Minimum viable metapopulation size, extinction debt, and the conservation of a declining species.

A key question facing conservation biologists is whether declines in species' distributions are keeping pace with landscape change, or whether current distributions overestimate probabilities of future persistence. We use metapopulations of the marsh fritillary butterfly Euphydryas aurinia in the United Kingdom as a model system to test for extinction debt in a declining species. We derive parameters for a metapopulation model (incidence function model, IFM) using information from a 625-km2 landscape where habitat patch occupancy, colonization, and extinction rates for E. aurinia depend on patch connectivity, area, and quality. We then show that habitat networks in six extant metapopulations in 16-km2 squares were larger, had longer modeled persistence times (using IFM), and higher metapopulation capacity (lambdaM) than six extinct metapopulations. However, there was a > 99% chance that one or more of the six extant metapopulations would go extinct in 100 years in the absence of further habitat loss. For 11 out of 12 networks, minimum areas of habitat needed for 95% persistence of metapopulation simulations after 100 years ranged from 80 to 142 ha (approximately 5-9% of land area), depending on the spatial location of habitat. The area of habitat exceeded the estimated minimum viable metapopulation size (MVM) in only two of the six extant metapopulations, and even then by only 20%. The remaining four extant networks were expected to suffer extinction in 15-126 years. MVM was consistently estimated as approximately 5% of land area based on a sensitivity analysis of IFM parameters and was reduced only marginally (to approximately 4%) by modeling the potential impact of long-distance colonization over wider landscapes. The results suggest a widespread extinction debt among extant metapopulations of a declining species, necessitating conservation management or reserve designation even in apparent strongholds. For threatened species, metapopulation modeling is a potential means to identify landscapes near to extinction thresholds, to which conservation measures can be targeted for the best chance of success.     

Cobalt distribution and speciation: effect of aging, intermittent submergence, in situ rice roots

The speciation and distribution of Co in soils is poorly understood. This study was conducted using x-ray absorption spectroscopy (XAS) techniques to examine the influence of soluble cobalt in the +2 oxidation state (Co[II]) aging, submergence-dried cycling, and the presence of in vivo rice roots on the speciation and distribution of added Co(II) in soils. In the aging and submerged-dried cycling studies, Co was found to be associated with Mn oxide fraction (23 to 100% of total Co) and Fe oxide fractions (0 to 77% of total Co) of the soils as either Co(II) species or a mixed Co(II), and Co in the +3 oxidation state (Co[III]) species. The surface speciation of Co in the Mn oxide fraction suggests an innersphere complex was present and the speciation of Co in the Fe oxide fraction was an innersphere surface complex. The in vivo root box experiments showed similar Co speciation in the Mn oxide fraction (13 to 76% of total Co) as the aging and submerged-dried cycling studies. However, the Fe oxide fraction of the soil was unimportant in Co retention. A significant amount (24 to 87% of total Co) of the Co in root box treatments was identified as a Co precipitate. The importance of this finding is that in the presence of rice roots, the Co is redistributed to a Co precipitate. This work confirmed earlier macroscopic work that Mn oxides are important in the sequestration of Co in soils and the influence of roots needs to be taken into account when addressing Co speciation. The information gained from this study will be used to improve models to predict the lability and hence the availability of Co in terrestrial environments.     

Recovery or decline of the northwestern Black Sea: A societal choice revealed by socio-ecological modelling

During recent decades anthropogenic activities have dramatically impacted the Black Sea ecosystem. High levels of riverine nutrient input during the 1970s and 1980s caused eutrophic conditions including intense algal blooms resulting in hypoxia and the subsequent collapse of benthic habitats on the northwestern shelf. Intense fishing pressure also depleted stocks of many apex predators, contributing to an increase in planktivorous fish that are now the focus of fishing efforts. Additionally, the Black Sea's ecosystem changed even further with the introduction of exotic species. Economic collapse of the surrounding socialist republics in the early 1990s resulted in decreased nutrient loading which has allowed the Black Sea ecosystem to start to recover, but under rapidly changing economic and political conditions, future recovery is uncertain.     

‘Natural disasters’ and newspapers: Post-tsunami environmental discourse

In this paper we explore the concept of ‘natural disasters’ as opportunities for influencing public perceptions of the environment through the media. We provide a critical analysis of the discourse in a selection of newspaper articles and identify the way in which various actors have utilised UK national newspaper coverage of the Asian tsunami to promote particular agendas and to legitimise policies and actions. A systematic and iterative sampling approach was developed that allowed us to combine quantitative and qualitative methods to search for articles that contained content directly related to the environmental aspects of the tsunami. Three main themes emerged; coastal ecosystems, the fisheries sector, and redevelopment. The discourse within these areas was markedly different. While the coastal ecosystems discourse was hegemonic in terms of narratives and actor coalitions, the fisheries and redevelopment discourse incorporated a more diverse set of actors and storylines that perhaps reflects the lack of consensus on the best way of achieving sustainable solutions. We also contrast the limited discussion and representation of tsunami-related environmental issues within UK national newspapers with the more detailed discussion within the peer-reviewed literature and the grey literature. We argue that ‘natural disasters’ provide both opportunities and risks for raising awareness of environmental issues, mobilising funding and directing action to environmentally and socially vulnerable areas of the world, and that consequently NGOs, intergovernmental bodies and government departments should be mindful of the long-term consequences of global media attention.     

Treatment of mixed contamination in water using cyclodextrin‐based materials

This study investigated the effectiveness of a cyclodextrin‐based solid material for the removal of mixed dissolved contaminants. The solid material was prepared by condensation of α‐cyclodextrin. The removal efficiency was found to be 70 percent for total heavy metals (cadmium, lead, chromium, iron, nickel, cobalt, and mercury) to 98 percent for polychlorinated biphenyls (PCBs). The optimum pH for heavy metal removal was approximately 5 and for PCBs it was in the range of 5–7. All of these heavy metals were successfully recovered from the spent cyclodextrin‐based material using nitric acid, allowing the material to be reused for further passes. The results also showed that the presence of alkaline and alkaline earth metals did not have a significant effect on the removal efficiency, indicating that the cyclodextrin‐based material could selectively remove the heavy metals of concern without being consumed by alkaline and alkaline‐earth metals. © 2006 Government of Canada.     

Birth season testosterone levels in male Verreaux’s sifaka, Propithecus verreauxi: insights into socio-demographic factors mediating seasonal testicular function

Previous research suggests that although reproduction and testicular function in wild sifaka (Propithecus verreauxi) are highly seasonal, birth season elevations in fecal testosterone (T) in transferring males indicate that social factors may be as important as climatic factors in regulating reproductive function in sifaka. This paper examines the relationship of male dispersal and social status to the patterning of birth season aggression and testicular function in P. verreauxi at Beza Mahafaly Special Reserve, Madagascar. Behavioral and hormonal data were collected from a total of 38 adult males, 15 residing in seven stable groups and 23 living in eight unstable groups, yielding 186 fecal samples and 493 focal animal hours of observation. The results suggest that birth season elevations in fecal testosterone are the consequence of social disruption resulting from male movements between groups and the particular responses of individual males to dispersal events. Hormonal responses to dispersal events appear to precede behavioral responses and occasionally register reactions not concomitantly evident in the behavioral response, and may be predictive of future events. Hormonal reactions occurred primarily in resident alpha males, suggesting that they differ in their assessment of destabilizing influences, perhaps due to different reproductive opportunities and/or investment. These findings are important for the new insights they provide into the role of androgens in mediating male dispersal, life history, and reproductive strategies, and suggest that investigations of androgen-behavior interactions in free-ranging populations can be a powerful new tool for assessing the contextual and motivational basis of social behavior. Received: 22 November 1999 / Revised: 27 April 2000 / Accepted: 15 October 2000