Estimating abundance: a non parametric mark recapture approach for open and closed systems

We present a novel, non-parametric, frequentist approach for capture-recapture data based on a ratio estimator, which offers several advantages. First, as a non-parametric model, it does not require a known underlying distribution for parameters nor the associated assumptions, eliminating the need for post-hoc corrections or additional modeling to account for heterogeneity and other violated assumptions. Second, the model explicitly deals with dependence of trials by considering trials to be dependent; therefore, cluster sampling is handled naturally and additional adjustments are not necessary. Third, it accounts for ordering, utilizing the fact that a system with a small population will have a greater frequency of recaptures “early” in the survey work compared to an identical system with a larger population. We provide mathematical proof that our estimator attains asymptotic minimum variance under open systems. We apply the model to a data set of bottlenose dolphins (Tursiops truncatus) and compare results to those from classic closed models. We show that the model has an impressive rate of convergence and demonstrate that there’s an inverse relationship between population size and the proportion of the population that need to be sampled, while achieving the same degree of accuracy for abundance estimates. The model is flexible and can apply to ecological situations as well as other situations that lend themselves to capture recapture sampling.     

Physiological tolerance predicts species composition at different scales in a barnacle guild

This study examined how the species composition of an intertidal barnacle guild varied according to physical gradients in the environment at small scales governed by microclimates, medium scales of wave exposure and large scales of latitude. Barnacle distributions at small and medium scales were sampled in Ireland between 51°29′ and 52°44′N and 6°50′ and 10°08′W. Sampling on European shores spanned ~18° latitude from 37°05′ to 55°16′N. Barnacle surveys mainly took place in 2003–2004. An index of wave fetch was calculated along the wave exposure gradient using a digital coastline-based model that was supported by a biological exposure scale. A ‘dryness’ index was defined according to mean monthly wind speed, fetch along the average wind direction and mean monthly air or sea surface temperatures for 2 years (January 2001–December 2002) which is the period when the most recent adults in the barnacle community would have settled and grown to adulthood. The proportion of the dry-loving barnacle Chthamalus montagui Southward increased within the barnacle guild at all scales as the habitat became warmer and drier. Barnacle densities were high in all habitats, mean densities ranged from a minimum of 4.16 cm⁻² on moderately exposed shores to a maximum of 6.27 cm⁻² in sunlit or south-facing microclimates. Percentage cover of barnacles across the gradient of latitudes was usually >70%. The results suggest that the distribution and abundance of interacting barnacle species on European coasts is strongly controlled by abiotic factors, most likely temperature and desiccation.     

Population and leaf-level variation of iridoid glycosides in the invasive weed Verbascum thapsus L. (common mullein): implications for herbivory by generalist insects

Plant–insect interactions, which are strongly mediated by chemical defenses, have the potential to shape invasion dynamics. Despite this, few studies have quantified natural variation in key defensive compounds of invasive plant populations, or how those defenses relate to levels of herbivory. Here, we evaluated variation in the iridoid glycosides aucubin and catalpol in rosette plants of naturally occurring, introduced populations of the North American invader, Verbascum thapsus L. (common mullein; Scrophulariaceae). We examined two scales that are likely to structure interactions with insect herbivores—among populations and within plant tissues (i.e., between young and old leaves). We additionally estimated the severity of damage incurred at these scales due to insect chewing herbivores (predominantly grasshoppers and caterpillars), and evaluated the relationship between iridoid glycoside content and leaf damage. We found significant variation in iridoid glycoside concentrations among populations and between young and old leaves, with levels of herbivory strongly tracking leaf-level investment in defense. Specifically, across populations, young leaves were highly defended by iridoids (averaging 6.5× the concentration present in old leaves, and containing higher proportions of the potentially more toxic iridoid, catalpol) and suffered only minimal damage from generalist herbivores. In contrast, old leaves were significantly less defended and accordingly more substantially utilized. These findings reveal that quantitative variation in iridoid glycosides is a key feature explaining patterns of herbivory in an introduced plant. In particular, these data support the hypothesis that defenses limit the ability of generalists to feed on mullein’s well-defended young leaves, resulting in minimal losses of high-quality tissue, and increasing performance of this introduced species.     

Arsenic-induced health crisis in peri-urban Moyna and Ardebok villages, West Bengal, India: an exposure assessment study

Drinking of arsenic (As)-contaminated groundwater has adverse effects on health of millions of people worldwide. This study aimed to determine the degree of severity of As exposure from drinking water in peri-urban Moyna and Ardebok villages, West Bengal, India. Arsenic concentrations in hair, nail and urine samp les of the individuals were determined. Arsenical dermatosis, keratosis and melanosis were investigated through medical evaluation. We have evaluated the association between As exposure from drinking water, and keratosis and melanosis outcomes. The results showed that 82.7?% of the sampled tube wells contain As concentrations above 10?μg/L, while 57.7?% contain As concentrations above 50?μg/L. The hair, nail and urine As concentrations were positively correlated with As concentrations in drinking water. In our study population, we observed a strong association between As concentrations ranging 51-99?μg/L and keratosis and melanosis outcomes, although the probability decreases at higher concentration ranges perhaps due to switching away from the use of As-contaminated tube wells for drinking and cooking purposes. High As concentrations in hair, nail and urine were observed to be associated with the age of the study population. The level of As concentrations in hair, nail and urine samples of the study population indicated the degree of severity of As exposure in the study region.     

Metabolisms of injustice: municipal solid-waste management and environmental equity in Barcelona's Metropolitan Region

Environmental justice studies that focus on the management of municipal solid waste (MSW) typically examine the unequal distribution of associated health and environmental risks in minority social groups and the political processes that generate these inequalities. With the aim to complement current views on the field, in this work, we explore whether there is an issue of environmental justice in municipal systems' grade of self-sufficiency in treating the MSW that they generate and in their effort to close their material cycles. The methodology used is based on the concept of urban metabolism and is applied to 12 coastal municipalities of Barcelona's Metropolitan Region in Spain. The metabolism of the MSW flows of each system is analysed to examine (i) the system's efficiency to close its MSW cycles, corresponding to an indicator of environmental sustainability, and (ii) the MSW export and import flows, as an indicator of social sustainability. The results demonstrate a positive correlation between socioeconomic status and the externalisation of MSW treatment-related hazards. The proposed indicator proves to be an excellent tool for the evaluation of both the environmental and social performance of a system considering MSW management.     

Malthusian overfishing and efforts to overcome it on Kenyan coral reefs

This study examined trends along a gradient of fishing intensity in an artisanal coral reef fishery over a 10-year period along 75 km of Kenya's most populated coastline. As predicted by Malthusian scenarios, catch per unit effort (CPUE), mean trophic level, the functional diversity of fished taxa, and the diversity of gear declined, while total annual catch and catch variability increased along the fishing pressure gradient. The fishery was able to sustain high (approximately 16 Mg x km(-2) x yr(-1)) but variable yields at high fishing pressure due to the dominance of a few productive herbivorous fish species in the catch. The effect of two separate management strategies to overcome this Malthusian pattern was investigated: fisheries area closure and elimination of the dominant and most "competitive" gear. We found that sites within 5 km of the enforced closure showed significantly lower total catch and CPUE, but increased yield stability and trophic level of catch than predicted by regression models normalized for fishing effort. Sites that had excluded illegal beach seine use through active gear management exhibited increased total catch and CPUE. There was a strong interaction between closure and gear management, which indicates that, for closures to be effective at increasing catch, there must be simultaneous efforts at gear management around the periphery of the closures. We propose that Malthusian effects are responsible for the variation in gear and catch and that active management through reduced effort and reductions in the most competitive gear have the greatest potential to increase the functional and trophic diversity and per-person productivity.     

Elevated concentrations of endotoxin in indoor air due to cigarette smoking

Exposure to environmental tobacco smoke (ETS) is an important worldwide public health issue. The present study demonstrates that cigarette smoke can be a major source of endotoxin (lipopolysaccharide, LPS) in indoor environments. Gas-chromatography/mass-spectrometry was used to determine 3-hydroxy fatty acids as markers of endotoxin in air-borne house dust in homes of smokers and non-smokers. Air concentrations of endotoxin were 4-63 times higher in rooms of smoking students than in identical rooms of non-smoking students. The fact that cigarette smoke contains large amounts of endotoxin may partly explain the high prevalence of respiratory disorders among smokers and may also draw attention to a hitherto neglected risk factor of ETS.     

Habitat associations and diet of young-of-the-year Pacific cod (<Emphasis Type="Italic">Gadus macrocephalus</Emphasis>) near Kodiak,Alaska

The influence of environmental variables and habitat on growth and survival of juvenile gadoid species in the Atlantic has been clearly demonstrated; conversely, in the North Pacific little is known about the habitat and ecology of juvenile Pacific cod (Gadus macrocephalus Tilesius). The hypothesis that density of young-of-the-year (YOY) Pacific cod in nearshore habitats is predicted by shallow depth and the presence of eelgrass and macroalgae was tested in a variety of nearshore habitats adjacent to commercial fishing grounds near Kodiak Island, AK. From 10 to 22 August 2002, a beach seine and small-meshed beam trawl were used to capture YOY Pacific cod (n = 254) ranging from 42 to 110 mm fork length. Depth, water temperature, salinity, sediment grain size, and percent cover by emergent structure (i.e. tube-dwelling polychaetes, sea cucumber mounds, macroalgae) were measured prior to fishing. Density of YOY Pacific cod was highest in areas of moderate depth (15–20 m) and positively and linearly related to percent cover by sea cucumber mounds and to salinity. No previous studies have documented fish utilizing sea cucumber mounds as habitat. Furthermore, eelgrass and macroalgae were inconsequential to cod distribution. Diets consisted mainly of small calanoid copepods, mysids, and gammarid amphipods and were significantly related to cod length and depth. This work provides important information on previously undocumented factors that affect distribution and feeding of YOY Pacific cod, which ultimately influence growth and survival in this species.     

Spatial distribution of polybrominated diphenyl ethers and polybrominated biphenyls in lake trout from the Laurentian Great Lakes

Concentrations of two types of brominated flame-retardants (BFRs); polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) were determined in a single age class of lake trout (Salvelinus namaycush) collected from the Laurentian Great Lakes in 1997. Mean concentrations of total PBDE were highest in samples from Lake Ontario at 95+/-22 ng/g wet weight (ww) or 434+/-100 ng/g lipid weight (lw) while the lowest concentrations were observed in Lake Erie lake trout (27+/-8.6 ng/g ww, 117+/-37 ng/g lw). In all samples, the predominant PBDE congeners were 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), and 2,2',4,4', 6-pentabromodiphenyl ether (BDE-100), which are the primary components of the commonly used penta-BDE formulation flame retardant. Lake trout collected from Lake Huron had the highest concentrations of PBBs (3.1+/-1.7 ng/g ww, 15+/-8.5 ng/g lw), while the lowest levels were detected in fish from Lake Superior (0.25+/-0.13 ng/g ww, 1.7+/-0.89 ng/g lw). In all lake trout samples, 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), a major constituent of the flame-retardant FireMaster BP-6, was the predominant PBB congener.