Statistical evaluation of chronic toxicity data on aquatic organisms for the hazard identification: the chemicals toxicity distribution approach

Presently, in the Globally Harmonised System of Classification and Labelling of Chemicals the classification of substances for long-term effects to aquatic life is based on acute toxicity in combination with degradation and/or bioaccumulation potential. Recently an OECD Working Group was created to develop the classification scheme to accommodate chronic toxicity data related to aquatic organisms for assigning a chronic hazard category. This study focuses on a new approach for setting chronic toxicity cut-off values based on Chemicals Toxicity Distributions (CTDs). A CTD is obtained through statistical fitting of the data used by regulatory bodies for setting hazard-based classifications. The CTDs were made using the lowest aquatic NOEC value of each chemical. A review of different toxicological sources reporting acute aquatic toxicities was carried out. Initially, the data were arranged according to the specific source and distributions for key taxonomic groups (i.e. fishes, crustaceans and algae) were evaluated separately. In most cases, no significant departures from normality were observed. Thereafter, a compiled database containing >900 values was developed and the CTDs were constructed for each taxonomic group. Significant deviation from normality (P < 0.05) was observed in the fishes and crustaceans' CTDs. However, this deviation was apparently produced by the presence of only seven values with NOECs <1 x 10(-5) mg l(-1), while high correlation between the data and the normal scores (r-values>or= 0.989) indicated that the data were samples from normal distributions. From these observations, potential cut-off values would allow quantitative estimations of the percentage of chemicals falling into each specific category. This approach results in a simple classification hazard scheme where most chemicals are covered in one of the categories, allowing a clear distribution of the chemicals among three categories for chronic toxicity.     

Understanding conservation conflicts associated with rodent outbreaks in farmland areas

Rodent outbreaks affect many farmland areas worldwide and the negative environmental impacts of control campaigns cause intense social tensions. In such conservation conflicts, understanding stakeholders’ viewpoints is critical to promote ecologically sustainable management. We used Q-methodology, a framework standing between qualitative and quantitative social research, to investigate human subjectivity and understand conflicts caused by rodent outbreaks in Spain. We interviewed farmers, conservationists, hunters, and governmental agencies, and identified five main discourses about the origins and consequences of the conflictive situation. Finding sustainable management is impaired by opposing views about causes and consequences of vole outbreaks and their management, which are at the root of the conflict. Social tensions will likely remain until the underlying conflicts between people holding different views are also managed. Decision-making should therefore focus on mitigating underlying conflicts. Using trained independent mediators would help the effective resolution of conservation conflicts caused by rodent outbreaks and their management.

     

Sardine (Sardina pilchardus) spawning seasonality in European waters of the northeast Atlantic

Egg data from ichthyoplankton monitoring sites in the western English Channel (1988–2003) and northern Spain (1990–2000) and macroscopic maturity data from biological samples of purse seine landings in western and southern Iberia (1980–2004) are used to describe the spawning seasonality of sardine (Sardina pilchardus) in European waters of the northeast Atlantic using generalised additive models. The fitted models reveal a double peak in spawning activity during early summer and autumn in the western Channel, a wider spring peak off northern Spain and a broad winter season in the western and southern Iberian Peninsula. At all sites, a high probability of spawning activity was observed over at least 3 months of the year, with the duration of the season increasing with both decreasing latitude and increasing fish size. Off western and southern Iberia there are indications that the spawning season has been of longer duration in recent years for all size classes (reaching in some cases 8 months of the year for large fish). These patterns are in general agreement with existing literature and theoretical expectations of sardine spawning being driven locally by the seasonal cycle of water temperature, assuming preferences for spawning at 14 –15°C and avoidance for temperatures below 12°C and above 16°C. Regional quotient plots indicated that spawning tolerance to higher temperatures increases progressively with decreasing latitude. Despite the weak evidence for geographical differences in temperature tolerance that may have some genetic origin, the degree of spatio-temporal overlap in sardine-spawning activity within Atlantic European waters is unlikely to promote any reproductive isolation in that area.     

Population genetic structure of the prosobranch Nassarius reticulatus (L.) in a ria seascape (NW Iberian Peninsula) as revealed by RAPD analysis

Randomly amplified polymorphic DNA (RAPD) banding patterns were compared between samples of the netted dogwhelk Nassarius reticulatus from 11 locations along the NW Iberian Peninsula coast. To detect if rias (estuaries formed by drowned river valleys) might promote genetic differentiation, five sampling sites were located within a ria (ria of Muros) and the remaining six were scattered along open-coast areas at increasing distances from the ria mouth. Population differentiation statistics (Φ-values) were estimated using a hierarchical analysis of molecular variance (AMOVA) with samples sorted into two groups: open-coast and ria populations. Despite a high potential to disperse, AMOVA demonstrated a modest, statistically significant genetic heterogeneity among N. reticulatus populations. Most of the genetic structure resided in differences among open-coast populations; ria populations were genetically homogeneous. No obvious geographical pattern was detected for the pairwise genetic distances (non-metric multidimensional scaling; UPGMA tree; Mantel test). Unlike previous studies with other species at a variety of estuarine systems other than rias, there was no evidence that the ria of Muros may enhance the genetic divergence of N. reticulatus populations. This discrepancy is discussed in relation to the biological features of the species (high dispersal potential and a preference for mid-low estuarine habitat) and the strong hydrographic connectivity between ria and neighbouring off-shore waters.     

Immission patterns of airborne pollutants in Argentina and Germany II. Biomonitoring of organochlorine compounds and polycyclic aromatics

The air pollution profiles of organic xenobiotics (including chlorinated insecticides and benzenes, PCBs and PAHs) were comparatively analyzed in the climatically different regions of Leipzig-Halle (Germany) and Greater Mendoza (Argentina) using two-year-old pine needles (Pinus sylvestris L.) as passive biomonitors. In addition to total compound contents, the levels of potentially bioavailable fraction in the inner needle compartment were determined. The peak levels of chlorinated insecticides and PAHs in an urban park in Mendoza were found to exceed the maximum levels in the Leipzig-Halle region by one to two orders of magnitude, indicating the recent substantial tropospheric input of the compounds from local sources. Bioavailable fractions were observed to exhibit considerable variations for some of these compounds, which became even more distinct when needle samples from Germany and Argentina were compared. Generally speaking, an increase in permeability under semiarid climatic conditions was observed for most of the xenobiotics examined. The discussion of the results reflects the problems associated with using biomonitoring for semivolatile compounds. Interpretation takes into account pollution measurements in the air at Argentine and German reference sites.     

Living within fallen palm leaves: the discovery of an unknown Blommersia (Mantellidae: Anura) reveals a new reproductive strategy in the amphibians of Madagascar

We describe a new mantelline frog of the genus Blommersia found in rainforest in North East Madagascar, from the protected areas of Ambatovaky, Betampona, Masoala, and Zahamena. Blommersia angolafa n.sp. is a small frog, with a body size of 17–21 mm, expanded finger and toe tips, and colouration ranging from yellow to dark brown, with pale-bluish spots on the flanks and light tips of fingers and toes. A peculiar aspect characterising this new species is its novel life history and reproductive mode. Both sexes live and breed in a phytotelmic habitat of water accumulated within fallen prophylls and fallen leaf sheaths of at least three species of Dypsis palms. Within these phytotelmata, egg laying and complete larval development occur. Thus, B. angolafa n.sp. represents a new evolutionary lineage of Malagasy frogs in which phytotelmy is known. Up to now, reproduction in phytotelmata in Malagasy frogs has been reported for many cophyline microhylids, most species of Guibemantis, Mantella laevigata, and possibly in a still-undescribed species belonging to the genus Spinomantis. We consider the reproductive mode of B. angolafa as a derived character, having evolved from the more typical reproduction in lentic water bodies. The general scarcity of lentic habitats in Malagasy rainforests may have provided the conditions that favoured the evolution of this phytotelmic breeding strategy. The new species, being specialised to a habitat represented by a few selected Dypsis species, potentially suffers the selective exploitation of these palms.