Mean Number Of Taxa Research Articles

NAMBER: A biotic index for assessing the ecological quality of mesophotic biogenic reefs in the northern Adriatic Sea

Abstract The aim of the present study was to propose a biotic index (North Adriatic Mesophotic BiogEnic Reefs, NAMBER) suitable for assessing the ecological quality of the mesophotic biogenic reefs of the northern Adriatic continental shelf based on photographic sampling. At each of the 20 study sites, the degree of bioconstruction (expressed as percentage cover of crustose coralline algae), the α‐diversity (expressed as the mean number of taxa), and the degree of sensitivity to human disturbance and climate change (based on literature data and expert judgement) of the benthic assemblages were selected as descriptors and combined in the NAMBER index, using the best values that the three metrics can currently achieve in the studied region as a reference. The study highlighted that there was large spatial heterogeneity among reefs and high variability in the ecological quality values obtained by NAMBER, ranging from bad to high. The index indicates that reefs lying furthest from the coast, under substantially lower anthropogenic pressure, have a generally higher status of environmental quality. However, a clear geographical pattern did not emerge, as reefs close together often had different ecological qualities. The NAMBER index, which combines three ecological descriptors, in accordance with the requirements of the European Marine Strategy Framework Directive, represents a specific adaptation to the northern Adriatic Sea of a multimetric index previously developed for the north‐western Mediterranean Sea, capitalizing on previous knowledge and research efforts. This multimetric biotic index provides an effective standardized tool for monitoring programmes and environmental impact assessments in the northern Adriatic mesophotic biogenic reefs and lays the foundation for ecosystem‐based management and conservation in this basin.

Zooplankton distribution and community structure as a function of environmental variables in the Niger River and its tributaries in Niger

The Niger River and its main tributaries (Sirba, Tapoa and Mékrou) in Niger were sampled during high and low water flow with the objectives of (1) comparing the taxonomic structure, diversity and abundance of the zooplankton community (rotifers, copepods, crustaceans) along the river and (2) determining which environmental or biological factors influence the distribution of the zooplankton communities most strongly. The impact of the tributaries at high-flow was also evaluated. Rotifers (32 taxa) were the most abundant and diverse followed by Cladocerans (13 taxa) and Copepods (three taxa). The mean number of taxa (16.5 and 17.6, respectively), the Shannon-Weaver diversity index (2.7 and 2.8, respectively) and the evenness (0.7 and 0.7, respectively) did not vary significantly between the high- or low-flow periods, or along the length of the Niger River and its tributaries. The mean zooplankton abundance was highest during low-flow periods (40 × 103 ± 45 × 103 ind. m−3) but showed no specific spatial pattern. During high-flow sampling, the mean zooplankton abundance (3 × 103 ± 2 × 103 ind. m–3) increased progressively downstream. RDA analysis showed that rotifers are associated with high conductivity and NO2 − concentrations, copepods with chlorophyll a, while cladocerans were abundant when conductivity, chlorophyll a and NO2 − concentrations were low.

Potential Implications of Excluding Live‐Bottom Habitat from a Bottom‐Trawl Survey in the Eastern Gulf of Mexico

AbstractData provided by the Southeast Area Monitoring and Assessment Program (SEAMAP) shrimp/groundfish trawl survey have long been used in assessing diverse managed taxa, including several reef fishes; however, there are rising concerns over the impacts of trawling on live‐bottom habitats. Using data collected from summer SEAMAP trawl surveys (2009–2016; N = 1,103), we examined how avoiding areas of live‐bottom habitat might affect the survey's ability to assess interannual changes in abundance of managed reef fish taxa. Trawl samples at 48% of sampling sites contained <50 kg of sponge, and 12% of sampling sites contained at least 50 kg of sponge, while 40% of sites had zero sponge bycatch. Mean number of taxa, taxonomic richness, and taxonomic diversity were significantly higher as sponge bycatch increased, while the total number of individuals remained the same. To examine interannual variability of managed reef fish taxa, annual indices of relative abundance were calculated on different subsets of data (all data, data excluding sites with sponge bycatch ≥50 kg, and data excluding all sites with sponge bycatch). For Red Snapper Lutjanus campechanus and pink shrimp Farfantepenaeus duorarum, indices and general trends were largely unaffected by excluding sites with sponge, but for most selected taxa (e.g., Gray Triggerfish Balistes capriscus and Red Grouper Epinephelus morio), overall trends were affected by excluding sites that contained sponge bycatch, and in some cases the frequency of occurrence did not meet the requirement to calculate an index of abundance (i.e., <5%) when sponge sites were excluded (e.g., Hogfish Lachnolaimus maximus). Efforts to mitigate survey interactions with live‐bottom habitats will likely alter the utility of survey data and the ability to assess managed species, so careful consideration is needed to evaluate any trade‐offs between the benefits of the trawl survey for fishery assessments and the benefits of protecting the habitat.

A phytosociological survey of aquatic vegetation in the main freshwater lakes of Greece

Aims: This study aims to contribute to the knowledge of European freshwater lake ecosystems with updated and new information on aquatic plant communities, by conducting national-scale phytosociological research of freshwater lake vegetation in Greece. Moreover, it investigates the relationship between aquatic plant communities and lake environmental parameters, including eutrophication levels and hydro-morphological conditions.Study area: Lakes in Greece, SE Europe.Methods: 5,690 phytosociological relevés of aquatic vegetation were sampled in 18 freshwater lake ecosystems during 2013–2016. The relevés were subjected to hierarchical cluster and indicator species analyses in order to identify associations and communities of aquatic vegetation, as well as to describe their syntaxonomy. Multiple regression analysis was applied to investigate the relationship between vegetation syntaxa and environmental parameters of lakes, i.e. physico-chemical parameters and water level fluctuation.Results: Ninety-nine plant taxa belonging to 30 different families were recorded. Forty-six vegetation types were identified and described by their ecological characteristics, diagnostic taxa and syntaxonomical status. Thirteen vegetation types, the largest number belonging to the vegetation classCharetea, are considered to be new records for Greece. The distribution of the vegetation types recorded in the 18 freshwater lakes was found to depend on environmental parameters and levels of eutrophication.Conclusions: An updated aquatic vegetation inventory was produced for Greek lakes, and primary results showed that the presence/absence of aquatic plant communities and the community composition in freshwater lakes can be utilized to assess the pressure of eutrophication on lake ecosystems.Taxonomic reference: Euro+Med (2006–).Abbreviations: MNT = Mean number of taxa; WFD = Water Framework Directive.

Multi-functionality of the few: current and past uses of wild plants for food and healing in Liuba\u0144 region, Belarus

BackgroundThis study examined the use of wild plants in the food, medicinal and veterinary areas within a small territory limited to one village council in the Liubań district of Belarus. The objectives of the research were to document the current and past uses of wild plants in this region for food and human/animal medication; to analyse the food, medicinal and veterinary areas in the context of wild plants; and to qualitatively compare the results with relevant publications concerning the wild food plants of Belarus.MethodsFieldwork was carried out as a practical part of a development cooperation project in May 2016 in 11 villages of the Liubań district. One hundred thirty-four respondents were selected randomly. Information about local uses of wild plants was obtained via semi-structured interviews and the folk-history method. Interview records were digitalized and the data structured in Detailed Use Records (DUR), which were divided into food, medicinal and veterinary areas and then analysed to ascertain local perceptions.ResultsA total of 2252 DUR of wild plants were recorded. Eighty-eight wild plant taxa belonging to 45 plant families were used across all three areas. Of these, 58 taxa were used in the food, 74 in the medicinal and 23 in the veterinary areas. A relatively high percentage of the taxa were used in both the food and medicinal areas (55%) and an even greater percentage in both the medicinal and veterinary areas (87%). Comparison with earlier research on wild food plants shows the considerable difference among seldom-mentioned taxa or uses, showing possible regional differences despite the homogenization of the population during the Soviet era.ConclusionsAs the majority of taxa with overlapping uses belonged to the most utilized plants, there appears to be clear a tendency to use plants in several different areas once they are brought into the home. This may be due to the need to maximize the versatility of limited resources. While the number of wild taxa used is relatively high, the mean number of taxa used per person is quite low, which indicates the relatively minor importance of wild plants in the respective areas in the study region. The low importance of snacks signals that unintended contact with nature has been lost.

Assessment of biodiversity and environmental quality using macrozoobenthos communities in the seagrass meadow (Gulf of Gdańsk, southern Baltic)

Abstract This study shows the macrozoobenthic biodiversity and the quality status of the Zostera marina meadow in the Gulf of Gdansk. To our knowledge, this is the first study focused on the assessment of environmental quality based on macrofauna occurring on such a small and specific habitat as a seagrass meadow. The meadow is dominated by Zostera marina, but also Zanichellia palustris and Potamogeton pectinatus are present. Compared to the soft bottom macrofauna in the southern Baltic, the biodiversity of macrozoobenthos is very high, which is reflected in 33 taxa observed during the whole research, while the mean number of taxa was 12. There were also some taxa found only on the bottom overgrown with vegetation, e.g. Idotea balthica or even taxa that are currently rarely observed in the Gulf of Gdansk, e.g. Gammarus locusta or Gammarus ineaquicauda. Nineteen percent of the stations were classified into the very good quality status and 50% into the good quality status, so the environmental status of this meadow based on the BQI index is assessed as good. Given these results, this is probably one of the best preserved meadows in the southern Baltic.

Bacterial diversity of symptomatic primary endodontic infection by clonal analysis

The aim of this study was to explore the bacterial diversity of 10 root canals with acute apical abscess using clonal analysis. Samples were collected from 10 patients and submitted to bacterial DNA isolation, 16S rRNA gene amplification, cloning, and sequencing. A bacterial genomic library was constructed and bacterial diversity was estimated. The mean number of taxa per canal was 15, ranging from 11 to 21. A total of 689 clones were analyzed and 76 phylotypes identified, of which 47 (61.84%) were different species and 29 (38.15%) were taxa reported as yet-uncultivable or as yet-uncharacterized species. Prevotella spp., Fusobacterium nucleatum, Filifactor alocis, and Peptostreptococcus stomatis were the most frequently detected species, followed by Dialister invisus, Phocaeicola abscessus, the uncharacterized Lachnospiraceae oral clone, Porphyromonas spp., and Parvimonas micra. Eight phyla were detected and the most frequently identified taxa belonged to the phylum Firmicutes (43.5%), followed by Bacteroidetes (22.5%) and Proteobacteria (13.2%). No species was detected in all studied samples and some species were identified in only one case. It was concluded that acute primary endodontic infection is characterized by wide bacterial diversity and a high intersubject variability was observed. Anaerobic Gram-negative bacteria belonging to the phylum Firmicutes, followed by Bacteroidetes, were the most frequently detected microorganisms.

Long‐term effects of climatic–hydrological drivers on macroinvertebrate richness and composition in two Mediterranean streams

Summary The unique information provided by multiyear data sets can aid in detecting major long‐term trends and making predictions with respect to environmental and biological variables. These trends are expected to differ among climatic regions but little information exists concerning long‐term variability within a particular climate region. We analysed the long‐term (14‐year time span) patterns in species richness and composition of aquatic insects (EPT: Ephemeroptera, Plecoptera and Trichoptera) in relation to changes in temperature, precipitation and discharge in two reference streams in Catalonia (north‐east Spain). Our study sites were located in the Mediterranean macroclimate region but in different mesoclimatic areas, one in the Wet Mediterranean climate area and the other in the Dry Mediterranean climate area (WM and DM, respectively). At the macroclimate scale, precipitation decreased and the frequency of drought events increased during the 14‐year period. Although the mean number of taxa in each of the two sites remained similar, there was a replacement of species characteristic of riffle‐like conditions by species characteristic of pool‐like conditions over time in both sites. EPT composition differed between sites at the mesoclimate scale, demonstrating the importance of regional factors. In particular, changes in EPT composition were less variable in WM than in DM both in the short term and in the long term, indicating that the WM site was less constrained by climate than the DM site. Such differences between mesoclimates are related to differences in flood magnitude (higher in WM) and drought frequency (more frequent in DM) as well as local hydromorphological differences. Our findings indicate that the streams responded similarly to long‐term patterns in large‐scale variables (i.e. those affecting the overall macroclimatic region), but differed with respect to the effect of local‐scale variables (i.e. those differentially affecting each mesoclimatic area). Predictive bio‐assessment models that use reference conditions must incorporate long‐term variability to accurately assess the ecological status of Mediterranean climate streams.

Diversity of demersal and megafaunal assemblages inhabiting sandbanks of the Irish Sea

Sandbanks are marine habitats of conservation importance under the EU Habitats Directive. These habitats are becoming subject to impacts of several human activities including fishing, aggregation extraction, and construction of offshore wind farms that may have detrimental effects on their structure and functioning. We characterised and com- pared the diversity and biological traits of demersal fish and megafaunal invertebrate assemblages inhabiting three sand- banks, one in the vicinity of a small existing wind farm and two which are proposed sites for future wind farm installa- tions. Samples in the vicinity of the offshore wind farm were compared with two control sites on the same sandbank. There were significant differences in mean number of taxa, abundance and structure of assemblages between sand- banks. However, biological traits analyses (BTA) showed no differences in the functional traits of assemblages among sandbanks, suggesting functional redundancy. Despite a significant spatial variation in structure and Shannon diver- sity of assemblages between sites within sandbanks, fish and megafaunal assemblage did not differ between sites near wind turbines and the controls. The natural spatial variabil- ity in the diversity and biological traits of demersal and megafaunal assemblages inhabiting this naturally highly disturbed environment is larger than any changes associated with the presence of the wind turbines. This study provides important baseline data against which potential future impacts of human activities can be tested.

Exploring Bacterial Diversity of Endodontic Microbiota by Cloning and Sequencing 16S rRNA

Introduction The characterization of microbial communities infecting the endodontic system in each clinical condition may help on the establishment of a correct prognosis and distinct strategies of treatment. The purpose of this study was to determine the bacterial diversity in primary endodontic infections by 16S ribosomal-RNA (rRNA) sequence analysis. Methods Samples from root canals of untreated asymptomatic teeth (n = 12) exhibiting periapical lesions were obtained, 16S rRNA bacterial genomic libraries were constructed and sequenced, and bacterial diversity was estimated. Results A total of 489 clones were analyzed (mean, 40.7 ± 8.0 clones per sample). Seventy phylotypes were identified of which six were novel phylotypes belonging to the family Ruminococcaceae. The mean number of taxa per canal was 10.0, ranging from 3 to 21 per sample; 65.7% of the cloned sequences represented phylotypes for which no cultivated isolates have been reported. The most prevalent taxa were Atopobium rimae (50.0%), Dialister invisus, Prevotella oris, Pseudoramibacter alactolyticus, and Tannerella forsythia (33.3%). Conclusions Although several key species predominate in endodontic samples of asymptomatic cases with periapical lesions, the primary endodontic infection is characterized by a wide bacterial diversity, which is mostly represented by members of the phylum Firmicutes belonging to the class Clostridia followed by the phylum Bacteroidetes.

Are Water Framework Directive stream types biologically relevant? The case of the Mondego river, Portugal

Typology schemes are useful in partitioning natural spatial variability and thus helping implementing bioassessment methods. They have become widely accepted in Europe after the publication of the Water Framework Directive (WFD). The major objective of this study was to test if six Portuguese pre-defined physical stream-types (using System-B of the WFD) are concordant with macroinvertebrate assemblages collected in 31 undisturbed sites in a Portuguese river basin. A top-down (stream types defined by physical attributes) and a bottom-up approach (river classes defined by biological communities) were used. No significant differences were found in the mean number of taxa and abundance of different physical stream types and few taxa are characteristic of specific stream types. Discriminant analysis (DA) considering family-level composition revealed that all stream-types were significantly different and the cross-validation process showed that all stream-types had more than 50% of their samples correctly assigned. On the other hand, the bottom-up approach based on a correspondence analysis (CA) showed some overlap of the macroinvertebrate communities of pre-defined stream types, indicating that variations in the macroinvertebrate community structure was primarily related to altitude, mineralisation and a temporal gradient. DA cross-validation and CA results suggest that tested stream types do not account for natural temporal changes known to affect macroinvertebrate communities in this Mediterranean basin and that the WFD typology should account for these natural variations. The exclusion of natural variability could indicate impairment when it does not exist or no impairment when it does exist (type I and II statistical errors).

Effects of sediment pollution on food webs in a tropical river (Borneo, Indonesia)

The impact of pollution on the trophic ecology of the Kelian River (Borneo, Indonesia) was studied by comparing food webs (on the basis of gut analysis and field and laboratory observations) at six sites. The upper sites were in pristine rainforest but the river became increasingly polluted downstream, largely owing to sedimentation from alluvial gold mining activities. Four previous studies all showed a downstream decrease in macroinvertebrates (mean abundance: 272 per 400 cm2 at Site 1 dropped to 2.6 at Site 6; mean number of taxa: 37.6 at Site 1 down to 1.6 at Site 6), and this was highly correlated with suspended solids. Food webs also reflected the effect of pollution. Cleaner sites had more complex food webs, with more elements, links, higher linkage density and higher complexity than did downstream polluted sites, which lacked grazers, shredders and filterers. Several taxa that were grazers at clean sites became collector-gatherers at polluted sites. Despite the enormous impact of pollution, cessation of alluvial mining activities resulted in some recovery. The resilience of the fauna is likely to be enhanced by the tropical conditions with high rainfall, rapid flow rates and high temperatures, coupled with rapid life cycles. Fish distribution and diets did not appear to be affected by pollution.

Bootstrapping to investigate the effect of number of macroinvertebrate samples on confidence limits of the mean

A resampling technique (bootstrapping) was used to evaluate the effects of increasing sample number on the confidence limits of mean density and the mean number of taxa (Families) in addition to the performance of four different sampling devices used to collect macroinvertebrates in three streams of contrasting anthropogenic impact. The four sampling devices were a Hess sampler, a modified Hess sampler equipped with an internal water pump, a Surber sampler, and a two-pole kick-net. In general, confidence limits decreased predictably as the number of samples increased, most notably with the addition of a third sample. The density of organisms captured with the Surber sampler was significantly lower than that of the Hess sampler but greater than that of the kick-net sampler. No significant difference in the number of Families was found among sampling devices. Based upon a minimal 10% reduction in confidence limits compared to the previous sample, a minimum of four replicates was suggested when using the Surber sampler. In general, other methods required a greater number of replicates that the Surber to adequately represent density, but this did not hold when applied to the number of taxa. Despite the inconvenience of having to bend down to use the Surber sampler, this study found no evidence to reject its apparent popularity as a sampling method for macroinvertebrates.

Cultivable bacteria in infected root canals as identified by 16S rRNA gene sequencing

Traditionally, cultivable bacteria isolated from infected root canals have been identified by phenotype-based methods. Because 16S ribosomal RNA (rRNA) gene sequencing has emerged as a more accurate and reliable tool for bacterial identification, the present study applied this approach to identify bacterial isolates recovered from the root canals of teeth with chronic apical periodontitis. Anaerobic techniques were used for culturing; identification of the isolates was carried out by polymerase chain reaction amplification and sequencing of the V5-V8 region of the 16S rRNA gene. Bacteria were found in all samples. The mean number of taxa per canal was 3.1, ranging from 2 to 8. The median number of cultivable bacterial cells in the root canals was 4.2 x 10(5), ranging from 2.8 x 10(3) to 3.3 x 10(7). Eighty-seven strains belonging to 52 bacterial taxa were identified. The most prevalent taxa were Fusobacterium nucleatum, Porphyromonas gingivalis, Pseudoramibacter alactolyticus, Micromonas micros and streptococci. The following bacterial phyla were represented in this study: Firmicutes (22 taxa, 46% of the identified isolates), Actinobacteria (14 taxa, 25.3% of the isolates), Bacteroidetes (eight taxa, 13.8% of the isolates), Fusobacteria (three taxa, 9.2% of the isolates) and Proteobacteria (five taxa, 5.7% of the isolates). Some of the isolates represented unnamed species not previously cultivated and characterized. In conclusion, our findings using a combined anaerobic culture-molecular identification approach confirmed the polymicrobial nature of primary endodontic infections with dominance of anaerobic bacteria. Notably several bacteria that are difficult or impossible to identify by phenotypic means were identified, including previously uncultivated taxa, cultivated-but-not-yet-characterized taxa and newly named species.

Stream Macroalgae of the Hawaiian Islands: A Floristic Survey

ABSTRACT Between January 2001 and May 2003, 167 stream segments on the islands of Kaua‘i, O‘ahu, Maui, and Hawai‘i were sampled for stream macroalgae and measured for a series of physical and chemical conditions. Conditions ranged more widely than previously reported, which is likely due to the greater diversity of habitats accessed and the year-round sampling representation in this study. Water temperature ranged from 12.5 to 27.5 °C (mean = 21.4 °C ± 2.4), pH from 5.5 to 8.9 (mean = 7.8 ± 0.5), and specific conductance from 20 to 490 μS·cm−1 (mean = 102 μS·cm−1 ± 75.9). A total of 160 specific and subspecific taxa was identified, of which 27 are new records for the Hawaiian Archipelago. The Chlorophyta compose the majority of the taxa, followed by the Cyanobacteria, Rhodophyta, Bacillariophyta, and Tribophyta. The mean number of taxa per stream segment was 5.0 ± 2.7, which is the highest such value reported. Grouping of taxa by morphological form demonstrates that the majority of taxa were free filament...

CONTRASTING EFFECTS OF MEAN INTENSITY AND TEMPORAL VARIATION OF DISTURBANCE ON A ROCKY SEASHORE

Understanding the extent to which natural assemblages withstand changes in the regime of disturbance has considerable practical and theoretical interest. In this paper we examine the separate and interactive effects of intensity, temporal variation, and spatial extent of disturbance on temporal variance in assemblages of algae and invertebrates of rocky shores in the northwest Mediterranean. Temporal variation of disturbance is a predictor variable in the experiment, while temporal variance in abundance and number of taxa and in structure of assemblages are response variables. Multivariate analyses detected a positive relationship between intensity of disturbance and temporal variance in the structure of assemblages, while temporal variation of disturbance elicited the opposite effect. Univariate analyses conducted on the most abundant taxa revealed idiosyncratic patterns, while temporal variance in mean number of taxa was greatly reduced by disturbance, with no distinction among levels of intensity, temporal variation, or spatial extent. These outcomes suggest caution in interpreting the results of experiments in which intensity and temporal variation of disturbance cannot be separated. Distinguishing between these traits of disturbance may be key to predicting the ecological consequence of environmental fluctuations, including those expected under modified climate scenarios.

Benthic meiofauna responses to five forest harvest methods

Benthic meiofauna were collected from the pools of minute (0 order) streams in the Ouachita National Forest, Arkansas during March 21–23, 1996 to see if benthic communities responded to forest harvest methods in a similar manner as plankton communities collected two years prior. The study streams and their watersheds (2–6 ha) were located in 14–16 ha forest stands that were selected for comparability of stands. Five treatment stands were paired with adjacent undisturbed reference stands (10 total). Treatment stands were subjected to one of five harvest methods listed in order of decreasing severity of harvest disturbance to the stands: (1) clearcut; (2) pine seed-tree; (3) pine shelterwood; (4) pine-hardwood group selection; and (5) pine single-tree selection. The mean number of taxa per site was 14 with a range of 9–20 taxa including rotifers, copepods, nematodes, dipterans, ostracods and `other' meiofauna. Densities of total meiofauna (mean=2449 No. l −1) were significantly higher (p= 0.002) in treated sites. Highest densities occurred in single-tree and clearcut treatments. Rotifers were significantly more numerous at the single-tree treatments (p=0.03) and nematodes were significantly greater at the clearcut treatments (p=0.03). We conclude that benthic meiofauna in these headwater streams are sensitive to silviculture practices and that the impact of forest harvest persists for at least 2.5 years.

Meiofauna in intermittent streams differ among watersheds subjected to five methods of timber harvest

Meiofauna were collected from the pools of small (0 order) streams in the Ouachita National Forest, Arkansas to examine the impact of forest harvest methods. The study streams and their watersheds (2–6 ha) were located in 14–16 ha forest stands that were selected based on comparability of stands. Five treatment stands were paired with adjacent undisturbed reference stands (10 total). Treatment stands were subjected to one of five harvest methods, listed in order of decreasing severity of harvest disturbance to the stands: (1) clearcut; (2) pine seed-tree; (3) pine shelterwood; (4) pine-hardwood group selection; and (5) pine single-tree selection. Although the mean density of meiofauna collected in 22 l samples pumped from pools was low (1 No. l −1), significant differences were identified. Densities of total meiofauna, harpacticoid copepods, nauplii, ostracods and `other' meiofauna varied significantly by site and treatment (forest harvest). The highest densities of these taxa occurred at the single-tree treatment sites. Greater densities of meiofauna corresponded to greater diversity. The mean number of taxa per site was 11 with a range of 5–24. Rotifers, copepods, nematodes, ostracods and `other' meiofauna taxa were collected. The pattern of diversity of meiofauna at treatment sites from the least intensive (single-tree) to most intensive (clearcut) suggests a curve related to disturbance intensity.

Palaeoenvironment of Maastrichtian ostracods from ODP Holes 1049B, 1050C and 1052E in the Western North Atlantic

Abstract. The Maastrichtian ostracods recovered from ODP Holes 1049B, 1050C and 1052E on the Blake Nose, Western North Atlantic, are investigated. The three sites are located on a depth transect encompassing middle to lower bathyal, Late Cretaceous palaeodepths. Fourteen samples ranging in age from early to late Maastrictian are investigated from Hole 1052E, which is the shallowest site. The early Maastrichtian G. falsostuarti–G. gansseri Zone of Hole 1052E yields rare ostracods. The species richness, abundance and faunal density are on average considerably higher in the late Maastrichtian R. fructicosa and A. mayaroensis Zones of Hole 1052E, possibly, at least partly, as a result of palaeoceanographical changes that were also responsible for the disappearance of the inoceramid bivalves at this location. A palaeobathymetrical comparsion among the late Maastrichtian ostracod assemblages recorded from Holes 1049B, 1050C and 1052E shows that the faunal density and mean number of taxa are inversely correlated with palaeodepth; however, the dominance of the platycopid genus Cytherella increases with palaeodepth. A dominance of platycopids may signify environmental stress related to low oxygen content. The dominance of the benthic foraminifer Nuttalides trumpeyi in the Late Cretaceous of Holes 1049B and 1050C provides additional evidence of oxygen deficiency. From a total of 28 genera recorded from Holes 1049B, 1050C and 1052E, 14 were previously recorded from Hole 689B, a high latitude hole in the Southern Ocean, and show that many ostracod genera display a wide latitudinal distribution in the Late Cretaceous deep sea, although more geographically restricted genera are also present, analogous with modern and Tertiary oceans.

Distribution and Floristics of Bryophytes in Soil Crusts in Semi-Arid and Arid Eastern Australia

A total of 56 bryophyte taxa associated with biological soil crusts was collected from 282 sites in semi-arid and arid eastern Australia. The 41 moss taxa and 15 liverwort taxa found were dominated by the families Pottiaceae and Ricciaceae respectively. Bryophytes were present at 224 of the 282 sites, and their distribution varied widely according to different landscapes. The mean number of taxa per site ranged from 8.9 on plains with red earths to 2.1 on active floodplains. The most common bryophytes found in the survey area were Bryum pachytheca, Didymodon torquatus, Gigaspermum repens, Goniomitrium enerve, Desmatodon convolutus, Stonea oleaginosa, Crossidium davidai, Riccia limbata and Riccia lamellosa. In this paper, the distribution of bryophytes in relation to landscape types, and some strategies for surviving in arid environments and their roles in biodiversity and rangeland condition assessment are discussed. Their distribution is compared with other published and unpublished studies from similar areas of Australia.