Trophic cascade induced by molluscivore predator alters pore-water biogeochemistry via competitive release of prey

Effects of predation may cascade down the food web. By alleviating interspecific competition among prey, predators may promote biodiversity, but the precise mechanisms of how predators alter competition have remained elusive. Here we report on a predator-exclosure experiment carried out in a tropical intertidal ecosystem, providing evidence for a three-level trophic cascade induced by predation by molluscivore Red Knots (Calidris canutus) that affects pore water biogeochemistry. In the exclosures the knots' favorite prey (Dosinia isocardia) became dominant and reduced the individual growth rate in an alternative prey (Loripes lucinalis). Dosinia, a suspension feeder, consumes suspended particulate organic matter (POM), whereas Loripes is a facultative mixotroph, partly living on metabolites produced by sulfur-oxidizing chemoautotrophic bacteria, but also consuming suspended POM. Reduced sulfide concentrations in the exclosures suggest that, without predation on Dosinia, stronger competition for suspended POM forces Loripes to rely on energy produced by endosymbiotic bacteria, thus leading to an enhanced uptake of sulfide from the surrounding pore water. As sulfide is toxic to most organisms, this competition-induced diet shift by Loripes may detoxify the environment, which in turn may facilitate other species. The inference that predators affect the toxicity of their environment via a multi-level trophic cascade is novel, but we believe it may be a general phenomenon in detritus-based ecosystems.     

Native ecotypic variation and the role of host identity in the spread of an invasive herbivore, Cactoblastis cactorum

Environmental niche models (ENMs) have gained enormous popularity as tools to investigate potential changes in species distributions resulting from climate change and species introductions. Despite recognition that species interactions can influence the dynamics of invasion spread, most implementations of ENMs focus on abiotic factors as the sole predictors of potential range limits. Implicit in this approach is the assumption that biotic interactions are relatively unimportant, either because of scaling issues, or because fundamental and realized niches are equivalent in a species' native range. When species are introduced into exotic landscapes, changes in biotic interactions relative to the native range can lead to occupation of different regions of niche space and apparent shifts in physiological tolerances. We use an escaped biological control organism, Cactoblastis cactorum (Berg.), to assess the role of the environmental envelope as compared with patterns of host-herbivore associations based on collections made in the native range. Because all nonnative populations are derived from a single C. cactorum ecotype, we hypothesize that biotic interactions associated with this ecotype are driving the species' invasion dynamics. Environmental niche models constructed from known native populations perform poorly in predicting nonnative distributions of this species, except where there is an overlap in niche space. In contrast, genetic isolation in the native range is concordant with the observed pattern of host use, and strong host association has been noted in nonnative landscapes. Our results support the hypothesis that the apparent shift in niche space from the native to the exotic ranges results from a shift in biotic interactions, and demonstrate the importance of considering biotic interactions in assessing the risk of future spread for species whose native range is highly constrained by biotic interactions.     

Height-growth response to climatic changes differs among populations of Douglas-fir: a novel analysis of historic data

Projected climate change will affect existing forests, as substantial changes are predicted to occur during their life spans. Species that have ample intraspecific genetic differentiation, such as Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), are expected to display population-specific growth responses to climate change. Using a mixed-effects modeling approach, we describe three-year height (HT) growth response to changes in climate of interior Douglas-fir populations. We incorporate climate information at the population level, yielding a model that is specific to both species and population. We use data from provenance tests from previous studies that comprised 236 populations from Idaho, Montana, and eastern Washington, USA. The most sensitive indicator of climate was the mean temperature of the coldest month. Population maximum HT and HT growth response to changes in climate were dependent on seed source climate. All populations had optimum HT growth when transferred to climates with warmer winters; those originating in sites with the warmest winters were taller across sites and had highest HT growth at transfer distances closest to zero; those from colder climates were shortest and had optimum HT growth when transferred the farthest. Although this differential response damped the height growth differences among populations, cold-climate populations still achieved their maximum growth at lower temperatures than warm-climate populations. The results highlight the relevance of understanding climate change impacts at the population level, particularly in a species with ample genetic variation among populations.     

Sediments distribution of trace metals in a coastal lagoon (Southern Sardinia,Mediterranean Sea): assessment of contamination and ecological risk

Coastal lagoons are subject to several sources of contaminations. To shade light on the contamination level of the Santa Gilla lagoon (Tyrrhenian Sea) we investigated the spatial distribution of Cr, Ni, Pb, Zn and Hg in sediments and their correlation with grain size and organic matter contents. Moreover, sediment contamination levels and the ecological risk associated with metal concentration were assessed using different abiotic indicators. The lagoon is characterised by low levels of contamination, with exceptions for Pb and Hg, whose distribution reflects the position of an old chlor-alkali plant and that of an airport. These results indicate that the restoration put in place 30 years ago have not reached the expected target and that the presence of the airport deserves further attention. In the outer section of the lagoon, where clam fishery occurs, we observed low levels of contamination suggesting that such artisanal fishery could somehow help mobilising metals. We conclude that the area exposed to Hg pollution, though tentatively restored, still suffers of a potential risk of ecosystem deterioration. We pinpoint that further investigations on the mobility, bioavailability and toxicity of metals are needed to finally address the actual impairment of the Santa Gilla lagoon.     

Bio-methane production from tomato pomace: preliminary evaluation of process intensification through ultrasound pre-treatment

Journal of Material Cycles and Waste Management - The effect of ultrasound pre-treatment (for 5, 15, and 30 min) on tomato pomace methane yield was evaluated. With respect to the control...     

Increasing the capacity of community development corporations for brownfield redevelopment: an inside-out approach

While the redevelopment of brownfield sites has been the mainstay of public agencies and private developers, this paper argues that in order to promote just redevelopment that encourages participation and targets weak market sites, a community-based approach to brownfield redevelopment should be encouraged. Furthermore, this paper maintains that community development corporations (CDCs) could be the ideal agents to spur community development and address environmental justice concerns through their increased involvement in brownfield redevelopment projects. In order to promote these positions, we first describe this new approach, which focuses on building the capacity of CDCs to meaningfully participate in brownfield redevelopment. We then offer four proposals designed to increase this capacity. We conclude with a discussion of how community-based brownfield redevelopment connects to larger issues of democratic decision-making, environmental justice, and urban revitalisation.     

Community energy plans in Canadian cities: success and barriers in implementation

Climate change and sustainable development concerns have motivated some municipalities in Canada to develop community energy plans, which focus on energy needs at the local level for the development of efficient, economical and environmental energy systems. Five Canadian cities that were early adopters of community energy planning principles were studied to assess whether implementation has occurred and what barriers have been experienced. The cities achieved success in the implementation of energy management in municipal operations despite barriers in jurisdiction, perception of cost, communication and capacity, but energy management in the community had not been fully implemented and long-term changes were not prevalent. While reductions were made in the greenhouse gas (GHG) emissions produced by municipal operations, the community's overall GHG emissions were not significantly reduced. Long-term impacts on a city's function and growth will be key if community energy planning is to significantly impact community-wide GHG emissions and energy use.     

The significance and praxis of community‐based sustainability projects: Community gardens in western Australia

Abstract

Sustainability projects initiated by community groups can be significant in their contribution to the overall process of Local Agenda 21 planning and in their substantive contribution to sustainable communities. Community gardens differ from public gardens in that they are managed by community members rather than by local governments, although they may be located on council land. Community gardens vary in type from collections of individual plots to large‐scale collaborative projects for the benefit of the wider community. Their roles include the production of fresh organic food; the creation of community places; and the use and dissemination of community science and innovative technologies. This paper reviews the types and roles of community gardens, and provides a case study of a community garden in Western Australia. It analyses the lessons learned from this particular case and the potential contribution of community gardens to Local Agenda 21 planning and to physical, ecological, sociocultural and economic sustainability.     

The Nature Conservancy's approach to prioritizing conservation action

Like many conservation organizations and federal and state agencies, The Nature Conservancy is in the process of large-scale planning and prioritization efforts. To improve the efficiency of these planning efforts, the Conservancy has developed a methodology for these efforts. The results of these planning efforts will be a conservation blueprint which identifies the conservation areas necessary for conserving biodiversity and a subset of those areas where the Conservancy will focus its immediate efforts over the next 10 years. The subset of all the conservation areas identified in the planning process help The Nature Conservancy determine where it will work. This subset of areas (referred to as action sites) is selected using a tool which ranks key criteria for each conservation area. These criteria include the current conservation status of each area, complementarity to other areas selected, the diversity and viability of targets at the area, the urgency and degree of threats to the targets, the feasibility or opportunity to abate the threats at the area and the leverage potential of working at a conservation area. Taken together, these criteria help planners to select the areas where they will focus their conservation efforts.     

A framework for sustainable invasive species management: Environmental,social, and economic objectives

Applying the concept of sustainability to invasive species management (ISM) is challenging but necessary, given the increasing rates of invasion and the high costs of invasion impacts and control. To be sustainable, ISM must address environmental, social, and economic factors (or “pillars”) that influence the causes, impacts, and control of invasive species across multiple spatial and temporal scales. Although these pillars are generally acknowledged, their implementation is often limited by insufficient control options and significant economic and political constraints. In this paper, we outline specific objectives in each of these three “pillars” that, if incorporated into a management plan, will improve the plan’s likelihood of sustainability. We then examine three case studies that illustrate how these objectives can be effectively implemented. Each pillar reinforces the others, such that the inclusion of even a few of the outlined objectives will lead to more effective management that achieves ecological goals, while generating social support and long-term funding to maintain projects to completion. We encourage agency directors and policy-makers to consider sustainability principles when developing funding schemes, management agendas, and policy.