The cellular basis of photobehavior in the tufted parenchymella larva of demosponges

The mechanisms by which light elicits a phototactic response in sponge larvae remain poorly understood. Here we investigate histological and behavioral aspects of the photoresponse in parenchymella larvae of three demosponges. Two species are photonegative during their entire larval life, while the other, initially photopositive, becomes photonegative only after swimming in the laboratory for 4 h to 6 h. All larvae are bullet-shaped, with a uniformly ciliated surface, except at their posterior end, which is unciliated but surrounded by a distinctive ring of long cilia, the tuft. The short cilia beat metachronally, generating the thrust to move the larva forward with clockwise rotation. The long cilia of the tuft do not beat metachronally and are apparently more involved in maneuvering than in the generation of thrust. Transmission electron microscopy revealed in one species that the axoneme of the short cilia contains a distinctive "9×3+2" microtubule pattern at its base, but the presence of such an arrangement in cilia of the tuft remains uncorroborated. Nevertheless, the differences in beating characteristics between the monociliated cells of the tuft and those in the rest of the body correspond to other cytological differences. Cilia of the tuft have a type-I basal body, a large basal foot, and a branched rootlet, whereas the remaining cilia have a type-II basal body, a smaller and simpler basal foot, and an unbranched rootlet. Furthermore, the cells forming the tuft have a characteristic distal protrusion filled with pigments and mitochondria. Several of these traits suggest that the monociliated cells of the tuft are involved in the larval photoresponse both as sensors and effectors. Drastic changes in light intensity have no effect on the beating of the short cilia. In contrast, they cause a predictable and instantaneous movement of each cilium in the tuft, triggering expansions and contractions of either a part or the entire tuft, which in turn alters the direction of swimming. Observations on free-swimming larvae suggest that the tuft works as a passive light-sensitive rudder in both photonegative species that contract their posterior cilia under high irradiance and in photopositive species that expand their cilia under high irradiance. However, in photonegative larvae that expand the tuft under high irradiance, an active ciliary coordination by the larva needs to be invoked to explain a deviation of the swimming trajectory.     

Assessing the impact of land-applied biosolids from a thermomechanical (TMP) pulp mill to a suite of terrestrial and aquatic bioassay organisms under laboratory conditions

The potential impact on a variety of bioassay organisms when pulp-mill biosolids from a thermomechanical pulp mill (western Canada) were applied to a reference soil has been investigated in a laboratory setup. The current research assessed acute, chronic, and reproductive impacts using a battery of terrestrial and aquatic organisms. Terrestrial organisms were exposed to soil amended with different concentrations of biosolids, while aquatic organisms were used to assess the impact of biosolids' runoff into receiving waters. The former bioassays showed that an application rate of 20 tonneshectare(-1) (tha(-1)) "bone-dry" biosolids applied to reference soil produced no observable adverse impact on the terrestrial organisms. In the latter assays, undiluted (100%) and 50% diluted biosolids' runoff into receiving water had a detrimental impact on the aquatic organisms. However, concentrations not exceeding 25% (environmentally relevant concentrations) had neither an acute nor chronic impact compared to reference populations. The organisms' abilities to reproduce were also unaltered. While this study only examined the biosolids from one mill, there is the potential that land-application of characteristically well-defined pulp mill biosolids may constitute an acceptable way of disposing of pulp and paper mill biosolid residues. However, the biosolids coming from different mills, with differing processes, must be dealt with on a case-by-case situation. Each series of biosolids must be rigorously tested for toxicological impact in the laboratory under tightly controlled conditions. Subsequently, field experimentation must be conducted before definitive conclusions can be made.     

Extinction Debts and Risks Faced by Abundant Species

A recent model indicating that good competitiors and abundant species face the greatest risk of extinction from habitat destruction is critically examined. The conclusions drawn from the model are shown to rely on a number of assumptions regarding the mechanism of species coexistence, the relationship between abundance and competitive ability, and spatial characteristics of habitat destruction. The generality of these assumptions is questioned. Of particular concern are the assumptions that good competitors are poor dispersers, and that good competitors are the most abundant species. Furthermore, we suggest that the spatial scale of metapopulation dynamics in the model may not be appropriate for representing impacts of habitat destrustion. Empirical evidence is discussed indicating the limited applicability of the model for describing effects of habitat destruction on risks of species extinctions. Examples from a number of fragmented systems demonstrate that poor competitors and rare species are vulnerable to habitat destruction.     

Exploring the current status of water governance and outcomes of community-based monitoring across the Oak Ridges Moraine,Southern Ontario,Canada

ABSTRACT

Community-based monitoring (CBM) activities are becoming increasingly prevalent in response to multiple factors, including reduced governmental capacity and increased public interest in environmental management. This research aims to explore how CBM has evolved in the Oak Ridges Moraine (ORM), southern Ontario, including an examination of strengths and challenges. Interviews with CBM stakeholders, provincial government staff, and conservation authority staff were combined with document analysis to explore the evolution and outcomes of ORM CBM activities. Results indicate that there is active CBM on the ORM and conservation authorities play a role in the shaping of CBM activities, although significant barriers remain to civil society participation in water governance. The case study results from the ORM were also considered in light of research emerging from the Nova Scotia experience of numerous civil society organisations involved in CBM.     

新疆雪豹种群密度监测方法探讨

2004-2010年间,前后累计270多天,新疆雪豹研究小组在新疆北塔山、阿尔泰山、昆仑山、天山东部和托木尔峰地区20多个地点(山谷),对雪豹(Uncia uncia)的痕迹进行了全面调查,共计完成150多条样线,总长度接近190 km,痕迹数平均为1～3个·km-1.记录到的痕迹有粪团、嗅痕(气味标记)、足迹链、刨痕(刨坑)、爪痕、卧迹、毛发、尿迹、血迹、剩余食物(动物尸体)和吼声等.通过痕迹学的分析,初步掌握雪豹的领域范围、分布规律和相对密度.之后开展了红外相机拍摄、雪豹食物资源普查、市场毛皮调查、贸易通道调查、杀戮案件搜集、民间问卷调查、非政府组织(NGO)社区服务与牧业冲突调研等工作.同期布设红外相机36台,约2094个照相日,计50 256 h,回收胶卷71个,回收清晰雪豹照片32张,平均拍摄率或"捕获率"(capture rate)达1.53%.确定在托木尔峰250 km2范围内有5～8只雪豹活动,密度为2.0～3.2只·(100 km2)-1.在比较分析各种监测结果的基础上,讨论了新疆雪豹种群密度不同监测方法的优点与局限性.     

Simultaneous-count models to estimate abundance from counts of unmarked individuals with imperfect detection

We developed a method to estimate population abundance from simultaneous counts of unmarked individuals over multiple sites. We considered that at each sampling occasion, individuals in a population could be detected at 1 of the survey sites or remain undetected and used either multinomial or binomial simultaneous-count models to estimate abundance, the latter being equivalent to an N-mixture model with one site. We tested model performance with simulations over a range of detection probabilities, population sizes, growth rates, number of years, sampling occasions, and sites. We then applied our method to 3 critically endangered vulture species in Cambodia to demonstrate the real-world applicability of the model and to provide the first abundance estimates for these species in Cambodia. Our new approach works best when existing methods are expected to perform poorly (i.e., few sites and large variation in abundance among sites) and if individuals may move among sites between sampling occasions. The approach performed better when there were >8 sampling occasions and net probability of detection was high (>0.5). We believe our approach will be useful in particular for simultaneous surveys at aggregation sites, such as roosts. The method complements existing approaches for estimating abundance of unmarked individuals and is the first method designed specifically for simultaneous counts.     

Evaluating ultrasonography as a non-lethal method for the assessment of maturity in oviparous elasmobranchs

Due to the impacts of commercial fishing on elasmobranchs, future research and management necessitates reliable and accurate information on life history. For females, maturity assessment is limited to dissection, and it is not desirable to be removing large numbers in order to assess the reproductive characteristics of a population. The present study evaluated ultrasonography as a potential, non-lethal method for assessing the maturity status of two oviparous elasmobranchs, the thornback ray (Raja clavata) and small-spotted catshark (Scyliorhinus canicula). Ultrasound permitted visualisation and measurement of the ovary in R. clavata, and the shell gland, ovarian follicles and egg capsules within the oviducts for S. canicula. With the exception of the ovary in R. clavata, the dimensions of these structures on the sonograms were directly corroborated by in situ measurements, and ultrasound was verified as an accurate and reliable method of making quantitative and qualitative assessments of these internal reproductive structures.     

Considering extinction of dependent species during translocation, ex situ conservation, and assisted migration of threatened hosts

Translocation, introduction, reintroduction, and assisted migrations are species conservation strategies that are attracting increasing attention, especially in the face of climate change. However, preventing the extinction of the suite of dependent species whose host species are threatened is seldom considered, and the effects on dependent species of moving threatened hosts are unclear. There is no published guidance on how to decide whether to move species, given this uncertainty. We examined the dependent-host system of 4 disparate taxonomic groups: insects on the feather-leaf banksia (Banksia brownii), montane banksia (B. montana), and Stirling Range beard heath (Leucopogon gnaphalioides); parasites of wild cats; mites and ticks on Duvaucel's gecko (Hoplodactylus duvaucelii) and tuatara (Sphenodon punctatus); and internal coccidian parasites of Cirl Bunting (Emberiza cirlus) and Hihi (Notiomystis cincta). We used these case studies to demonstrate a simple process for use in species- and community-level assessments of efforts to conserve dependents with their hosts. The insects dependent on Stirling Range beard heath and parasites on tigers (Panthera tigris) appeared to represent assemblages that would not be conserved by ex situ host conservation. In contrast, for the cases of dependent species we examined involving a single dependent species (internal parasites of birds and the mite Geckobia naultina on Duvaucel's gecko), ex situ conservation of the host species would also conserve the dependent species. However, moving dependent species with their hosts may be insufficient to maintain viable populations of the dependent species, and additional conservation strategies such as supplementing populations may be needed.     

Predicting species distributions from samples collected along roadsides

Predictive models of species distributions are typically developed with data collected along roads. Roadside sampling may provide a biased (nonrandom) sample; however, it is currently unknown whether roadside sampling limits the accuracy of predictions generated by species distribution models. We tested whether roadside sampling affects the accuracy of predictions generated by species distribution models by using a prospective sampling strategy designed specifically to address this issue. We built models from roadside data and validated model predictions at paired locations on unpaved roads and 200 m away from roads (off road), spatially and temporally independent from the data used for model building. We predicted species distributions of 15 bird species on the basis of point-count data from a landbird monitoring program in Montana and Idaho (U.S.A.). We used hierarchical occupancy models to account for imperfect detection. We expected predictions of species distributions derived from roadside-sampling data would be less accurate when validated with data from off-road sampling than when it was validated with data from roadside sampling and that model accuracy would be differentially affected by whether species were generalists, associated with edges, or associated with interior forest. Model performance measures (kappa, area under the curve of a receiver operating characteristic plot, and true skill statistic) did not differ between model predictions of roadside and off-road distributions of species. Furthermore, performance measures did not differ among edge, generalist, and interior species, despite a difference in vegetation structure along roadsides and off road and that 2 of the 15 species were more likely to occur along roadsides. If the range of environmental gradients is surveyed in roadside-sampling efforts, our results suggest that surveys along unpaved roads can be a valuable, unbiased source of information for species distribution models.