The effect of patch constellation on the exchange of individuals between habitat-islands

Metapopulation models assume that inter-patch dispersal dominantly depends on distance between patches and the dispersal capability of organisms in question. We used a spatially explicit, individual-based model to investigate the potential effect of patch constellation on the exchange of individuals between patches. We simulated migration of individuals from a start- into a target-patch with both patches having the same size and shape. Simulation experiments were carried out for four patch constellations and two different movement patterns. Our results demonstrate a substantial effect of patch constellation on the exchange of individuals. They also show that the magnitude and even the direction of this effect crucially depends on their movement pattern. We conclude that particularly for highly correlated movement patterns patch shape and constellation can not readily be ignored when modelling inter-patch dispersal between habitat-islands.     

Native plant restoration combats environmental change: development of carbon and nitrogen sequestration capacity using small cordgrass in European salt marshes

Restoration of salt marshes is critical in the context of climate change and eutrophication of coastal waters because their vegetation and sediments may act as carbon and nitrogen sinks. Our primary objectives were to quantify carbon (C) and nitrogen (N) stocks and sequestration rates in restored marshes dominated by Spartina maritima to provide support for restoration and management strategies that may offset negative aspects of eutrophication and climate change in estuarine ecosystems. Sediment C content was between ca. 13 mg C g^?1and sediment N content was ca. 1.8 mg N g^?1. The highest C content for S. maritima was recorded in leaves and stems (ca. 420 mg C g^?1) and the lowest in roots (361?±?4 mg C g^?1). S. maritima also concentrated more N in its leaves (31?±?1 mg N g^?1) than in other organs. C stock in the restored marshes was 29.6 t C ha^?1; ca. 16 % was stored in S. maritima tissues. N stock was 3.6 t N ha^?1, with 8.3 % stored in S. maritima. Our results showed that the S. maritima restored marshes, 2.5 years after planting, were sequestering atmospheric C and, therefore, provide some mitigation for global warming. Stands are also capturing nitrogen and reducing eutrophication. The concentrations of C and N contents in sediments, and cordgrass relative cover of 62 %, and low below-ground biomass (BGB) suggest restored marshes can sequester more C and N. S. maritima plantations in low marshes replace bare sediments and invasive populations of exotic Spartina densiflora and increase the C and N sequestration capacity of the marsh by increasing biomass production and accumulation.     

Disaster threat: Preparedness and potential response of the lowest income quartile

For a community to manage hazards successfully, those who are responsible for planning and implementing responses to a disaster threat situation must understand the social and economic realities of populations at risk. A random sample survey of residents in the vicinity of a US Army chemical weapons storage depot in Alabama confirms that those in the lowest quartile of household income (i.e., less than US $25,000 in 1999) differ in important ways from the rest of the sample. Using economic status as a grouping variable resultedin identifying a concentration of individuals with special needs. This group differed significantly from the remainder of the sample as to demographic and attitudinal characteristics, hazard knowledge and concerns, emergency preparedness, and emergency decision-making and their likelihood of taking protective actions. Respondents in the lowest income quartile reported greater restrictions in physical abilities, fewer community contacts, a heightened concern about area hazards, and limited resources for taking preparedness and response actions.     

Correlates of group size in a cooperatively breeding cichlid fish (Neolamprologus pulcher)

Neolamprologus pulcher, a cooperatively breeding cichlid fish from Lake Tanganyika, lives in permanent social groups comprising one breeding pair and helpers of both sexes. Variation in group size (1-14 helpers) provides an opportunity to investigate factors that affect how many helpers remain in a group and in turn how group size affects reproductive success. This field study showed that larger groups live in larger territories with more shelter. Group size was more strongly correlated with territory quality than with breeder size. Experimental enhancement of territory quality did not affect group size but group size decreased when territory quality was reduced. Breeders living in a large group benefit because such individuals feed more often and have lower workloads and greater reproductive success. Helpers in larger groups also fed more frequently but did not have lower workloads. This is one of the first experimental studies to examine the factors influencing group size in cooperative breeders.     

Assessing inundation damage and timing of adaptation: sea level rise and the complexities of land use in coastal communities

Climate change exacerbates the public policy challenges already present in managing contested landscapes. Coastal managers deal with multiple stressors and multiple stakeholders and have a difficult challenge in managing competing land use as sea level rise (SLR) reduces the amount of prized coastal land. The information needed to inform on the type and timing of adaptation strategies reflects a major gap in the planning and implementation of adaptation options. We present here an inundation risk assessment framework (IRAF) for estimating the impacts of increasing SLR inundation extent probabilities and the cost of inundation damage through time for public and private infrastructure assets. The framework integrates the cost of damage across asset classes in order to help decision-makers judge the economic utility of various adaptation options and the timing of implementation. We provide an example of this methodology using a case study from Southeast Australia in a low lying estuarine region with an increasingly urbanized population. The methodology shows a clear pathway in which to integrate multiple asset classes into a temporally based damage cost analysis. Such methodology will help address the timing of adaptation and allow for the development of trigger points to guide adaptation planning. Thus, the framework developed in this paper can be easily transferred to other regions and countries facing the same types of SLR risks. As SLR and inundation encroachment continue to occur, decisions regarding protection, repair, and retreat will be made depending on the resources available to local governments. The challenge is to balance decision making with both the timing of implementation as well as costs (both of action and inaction). By understanding the areas of land lost to inundation and the cost of inaction through time, local governments can assess the rationality of adaptation at points in the present and future.     

Strategic adaptation of nitrogen management for El Niño Southern Oscillation-induced winter wheat system

The rainfall anomaly (RA) associated with El Niño-Southern Oscillation (ENSO) has various unwanted impacts on agricultural system globally. The loss of inorganic nitrogen (N) depending on extreme wet or dry conditions is a major concern. The main objective of this study was to adapt site-specific N strategies to mitigate the effects of ENSO on yields of winter wheat (Triticum aestivum L.; WW) system. After thorough calibration and evaluation, Decision Support Systems for Agrotechnology Transfer (DSSAT, version 4.5) model suite was adapted. Seasonal analysis was used to compare the variability in simulated leached-N, N uptake, and WW yields under long-term historical real-weather conditions. The site X climate interactions and impacts of weather factors on WW yields were assessed across 60 growing seasons in three phases of ENSO: El Niño (EN), La Niña (LN), and neutral (NT). Based on RA, the simulated yields were lower during LN than EN (11 %) and NT (12 %) on coastal sandy-loam soils and higher during LN than EN (13 %) and NT (8 %) on heavy silt loam soils at valley. N strategy with basal of 22 kg N ha^?1?+?a split of 112 kg N ha^?1 at Feekes (F) 4 stage of WW was adapted for maximum yield and minimum N leaching during LN at valley and NT at coastal sites. However, basal of 22 kg N ha^?1?+?two equal splits of 56 kg N ha^?1 at both F4 and F6 was found as the most adaptable N strategy during both EN and NT phases at valley and EN and LN at coastal sites.     

A pilot study of pesticides and PCBs in the breast milk of women residing in urban and agricultural communities of California

Currently, there is no nationally representative human milk biomonitoring program in the United States (U.S.) and no studies have reported non-persistent pesticides in the milk of U.S. women. In this pilot study we developed a multiresidue laboratory method to measure non-persistent and persistent pesticides and polychlorinated biphenyl (PCB) congeners in human milk samples from women residing in the agricultural region of Salinas, CA (n = 13) and the urban San Francisco Bay Area, CA (n = 21). Samples were collected from 2002-2007. Median concentrations in pg g(-1) milk among urban and agricultural women, respectively were reported for: chlorpyrifos (24.5 and 28.0), cis-permethrin (81.9 and 103), trans-permethrin (93.1 and 176), hexachlorobenzene (191 and 223), β-hexachlorocyclohexane (220 and 443), o,p'-DDT (36.6 and 62.4), p,p'-DDT,(107 and 102), o,p'-DDE (5.65 and 5.17), p,p'-DDE (3170 and 3490), dacthal (2.79 and 3.43), PCB 118 (92.8 and 17.0), PCB 138 (183 and 38.2), PCB 153 (242 and 43.6) and PCB 180 (239 and 683). Among urban women, median concentrations were 4.02 and 4.32 pg g(-1) milk for chlorpyrifos-methyl and propoxur, respectively. These results suggest that neonates and young children may be exposed to persistent and non-persistent pesticides and PCBs via breast milk.     

Evidence for ecological matching of whole AM fungal communities to the local plant-soil environment

The range of ecological roles exhibited by arbuscular mycorrhizal (AM) fungi depends on functional differences among naturally occurring local assemblages of AM species. While functional differences have been demonstrated among AM fungal species and among geographic isolates of the same species, almost nothing is known about functional differences among whole communities of naturally occurring AM fungi. In the greenhouse, we reciprocally transplanted whole AM fungal communities between plant-soil systems representing a serpentine grassland and a tallgrass prairie, using as hosts two grasses common to both systems. For Sorghastrum nutans, native fungi consistently enhanced plant growth more than fungi switched from the alternate system. For Schizachyrium scoparium, foreign and native fungi promoted plant growth similarly in both the serpentine and prairie systems. Thus, the use of foreign inoculum in restoration could change the relative performance, and potentially the competitive abilities, of co-occurring plant species. Moving AM fungal inocula into foreign environments also caused changes in the taxonomic composition of the resultant spore communities, demonstrating their response to environmental influences. These results provide strong evidence for functional differences among naturally occurring AM communities and suggest that a particular AM fungal community may be better matched ecologically to its local habitat than communities taken from other locations.     

Vulnerability of the northern Mongolian steppe to climate change: insights from flower production and phenology

The semiarid, northern Mongolian steppe, which still supports pastoral nomads who have used the steppe for millennia, has experienced an average 1.7 degrees C temperature rise over the past 40 years. Continuing climate change is likely to affect flowering phenology and flower numbers with potentially important consequences for plant community composition, ecosystem services, and herder livelihoods. Over the growing seasons of 2009 and 2010, we examined flowering responses to climate manipulation using open-top passive warming chambers (OTCs) at two locations on a south-facing slope: one on the moister, cooler lower slope and the other on the drier, warmer upper slope, where a watering treatment was added in a factorial design with warming. Canonical analysis of principal coordinates (CAP) revealed that OTCs reduced flower production and delayed peak flowering in graminoids as a whole but only affected forbs on the upper slope, where peak flowering was also delayed. OTCs affected flowering phenology in seven of eight species, which were examined individually, either by altering the time of peak flowering and/or the onset and/or cessation of flowering, as revealed by survival analysis. In 2010, which was the drier year, OTCs reduced flower production in two grasses but increased production in an annual forb found only on the upper slope. The particular effects of OTCs on phenology, and whether they caused an extension or contraction of the flowering season, differed among species, and often depended on year, or slope, or watering treatment; however, a relatively strong pattern emerged for 2010 when four species showed a contraction of the flowering season in OTCs. Watering increased flower production in two species in 2010, but slope location more often affected flowering phenology than did watering. Our results show the importance of taking landscape-scale variation into account in climate change studies and also contrasted with those of several studies set in cold, but wetter systems, where warming often causes greater or accelerated flower production. In cold, water-limited systems like the Mongolian steppe, warming may reduce flower numbers or the length of the flowering season by adding to water stress more than it relieves cold stress.     

Composition of a deep scattering layer overlying a mid-ocean ridge hydrothermal plume

Three sets of zooplankton trawls with multiple nets were deployed in June 1990 within a deep (2000 m) scattering layer overlying the central hydrothermal vent field on the Endeavour segment of Juan de Fuca Ridge in the northeast Pacific. Trawl data were collected concurrently with temperature, salinity, light attenuation and acoustic (150 kHz) backscatter profiles. We describe the composition, size distribution and biomass of zooplankton collected in the net samples, and compare biomass distributions with physical characteristics of the hydrothermal plume. The nine discrete trawl samples (1 mm mesh) contained zooplankton biomass of between 0.3 and 21 mg dry wt m^-3 with the highest biomass samples coincident with large and positive (+20 dB) acoustic backscatter anomalies observed above the top of the hydrothermal plume. Lowest biomass samples were coincident with small, negative (-5 dB) backscatter anomalies within the core of the plume. Results suggest that the region within a hundred meters of the top of the plume was a zone of enhanced zooplankton concentration associated with nutrition enrichment related to the plume. In contrast, the plume core was a zone of faunal depletion, presumably linked to adverse plume chemistry. The species composition and size distribution profiles from net samples revealed that the epi-plume assemblage contained several trophic levels of bathypelagic fauna, but did not contain benthic larvae or vent-related benthopelagic fauna.