Factors affecting the photosynthetic capacity of laboratory cultures of the diatom Phaeodactylum tricornutum

The light-saturated photosynthetic capacity of cultures of Phaeodactylum tricornutum Bohlin grown under different conditions has been measured. In batch cultures grown in a regime of alternating light and dark periods, the photosynthetic capacity reaches a maximum before the end of the exponential phase of growth, and declines thereafter. In cultures illuminated at 0.7 mW (milliwatt)/cm², there is a 75% falloff in photosynthetic capacity per cell over an 8 day period following the time of maximum photosynthetic capacity. At 1.75 mW/cm², the corresponding fall-off is 85% over a 4 day period. Cultures exposed to a prolonged period of darkness (up to 16 days at 18°C) maintain a high photosynthetic capacity. Incubation in darkness also protects the cells from the deleterious effects of high temperature (28°C) upon photosynthetic capacity. The various fluctuations of photosynthetic capacity occur without any accompanying major changes in the concentration of chlorophyll a. Evidence from estimations of total protein and of the gross pattern of photosynthetic assimilation under different conditions suggests that the changes in photosynthetic capacity are largely controlled by the enzymic component of the photosynthetic machinery. By carefully controlling the conditions of dark incubation, the photosynthetic capacity can be reduced to a very low level without significantly affecting chlorophyll a concentration. Since the effect on photosynthetic capacity is reversible, it is possible to study aspects of chloroplast development without the complication of an associated synthesis of chlorophyll.     

Assessing the global zoo response to the amphibian crisis through 20‐year trends in captive collections

Global amphibian declines are one of the biggest challenges currently facing the conservation community, and captive breeding is one way to address this crisis. Using information from the International Species Information System zoo network, we examined trends in global zoo amphibian holdings across species, zoo region, and species geographical region of origin from 1994 to 2014. These trends were compared before and after the 2004 Global Amphibian Assessment to assess whether any changes occurred and whether zoo amphibian conservation effort had increased. The numbers of globally threatened species (GTS) and their proportional representation in global zoo holdings increased and this rate of increase was significantly greater after 2004. North American, European, and Oceanian GTS were best represented in zoos globally, and proportions of Oceanian GTS held increased the most since 2004. South American and Asian GTS had the lowest proportional representation in zoos. At a regional zoo level, European zoos held the lowest proportions of GTS, and this proportion did not increase after 2004. Since 1994, the number of species held in viable populations has increased, and these species are distributed among more institutions. However, as of 2014, zoos held 6.2% of globally threatened amphibians, a much smaller figure than for other vertebrate groups and one that falls considerably short of the number of species for which ex situ management may be desirable. Although the increased effort zoos have put into amphibian conservation over the past 20 years is encouraging, more focus is needed on ex situ conservation priority species. This includes building expertise and capacity in countries that hold them and tracking existing conservation efforts if the evidence‐based approach to amphibian conservation planning at a global level is to be further developed.     

What Level of Information Enables the Public to Act Like Experts When Evaluating Ecological Goods?

Although contingent valuation is widely discussed in the literature as a technique for environmental valuation, it is well recognized that a number of problems are associated with its use. This paper seeks to address two of these problems: the difficulty of externally verifying the results of a CV study; and the choice of an appropriate level of information to provide to respondents. Four sites were evaluated, first by expert ecologists and then by the general public using the CV method. In conducting the CV, six different categories of information were presented to different groups of respondents to test which was most appropriate.The results show that, given an information set consisting of photographic,textual and ecological data, respondents to a CV study were able to rank the four sites in the same order as ecological experts. This may be seen as a form of external verification to the results of the contingent valuation.     

The local governance of climate change: new tools to respond to old limitations in Esmeraldas,Ecuador

This article argues that climate change, seen as a socially constructed anticipation of natural disasters and a future-risk that plays out in present politics, is enabling the emergence of new modes of governance in cities of the global south. The article focuses on the process by which the city of Esmeraldas, Ecuador, developed a Climate Change Adaptation and Mitigation Strategy. Within the context of climate change adaptation, Esmeraldas mobilised new discourses, stakeholders, and planning mechanisms to address pre-existing urban planning and development limitations. This discursively enabled the municipality's ongoing governance project by leveraging resources, creating consensus, and informing practice. Climate change adaptation thus became an important mechanism for engaging with local priorities, particularly those of the most vulnerable populations, and for bridging the gap between the formal world of policymaking and the reality of life in the city, which is more often structured by informality.     

Ecosystem Response to Climatic Change: The Importance of the Cold Season

Winter climate and snow cover are the important drivers of plant community development in polar regions. However, the impacts of changing winter climate and associated changes in snow regime have received much less attention than changes during summer. Here, we synthesize the results from studies on the impacts of extreme winter weather events on polar heathland and lichen communities. Dwarf shrubs, mosses and soil arthropods were negatively impacted by extreme warming events while lichens showed variable responses to changes in extreme winter weather events. Snow mould formation underneath the snow may contribute to spatial heterogeneity in plant growth, arthropod communities and carbon cycling. Winter snow cover and depth will drive the reported impacts of winter climate change and add to spatial patterns in vegetation heterogeneity. The challenges ahead lie in obtaining better predictions on the snow patterns across the landscape and how these will be altered due to winter climate change.     

Fate of pathogens in a simulated bioreduction system for livestock carcasses

The EU Animal By-Products Regulations generated the need for novel methods of storage and disposal of dead livestock. Bioreduction prior to rendering or incineration has been proposed as a practical and potentially cost-effective method; however, its biosecurity characteristics need to be elucidated. To address this, Salmonella enterica (serovars Senftenberg and Poona), Enterococcus faecalis, Campylobacter jejuni, Campylobacter coli and a lux-marked strain of Escherichia coli O157 were inoculated into laboratory-scale bioreduction vessels containing sheep carcass constituents. Numbers of all pathogens and the metabolic activity of E. coli O157 decreased significantly within the liquor waste over time, and only E. faecalis remained detectable after 3months. Only very low numbers of Salmonella spp. and E. faecalis were detected in bioaerosols, and only at initial stages of the trial. These results further indicate that bioreduction represents a suitable method of storing and reducing the volume of livestock carcasses prior to ultimate disposal.     

Chemical plant risk assessment: Uncertainties and development needs

A brief review is given covering the development of major hazards risk assessment since the Flixborough disaster of 1974, with special reference to the introduction of new regulations. The importance of risk assessment in the management of major hazards is discussed by reference to the Canvey Island studies, and it is suggested that the problem of uncertainties in the estimation of risks by analysis has not been adequately treated. Examples are given to illustrate the magnitude of such uncertainties in the consequence modelling of accidental releases from a chemical plant. In addition to suggested development needs in risk analysis techniques, topics are suggested which call for development in the evaluation and management of risks.     

Modelling strategies for the management of the critically endangered Carpentarian rock-rat (Zyzomys palatalis) of northern Australia

The Carpentarian rock-rat (Zyzomys palatalis) is a critically endangered endemic rodent known from only four sandstone gorges in the southeast Gulf of Carpentaria, Northern Territory, Australia. These gorges harbour thickets of monsoon rainforest and broadleaf woodland, surrounded by a Eucalypt savanna matrix. The long-term persistence of Z. palatalis is threatened by altered fire regimes, grazing by feral animals and stock, weed intrusion, and the stochastic hazards associated with small, fragmented populations. To assess the relative importance of these threats and develop practical management options, a population and habitat simulation model was developed, based on the best existing data. Population viability was predicted to be highly sensitive to the frequency of hot, late dry-season fires. Progressive habitat degradation (due predominantly to intense late dry-season fires) is likely to substantially reduce population size and lead to the probable extinction of the species within the next 100 years. The most effective management strategy to counteract this threat would be regular, controlled, fuel reduction burns in the vegetation around the gorge entrances during the early dry season. Establishing a new population (through translocation of captive-bred individuals) would not appreciably reduce extinction risk, but could provide valuable additional data on the impact of threats, if conducted as an adaptive management experiment.