A manipulative experiment to evaluate predicted changes in intertidal, macro-faunal assemblages after contamination by heavy metals

Concentrations of heavy metals (zinc, copper and lead) were manipulated experimentally to test the hypotheses about effects on intertidal, soft-sediment assemblages of animals in two sand-flats in Port Hacking, Australia. Hypotheses about changes in the structure and composition of whole assemblages and changes in mean abundance and variability of individual taxa were tested. Specific hypotheses were derived a priori from repeated observations of assemblages in urban and non-urban areas of Port Hacking.After manipulation, concentrations of metals were similar to those in sediments near urban areas. Nevertheless, responses of assemblages to the increased concentrations of metals were weak. Polychaetes, spionids and amphipods responded to experimental treatments. Changes were, however, not consistent among times and places and generally not in agreement with what had been predicted. Significant spatial and temporal variability were detected for all variables investigated. Increased concentrations of metals did not affect variability or overall structure of assemblages. Thus, there was little evidence that increased concentrations of metals caused benthic assemblages in pristine areas to become more similar to those in areas contaminated by human activities.Several potential explanations for the discrepancy between previously observed correlative patterns and the results presented here are discussed. These include a critical assessment of different aspects of the experimental study, such as lack of statistical power, insufficient basis for prediction, artefacts due to experimental procedures and issues to do with the difference between evidence based on correlation and manipulation. Explicit comparisons showed that there were significant effects of physical disturbance due to repeated sampling and that assemblages of animals at the start of the experiment were different from those previously observed in uncontaminated areas. These observations were surprising and made interpretation more difficult. Nevertheless, it is possible that the metals investigated really contribute only marginally to previously observed differences between urban and non-urban areas. Repeated comparisons between observations of patterns and manipulative experiments like these can only improve the basis for prediction and the power of current mechanistic models.     

Comparative efficiency of clove oil and rotenone for sampling tropical reef fish assemblages

A quantitative examination of the reef fish assemblage at Orpheus Island, Great Barrier Reef, contrasting clove oil and rotenone, sampled 365 individuals of 47 species with clove oil v. 536 individuals of 53 species with rotenone. Number of species and individuals were not found to differ significantly between the two techniques, largely due to variation among samples. Neopomacentrus bankieri (Pomacentridae) and Eviota queenslandica (Gobiidae) were the most dominant in the samples using either technique. Although the samples appeared to be comparable, only 31 species (45%) in eight families were common to both techniques. Fishes often recovered before collection when using clove oil and were not driven out of the reef during induction to anaesthesia. Although the samples collected with clove oil approximate the results obtained using rotenone, enclosed rotenone stations are the preferred method for providing relatively complete quantitative samples.     

Climatic stress, food availability and human activity as determinants of endemism patterns in the Mediterranean region: the case of dung beetles (Coleoptera, Scarabaeoidea) in the Iberian Peninsula

Abstract. A study to assess the influence of abiotic (climatic conditions) and biotic factors (food resources, habitat preference and human activity) on endemism patterns of dung beetles in the Mediterranean region was conducted in the Iberian Peninsula and the Balearic Islands. The Thermicity Index (It), the Mediterraneity Index (Im3) and the Aridity Index (Ia) were used to assess the influence of abiotic factors. Relative rabbit density (DR), the proportion of landscape used historically for grazing by sheep and goats and the nature of the food resource were used to assess the influence of biotic factors. Relative endemism (EN) of dung beetle assemblages was positively and significantly related with all of the factors considered. However, the Aridity and Mediterraneity Indices are the best predictors of EN. The predicted endemism (EN = 0.017 Ia + 0.004 Im3 + 0.422) was highly positively and significantly related with the observed endemism. Dung beetle assemblages with the highest relative endemism were observed in the south-eastern part of the Iberian Peninsula. This distribution corresponded to the highest Aridity and Mediterraneity. In contrast, dung beetle assemblages with lower endemism were located in more humid and temperate areas. Assemblages of dung beetles with the highest endemism comprise many species adapted to aridity and the exploitation of dry dung pellets. Conservation of traditional grazing activity by pellet-dropping sheep and goats might benefit the maintenance of dung beetle biodiversity in Mediterranean ecosystems.     

黔东早—中寒武世凯里组疑源类组合及其界线意义

通过对台江八郎和丹寨两条剖面凯里组中疑源类化石的分析,研究,台江剖面产疑源类化石有17属35各（12未定种）,其中以Leiosphaeridia,Synsphareidium,Cymatiosphaera,Pterospermella最为丰富,可划分为3个组合,即Cymatiosphaera cf.cristata-Fimbriaglomerella memebrancea组合,Cristallinium-Micrhystridium-Pterospermella组合和Dictyotidium-Granomarginata组合,丹寨平寨剖面凯里组所产疑源类化石有：13属21种（5未定种）,同样划分为3个组合,即Leiosphaeridia-Tasmanites组合,Retisphaeridium-Micrhystridium tentatium组合和Baltisphaeridium-Bubomorpha hunjiangensis组合,本文对两条剖面中的凝源类化石的组成,相对含量做了详细的统计,发现在八郎剖面9－2层和平寨剖面3层疑源类的丰度,分异度开始发生明显的变化,表现由早寒武世向中寒武世疑源类组合面貌的转变,这一疑源类转变层位正好是与三叶虫划分的中,下寒武统界线的层位位置相一致,这充分表明疑源类化石可作为划分中,下寒武统的极有价值的微体生物化石证据。     

Sievoides kocyigiti n. gen., n. sp., Mesoendothyra altineriana n. sp. and Kurnubia feleensis n. sp. from Kimmeridgian shallow water limestones intercalated with alkaline igneous rocks, Western Taurus, Turkey

In the framework of the palaeogeographical reconstruction of the Western Taurus during Jurassic, the study of northern and eastern boundary of the Taurids started. Detailed facies analysis evidenced the position of the Barla Dag ramp between two elevated areas: the southern rimmed shelf extension of the platform system and the northern neritic-beach-land plain. In the basal biostratigraphical and ecological characteristics of the Balcikhisar volcano-sedimentary sequence, correlated with the Fele outcrop, one genus and three new species of foraminifers have been found: Sievoides kocyigiti n. gen., n. sp. and Mesoendothyra altineriana n. sp. from neritic environment, and Kurnubia feleensis n. sp. from rimmed shelf lagoon. Both carbonate sedimentary deposits are intercalated with spilitic-basalt pillow lava flows. The age of the new three species is Kimmeridgian, controlled by some foraminifer golden hooks.     

Role of atelomixis in replacement of phytoplankton assemblages in Dom Helvécio Lake, South-East Brazil

Scale and frequency of changes in a lake’s physical structure, light dynamics, and availability of nutrients are closely related to phytoplankton ecology. Since phytoplankton assemblages were first described, phytoplankton ecologists concluded that these assemblages provide insight into phytoplankton responses to environmental changes. Objectives of this study were to investigate ecology of phytoplankton during a complete hydrological cycle in the deepest natural lake in Brazil, Dom Helvécio, and to sort species into the list of assemblages, checking its accordance with environmental changes in a tropical system within the middle Rio Doce Lake district, South-East Brazil. Canonical Correspondence Analysis, t-test, Mann–Whitney U-test, and Kruskal–Wallis test were used to analyze climatological, environmental, and plankton data, which were obtained monthly in 2002. A new phytoplankton assemblage, N_A (atelomixis-dependent desmids), is suggested because atelomixis (robust movement of water occurring once a day) contributed to replacement of species in Dom Helvécio Lake. Stability of stratification, water chemistry, and composition of phytoplankton assemblages characterized two periods. The first period occurred in six rainy months (Jan–Mar and Oct–Dec) when the lake was stratified and phytoplankton was dominated by two assemblages: N_A and F. The second period occurred in six dry months (Apr–Sep) when the lake was nonstratified and phytoplankton was dominated by four assemblages: S2, X1, A, and L_O. Results suggest that phytoplankton in Dom Helvécio Lake was shaped by seasonal and daily changes of water temperature, even with its lower amplitude of variation within 2002 (El Niño year). These changes promoted water column stratification or mixing, reduced light, and increased nutrient availability. Temperature, therefore, is similarly important to phytoplankton ecology in tropical regions as it is in temperate ones. Sorting phytoplankton species into assemblages matched well with environmental changes and periods identified so it is also suggested that this can be further used as an appropriate tool to manage water quality when evaluating tropical lakes.     

Seasonal differences and response to a tropical storm reflected in diatom assemblage changes in a southwest Florida watershed

Because estuaries are dynamic on many temporal scales, it is difficult to differentiate long-term shifts from those resulting from erratic pulse events like severe storms. Diatoms are abundant and diverse in estuaries, and may characterize these dynamics across relevant time scales. The climate of south Florida is subtropical, with dry winters and wet summers that may also harbor tropical storms and cyclones. We investigated whether these repeated seasonal drivers of change in estuaries differ from the influence of tropical cyclones on planktonic and benthic diatom assemblages. Diatom assemblages and environmental parameters were measured in the Charlotte Harbor watershed of southwest Florida to identify differences between the wet and dry seasons and changes that occurred following Tropical Storm Debby in 2012. Indicator taxa that were significantly affiliated with each season and post-storm conditions were identified. Diatom assemblages across the watershed were similar in wet and dry seasons, but differences increased following the tropical storm. The reduction in community dispersion following the storm was pronounced in each of the major drainages of the estuary. There were spatially-distinct responses of diatoms to environmental changes driven by the storm. These results suggest that past storm activity could be detected using diatoms preserved in estuarine sediments using both single indicator-species as well as community approaches.     

Regional versus local drivers of water quality in the Windermere catchment,Lake District,United Kingdom: The dominant influence of wastewater pollution over the past 200 years

Freshwater ecosystems are threatened by multiple anthropogenic stressors acting over different spatial and temporal scales, resulting in toxic algal blooms, reduced water quality and hypoxia. However, while catchment characteristics act as a ‘filter’ modifying lake response to disturbance, little is known of the relative importance of different drivers and possible differentiation in the response of upland remote lakes in comparison to lowland, impacted lakes. Moreover, many studies have focussed on single lakes rather than looking at responses across a set of individual, yet connected lake basins. Here we used sedimentary algal pigments as an index of changes in primary producer assemblages over the last ~200 years in a northern temperate watershed consisting of 11 upland and lowland lakes within the Lake District, United Kingdom, to test our hypotheses about landscape drivers. Specifically, we expected that the magnitude of change in phototrophic assemblages would be greatest in lowland rather than upland lakes due to more intensive human activities in the watersheds of the former (agriculture, urbanization). Regional parameters, such as climate dynamics, would be the predominant factors regulating lake primary producers in remote upland lakes and thus, synchronize the dynamic of primary producer assemblages in these basins. We found broad support for the hypotheses pertaining to lowland sites as wastewater treatment was the main predictor of changes to primary producer assemblages in lowland lakes. In contrast, upland headwaters responded weakly to variation in atmospheric temperature, and dynamics in primary producers across upland lakes were asynchronous. Collectively, these findings show that nutrient inputs from point sources overwhelm climatic controls of algae and nuisance cyanobacteria, but highlights that large‐scale stressors do not always initiate coherent regional lake response. Furthermore, a lake's position in its landscape, its connectivity and proximity to point nutrients are important determinants of changes in production and composition of phototrophic assemblages.