Assessing the current state of ecological connectivity in a large marine protected area system

The establishment of marine protected areas (MPAs) is a critical step in ensuring the continued persistence of marine biodiversity. Although the area protected in MPAs is growing, the movement of individuals (or larvae) among MPAs, termed connectivity, has only recently been included as an objective of many MPAs. As such, assessing connectivity is often neglected or oversimplified in the planning process. For promoting population persistence, it is important to ensure that protected areas in a system are functionally connected through dispersal or adult movement. We devised a multi-species model of larval dispersal for the Australian marine environment to evaluate how much local scale connectivity is protected in MPAs and determine whether the extensive system of MPAs truly functions as a network. We focused on non-migratory species with simplified larval behaviors (i.e., passive larval dispersal) (e.g., no explicit vertical migration) as an illustration. Of all the MPAs analyzed (approximately 2.7 million km²), outside the Great Barrier Reef and Ningaloo Reef, <50% of MPAs (46-80% of total MPA area depending on the species considered) were functionally connected. Our results suggest that Australia's MPA system cannot be referred to as a single network, but rather a collection of numerous smaller networks delineated by natural breaks in the connectivity of reef habitat. Depending on the dispersal capacity of the taxa of interest, there may be between 25 and 47 individual ecological networks distributed across the Australian marine environment. The need to first assess the underlying natural connectivity of a study system prior to implementing new MPAs represents a key research priority for strategically enlarging MPA networks. Our findings highlight the benefits of integrating multi-species connectivity into conservation planning to identify opportunities to better incorporate connectivity into the design of MPA systems and thus to increase their capacity to support long-term, sustainable biodiversity outcomes.     

Simulations of the flow in the Mahakam river–lake–delta system,Indonesia

Large rivers often present a river–lake–delta system, with a wide range of temporal and spatial scales of the flow due to the combined effects of human activities and various natural factors, e.g., river discharge, tides, climatic variability, droughts, floods. Numerical models that allow for simulating the flow in these river–lake–delta systems are essential to study them and predict their evolution under the impact of various forcings. This is because they provide information that cannot be easily measured with sufficient temporal and spatial detail. In this study, we combine one-dimensional sectional-averaged (1D) and two-dimensional depth-averaged (2D) models, in the framework of the finite element model SLIM, to simulate the flow in the Mahakam river–lake–delta system (Indonesia). The 1D model representing the Mahakam River and four tributaries is coupled to the 2D unstructured mesh model implemented on the Mahakam Delta, the adjacent Makassar Strait, and three lakes in the central part of the river catchment. Using observations of water elevation at five stations, the bottom friction for river and tributaries, lakes, delta, and adjacent coastal zone is calibrated. Next, the model is validated using another period of observations of water elevation, flow velocity, and water discharge at various stations. Several criteria are implemented to assess the quality of the simulations, and a good agreement between simulations and observations is achieved in both calibration and validation stages. Different aspects of the flow, i.e., the division of water at two bifurcations in the delta, the effects of the lakes on the flow in the lower part of the system, the area of tidal propagation, are also quantified and discussed.     

Habitat,movements and environmental preferences of dusky sharks,Carcharhinus obscurus,in the northern Gulf of Mexico

The dusky shark (Carcharhinus obscurus) is the largest member of the genus Carcharhinus and inhabits coastal and pelagic ecosystems circumglobally in temperate, subtropical and tropical marine waters. In the western North Atlantic Ocean (WNA), dusky sharks are overfished and considered vulnerable by the International Union for the Conservation of Nature. As a result, retention of dusky sharks in commercial and recreational fisheries off the east coast of the United States (US) and in the northern Gulf of Mexico is prohibited. Despite the concerns regarding the status of dusky sharks in the WNA, little is known about their habitat utilization. During the summers of 2008–2009, pop-up satellite archival tags were attached to ten dusky sharks (one male, nine females) at a location where they have been observed to aggregate in the north central Gulf of Mexico southwest of the Mississippi River Delta to examine their movement patterns and habitat utilization. All tags successfully transmitted data with deployment durations ranging from 6 to 124 days. Tag data revealed shark movements in excess of 200 km from initial tagging locations, with sharks primarily utilizing offshore waters associated with the continental shelf edge from Desoto Canyon to the Texas/Mexican border. While most sharks remained in US waters, one individual moved from the northern Gulf of Mexico into the Bay of Campeche off the coast of Mexico. Sharks spent 87 % of their time between 20 and 125 m and 83 % of their time in waters between 23 and 30 °C. Since dusky sharks are among the most vulnerable shark species to fishing mortality, there is a recovery plan in place for US waters; however, since they have been shown to make long-distance migrations, a multi-national management plan within the WNA may be needed to ensure the successful recovery of this population.     

Density dependence in social behaviour: home range overlap and density interacts to affect conspecific encounter rates in a gregarious ungulate

Sociality is poorly understood in the context of population processes. We used wild, female elk (Cervus canadensis) equipped with proximity-logging radio collars (n?=?62) from Manitoba, Canada (2007–2009), to test for modifying effects of population density (two areas: 0.42 and 0.22 animals/km²) on the relationship between two measures of sociality. This included the rate at which collared individuals encountered one another per year (encounters logged as animals ranging to within 1.4 m of each other) and the extent to which animals overlapped in annual home range (proportion of shared minimum convex polygon ranges). Overlap was significantly greater in the high density area compared to that of the low, but not if we only considered individuals that directly encountered each other, implying that familiar individuals will maintain a constant degree of range overlap regardless of density. Encounter rate was nonlinearly related to home range overlap. This relationship was also density-dependent, exhibiting negative density dependence at high proportions of overlap, primarily in the high density subpopulation. Sociality, as defined by two interacting measures of behaviour—encounter rate and home range overlap—exhibits a complex nonlinear relationship; we discuss the implications of these results as they pertain to sociobiology, resource competition, and pathogen transmission.     

Experimental tree removal in tallgrass prairie: variable responses of flora and fauna along a woody cover gradient

Woody plant encroachment is a worldwide phenomenon in grassland and savanna systems whose consequence is often the development of an alternate woodland state. Theoretically, an alternate state may be associated with changes in system state variables (e.g., species composition) or abiotic parameter shifts (e.g., nutrient availability). When state-variable changes are cumulative, such as in woody plant encroachment, the probability of parameter shifts increases as system feedbacks intensify over time. Using a Before-After Control-Impact (BACI) design, we studied eight pairs of grassland sites undergoing various levels of eastern redcedar (Juniperus virginiana) encroachment to determine whether responses of flora and fauna to experimental redcedar removal differed according to the level of pretreatment redcedar cover. In the first year after removal, herbaceous plant species diversity and evenness, woody plant evenness, and invertebrate family richness increased linearly with pretreatment redcedar cover, whereas increases in small-mammal diversity and evenness were described by logarithmic trends. In contrast, increases in woody plant diversity and total biomass of terrestrial invertebrates were accentuated at levels of higher pretreatment cover. Tree removal also shifted small-mammal species composition toward a more grassland-associated assemblage. During the second year postremoval, increases in herbaceous plant diversity followed a polynomial trend, but increases in most other metrics did not vary along the pretreatment cover gradient. These changes were accompanied by extremely high growing-season precipitation, which may have homogenized floral and faunal responses to removal. Our results demonstrate that tree removal increases important community metrics among grassland flora and fauna within two years, with some responses to removal being strongly influenced by the stage of initial encroachment and modulated by climatic variability. Our results underscore the importance of decisive management for reversing the effects of woody plant encroachment in imperiled grassland ecosystems.     

Social chemistry

This article is both an essay to propose social chemistry as a new scientific discipline and a preface of the books Environmental Chemistry for a Sustainable World. Environmental chemistry is a fast emerging discipline aiming at the understanding the fate of pollutants in ecosystems and at designing novel processes that are safe for ecosystems. Past pollution should be cleaned, and future pollution should be predicted and avoided (Lichtfouse et al. 2005a). Such advices are still not applied by humans as demonstrated by the Fukushima nuclear event and global warming. Human errors are repeatable. We therefore suggest a possible solution, which involves bridging chemistry and society by integrating social sciences in chemical research. In particular, citizen discourse analysis should be useful to design chemicals that are both innovative and accepted by society. Then, we present the recent success of environmental chemistry through the foundation of the Association of Chemistry and the Environment; the increase in the impact factor of Environmental Chemistry Letters from 0.814 in 2006 to 2.109 in 2009; and over 35,000 chapter downloads of the book Environmental Chemistry. Lastly, we highlight major topics of the new book series Environmental Chemistry for a Sustainable World (Lichtfouse et al. 2011a, b). The two first volumes are entitled Nanotechnology and Health Risk, and Remediation of Air and Water Pollution.     

Fast and complete removal of the 5-fluorouracil drug from water by electro-Fenton oxidation

Cytostatic drugs are a troublesome class of emerging pollutants in water owing to their potential effects on DNA. Here we studied the removal of 5-fluorouracil from water using the electro-Fenton process. Galvanostatic electrolyses were performed with an undivided laboratory-scale cell equipped with a boron-doped diamond anode and a carbon felt cathode. Results show that the fastest degradation and almost complete mineralization was obtained at a Fe²⁺ catalyst concentration of 0.2 mM. The absolute rate constant for oxidation of 5-fluorouracil by hydroxyl radicals was 1.52 × 10⁹ M^?1 s^?1. Oxalic and acetic acids were initially formed as main short-chain aliphatic by-products, then were completely degraded. After 6 h the final solution mainly contained inorganic ions (NH₄ ⁺, NO₃ ^? and F^?) and less than 10% of residual organic carbon. Hence, electro-Fenton constitutes an interesting alternative to degrade biorefractory drugs.     

Publishing science without results and recycling research

Most scientists focus too much on publishing original articles. In doing so, scientists are restricting their writing skills to this form of highly specialised publication, which is poorly readable by scientists from other disciplines. In the context of rising interdisciplinary research and data abundance, there is a need for more publications that recycle existing research and communicate to a wider audience. Therefore, I present here five types of publications that do not require additional experiments, namely reviews, methods, data papers, meta-analyses and videos. Benefits include more citations, larger visibility, wider dissemination, easier job finding, grant success and better recycling of research.     

Climate change threatens polar bear populations: a stochastic demographic analysis

The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in lambda in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log lambdas, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log lambdas approximately - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic declines in the polar bear population by the end of the 21st century. These projections were instrumental in the decision to list the polar bear as a threatened species under the U.S. Endangered Species Act.