Linking Ecological Sustainability and World Food Needs

Ecological approaches to agriculture can provide useful guidelines for addressing world food needs, while avoiding adverse environmental and social impacts. Experiments in both natural and agricultural ecosystems suggest that systems with high plant diversity may be more productive, more stable and more resilient than species-poor systems. In addition, systems with high plant diversity support higher levels of biodiversity in other functional groups, which may enhance the productivity of the plant component. Given these benefits of diverse systems, various approaches for converting conventional high input agricultural systems to more sustainable systems are addressed. Andow and Hidaka's (1989) concept of production syndromes is considered in the context of conversion to sustainable agriculture.     

‘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.     

Polyphenols and their influence on gut function and health in ruminants: a review

Polyphenols in plants can protect proteins from degradation and improve the efficiency of conversion of plant protein to animal protein (meat and milk), but can this be achieved in a way that is environmentally sustainable, profitable to the livestock farmer and is consistent with aspirations for improved livestock nutrition, health, welfare and product quality? Given that grazed and conserved forage is the bedrock of sustainable ruminant production, this paper attempts to consider what challenges are ahead in terms of enhancing productive efficiency, reducing the polluting footprint of livestock agriculture and alleviating the endemic parasitism that occurs with grazing animals.     

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.     

Bridging the generation gap in plants: pollination, parental fecundity, and offspring demography

Despite extensive study of pollination and plant reproduction on the one hand, and of plant demography on the other, we know remarkably little about links between seed production in successive generations, and hence about long-term population consequences of variation in pollination success. We bridged this "generation gap" in Ipomopsis aggregata, a long-lived semelparous wildflower that is pollinator limited, by adding varying densities of seeds to natural populations and following resulting plants through their entire life histories. To determine whether pollen limitation of seed production constrains rate of population growth in this species, we sowed seeds into replicated plots at a density that mimics typical pollination success and spacing of flowering plants in nature, and at twice that density to mimic full pollination. Per capita offspring survival, flower production, and contribution to population increase (lambda) did not decline with sowing density in this experiment, suggesting that typical I. aggregata populations freed from pollen limitation will grow over the short term. In a second experiment we addressed whether density dependence would eventually erase the growth benefits of full pollination, by sowing a 10-fold range of seed densities that falls within extremes estimated for the natural "seed rain" that reaches the soil surface. Per capita survival to flowering and age at flowering were again unaffected by sowing density, but offspring size, per capita flower production, and lambda declined with density. Such density dependence complicates efforts to predict population dynamics over the longer term, because it changes components of the life history (in this case fecundity) as a population grows. A complete understanding of how constraints on seed production affect long-term population growth will hinge on following offspring fates at least through flowering of the first offspring generation, and doing so for a realistic range of population densities.     

Postcopulatory sexual selection favours intrinsically good sperm competitors

We used guppies to study repeatability in sperm competitiveness and postcopulatory sexual selection on male ornamentation. In a block design involving 25 pairs of males, artificial insemination was used to mate each pair (A and B) to four unrelated females—two that were mated with the combined ejaculates of both males (sperm-competition treatment) and two receiving sperm from each of the two males individually (single-male treatment). Our analysis revealed significantly repeatable patterns of paternity across females in the sperm-competition treatment, suggesting that certain males are intrinsically better sperm competitors than others, irrespective of female identity. Next, we compared mean brood success (number of offspring per brood) between sperm competition and single-male treatments. We found no significant effect of treatment on female fecundity, suggesting that the previously reported direct benefits of polyandry in this species may be due to factors such as differential maternal effects or differences in the number of inseminated sperm between treatments. Our artificial insemination assay was designed to control both factors. Finally, we determined whether variation in relative paternity was random with respect to male phenotype. Unlike previous work on Trinidadian populations, we found no significant relationship between male sexual ornamentation and sperm competitiveness in the focal population.     

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.     

International cross-validation of a BOD5 surrogate

BOD5 dates back to 1912 when the Royal Commission decided to use the mean residence time of water in the rivers of England, 5 days, as a standard to measure the biochemical oxygen demand. Initially designed to protect the quality of river waters from extensive sewage discharge, the use of BOD5 has been quickly extended to waste water treatment plants (WWTPs) to monitor their efficiency on a daily basis. The measurement has been automatized but remains a tedious, time- and resource-consuming analysis. We have cross-validated a surrogate BOD5 method on two sites in France and in the USA with a total of 109 samples. This method uses a fluorescent redox indicator on a 96-well microplate to measure microbial catabolic activity for a large number of samples simultaneously. Three statistical tests were used to compare surrogate and reference methods and showed robust equivalence.     

Individual variation in foraging behavior reveals a trade-off between flexibility and performance of a top predator

There is increasing evidence that behavioral flexibility is associated with the ability to adaptively respond to environmental change. Flexibility can be advantageous in some contexts such as exploiting novel resources, but it may come at a cost of accuracy or performance in ecologically relevant tasks, such as foraging. Such trade-offs may, in part, explain why individuals within a species are not equally flexible. Here, we conducted a reversal learning task and predation experiment on a top fish predator, the Northern pike (Esox lucius), to examine individual variation in flexibility and test the hypothesis that an individual’s behavioral flexibility is negatively related with its foraging performance. Pikes were trained to receive a food reward from either a red or blue cup and then the color of the rewarded cup was reversed. We found that pike improved over time in how quickly they oriented to the rewarded cup, but there was a bias toward the color red. Moreover, there was substantial variation among individuals in their ability to overcome this red bias and switch from an unrewarded red cup to the rewarded blue cup, which we interpret as consistent variation among individuals in behavioral flexibility. Furthermore, individual differences in behavioral flexibility were negatively associated with foraging performance on ecologically relevant stickleback prey. Our data indicate that individuals cannot be both behaviorally flexible and efficient predators, suggesting a trade-off between these two traits.