Assessment of monitoring power for highly mobile vertebrates

Monitoring of population trends is a critical component of conservation management, and development of practical methods remains a priority, particularly for species that challenge more standard approaches. We used field-parameterized simulation models to examine the effects of different errors on monitoring power and compared alternative methods used with two species of threatened pteropodids (flying-foxes), Pteropus conspicillatus and P. poliocephalus, whose mobility violates assumptions of closure on short and long timescales. The influence of three errors on time to 80% statistical power was assessed using a Monte Carlo approach. The errors were: (1) failure to count all animals at a roost, (2) errors associated with enumeration, and (3) variability in the proportion of the population counted due to the movement of individuals between roosts. Even with perfect accuracy and precision for these errors only marginal improvements in power accrued (-1%), with one exception. Improving certainty in the proportion of the population being counted reduced time to detection of a decline by over 6 yr (43%) for fly-out counts and almost 10 yr (71%) for walk-through counts. This error derives from the movement of animals between known and unknown roost sites, violating assumptions of population closure, and because it applies to the entire population, it dominates all other sources of error. Similar errors will accrue in monitoring of a wide variety of highly mobile species and will also result from population redistribution under climate change. The greatest improvements in monitoring performance of highly mobile species accrue through an improved understanding of the proportion of the population being counted, and consequently monitoring of such species must be done at the scale of the species or population range, not at the local level.     

Variability in the chemistry of private drinking water supplies and the impact of domestic treatment systems on water quality

Tap water from 497 properties using private water supplies, in an area of metalliferous and arsenic mineralisation (Cornwall, UK), was measured to assess the extent of compliance with chemical drinking water quality standards, and how this is influenced by householder water treatment decisions. The proportion of analyses exceeding water quality standards were high, with 65 % of tap water samples exceeding one or more chemical standards. The highest exceedances for health-based standards were nitrate (11 %) and arsenic (5 %). Arsenic had a maximum observed concentration of 440 µg/L. Exceedances were also high for pH (47 %), manganese (12 %) and aluminium (7 %), for which standards are set primarily on aesthetic grounds. However, the highest observed concentrations of manganese and aluminium also exceeded relevant health-based guidelines. Significant reductions in concentrations of aluminium, cadmium, copper, lead and/or nickel were found in tap waters where households were successfully treating low-pH groundwaters, and similar adventitious results were found for arsenic and nickel where treatment was installed for iron and/or manganese removal, and successful treatment specifically to decrease tap water arsenic concentrations was observed at two properties where it was installed. However, 31 % of samples where pH treatment was reported had pH < 6.5 (the minimum value in the drinking water regulations), suggesting widespread problems with system maintenance. Other examples of ineffectual treatment are seen in failed responses post-treatment, including for nitrate. This demonstrates that even where the tap waters are considered to be treated, they may still fail one or more drinking water quality standards. We find that the degree of drinking water standard exceedances warrant further work to understand environmental controls and the location of high concentrations. We also found that residents were more willing to accept drinking water with high metal (iron and manganese) concentrations than international guidelines assume. These findings point to the need for regulators to reinforce the guidance on drinking water quality standards to private water supply users, and the benefits to long-term health of complying with these, even in areas where treated mains water is widely available.     

Competitive interactions between co-occurring herbivorous gastropods

The competitive interactions between two species of limpet, Patelloida alticostata (Angas), and Cellana tramoserica (Sowerby) were investigated at two sites; a low-lying intertidal platform and an adjacent subtidal reef located in southeastern Australia, during 1977 and 1982. C. tramoserica was relatively more abundant and larger in shell length than P. alticostata at the intertidal site, but P. alticostata was the more abundant species subtidaily. Fences were used to enclose various combinations of the two species to compare both intra- and inter-specific interactions. By repeating this design at two different, but adjacent sites, it was possible to test the generality of any interactions, and to investigate whether the nature of these could explain the observed differences in the relative abundances between the two sites. Intraspecific increases in density affected C. tramoserica more than P. alticostata at both sites. These effects were manifested both lethally (increased mortality at the intertidal site) and sublethally (as decreased growth and tissue weight at the subtidal site). Interspecific comparisons were asymmetrical, but were similar at both sites: C. tramoserica affected P. alticostata more than P. alticostata affected C. tramoserica. These latter effects were, however, only similar, or minor in comparison with the strong intraspecific effect that C. tramoserica had on itself. This suggests that, as has been found in some previous studies, competitive exclusion of the subordinate species (P. alticostata) is unlikely because of the greater intraspecific effects on the superior competitor (C. tramoserica). Furthermore, because there was little difference in the relative competitive abilities of the two species in the two habitats, competition between the species was probably not responsible for the different relative abundances between the two adjacent areas.     

A 40+ year record of Cd,Hg, Pb,and U deposition in sediments of Patroon Reservoir,Albany County,NY, USA

Sediments of the Patroon Creek watershed (33 km(2)) are known to contain significant concentrations of heavy metals derived from two industrial sites within the watershed. Mercury Refining, Inc (Mereco) has stored and recycled Hg from 1955 to the present day, and National Lead Industries (NLI) manufactured aircraft components containing Cd, Pb, and U from 1958 to 1984. Here we present the first record of heavy metal deposition as preserved in a 3-m long sediment core collected in 1999 from Patroon Reservoir, a small water body (1.3 ha) downstream of the industrial sites. Bulk sediment samples were collected from the core at 0.05-m intervals and analyzed for total Cd, Pb, and U by ICP-MS and total Hg by CVAAS. Total Hg increases from less than 1 mg kg(-1) (dw) below 1.68 m, to a maximum of 6.2 mg kg(-1) at 0.80 m, and then declines to the sediment-water interface. Total Cd, Pb, and U concentrations increase abruptly above 1.68 m to maximum values of 25, 320, and 3600 mg kg(-1) (dw), respectively, and then decline gradually upwards. By correlating metal profiles with industrial history, we conclude that the 1.68 m horizon was deposited no earlier than 1958, the beginning of aircraft component manufacturing at NLI. The average, apparent sedimentation rate within the reservoir has a minimum value of approximately 0.04 m year(-1) for the 41-year period from 1958 to 1999. In the interval 0--1.68 m, average concentrations of Cd, Hg, Pb, and U are 1.69, 1.50, 461, and 13 mg kg(-1), respectively. These levels are comparable with other lake, reservoir and stream sediments that have been moderately to severely impacted by industrial pollution and are above levels expected to be detrimental to aquatic organisms.     

Prenatal Diagnosis of congenital disorder of glycosylation type Ia (CDG-Ia) by cordocentesis and transferrin isoelectric focussing of serum of a 27-week fetus with non-immune hydrops

Blood was obtained by cordocentesis from a fetus with non-immune hydrops demonstrated by ultrasound scanning at 27 weeks' gestation. Abnormalities of serum transferrin isoelectric focussing (IEF) were identified, characteristic of a congenital disorder of glycosylation type I (CDG-Ia). A diagnosis of CDG-Ia was confirmed by enzyme analysis of cultured amniocytes. This is the first report of CDG-Ia diagnosed by serum analysis in a fetus. Previous reports have warned that diagnostic abnormalities do not appear in serum until several weeks after birth. The sensitivity of cordocentesis transferrin IEF is unknown but is less than 100% effective because cases have been diagnosed postnatally after normal prenatal or neonatal studies. Enzyme analysis or mutation analysis is required for diagnosis of congenital disorder of glycosylation (CDGs) regardless of whether a diagnostic transferrin pattern is identified prenatally. The analysis of a small sample of serum, from cordocentesis, performed to check for fetal anemia, simplified the investigation, diagnosis, and genetic counselling of a case of non-immune hydrops detected at 27 weeks' gestation. This might be a useful test for other cases in these circumstances, as fetal blood is usually collected to check for anemia. Copyright © 2006 John Wiley & Sons, Ltd.     

Removal processes for arsenic in constructed wetlands

Arsenic pollution in aquatic environments is a worldwide concern due to its toxicity and chronic effects on human health. This concern has generated increasing interest in the use of different treatment technologies to remove arsenic from contaminated water. Constructed wetlands are a cost-effective natural system successfully used for removing various pollutants, and they have shown capability for removing arsenic. This paper reviews current understanding of the removal processes for arsenic, discusses implications for treatment wetlands, and identifies critical knowledge gaps and areas worthy of future research. The reactivity of arsenic means that different arsenic species may be found in wetlands, influenced by vegetation, supporting medium and microorganisms. Despite the fact that sorption, precipitation and coprecipitation are the principal processes responsible for the removal of arsenic, bacteria can mediate these processes and can play a significant role under favourable environmental conditions. The most important factors affecting the speciation of arsenic are pH, alkalinity, temperature, dissolved oxygen, the presence of other chemical species - iron, sulphur, phosphate -, a source of carbon, and the wetland substrate. Studies of the microbial communities and the speciation of arsenic in the solid phase using advanced techniques could provide further insights on the removal of arsenic. Limited data and understanding of the interaction of the different processes involved in the removal of arsenic explain the rudimentary guidelines available for the design of wetlands systems.     

Social information and community dynamics: nontarget effects from simulating social cues for management

Artificially creating social stimuli may be an effective tool for facilitating settlement by rare and/or declining species into suitable habitat. However, the potential consequences for other community members have not been explored and should be considered when evaluating the overall utility of using such management strategies. I report on nontarget, community-wide effects that occurred when manipulating social cues of two competitors that are species of concern in the western United States, the dominant Least Flycatcher (Empidonax minimus) and the subordinate American Redstart (Setophaga ruticilla). The experiment consisted of surveying birds during a pretreatment year, which allows for the control of baseline communities, and a treatment year, in which treatments were applied just prior to settlement by migratory birds. Treatments included broadcasting songs of flycatchers and redstarts and were compared to controls. While the addition of redstart cues did not significantly influence community structure, the addition of flycatcher cues reduced species richness of migratory birds by approximately 30%. This pattern was driven by an absence of local colonizations of small-bodied migrants to sites with added flycatcher cues, rather than by local extinctions occurring from manipulations. The artificial flycatcher stimuli were more responsible for declines in species richness than were changes in actual flycatcher densities. I conclude by identifying some fundamental issues that managers and conservation practitioners should weigh when considering simulating social cues for species conservation prior to implementation.     

The life history of Rhodophysema georgii in laboratory culture

Rhodophysema georgii Batt., a rare epiphyte on Zostera spp., was collected from lowtide-level lagoons at Bembridge (Isle of Wight), and its life history examined in laboratory culture. The tetraspores, the only method of reproduction known, gave rise to small crusts which again developed tetrasporangial sori on the surface, similar to those of the parental material. It is suggested that this direct type of life history is probably due to the repression of meiosis in the tetrasporangial mother cell.