The grain of spatially referenced economic cost and biodiversity benefit data and the effectiveness of a cost targeting strategy.

Facing tight resource constraints, conservation organizations must allocate funds available for habitat protection as effectively as possible. Often, they combine spatially referenced economic and biodiversity data to prioritize land for protection. We tested how sensitive these prioritizations could be to differences in the spatial grain of these data by demonstrating how the conclusion of a classic debate in conservation planning between cost and benefit targeting was altered based on the available information. As a case study, we determined parcel-level acquisition costs and biodiversity benefits of land transactions recently undertaken by a nonprofit conservation organization that seeks to protect forests in the eastern United States. Then, we used hypothetical conservation plans to simulate the types of ex ante priorities that an organization could use to prioritize areas for protection. We found the apparent effectiveness of cost and benefit targeting depended on the spatial grain of the data used when prioritizing parcels based on local species richness. However, when accounting for complementarity, benefit targeting consistently was more efficient than a cost targeting strategy regardless of the spatial grain of the data involved. More pertinently for other studies, we found that combining data collected over different spatial grains inflated the apparent effectiveness of a cost targeting strategy and led to overestimation of the efficiency gain offered by adopting a more integrative return-on-investment approach.

The impact of projected increases in urbanization on ecosystem services.

Alteration in land use is likely to be a major driver of changes in the distribution of ecosystem services before 2050. In Europe, urbanization will probably be the main cause of land-use change. This increase in urbanization will result in spatial shifts in both supplies of ecosystem services and the beneficiaries of those services; the net outcome of such shifts remains to be determined. Here, we model changes in urban land cover in Britain based on large (16%) projected increases in the human population by 2031, and the consequences for three different services--flood mitigation, agricultural production and carbon storage. We show that under a scenario of densification of urban areas, the combined effect of increasing population and loss of permeable surfaces is likely to result in 1.7 million people living within 1 km of rivers with at least 10 per cent increases in projected peak flows, but that increasing suburban 'sprawl' will have little effect on flood mitigation services. Conversely, losses of stored carbon and agricultural production are over three times as high under the sprawl as under the 'densification' urban growth scenarios. Our results illustrate the challenges of meeting, but also of predicting, future demands and patterns of ecosystem services in the face of increasing urbanization.

Directed motion in the sea: efficient swimming by reef fish larvae.

Directed motion of marine organisms is examined with a focus on efficient behaviour, where efficient swimming minimizes either energetic expenditure or transit time. The swimming behaviour of late pelagic stage reef fish larvae is modelled to illustrate relevant concepts. To swim efficiently in the sea, an organism should exploit current-driven movements of the medium. Favourable currents should be ridden and unfavourable currents avoided. Relatively short movements to control advection can have a greater effect than longer swimming bouts used for independent horizontal locomotion. If larvae exploit the vertical structure of the water column, then the extent to which they can influence their dispersal will be substantially increased.

An invitation to ecological economics.

The emerging interdisciplinary field of ecological economics should be a recognized research priority. Only through a combination of sound ecology and good economics can we hope to manage our exploitation of the biosphere in a manner that is both sustainable and efficient. This article is an invitation to ecologists to use economic tools and to participate in ecological economic debate. To this end, we review basic ecological economic concepts and discuss how the field has arisen, what benefits it offers, and what challenges it must overcome.

When to press on or turn back: dispersal strategies for reef fish larvae.

Events that occur during the pelagic larval stage are thought to be important determinants of reef fish population dynamics. Recent research contradicts the early paradigm of larvae being advected as passive propagules and indicates that many late stage larvae have well-developed sensory and locomotory capabilities. Whether and how larvae use these capabilities to influence their dispersal is unknown. We compare alternative hypotheses regarding larval behavior. Contrary to the trend in dispersal modeling, we focus on larval biology rather than physical oceanographic considerations. Specifically, we present two streams of models: one that describes a return-based strategy and one in which dispersal is a central component. The models depend on different sets of behavioral assumptions for a pomacentrid species and for acanthurids, two groups with contrasting early life histories. Whether dispersal or return-based strategies are favored depends on the efficiency and sustainability of larval swimming methods and the environmental conditions experienced during dispersal. We argue that dispersal models should consider a variety of behavioral hypotheses and that the sensitivity of results to the behavioral assumptions made should be quantified.