Macroinvertebrate taxa display increased fidelity to preferred biotopes among disturbed sites in a hydrologically variable tropical river

Understanding the biotope requirements of the various aquatic biota is crucial for effective biomonitoring. Yet, the biotope preferences of macroinvertebrates in Afrotropical rivers have been poorly studied. In this study, we investigated the influence of human disturbance and flow-driven biotope changes on the β-diversity and biotope preferences of macroinvertebrates in the Mara River, Kenya. Macroinvertebrates were sampled from various biotopes at seven reference and nine impaired sites in wet and dry seasons. β-Diversity was determined (i) for each biotope and (ii) at the site scale, combining all biotopes sampled, and macroinvertebrate biotope preferences were assessed among biotopes between reference and impaired sites. Minor β-diversity differences were observed between reference and impaired sites based on relative abundance data, but differences were greater when the presence–absence data were used. There were no statistically significant changes in macroinvertebrate biotope preference due to human disturbance, but fidelity to preferred biotopes increased at impaired sites. In fast-flowing waters, Simuliidae, Baetidae, Tricorythidae, and Hydropsychidae dominated stable rocky substrates and were the most sensitive to flow alteration. This study adds valuable information on the effects of biotope reduction/loss and flow alteration on the diversity and biotope preferences of macroinvertebrates in Afrotropical rivers, and contributes to improvement of relevant bioassessment protocols and biodiversity conservation efforts.

     

Testate amoebae communities in the southern tundra and forest-tundra of Western Siberia

The species composition and community structure of soil-inhabiting testate amoebae communities have been studied in biotopes of different types in the southern tundra and forest-tundra of the Tazovskaya Lowland, Western Siberia. A total of 93 species and forms have been identified. It has been found that the species richness of testate amoebae is much lower in dry than in moist biotopes due to a lower level of beta-diversity, with alpha diversity being the same (on average, 16.9 and 17.1 species per sample, respectively). Factors acting at the microbiotope level (biotope type and moisture) play the most important role in the formation of species richness; biotope features (soils and vegetation) are second in importance. In moist habitats, local communities of testate amoebae from different microbiotopes (mosses, lichens, or litter) are fairly similar in species structure, and communities from different moist biotopes are heterogeneous. In dry areas, the opposite situation is observed: local communities differ at the microbiotope level but are similar at the biotope level. The abundance of testate amoebae in moist biotopes reaches 200 × 10³ ind./g dry soil, being an order of magnitude lower in dry biotopes.     

Diversity and classification of rheophilic communities of macrobenthos in middle latitudes of European Russia

Based on original data (450 samples from 115 streams of European Russia middle latitudes--from Pskov to Kostroma Regions) the attempt is made to describe the overall diversity of rheophilic communities dwelling on streams bottom and in macrophytes. In total, 39 community types were identified by the Brown-Blankuet method; their taxonomical and structural characteristics are described; the associations with biotopes are outlined; and a biotopical nomenclature is proposed. All communities are subdivided into four biotopical classes: crenal (springs and springbrooks with mixed substrates), rhitral (stony and woody substrates), phythal (macrophytes), and pelal (soft ground). It is shown that all communities may be divided by their organization as R-type of M-type community. 36 out of 39 studied communities belong to R-type and are characterized mainly by prevalence of insect, unstable dominance, and rather distinct association to the biotope. In M-type communities (3 out of 39 studied communities) eurybiontic mullusk Viviparus viviparus and amphipod Dikerogammarus haemobaphes predominate; these communities are interbiotopic, with stable species structure and high total abundance. The effect of the study spatial scale on the definition of communities is discussed along with problems of the communities dynamics.     

Modelling potential biotope composition on a regional scale revealed that climate variables are stronger drivers than soil variables

Aim

Environmental conditions define the suitability of an area for biotopes, and any area can be suitable for several biotopes. However, most previous studies modelled the distribution of single biotopes ignoring the potential co-occurrence of biotopes in one area, which limits the usefulness of such models for conservation and restoration planning. In this study, we described the potential biotope composition of an area in response to environmental conditions.

Location

Bavaria, Federal State of Germany.

Methods

Based on the Bavarian biotope mapping data, we modelled the distribution of 29 terrestrial biotopes based on six climate variables and six chemical and four physical soil properties using the species distribution modelling algorithm Maxent.

Results

For most biotopes, we found that climate variables were more important than soil variables for the biotope distribution and that the area of the predicted biotope distribution was larger than the observed distribution. The potential biotope composition illustrated that while 8% of the area in Bavaria was not sufficiently suitable for any analysed biotope, 92% of the modelled area in Bavaria was suitable for at least one biotope, 84% for two and 77% for at least three biotopes. The difference in suitability between the most suitable biotopes in composition was minor. Further, over one-quarter of the modelled area was suitable for 6–8 different biotopes.

Main Conclusions

Our study showed that considering a composition of potentially suitable biotopes in a raster cell, instead of only the most suitable biotope, provides valuable information to identify conservation priorities and restoration opportunities.     

Composition of Archaea in Seawater,Sediment, and Sponges in the Kepulauan Seribu Reef System,Indonesia

Coral reefs are among the most diverse and productive ecosystems in the world. Most research has, however, focused on eukaryotes such as corals and fishes. Recently, there has been increasing interest in the composition of prokaryotes, particularly those inhabiting corals and sponges, but these have mainly focused on bacteria. There have been very few studies of coral reef Archaea, despite the fact that Archaea have been shown to play crucial roles in nutrient dynamics, including nitrification and methanogenesis, of oligotrophic environments such as coral reefs. Here, we present the first study to assess Archaea in four different coral reef biotopes (seawater, sediment, and two sponge species, Stylissa massa and Xestospongia testudinaria). The archaeal community of both sponge species and sediment was dominated by Crenarchaeota, while the seawater community was dominated by Euryarchaeota. The biotope explained more than 72 % of the variation in archaeal composition. The number of operational taxonomic units (OTUs) was highest in sediment and seawater biotopes and substantially lower in both sponge hosts. No “sponge-specific” archaeal OTUs were found, i.e., OTUs found in both sponge species but absent from nonhost biotopes. Despite both sponge species hosting phylogenetically distinct microbial assemblages, there were only minor differences in Kyoto Encyclopedia of Genes and Genomes (KEGG) functional pathways. In contrast, most functional pathways differed significantly between microbiomes from sponges and nonhost biotopes including all energy metabolic pathways. With the exception of the methane and nitrogen metabolic pathway, all energy metabolic pathways were enriched in sponges when compared to nonhost biotopes.     

Intertidal rocky shore biotopes of the Azores: a quantitative approach

Rocky littoral communities of the Azores are dominated by macroalgae where turf formations represent the main life form as on many subtropical and tropical shores. The present study aimed at describing and classifying benthic intertidal biotopes of the Azores using clear quantification and data analysis methodologies to be used in similar studies for spatial and/or temporal comparison. This numerical approach intends to have management and conservation applicability. Thirty study locations along the coast of São Miguel island were characterised by substratum type (cobbles, boulders or bedrock – different stability levels) and exposure to wave action (high, medium or low exposure), from June to August 2002. Algae, sessile and sedentary invertebrates were recorded along transects, and the more conspicuous taxa quantified. Community structure is mainly shaped by substratum stability – unstable cobble communities are separate from those of more stable boulders and bedrock. Boulders present an intermediate community composition between cobbles and bedrock. Exposure to wave action induces smaller variation in community composition. Sixteen biotopes have been recognised. Ultimately the present paper provides an objective set of biotope definition tools for a broad public whose interest focuses on spatial and temporal comparison of coastal communities and associated habitats.     

Distribution of fish and the biotopic structure of the basin of the small salmon river (the Nachilova River,Western Kamchatka)

For one of the small Western Kamchatka rivers, according to the combination of several characteristics (watershed, channel slope, water abundance of the flow, pattern of bottom sediments), the classification of channel processes was performed, and on its basis, six biotopes successively replacing each other from the effluents to the mouth were separated. It was shown that against the background of relatively stable conditions of the summer-autumn period, an independent population of Salmonoidei, an assembly, is formed within each biotope. This is manifested in specific features of species composition, size and age structure, and the density of populating biotopes. The stability of the distribution of fish population is supported by constant species composition in particular biotopes over three years and by a comparatively high level of residence of the dominant salmon species.     

Re-evaluation of numerical classification methods for delimiting biofacies and biotopes in an estuarine environment

Zenetos, A. 1991 01 15: Re-evaluation of numerical classification methods for delimiting biofacies and biotopes in an estuarine environment. Lethaia . Vol. 24. pp. 13–26. Oslo. ISSN 0024–1164.
To test the applicability of numerical classificatory methods in defining biotopes and biofacies, several sets of data were combined using alternative measures of similarity and clustering techniques. In both types of analysis (biofacies and biotopes), results showed that binary data contain enough information and can give as good a picture as the quantitative data, provided [hat the appropriate techniques are used. Despite the inadequacy of the living mollusc data. biotope patterns produced by living and subfossil molluscs are similar, suggesting negligible post-mortem transportation and burial of the fauna in its place of occurrence. The biotopes delineated in this study are consistent with Eastwood's (1977) 'textural facies' patterns based on the sediment size distribution. In this line, it is suggested that the grain size of the substrate is the main factor determining the distribution of molluscs in the Eden estuary. Moreover. the fact that the same cluster analysis combination (D-coef./Ward's clustering) based on independent variables (fauna and sediment size distribution) led to similar results. emphasizes the objectivity of the methods used and the stability of the clusters generated. Mollusca. numerical taxonomy. biotopes. biofacies. Eden estuary .     

Does the surrounding landscape heterogeneity affect the butterflies of insular grassland reserves? A contrast between composition and configuration

Landscape homogenisation represents one of the gravest threats to the biodiversity of intensively farmed landscapes. In such landscapes, many species persist within remnants of (semi)natural habitats, such as in the steppe grasslands of Southern Moravia, SE Czech Republic. We investigated how the butterfly fauna of insular grassland reserves is affected by the heterogeneity of the surrounding farmland. We followed two lines of evidence, one based on species richness, the other on species community composition, considering two aspects of landscape heterogeneity, composition (amount of land cover types) and configuration (geometry of land cover patches). After statistically correcting for individual reserves characteristics, and within-reserves biotope composition, we found that reserves amidst heterogeneous landscapes contained more species. With increasing buffers around the reserves, the strength of the effects decreased for landscape composition, and increased for landscape configuration. Similar patterns applied for the butterfly assemblage composition, but in a rather subtle manner, not reflecting a specialist versus generalist dichotomy. However, more red-listed species inclined towards reserves amidst heterogeneous matrices. The species most tightly associated with heterogeneous landscapes were those whose populations likely span across multiple patches of relatively rare biotopes, whereas those indifferent to configuration were either those persisting at isolated sites, or those utilising common biotope types outside the reserves. The importance of landscape configuration suggests that relatively cheap restoration measures aimed at compartmentalisation the currently huge farmland units may substantially contribute to preserving biodiversity in intensively farmed regions.     

Macrophyte diversity and composition in relation to substratum characteristics in regulated and unregulated Danish streams

1. The objective of the present study was to examine how the physical stream environment in regulated and unregulated lowland streams affects the diversity and distribution of macrophyte communities. We analysed the abundance, distribution and composition of macrophytes, together with physical parameters, in seven regulated and seven unregulated unshaded Danish stream reaches. 2. Total macrophyte coverage was similar in the regulated and unregulated streams, but species richness and Shannon diversity were higher in the unregulated streams. Overall, we found fifty-two different species in the regulated stream reaches and sixty-two in the unregulated stream reaches. The spatial distribution of macrophytes on the stream bottom was more heterogeneous in the unregulated streams. 3. We found positive correlations between the coverage and diversity of macrophytes and the coverage of coarse-textured substratum types on the stream bottom, as well as between macrophyte coverage and diversity and substratum heterogeneity. We also found that the macrophytes were more heterogeneously distributed where substratum heterogeneity was greater. 4. The species growing both submerged and emergent were more abundant in the regulated streams, whereas species growing only submerged were more abundant in the unregulated streams. Species growing submerged, species growing both submerged and emergent, and species only growing emergent segregated differently in a canonical correspondence analysis ordination. The submerged species were primarily associated with coarser-textured substrata, whereas species growing both submerged and emergent, and species growing only emergent were associated with finer-textured substrata. 5. The most abundant species in the regulated streams, Sparganium emersum, accounting for almost one-third of the total macrophyte coverage, was primarily associated with clay and sandy bottom substrata, whereas the most abundant species in the unregulated streams, Batrachium peltatum, was primarily associated with gravel and stony substrata.     

广州南沙十四涌潮间带大型底栖动物的功能群

大型底栖动物根据食性可分为浮游生物食者(planktophagous, Pl)、植食者(phytophagous, Ph)、肉食者(carnivorous, C)、杂食者(omnivorous, O)和碎屑食者(detritivorous, D)五个功能群。本文根据2007-2008年度和2013-2014年度在茳芏(Cyperus malaccensis)、海桑(Sonneratia caseolaris)2种生境调查获得的各4个季度的大型底栖动物数据, 分析了广州南沙十四涌潮间带大型底栖动物功能群的生境差异、季节变化和年际变化。2007-2008年度采集到26种大型底栖动物, 低于2013-2014年度的36种。无论是2007-2008年度还是2013-2014年度, 茳芏、海桑生境的大型底栖动物均以植食者的栖息密度和生物量最高, 碎屑食者的栖息密度和生物量最低。生境比较得出, 茳芏生境大型底栖动物浮游生物食者(Pl)的丰富度指数(d)、均匀度指数(J)和多样性指数(H')均高于海桑生境。年度比较得出, 在茳芏和海桑生境, 2013-2014年度浮游生物食者的丰富度指数、均匀度指数和多样性指数均高于2007-2008年度, 这是因为2013-2014年度采集到红树蚬(Gelonia coaxans)和彩虹明樱蛤(Morerlla iridescens)等, 而2007-2008年度没有采集到。     

Plant functional diversity in agricultural margins and fallow fields varies with landscape complexity level: Conservation implications

A consensus has been established that functional traits rather than taxonomic diversity play a fundamental role in linking biodiversity with ecosystem processes and associated services. This study from Finland addressed an issue of relative values of fallow and field margin biotopes in conservation of plant functional diversity (based on six functional traits of relevance to ecosystem services, and diversity of multiple traits) in agricultural landscapes differing in their structural complexity. Relative covers of plant species were surveyed in sampling plots located in perennial fallow fields and three types of perennial margins (margins between crop fields, along forest edges and by river) in three types of landscape context (simple, intermediate and complex). Fallow fields significantly contributed to the total functional diversity only in simple landscapes. The river margins provided the greatest functional diversity, especially in reproduction and regeneration traits while crop margins were consistently characterized by the lowest functional diversity. Substantial functional diversity of fallow patches in simple landscapes was due to high abundance of functional species, while that of river margins stemmed from presence of unique species. The plant functional diversity progressively declined with agricultural landscapes becoming simplified. The study indicates non-cropped biotopes having complementary roles in ensuring multifunctionality of agro-landscapes and confirms importance of biotope mosaic for functional diversity.     

In-situ investigations on small-scale local and short-term changes of sublittoral macrobenthos in Lübeck Bay (western Baltic Sea)

In-situ studies on sublittoral soft bottom macrofauna (depth: 14–16 m) employing the underwater laboratory (UWL) “Helgoland” were carried out. Sets of samples were compared for small-scale local and short-term changes in species richness, faunal abundance, numerical dominance, diversity, evenness, homogeneity, and similarity. It could be shown that minor differences in sediment quality can cause conspicuous heterogeneity within a small sampling area (diameter: ca. 100 m). Both spatfall and mortality of benthic invertebrates can change the faunal structure within a short period (two months). The degree of change varies between species and thus at stations harbouring different faunal assemblages as well.     

The influence of biotope availability on macroinvertebrate assemblages in South African rivers: implications for aquatic bioassessment

1. Macroinvertebrate biotope preferences and the influence of differences in the availability of biotopes on individual taxa, macroinvertebrate assemblages and a biotic index, the South African Scoring System (SASS), were investigated in two regions of South Africa. 2. Among biotope differences in individual taxa and macroinvertebrate assemblages resulted in differences in SASS scores, with differences in assemblages being greater among biotopes than between sites. 3. All three metrics studied (SASS score, number of taxa and average score per taxon, ASPT), differed significantly among biotopes, with highest scores consistently recorded in the stones biotope, while lowest SASS scores and fewest taxa were recorded in the sand biotope. 4. SASS score and number of taxa were positively, while ASPT was negatively correlated with number of biotopes sampled. 5. The observed biotope differences highlight the importance of sampling and comparing data from sites separately for each biotope.     

Structure and biodiversity of nematode assemblages in the SW lagoon of New Caledonia

 Meiofaunal density and the taxonomic composition of nematodes were investigated in three bottom types of the SW lagoon of New Caledonia (SW Pacific). Meiofaunal density was significantly higher in white-sand bottoms than in other biotopes (grey-sand and muddy bottoms). Thirty-three nematode families and 172 genera were identified. Species diversity indices were significantly lower in back-reef white-sand than in seagrass grey-sand and coastal mud. The familial, generic and species diversity were analysed in relation to ecological and biotic parameters by multivariate factorial correspondence analysis and hierarchical clustering. The analysis at familial level was unable to discriminate between stations and biotopes. The analysis at generic level detected three main nematode associations related to microphytobenthic primary productivity, macrophyte biomass and silt content. Taxonomic composition of one white-sand station (Mbéré reef) differed from all others in relation to an increased chlorophyll/pheophytin ratio and a lower silt content. Grey-sand stations were split in two distinct groups. The first combined two of the three white-sand stations and the grey-sand stations, all of which were characterised by a medium silt content and a medium productivity. The second group combined the muddy bottom stations and the siltiest grey-sand stations which were characterised by a high silt content, a lower macroflora biomass and low productivity. Accepted: 22 October 1996     

Effects of dredged material disposal on benthic macrofauna near Itajaí Harbour (Santa Catarina,South Brazil)

From July 2006 to November 2007 the effects of sediment disposal on a macrobenthic association were evaluated at the dredged material disposal site, located 3 km northeast of Itajaí Harbour navigation channel. Seven sample sites were chosen, five inside the licensed disposal area and two outside. Five samples were collected from each site with a 0.042 m² Van-Veen grab. Nine sampling campaigns took place, one before, one during, and seven after the disposal operations. Evaluations were carried out through sediment and macrofauna composition analysis. An increase in coarse fractions of sediments was found during the first months, mainly within the licensed disposal area. Sites outside the area kept the same granulometric characteristics. Nested ANOVA showed that abundance, taxa richness and Shannon–Weaver diversity were significantly smaller after the disposal, and recovered the initial mean values after the disposal ends. PERMANOVA showed a high heterogeneity between the sites. It decreased until the fifth month after disposal operations, mainly in the sites inside the licensed area. These sites were characterized by low abundance and high variability among the samples. Eight to 16 months after disposal sites recovered their heterogeneity, indicating less variability among the samples of each site and distinct benthic macrofaunal composition. The high volume and frequency of sediment disposal were the main factors of environmental modifications, since the amount of deposited sediment on the seabed probably exceeded the natural sedimentation rates. The presence of a benthic macrofauna adapted to natural/human disturbances was crucial to the fast recovery verified in the area.     

Characteristics of plant communities containing St. John’s wort (<Emphasis Type="Italic">Hypericum perforatum</Emphasis> L.) in the Saratov Region

Analysis of 28 plant communities containing Hypericum perforatum L. in five different biotope types has been performed in 17 districts of the Saratov Region. A total of 325 species from 197 genera of 52 vascular plant species have been recorded, with plants characteristic of forest-edge, steppe, and anthropogenic biotopes prevailing in most communities. It has been shown that H. perforatum at the southeastern boundary of its range behaves as an explerent species. The main factor limiting its growth in biotopes of a certain type is the degree of disturbance in the structure of corresponding communities rather than by their taxonomic composition.