Sustained by Snakes? Seasonal Livelihood Strategies and Resource Conservation by Tonle Sap Fishers in Cambodia

This paper situates concerns for conservation of aquatic snakes and livelihood sustainability in Cambodia within a social–ecological systems context and thereby presents a challenge to conventional species-based conservation programmes. Fishing for low-value water snakes has become a widespread activity within the floating communities of Tonle Sap Lake in the last 20 years in response to new market opportunities, provided primarily by a crocodile farming industry. The scale and intensity of this new form of exploitation and reports of declines in catch per fisher have highlighted this activity as a conservation concern, yet its role within local livelihood strategies was previously unknown. We show that it is of increasing importance to the less well-off, and is linked to higher incomes within this group, where it potentially reduces their vulnerability to fluctuations and declines in fish catches. It is particularly important as a means to smooth seasonality of incomes in this flood pulse-driven social–ecological system. We argue that shifts between snake-hunting and fishing, as a market-driven adaptive livelihood strategy by the poor, may be more compatible with wider ecosystem conservation and development goals than alternatives such as increased fishing effort or converting floodplain habitats for seasonal agriculture.

Autotoxicity: Concept,Organisms, and Ecological Significance

The present review deals with the phenomenon of autotoxicity — a type of intraspecific allelopathy, where a plant species inhibits the growth of its own kind through the release of toxic chemicals into the environment. This phenomenon has been reported to occur in a number of weeds and crop plants in agroecosystem and wastelands causing the soil sickness. Besides, it plays a significant role in the orchards (of apple, pear, grapes, etc.) where it is the major reason of the replant problem, natural forests and coffee and tea plantations causing the regeneration problems. Not only the higher plants, but even some ferns and algae are also reported to show this phenomenon. Some plants have even developed extensive mechanisms to overcome this phenomenon, whereas the others have adapted to it by making structural and ecological changes providing to them a competitive ecological advantage over the others. Although autotoxicity is a natural phenomena providing selective benefit to the plant, yet the chemicals responsible for this have good potential for weed and pest management.     

The necessity of functional proteomics: protein species and molecular function elucidation exemplified by in vivo alpha A crystallin N-terminal truncation

Summary. Ten years after the establishment of the term proteome, the science surrounding it has yet to fulfill its potential. While a host of technologies have generated lists of protein names, there are only a few reported studies that have examined the individual proteins at the covalent chemical level defined as protein species in 1997 and their function. In the current study, we demonstrate that this is possible with two-dimensional gel electrophoresis (2-DE) and mass spectrometry by presenting clear evidence of in vivo N-terminal alpha A crystallin truncation and relating this newly detected protein species to alpha crystallin activity regulation by protease cleavage in the healthy young murine lens. We assess the present state of technology and suggest a shift in resources and paradigm for the routine attainment of the protein species level in proteomics.     

All Hands on Deck: Transdisciplinary Approaches to Emerging Infectious Disease

The increasing burden of emerging infectious diseases worldwide confronts us with numerous challenges, including the imperative to design research and responses that are commensurate to understanding the complex social and ecological contexts in which infectious diseases occur. A diverse group of scientists met in Hawaii in March 2005 to discuss the linked social and ecological contexts in which infectious diseases emerge. A subset of the meeting was a group that focused on “transdisciplinary approaches” to integrating knowledge across and beyond academic disciplines in order to improve prevention and control of emerging infections. This article is based on the discussions of that group. Here, we outline the epidemiological legacy that has dominated infectious disease research and control up until now, and introduce the role of new, transdisciplinary and systems-based approaches to emerging infectious diseases. We describe four cases of transboundary health issues and use them to discuss the potential benefits, as well as the inherent difficulties, in understanding the social–ecological contexts in which infectious diseases occur and of using transdisciplinary approaches to deal with them. The views expressed here by Marian McDonald and Josh Rosenthal are those of the authors and do not represent official views or policies of the U.S. Centers for Disease Control and Prevention or the National Institutes of Health.     

The Ecological Component of Ecological Risk Assessment: Lessons from a Field Experiment

To improve ecological relevance, regulatory agencies are promoting assessments of effects at higher levels of organization, an objective that requires an understanding of current ecological theories. One such theory, hierarchy theory, contends that the effects of a disturbance acting at one level of organization (e.g., population) are not, as a rule, transmitted to higher levels of organization (e.g., community). Conversely, effects at higher levels of organization only occur if lower level variables have been affected. Further, responses to disturbance depend on disturbance history. In this study, I determined the effects of a disturbance treatment at the population, guild, and community levels of organization for vegetation in five wetlands with a disturbance history ranging from highly to rarely disturbed. The 2-year field experiment revealed that the effects of the disturbance treatment were most strongly felt at the population level of organization in wetlands without a history of disturbance. These observed impacts took place against a backdrop of constant change. Thus, the eventual disappearance of treatment effects was not due to a return to the pre-treatment state, but rather a return to a trajectory similar to that exhibited by the control plots. The implications of these results for ecological risk assessment are: (1) the observed effects of a stressor in a system cannot be extrapolated to other systems unless they have similar disturbance histories, (2) detecting effects before they become serious requires monitoring at lower levels of organization, (3) recovery to a naturally innate state is not a viable concept, and (4) the traditional approach of using one post-treatment measurement to determine if reference and impact sites differ is of very questionable value.     

The Urban Funnel Model and the Spatially Heterogeneous Ecological Footprint

Urban ecological systems are characterized by complex interactions between the natural environment and humans at multiple scales; for an individual urban ecosystem, the strongest interactions may occur at the local or regional spatial scale. At the regional scale, external ecosystems produce resources that are acquired and transported by humans to urban areas, where they are processed and consumed. The assimilation of diffuse human wastes and pollutants also occurs at the regional scale, with much of this process occurring external to the urban system. We developed the urban funnel model to conceptualize the integration of humans into their ecological context. The model captures this pattern and process of resource appropriation and waste generation by urban ecosystems at various spatial scales. This model is applied to individual cities using a modification of traditional ecological footprint (EF) analysis that is spatially explicit; the incorporation of spatial heterogeneity in calculating the EF greatly improves its accuracy. The method for EF analysis can be further modified to ensure that a certain proportion of potential ecosystem services are left for in situ processes. Combining EF models of human appropriation with ecosystem process models would help us to learn more about the effects of ecosystem service appropriation. By comparing the results for food and water, we were able to identify some of the potentially limiting ecological factors for cities. A comparison of the EFs for the 20 largest US cities showed the importance of urban location and interurban competition for ecosystem services. This study underscores the need to take multiple scales and spatial heterogeneity into consideration to expand our current understanding of human–ecosystem interactions. The urban funnel model and the spatially heterogeneous EF provide an effective means of achieving this goal. Received 17 October 2000; accepted 31 May 2001.     

Adaptation,Ecological Impacts,and Risk Assessment: Insights from Research at Foundry Cove,Bayou Trepagnier,and Pass Fourchon

This paper takes a detailed look at the occurrence of genetic adaptations and ecological impacts at three contaminated sites (Foundry Cove, Bayou Trepagnier, Pass Fourchon) to assess the co-occurrence of adaptation and ecological impacts and the implications for risk assessment. Community-level ecological impacts were reported for all three sites. However, there was little evidence of population-level impacts (on the six populations that were also assessed for adaptation). Similarly, adaptation was found in only one of the populations. While this review provides an incomplete picture (adaptation was assessed on only a small subset of the species present and the reasons behind the lack of adaptation in the five populations remained unknown), it indicates that adaptation is uncommon even where ecological impacts are obvious. Theoretical considerations also predict that contaminants can have large impacts without resulting in an adaptation. While adaptation to a contaminant reflects an impact by that contaminant, the three case studies indicate that determining whether or not resistance has evolved does not appear to be a very efficient tool for detecting ecological impacts. Nevertheless, assessing the occurrence of adaptation does have a place in risk assessment, especially when assessing the likelihood of local extinction of a particular population     

Local Ecological Knowledge and Institutional Dynamics for Ecosystem Management: A Study of Lake Racken Watershed, Sweden

The sustainable use of resources requires that management practices and institutions take into account the dynamics of the ecosystem. In this paper, we explore the role of local ecological knowledge and show how it is used in management practices by a local fishing association in a contemporary rural Swedish community. We focus on the local management of crayfish, a common-pool resource, and also address the way crayfish management is linked to institutions at different levels of Swedish society. Methods from the social sciences were used for information gathering, and the results were analyzed within the framework of ecosystem management. We found that the practices of local fishing association resemble an ecosystem approach to crayfish management. Our results indicate that local users have substantial knowledge of resource and ecosystem dynamics from the level of the individual crayfish to that of the watershed, as reflected in a variety of interrelated management practices embedded in and influenced by institutions at several levels. We propose that this policy of monitoring at several levels simultaneously, together with the interpretation of a bundle of indicators and associated management responses, enhances the possibility of building ecological resilience into the watershed. Furthermore, we found that flexibility and adaptation are required to avoid command-and-control pathways of resource management. We were able to trace the development of the local fishing association as a response to crisis, followed by the creation of an opportunity for reorganization and the recognition of slow ecosystem structuring variables, and also to define the role of knowledgeable individuals in the whole process. We discuss the key roles of adaptive capacity, institutional learning, and institutional memory for successful ecosystem management and conclude that scientific adaptive management could benefit from a more explicit collaboration with flexible community-based systems of resource management for the implementation of policies as experiments. Received 26 April 2000; accepted 13 October 2000.     

Building Resilience in Lagoon Social–Ecological Systems: A Local-level Perspective

Building resilience in integrated human and nature systems or social–ecological systems (SES) is key for sustainability. Therefore, developing ways of assessing resilience is of practical as well as theoretical significance. We approached the issue by focusing on the local level and using five lagoon systems from various parts of the world for illustration. We used a framework based on four categories of factors for building resilience: (1) learning to live with change and uncertainty; (2) nurturing diversity for reorganization and renewal; (3) combining different kinds of knowledge; and (4) creating opportunity for self-organization. Under each category, the cases generated a number of items for building resilience, and potential surrogates of resilience, that is, variables through which the persistence of SES emerging through change can be assessed. The following factors were robust across all five lagoon SES cases: learning from crisis, responding to change, nurturing ecological memory, monitoring the environment, and building capacity for self-organization and conflict management.     

Community involvement in management for maintaining coral reef resilience and biodiversity in southern Caribbean marine protected areas

Climate change is posing new challenges to conservation because management policies on protected coral reefs are less effective than they were before the current ecosystem degradation. Coral reefs, the most diverse and complex marine ecosystem provide economic services for millions, but are seriously threatened worldwide because reef-building corals are experiencing bleaching phenomena and a steady decline in abundance. The resources of a Marine Protected Area (MPA) in Cartagena, Colombia, are in constant decline, despite a current management plan and on-site staff, urging new conservation actions. A multidisciplinary team gathered to evaluate management effectiveness including biophysical, socioeconomic and governance indicators. Coral cover and fish diversity and abundance were low both inside and outside the MPA, which suggests a limited efficiency of management. Currently, the MPA is a reef with low coral cover and high algae cover as well as large dead coral areas, which are generally signs of highly degraded reef habitats. Live coral cover in the MPA was represented by pioneer coral species such as Agaricia tenuifolia and Porites astreoides. Nonetheless, 35% of the scleractinian species sampled in the area harbored more than one zooxanthellae symbiont, which suggests potential resistance and resilience against coral bleaching. Maintenance of trophic structure and functional diversity is an important endeavor that should be a priority for management in order to allow ecosystem resilience. Social and governance indicators showed low-income levels and few opportunities for communities living in and around the park, low governability, weak communication among stakeholders and with authorities at different levels. As a result, problems related to over exploitation of resources were commonplace in the MPA. These results reflect low adaptive capacity of communities to comply with restrictive conservation rules, showing that establishment of a protected area is a necessary but insufficient condition to guarantee conservation goals. Ignoring the role of local communities only will exacerbate the problems associated with natural resources. Involvement of communities in strategic ecosystems management appears to be a requisite to improve effectiveness of protected areas, and participatory strategies, such as co-management, offer opportunities to improve governability while letting communities adapt to MPA needs.     

The influence of local elevation on the effects of secondary salinity in remnant eucalypt woodlands: Changes in understorey communities

Increasing land salinization in Australia is predicted to lead to severe declines in species diversity in affected areas, and perhaps significant numbers of species extinctions. Much of the diversity that will be lost consists of understorey and mid-storey species, yet the overwhelming majority of research has focussed on salinity tolerance in tree species. We investigated how the presence of a shallow, saline water table affected the understorey species composition, species richness and species diversity in two remnant Eucalyptus wandoo Blakely woodlands in the Western Australian wheatbelt. Species richness and species diversity were significantly lower in areas with a shallow water table at elevations < 0.5 m above the lowest local elevation, compared with both higher elevations and with areas of low elevation without a shallow water table. Species composition (Bray-Curtis similarities) was also significantly different in low elevation, saline areas. At one site, saline areas were colonized by native and alien species that were not present in the surrounding vegetation, yet the community that has developed does not contain either the species or structural diversity of the surrounding system. At the other site, no colonisation of saline areas by new species occurred. Even though small differences in elevation (< 0.5 m) at our study sites were important in moderating the impacts of salinity in areas with a shallow water table, the loss of species diversity, species richness and structural complexity in low-lying elevations indicated that the ecological risk from secondary salinity to species associated only with drainage lines, seasonally wet flats and other low-lying areas is severe. The priority is to identify those vegetation communities that are restricted to only low relative elevations within the landscape and that only occur in remnants predicted to be at a high risk of developing a shallow and saline water table.     

Ecological threshold responses in European lakes and their applicability for the Water Framework Directive (WFD) implementation: synthesis of lakes results from the REBECCA project

The objective of this synthesis is to present the key messages and draw the main conclusions from the work on lakes in the REBECCA project, pointing out their links to theoretical ecology and their applicability for the WFD implementation. Type-specific results were obtained from analyses of large pan-European datasets for phytoplankton, macrophytes, macroinvertebrates and fish, and indicators and relationships showing the impact of eutrophication or acidification on these biological elements were constructed. The thresholds identified in many of the response curves are well suited for setting ecological status class boundaries and can be applied in the intercalibration of classification systems. Good indicators for phytoplankton (chrysophytes, cyanobacteria) and macrophytes (isoetids and charaphytes) responses to eutrophication were identified, and the level of eutrophication pressure needed to reach the thresholds for these indicators was quantified. Several existing metrics developed for macrophytes had low comparability and need further harmonisation to be useful for intercalibration of classification systems. For macroinvertebrates, a number of metrics developed for rivers turned out to be less useful to describe lake responses to eutrophication and acidification, whereas other species based indicators were more promising. All the biological elements showed different responses in different lake types according to alkalinity and humic substances, and also partly according to depth. Better harmonisation of monitoring methods is needed to achieve better precision in the dose–response curves. Future research should include impacts of hydromorphological pressures and climate change, as well as predictions of timelags involved in responses to reduction of pressures.     

The cultivation bias: different communities of arbuscular mycorrhizal fungi detected in roots from the field,from bait plants transplanted to the field,and from a greenhouse trap experiment

The community composition of arbuscular mycorrhizal fungi (AMF) was investigated in roots of four different plant species (Inula salicina, Medicago sativa, Origanum vulgare, and Bromus erectus) sampled in (1) a plant species-rich calcareous grassland, (2) a bait plant bioassay conducted directly in that grassland, and (3) a greenhouse trap experiment using soil and a transplanted whole plant from that grassland as inoculum. Roots were analyzed by AMF-specific nested polymerase chain reaction, restriction fragment length polymorphism screening, and sequence analyses of rDNA small subunit and internal transcribed spacer regions. The AMF sequences were analyzed phylogenetically and used to define monophyletic phylotypes. Overall, 16 phylotypes from several lineages of AMF were detected. The community composition was strongly influenced by the experimental approach, with additional influence of cultivation duration, substrate, and host plant species in some experiments. Some fungal phylotypes, e.g., GLOM-A3 (Glomus mosseae) and several members of Glomus group B, appeared predominantly in the greenhouse experiment or in bait plants. Thus, these phylotypes can be considered r strategists, rapidly colonizing uncolonized ruderal habitats in early successional stages of the fungal community. In the greenhouse experiment, for instance, G. mosseae was abundant after 3 months, but could not be detected anymore after 10 months. In contrast, other phylotypes as GLOM-A17 (G. badium) and GLOM-A16 were detected almost exclusively in roots sampled from plants naturally growing in the grassland or from bait plants exposed in the field, indicating that they preferentially occur in late successional stages of fungal communities and thus represent the K strategy. The only phylotype found with high frequency in all three experimental approaches was GLOM A-1 (G. intraradices), which is known to be a generalist. These results indicate that, in greenhouse trap experiments, it is difficult to establish a root-colonizing AMF community reflecting the diversity of these fungi in the field roots because fungal succession in such artificial systems may bias the results. However, the field bait plant approach might be a convenient way to study the influence of different environmental factors on AMF community composition directly under the field conditions. For a better understanding of the dynamics of AMF communities, it will be necessary to classify AMF phylotypes and species according to their life history strategies.     

Indigenous Knowledge of Ecological Variability and Commons Management: A Case Study on Berry Harvesting from Northern Canada

Common property arrangements govern the subsistence harvest of berries in the Gwich’in region of the Northwest Territories, Canada. Some of these arrangements, including rules for resource access, sharing information and harvest sharing, enable the Gwich’in to deal with ecological variability. The rules change in response to year-to-year variations in the abundance and distribution of the species, spatially and temporally across the region. This paper illustrates the interrelationships between ecosystem dynamics and local institutions, a neglected area of commons research.An erratum to this article can be found at