Ecological correlates of duckling adoption among white-winged scoters Melanitta fusca: strategy, epiphenomenon, or combination?

Young waterfowl can frequently join foster females shortly after hatch, resulting in post-hatch brood amalgamation. Much uncertainty remains about physiological or ecological factors that motivate adoption including potential costs and benefits to fostered offspring as well as to females that either lose or accept young. Several hypotheses have been put forth to explain adoption. In this paper, we examine the salvage strategy (SSH) and accidental-mixing (AMH) hypotheses. According to the SSH, females abandon or lose their young due to substantial energetic constraints from incubation and brood rearing. The AMH posits that adoption results from local ecological conditions on breeding areas (i.e., adverse weather conditions, high brood densities) which act to separate offspring and mothers. We used multistate modeling to estimate relationships between probabilities of adoption by white-winged scoter (Melanitta fusca) ducklings from natal to foster females and a set of hypothesized ecological covariates. Results showed that most adoption occurred within 6 days of hatch; additionally, likelihood of adoption was positively related to inclement weather and negatively related to hatch date, size, and condition of natal females, and duckling condition. We conclude that adoption in this population is consistent with both the salvage strategy and accidental-mixing hypotheses. Ultimately, we suggest that adoption in our study population was foremost an outcome of intense gull predation but also of local environmental conditions.     

Relevance of wound-activated compounds produced by diatoms as toxins and infochemicals for benthic invertebrates

Plants evolve the production of wound-activated compounds (WACs) to reduce grazing pressure. In addition, several plant-produced WACs are recognized by various invertebrates, playing the role of infochemicals. Due to co-evolutionary processes, some invertebrates recognize plant infochemicals and use them to identify possible prey, detect the presence of predators or identify algae containing various classes of toxic metabolites. Different metabolites present in the same algae can play the role of toxins, infochemicals or both simultaneously. We investigated the infochemical activity of compounds extracted from three diatoms epiphytes of the seagrass Posidonia oceanica, by conducting choice experiments on invertebrates living in the same community or in close proximity. Furthermore, the specific toxicity of the extracts obtained from the same algae was tested on sea urchin embryos using a standard bioassay procedure, to detect the presence of toxins. The comparison of the two effects demonstrated that invertebrates are subjected to diatom wound-activated toxicants when these algae are not associated with their own habitat, but they are able to recognize volatile infochemicals derived from diatoms associated with their habitats. The specific toxicity of WACs was shown to be inversely correlated to the perceptive ability of invertebrates towards volatile compounds liberated by the same algae. Hence, when the recognition of specific algae by a given invertebrate species evolves, their detrimental effects on the receiving organism may be lost.     

PM2.5: global progress in controlling the motor vehicle contribution

It is well established that ambient particles in the size range of 2.5 microns or less case a wide variety of adverse health effects. According to a recent study from the World Health Organization, in 2010 these effects resulted in approximately 3.2million premature deaths with vehicles being one of the significant contributors. Diesel vehicle particulate emissions which are virtually all smaller than 2.5 microns raise additional special concerns due to their carcinogenicity and high ratio of black carbon （BC） to organic carbon; black carbon has recently been found to be the second most important contributor to climate change after carbon dioxide. Other pollutants emitted by diesels and other vehicles such as the oxides of nitrogen and volatile organic compounds also contribute to ambient particulate matter smaller than 2.5 microns in size （PM2.5） after undergoing secondary transformations in the atrno- sphere. Technologies have dramatically reduce vehicle been developed that can emissions when clean, low sulfur fuels are available and these technologies are being phased in throughout the industrialized world resulting in a global decrease in particulate matter （PM） and BC emissions from vehicles. However the vehicle population is growing rapidly in the developing world, leading to increases in emissions in many countries. Unless these rapidly industrializing countries move to state of the art vehicles and clean fuels, global PM, BC and NOx emissions from road vehicles will start to turn up over the next 10 to 15 years.     

Community participation in the management of forest reserves in the Northern Region of Ghana

The 1994 forest and wildlife policy of Ghana provides the basis for community participation in forest management through participatory forest management. Even though forest reserves in the Northern Region are said to be managed collaboratively, fringe communities are supposedly involved only in maintenance activities of the reserve boundaries and seedling planting in plantation programmes. The forest reserves are said to be threatened by illegal activities from the fringe communities. This study therefore examined the nature of community participation in the management of forest reserves.

It is a mixed method research in which structured interview schedule, in-depth interview and focus group discussion guides were used for data collection. Respondents comprised community members, forestry staff and NGOs. Communities’ participation was found to be passive and tokenistic and limited to boundary cleaning and providing labour on plantations. There is no formal collaboration between communities and Forest Services Division. Prospects to communities’ participation lie in the continuous flow of benefits and their active involvement in management decisions. Active involvement of communities in all decision-making processes, capacity building of communities and forestry staff, incentive schemes and awareness creation are recommended for promoting community participation in managing forest reserves in Northern Region.     

Vascular plant extinction in the continental United States and Canada

Extinction rates are expected to increase during the Anthropocene. Current extinction rates of plants and many animals remain unknown. We quantified extinctions among the vascular flora of the continental United States and Canada since European settlement. We compiled data on apparently extinct species by querying plant conservation databases, searching the literature, and vetting the resulting list with botanical experts. Because taxonomic opinion varies widely, we developed an index of taxonomic uncertainty (ITU). The ITU ranges from A to F, with A indicating unanimous taxonomic recognition and F indicating taxonomic recognition by only a single author. The ITU allowed us to rigorously evaluate extinction rates. Our data suggest that 51 species and 14 infraspecific taxa, representing 33 families and 49 genera of vascular plants, have become extinct in our study area since European settlement. Seven of these taxa exist in cultivation but are extinct in the wild. Most extinctions occurred in the west, but this outcome may reflect the timing of botanical exploration relative to settlement. Sixty-four percent of extinct plants were single-site endemics, and many occurred outside recognized biodiversity hotspots. Given the paucity of plant surveys in many areas, particularly prior to European settlement, the actual extinction rate of vascular plants is undoubtedly much higher than indicated here.     

Mapping risk for nest predation on a barrier island

Barrier islands and coastal beach systems provide nesting habitat for marine and estuarine turtles. Densely settled coastal areas may subsidize nest predators. Our purpose was to inform conservation by providing a greater understanding of habitat-based risk factors for nest predation, for an estuarine turtle. We expected that habitat conditions at predated nests would differ from random locations at two spatial extents. We developed and validated an island-wide model for the distribution of predated Diamondback terrapin nests using locations of 198 predated nests collected during exhaustive searches at Fisherman Island National Wildlife Refuge, USA. We used aerial photographs to identify all areas of possible nesting habitat and searched each and surrounding environments for nests, collecting location and random-point microhabitat data. We built models for the probability of finding a predated nest using an equal number of random points and validated them with a reserve set (N?=?67). Five variables in 9 a priori models were used and the best selected model (AIC weight 0.98) reflected positive associations with sand patches near marshes and roadways. Model validation had an average capture rate of predated nests of 84.14 % (26.17–97.38 %, Q1 77.53 %, median 88.07 %, Q3 95.08 %). Microhabitat selection results suggest that nests placed at the edges of sand patches adjacent to upland shrub/forest and marsh systems are vulnerable to predation. Forests and marshes provide cover and alternative resources for predators and roadways provide access; a suggestion is to focus nest protection efforts on the edges of dunes, near dense vegetation and roads.     

Living within constraints: irreversible chemical build-up and seasonal temperature-mediated die-off in a highly acidic (H2SO4) annual seaweed (Desmarestia viridis)

Seaweeds exhibit a number of adaptations to cope with strong selective pressures imposed by shallow marine environments. The exceptional ability of the annual, brown seaweed Desmarestia viridis, to produce and store high concentrations of sulfuric acid (H₂SO₄) in intracellular vacuoles, makes it a particularly compelling model for studies of causes and consequences of acid production in seaweeds. We used two laboratory experiments, as well as measurements of intracellular pH of sporophytes and sea salinity and temperature over an entire growth season at one site in Newfoundland and Labrador (Canada), to test hypotheses about effects of salinity and temperature on acid production and die-off in D. viridis. We show that the acid is continuously and irreversibly accumulated (resulting in an intracellular pH as low as 0.53) as the seaweed grows from recruit to adult (March–June) and that this build-up inevitably culminates into dramatic mass releases of acid and die-offs. Progressive, synchronous death among individuals is under the predominant control of sea temperature (death systematically occurred around 12 °C in both laboratory and field), which suggests the evolution of a life-history strategy in which death occurs at a time when individuals reach a size that may correspond to reproductive maturity. The seaweed exhibits a low tolerance to changes in salinity (death was inevitable below 29 psu), which likely imposes severe limitations on its distribution range throughout its existence as a sporophyte. Our findings suggest that major phenological events and survival in D. viridis are intimately linked to synergistic effects of oceanographic controls, which either impair the ability of the seaweed to retain the acid in its tissues (seasonal sea warming), or contribute to dissipating the acid that is released to the environment (wave and current action). They also provide novel insights into the ecophysiological and evolutionary constraints within which marine organisms adapt.     

Restoring native fish assemblages to a regulated California stream using the natural flow regime concept

We examined the response of fishes to establishment of a new flow regime in lower Putah Creek, a regulated stream in California, U.S.A. The new flow regime was designed to mimic the seasonal timing of natural increases and decreases in stream flow. We monitored fish assemblages annually at six sample sites distributed over approximately 30 km of stream for eight years before and nine years after the new flow regime was implemented. Our purpose was to determine whether more natural stream flow patterns would reestablish native fishes and reduce the abundances of alien (nonnative) fishes. At the onset of our study, native fishes were constrained to habitat immediately (<1 km) below the diversion dam, and alien species were numerically dominant at all downstream sample sites. Following implementation of the new flow regime, native fishes regained dominance across more than 20 km of lower Putah Creek. We propose that the expansion of native fishes was facilitated by creation of favorable spawning and rearing conditions (e.g., elevated springtime flows), cooler water temperatures, maintenance of lotic (flowing) conditions over the length of the creek, and displacement of alien species by naturally occurring high-discharge events. Importantly, restoration of native fishes was achieved by manipulating stream flows at biologically important times of the year and only required a small increase in the total volume of water delivered downstream (i.e., water that was not diverted for other uses) during most water years. Our results validate that natural flow regimes can be used to effectively manipulate and manage fish assemblages in regulated rivers.     

Disruption of coastal societies in the Pacific Islands from rapid sea-level fall about AD 1300: new evidence from northern Viti Levu Island, Fiji

This paper reports preliminary findings of a study in northern Viti Levu Island (Fiji) intended to test the model of the AD 1300 Event. This holds that around AD 1250–1350, during the transition between the Medieval Warm Period and the Little Ice Age, there was a rapid climate-driven sea-level fall of 70–80 cm which created a food crisis for coastal dwellers throughout the tropical Pacific Islands and led to conflict and the abandonment of open coastal settlements in favour of those in more defensible locations. Two main areas were targeted—the Ba River Valley and adjoining Vatia Peninsula (plus offshore islands)—and inland/offshore sites in defensible locations, particularly in caves, ridge-top rockshelters, and isolated hilltops, were surveyed and test excavations made. Results show that while some of these sites were established during the AD 1300 Event, most were established shortly afterwards, which is exactly what the model predicts. It is concluded that prehistoric populations in Fiji (and similar island groups) were affected by the food crisis during the AD 1300 Event and did respond in ways that profoundly and enduringly altered contemporary trajectories of societal evolution. This study has great implications for the preservation of the record of prehistoric settlement in Fiji (and other tropical Pacific Island groups) because, as a consequence of this climate-forced migration from coasts to inland/upland sites, large amounts of sediment were released from island interiors and carried to their coasts where they buried earlier settlements or redistributed their material signature. Since European arrival in such places around 150 years ago, a second wave of coastal sedimentation, largely driven by plantation agriculture development had similar effects. The current rise of sea level around Pacific Island coasts is the latest in a series of (largely human) threats to the preservation of their cultural heritage.