Physiological tolerance predicts species composition at different scales in a barnacle guild

This study examined how the species composition of an intertidal barnacle guild varied according to physical gradients in the environment at small scales governed by microclimates, medium scales of wave exposure and large scales of latitude. Barnacle distributions at small and medium scales were sampled in Ireland between 51°29′ and 52°44′N and 6°50′ and 10°08′W. Sampling on European shores spanned ~18° latitude from 37°05′ to 55°16′N. Barnacle surveys mainly took place in 2003–2004. An index of wave fetch was calculated along the wave exposure gradient using a digital coastline-based model that was supported by a biological exposure scale. A ‘dryness’ index was defined according to mean monthly wind speed, fetch along the average wind direction and mean monthly air or sea surface temperatures for 2 years (January 2001–December 2002) which is the period when the most recent adults in the barnacle community would have settled and grown to adulthood. The proportion of the dry-loving barnacle Chthamalus montagui Southward increased within the barnacle guild at all scales as the habitat became warmer and drier. Barnacle densities were high in all habitats, mean densities ranged from a minimum of 4.16 cm⁻² on moderately exposed shores to a maximum of 6.27 cm⁻² in sunlit or south-facing microclimates. Percentage cover of barnacles across the gradient of latitudes was usually >70%. The results suggest that the distribution and abundance of interacting barnacle species on European coasts is strongly controlled by abiotic factors, most likely temperature and desiccation.     

Role of climate and competitors in limiting fitness across range edges of an annual plant

It is often assumed that the geographic distributions of species match their climatic tolerances, but this assumption is not frequently tested. Moreover, few studies examine the relative importance of abiotic and biotic factors for limiting species ranges. We combined multiple approaches to assess the extent to which fitness of a widespread native annual legume, Chamaecrista fasciculata, decreases at and beyond its northern and western range edges, and how this is influenced by the presence of neighbors. First, we examined plant fitness and the effect of neighbors in natural populations at different geographic range locations for three years. Fitness decreased toward the northern range edge, but not the western edge. Neighbor removal had a consistently positive effect on seedpod production across all years and sites. Second, we established experimental populations at sites within the range, and at and beyond the northern and western range edges. We tracked individual fitness and recorded seedling recruitment in the following year (a complete generation) to estimate population growth rate. Individual fitness and population growth declined to near zero beyond both range edges, indicating that C. fasciculata with its present genetic composition will not establish in these regions, given conditions currently. We also carried out a neighbor removal treatment. Consistent with the natural populations, neighbors reduced seedpod production of reproductive adults. However, neighbors also increased early-season survival, and this positive effect early in life history resulted in a net positive effect of neighbors on lifetime fitness at most range locations. Our data show that the population growth rate of C. fasciculata includes values above replacement, and populations are well adapted to conditions up to the edge of the range, whereas the severely compromised fitness at sites beyond the edge precludes immediate establishment of populations and thereby impedes adaptation to these conditions.     

Living with Wildlife and Mitigating Conflicts Around Three Indian Protected Areas

Crop and livestock losses to wildlife are a concern for people neighboring many protected areas (PAs) and can generate opposition to conservation. Examining patterns of conflict and associated tolerance is important to devise policies to reduce conflict impacts on people and wildlife. We surveyed 398 households from 178 villages within 10 km of Ranthambore, Kanha, and Nagarahole parks in India. We compared different attitudes toward wildlife, and presented hypothetical response scenarios, including killing the problem animal(s). Eighty percent of households reported crop losses to wildlife and 13 % livestock losses. Higher crop loss was associated with more cropping months per year, greater crop variety, and more harvest seasons per year but did not vary with proximity to the PA, suggesting that PAs are not necessarily “sources” for crop raiders. By contrast, complaints of “depredating carnivores” were associated with people-grazing animals and collecting resources from PAs. Many households (83 %) engaged in mitigation efforts. We found that only fencing and guard animals reduce crop losses, and no efforts to lower livestock losses. Contrary to our expectations, carnivores were not viewed with more hostility than crop-raiding wildlife. Households reported greater inclination to kill herbivores destroying crops or carnivores harming people, but not carnivores preying on livestock. Our model estimated crop loss was 82 % across surveyed households (highest in Kanha), while the livestock loss experienced was 27 % (highest in Ranthambore). Our comparative study provides insights into factors associated with conflict loss and tolerance, and aids in improving ongoing conservation and compensation efforts.     

Optical fiber based methodology for assessment of thiocyanate in seawater

A new methodology for the assessment of thiocyanate (SCN(-)) is proposed based on optical fiber (OF) detection coupled to a liquid chromatography system (LC). The developed methodology showed an adequate performance for the analysis of SCN(-) comparable to a high performance liquid chromatography with UV detector (HPLC-UV) methodology: a detection limit of 3 μg L(-1), a linear range from 4 to 400 μg L(-1), and an analytical time of less than 6 min. The OF based methodology was of compact design and easy operation. This simple system has the potential to be used as a sensing approach for SCN(-) in seawater.     

Household disposal of pharmaceuticals: attitudes and risk perception in a UK sample

Pharmaceuticals can enter the environment through disposal in toilets, sinks and general waste. In the UK, household medicines are correctly disposed of by returning them to a pharmacy. This study examined household patterns of medicine waste, storage and disposal practices via a cross-sectional survey with 663 UK adults. Multiple regression was used to explore the contribution of key variables on self-reported medicines disposal behaviour. Analysis demonstrated that age, information, awareness, probability, attitude and intention all predicted correct disposal behaviour. Results indicate that multiple factors influence different disposal destinations uniquely. Affect and age increase disposal in sink/toilet but reduce disposal in bin. Presence of children increase bin and sink/toilet disposal but decrease pharmacy returns. Awareness and received information on correct disposal reduce bin disposal and increase pharmacy returns. The results suggest people use different mental models for each destination with disposal in sink/toilets and bins considered quicker and safer in the presence of children or for those feeling anxious. It is important to understand the capability, opportunity and motivation people have to return medicines to the pharmacy in addition to raising awareness of correct medicine disposal.

     

Ecological and physiological controls of species composition in green macroalgal blooms

Green macroalgal blooms have substantially altered marine community structure and function, specifically by smothering seagrasses and other primary producers that are critical to commercial fisheries and by creating anoxic conditions in enclosed embayments. Bottom-up factors are viewed as the primary drivers of these blooms, but increasing attention has been paid to biotic controls of species composition. In Washington State, USA, blooms are often dominated by Ulva spp. intertidally and Ulvaria obscura subtidally. Factors that could cause this spatial difference were examined, including competition, grazer preferences, salinity, photoacclimation, nutrient requirements, and responses to nutrient enrichment. Ulva specimens grew faster than Ulvaria in intertidal chambers but not significantly faster in subtidal chambers. Ulva was better able to acclimate to a high-light environment and was more tolerant of low salinity than Ulvaria. Ulvaria had higher tissue N content, chlorophyll, chlorophyll b: chlorophyll a, and protein content than Ulva. These differences suggest that nitrogen availability could affect species composition. A suite of five grazers preferred Ulva to Ulvaria in choice experiments. Thus, bottom-up factors allow Ulva to dominate the intertidal zone while resistance to grazers appears to allow Ulvaria to dominate the subtidal zone. While ulvoid algae are in the same functional-form group, they are not functionally redundant.     

Habitat selectivity of megalopae and juvenile mud crabs (<Emphasis Type="Italic">Scylla serrata</Emphasis>): implications for recruitment mechanism

Megalopae of several crab species exhibit active habitat selection when settling. These megalopae usually select structurally complex habitats which can provide refuge and food. The portunid mud crab, Scylla serrata, is commonly found within the muddy estuaries of the Indo-West Pacific after attaining a carapace width >40 mm. Despite substantial efforts, the recruitment mechanism of juvenile mud crabs to estuaries is not understood because their megalopae and early stage crablets (carapace width <30 mm) are rarely found. We used laboratory experiments to determine whether megalopae and early stage crablets are selective among three estuarine habitats which commonly occur in Queensland, Australia. These animals were placed in arenas where they had a choice of habitats: seagrass, mud or sand, and arenas where they had no choice. Contrary to the associations exhibited by other portunid crab megalopae, S. serrata megalopae were not selective among these estuarine habitats, suggesting that they tend not to encounter these habitats, or, gain no advantage by selecting one over the others. The crablets, however, strongly selected seagrass, suggesting that residing within seagrass is beneficial to the crablets and likely increases survival. This supports the model that for S. serrata, crablets and not megalopae tend to colonise estuaries, since a selective behaviour has evolved within crablets but not megalopae.     

Flow cytometry assessment of cytotoxicity and reactive oxygen species generation by single and binary mixtures of cadmium, zinc and copper on populations of the ciliated protozoan Tetrahymena thermophila

In the present study, we have assessed by flow cytometry, the cytotoxicity of the heavy metals Cd, Zn and Cu on populations of the ciliated protozoan Tetrahymena thermophila. The obtained LC(50) for these metals was estimated as 0.195mgCdl(-1), 3.58mgZnl(-1) and 0.47mgCul(-1), respectively. As a result, the toxicity rank for this eukaryotic microorganism is Cd>Cu>Zn. Using the same methodology and the Concentration Addition approach, the toxicity of binary mixtures of these metals was evaluated in order to detect the type of interaction between these metals. Results indicated that antagonism is the predominant interaction but it can change to additivity or even to synergism at high metal concentrations. Besides, the concentration ratio between metals plays also a crucial role in determining the type of metallic interaction, at least in Tetrahymena. Cytotoxicity data from single and bimetallic mixtures have been compared with those from selected microalgae, other species of ciliates, fish and mammalian cell lines and metazoan. By other hand, we have detected the mitochondrial generation of peroxides induced by both single and binary treatments with Cd, Zn and Cu on populations of Tetrahymena, using the specific fluorophore dyhidrorhodamine. The nature and concentrations of metal as well as the metallic ratio were important factors in reactive oxygen species production. All results found in T. thermophila are compared with previous reports in other organisms and, some explanations and hypothesis to support results are given, including the involvement of metallothioneins as antioxidants and their role in the binding of metal cations.     

Comparative assessment of wet and dry garment cleaning Part 1. Environmental and human health assessment

Water-based cleaning of specialty garments is emerging as a potential alternative to dry cleaning. Perchloroethylene, the solvent used in dry cleaning, poses significant human and ecosystem health concerns. This paper is part 1 of a two part series that analyzes the key environmental, human health, performance, economic, and regulatory factors which influence the future of the garment cleaning industry. This paper inventories the environmental releases and wastes associated with the consumption of perchloroethylene in modern dry cleaning machines which ranges from 2.0 to 5.2 kg per 100 kg of clothing cleaned. In addition, water, electricity, and other inputs for both perchloroethylene-based and water-based garment cleaning are compared using data from previous demonstration projects. Toxicological and epidemiological studies provide evidence for the carcinogenicity of perchloroethylene although this classification is controversial. Cancer risks at low levels of exposure associated with modern dry cleaning equipment and good housekeeping practices are unknown and require further investigation. Regardless of these uncertainties, water-based cleaning is preferable to dry cleaning from a human and environmental health perspective.