within the level of accuracy achieved during index development and, therefore, may approach the limits that can be achieved. The indices were strongly associated (Pearson’s r ¼ 0.75). The B-IBI was more conservative than the EMAP-VP BI, classifying 72.7% of the disagreements as degraded. The 55 sites where the indices disagreed were distributed in different habitats throughout the Bay except polyhaline sand. Many of the classification disagreements were at sites with index values close to, but on opposite sides of, the degraded–undegraded thresholds, with 49.1% of the B-IBI values within 0.5 units and 81.8% within 1.0 units; the corresponding values for sites where both indices agreed were only 23.4% and 62.7%, respectively. The pattern for the EMAP-VP BI was similar, with 61.8% and 74.6% of disagreements and only 18.8% and 38.9% of agreements within 0.5 and 1.0 units of the threshold. Although the close agreement suggests that either index is suitable for evaluating the benthic condition, the B-IBI offers some additional advantages. Copyright # 2002 John Wiley & Sons, Ltd.

Indicator Species — Restricted Taxa Approach in Coniferous and Hardwood Forests of Northeastern America

Abstract: Many calicioid lichens and fungi are dependent on mature forests containing trees of different ages and a varied light and humidity regime, making them good indicators of forest age and continuity [2, 7, 9]

Evaluation of measures for enlargement, renaturation and development of a dry grassland biotope by analysing differences in the carabid fauna (Coleoptera)

Abstract: Measures for enlargement and renaturation of a dry grassland biotope are evaluated by bioindication. On several sample plots in a dry grassland nature reserve and in adjacent formerly arable lands (enlargement areas) we analysed the temporal and spatial distribution of carabid species. As carabid beetles were used as an indicator group representative of other ecological mechanisms (e.g., reactions to environmental changes) the theme and problematic nature of this paper is of theoretical and general ecological interest also. By computing several faunistic parameters, the differences and the change of the carabid coenoses could be analysed statistically. Removing the topsoil is a very effective measure for renaturing dry grassland. This measure reduces significantly the high number of individuals and the high percentage of euryoecious carabid species, both typical for arable lands. On sample plots with removed topsoil, the percentage of endangered and protected species listed in the Red Data Lists was significantly higher than in sample plots with humus layers. There was no difference between sample plots with removed topsoil and sample plots with humus layer with respect to the percentage of thermophilic and xerophilic carabid species indicative of dry grassland biotopes. A further important factor for the success of restoring and enlarging dry grassland biotopes is the distance and the isolation of the enlargement fields. Isolated sample plots with no or little connection and a large distance to the nature reserve showed a significantly lower percentage of thermophilic and xerophilic carabid species indicative of dry grassland biotopes and a significantly lower percentage of endangered and protected species listed in the Red Data Lists than sample plots close to the nature reserve. Furthermore, in comparison to sample plots close to the nature reserve, the isolated sample plots showed significantly lower faunistic similarity to the nature reserve (Renkonen- and Soerensenindex) and a significantly higher percentage of euryoecious carabid species indicative of arable fields.

Polychaetes Associated with a Tropical Ocean Outfall: Synthesis of a Biomonitoring Program off O'ahu, Hawai'i

Abstract: A comparison of benthic polychaete communities off the Sand Island Wastewater Outfall was undertaken to recognize organic enrichment indicator species for Hawaiian waters. Primary-treatment sewage is discharged off the south shore of O'ahu at 70 m depth. A historical data set spanning 9 yr for seven sites at 70 m and two recent studies at 20, 50, and 100 m depths were analyzed. Geochemical data did not support the assumption that the outfall is an important source of organic enrichment in nutrient-poor sandy sediments within oligotrophic tropical waters. Five polychaete species, however, appeared particularly sensitive, positively or negatively, to environmental conditions near the outfall. Neanthes arenaceodentata (Nereididae) and Ophryotrocha adherens (Dorvilleidae) have been dominant at sites within the outfallOs zone of initial dilution (ZID). Since 1993, N. arenaceodentata has virtually disappeared, and O. adherens concurrently became abundant and continued to sourish at ZID sites. Well-known indicators within the Capitella capitata complex (Capitellidae) were present at ZID and control (far Þeld) sites though their ZID abundance was greater. Two sabellids, Euchone sp. B and Augeneriella dubia were inversely distributed, the smaller Euchone sp. B at far Þeld sites and larger A. dubia within ZID stations. The former was most likely restricted to a greater proportion of Þne sediment particles at two far Þeld sites. The most abundant and widespread polychaete off O'ahu's south shore was Pionosyllis heterocirrata (Syllidae), which does not seem to represent a sensitive indicator species. Ophryotrocha adherens was the most abundant indicator species within the ZID; P. heterocirrata was the most ubiquitous species at all sites and should always be expected in these sediments. Traditional measurements of numerical abundance, species richness, and diversity (H0) have not shown a clear distinction between ZID and far Þeld sites in annual analyses. An examination of composited data over an 11-yr period does support such a distinction. Multidimensional scaling (MDS) analyses clearly delineate different assemblages. We suggest that MDS analyses are sensitive to the community differences present near the outfall. The ZID community is clearly contained within the Environmental Protection AgencyÐapproved ZID boundary. Because each ZID and far Þeld site supports a diverse and coarsely similar polychaete fauna, no pollution level effects seem to be present.