Temporal and spatial variation in the growth rates of Baltic herring (<Emphasis Type="Italic">Clupea harengus membras</Emphasis> L.) larvae during summer

It has been suggested that larval survival determines the year-class strength in most marine fish species. During their growth and development, the ability of the larvae to catch prey and avoid predation will increase. However, the factors affecting short-term changes in the growth of Baltic Sea herring have been little studied in the field. We collected Baltic herring (Clupea harengus membras L.) larvae from five different towing areas in the Archipelago Sea (SW Finland) during May and June 1989, right after the main spawning season. Twenty thousand two hundred and ten larvae were analysed and the area-specific growth rate (i.e. increase in standard length) was estimated by tracing the larval cohorts from the length-frequency data. This represents the first Baltic herring study with daily sampling during a long study period. The growth rate was related to environmental factors, such as temperature, number of zooplankters, and wind speed and direction. Large variation in larval growth rate occurred between areas: lowest and highest growth rates were 0.18 and 0.52 mm·day^-1. Temperature was an important variable controlling larval-fish growth rate. An increase of one 1°C in average water temperature corresponded to an increase in growth rate of 0.043 mm·day^-1. This may have been caused either by a direct temperature effect (changes in metabolic rate) or by the indirect effect of changes in food availability. We also found the densest herring populations in the areas with highest average water temperature. However, temperature and larval growth rate both increased towards the inner archipelago.     

Identifying Conservation and Restoration Priorities for Saproxylic and Old-Growth Forest Species: A Case Study in Switzerland

Saproxylic (dead-wood-associated) and old-growth species are among the most threatened species in European forest ecosystems, as they are susceptible to intensive forest management. Identifying areas with particular relevant features of biodiversity is of prime concern when developing species conservation and habitat restoration strategies and in optimizing resource investments. We present an approach to identify regional conservation and restoration priorities even if knowledge on species distribution is weak, such as for saproxylic and old-growth species in Switzerland. Habitat suitability maps were modeled for an expert-based selection of 55 focal species, using an ecological niche factor analyses (ENFA). All the maps were then overlaid, in order to identify potential species’ hotspots for different species groups of the 55 focal species (e.g., birds, fungi, red-listed species). We found that hotspots for various species groups did not correspond. Our results indicate that an approach based on “richness hotspots” may fail to conserve specific species groups. We hence recommend defining a biodiversity conservation strategy prior to implementing conservation/restoration efforts in specific regions. The conservation priority setting of the five biogeographical regions in Switzerland, however, did not differ when different hotspot definitions were applied. This observation emphasizes that the chosen method is robust. Since the ENFA needs only presence data, this species prediction method seems to be useful for any situation where the species distribution is poorly known and/or absence data are lacking. In order to identify priorities for either conservation or restoration efforts, we recommend a method based on presence data only, because absence data may reflect factors unrelated to species presence.     

Helpers in colonial cooperatively breeding sociable weavers <Emphasis Type="Italic">Philetairus socius</Emphasis> contribute to buffer the effects of adverse breeding conditions

Some studies on the effects of helpers in cooperatively breeding vertebrates show a positive effect of helper presence on reproductive output whereas others find no effect. One possibility for this discrepancy is that helpers may have a positive effect when breeding conditions are adverse, while their effect might go unnoticed under good conditions. We investigate this hypothesis on sociable weavers Philetairus socius, a colonial cooperatively breeding passerine that inhabits a semi-arid region where breeding conditions vary markedly. We used multivariate mixed models to analyse the effect of helpers on reproduction under contrasting environmental and social conditions while controlling for parental and colony identity. We found that reproductive success in sociable weavers was primarily influenced by nest predation and rainfall. In addition, colony size was negatively associated with hatching and fledging success and number of young fledged per season. Helpers had a less prominent but significant influence on feeding rates and reproductive outcome. In agreement with expectations, the presence of helpers counteracted some of the negative effects of breeding in periods of low rainfall or in large colonies and was also associated with an increased number of young fledged per season. Our results illustrate that the effect of helpers might be detectable mostly under unfavourable conditions, but can contribute to improve reproductive performance in those situations.     

Are local extinctions and recolonizations continuing at the colder limits of marine fish distributions? Halobatrachus didactylus (Bloch & Schneider, 1801), a possible candidate

In this paper, we compare the populations of the Lusitanian toadfish Halobatrachus didactylus along the Portuguese shore, using a putative fragment of the mitochondrial control region and the first intron of the S7 ribosomal protein gene. This demersal species ranges from the tropical West African coast to the Iberian Peninsula and the Mediterranean, having its northern limit in the Tagus River. For the putative control region, a single haplotype occurs in all fish from Tagus and Sado (the location immediately to the south) with a clear increase in diversity to the South, peaking at Algarve (south Portugal). The data seem to point to a very recent Holocenic colonization of Tagus and Sado from the South (possibly Algarve). We suggest that even small oscillations in sea surface temperature (SST) may cause local extinctions and subsequent recolonizations in populations of thermophilic fish that are at the cold limit of their distributions.     

'Maturity' and the process of local sustainable development

Abstract

Although the household level is recognized as a potentially important area for the application of ecological footprint (EF) analysis, almost no work has been reported in the academic literature on EF analysis at this level. This paper describes the application of a new, diary-based data acquisition methodology used in a component approach to estimate the EF of a small number of households in Aberdeen, Scotland. Feedback from householders indicated that the diary proved useful in educating participants about their environmental impacts and made EF findings convincing. The methodology was, however, time consuming for both participants and researchers, and it is concluded that future household level applications of EF analysis might combine a simplified diary with other forms of data acquisition. Findings also suggest that the presentation of EF results alone is unlikely to promote more environmentally conscious attitudes amongst householders unless specific EF components are identified for the householder to act upon.     

Towards effective culvert design: monitoring seasonal use and behavior by Mediterranean mesocarnivores

Drainage culverts are known to be used by a diverse number of species. To date, most studies looking at culvert usage have been restricted to the dry season. This seasonal bias has limited our understanding of how different species respond to culverts and, consequently, our ability to find effective ways to promote the use of culverts as aids to species movement. The main goal of this study was to examine the role of highway culverts for mesocarnivores throughout the year. We addressed (1) the seasonality of culvert use, (2) the relative importance of culvert structure, highway features, and surrounding landscape on culvert use, (3) the influence of the water depth and cover on culvert use, and (4) the effect of culvert structure on individual behavior. Fifteen culverts were monitored along 2 highways in southern Portugal using video-surveillance cameras and marble dust for 10 consecutive days per season. We used generalized linear mixed models to determine which factors most affected the culvert use and behavior by mesocarnivores. Our results highlight the effect of seasonality and water on culvert use. Culvert use was positively related with species activity throughout the year. All species (except otters (Lutra lutra)) were less likely to use culverts that contained water more than 3 cm deep or covering more than 70 % of the culvert base. Based on our results, future surveys and culvert retrofit design should address (1) the importance of seasonality in the interpretation of results and (2) the complementarity of culvert-specific features (water, ledges, and naturalization).     

Monitoring pollution in River Mureş, Romania, part II: metal accumulation and histopathology in fish

As a part of an exposure and effect monitoring conducted along the river Mureş, Western Romania in 2004, the health status of two indigenous fish species, sneep (Chondrostoma nasus) and European chub (Leuciscus cephalus) was investigated upstream and downstream the city of Arad. In fish, histopathology was assessed in liver and gills, and heavy metals (cadmium, copper, lead and zinc) were analyzed in liver samples. In both fish species, histopathological reactions in the gills (epithelial lifting, focal proliferation of epithelial cells of primary and secondary lamellae and resulting fusion of secondary lamellae, hyperplasia and hypertrophy of mucous cells, focal inflammation and necrosis of epithelial cells) were most severe at the two sampling sites upstream Arad city, which were shown to be polluted by copper, cadmium, faecal coliforms and streptococci in a parallel study. At these two sites, also histopathology in the liver of L. cephalus was more prominent than at the two downstream sites. In C. nasus, symptoms in the liver (focal inflammation with lymphocytic infiltrations, macrophage aggregates and single cell necrosis) were also highly pronounced at the sampling site located directly downstream the municipal sewage treatment plant of Arad. With the exception of copper accumulation in L. cephalus caught at the most upstream sampling site, in both fish species cadmium and copper accumulation were exceptionally high and did not differ significantly between the four sampling sites.     

Does malaoxon play a role in the geno- and cytotoxic effects of malathion on human choriocarcinoma cells?

This investigation was undertaken to elucidate whether the active metabolite of malathion, malaoxon, has any role in exerting cyto- and genotoxic effects for human choriocarcinoma (JAR) cell line which is an acceptable model for human placental cells. Gas chromatography-mass spectrometry (GC-MS) analysis were separately performed on the cell compartment and supernatant cell culture medium after subjecting the cell line to different malathion concentrations (10–400 μg/mL) and for various incubation periods (0.5 to 24 hours). GC-MS analysis showed that the sonication performed for the disruption of the cells did not cause the chemical change of malathion. The uptake of malathion by the cells was relatively fast. However, the presence of malaoxon, even in trace amounts, could not be confirmed either in samples originating from disrupted cells or in the cell culture medium. Although the hydrolysis of malaoxon occurred in the culture medium, this degradation process could not be counted as a reason for the absence of malaoxon. Since both malathion and malaoxon standard compounds could be accurately detected and distinguished by the applied liquid-liquid extraction and GC-MS methods, one can conclude that, in the case of JAR cells, the parent compound, (i.e. malathion itself) is responsible for the observed in vitro cyto- and genotoxic effects. Our results indicate that the direct toxicity of malathion contributes to the complications of pregnancy observed for environmental malathion exposure.     

Human health implications of clinically relevant bacteria in wastewater habitats

The objective of this review is to reflect on the multiple roles of bacteria in wastewater habitats with particular emphasis on their harmful potential for human health. Indigenous bacteria promote a series of biochemical and metabolic transformations indispensable to achieve wastewater treatment. Some of these bacteria may be pathogenic or harbour antibiotic resistance or virulence genes harmful for human health. Several chemical contaminants (heavy metals, disinfectants and antibiotics) may select these bacteria or their genes. Worldwide studies show that treated wastewater contain antibiotic resistant bacteria or genes encoding virulence or antimicrobial resistance, evidencing that treatment processes may fail to remove efficiently these bio-pollutants. The contamination of the surrounding environment, such as rivers or lakes receiving such effluents, is also documented in several studies. The current state of the art suggests that only some of antibiotic resistance and virulence potential in wastewater is known. Moreover, wastewater habitats may favour the evolution and dissemination of new resistance and virulence genes and the emergence of new pathogens. For these reasons, additional research is needed in order to obtain a more detailed assessment of the long-term effects of wastewater discharges. In particular, it is important to measure the human and environmental health risks associated with wastewater reuse.