Deforestation and Avian Extinction on Tropical Landbridge Islands

Abstract: There are few empirical data, particularly collected simultaneously from multiple sites, on extinctions resulting from human‐driven land‐use change. Southeast Asia has the highest deforestation rate in the world, but the resulting losses of biological diversity remain poorly documented. Between November 2006 and March 2008, we conducted bird surveys on six landbridge islands in Malaysia and Indonesia. These islands were surveyed previously for birds in the early 1900s, when they were extensively forested. Our bird inventories of the islands were nearly complete, as indicated by sampling saturation curves and nonparametric true richness estimators. From zero (Pulau Malawali and Pulau Mantanani) to 15 (Pulau Bintan) diurnal resident landbird species were apparently extirpated since the early 1900s. Adding comparable but published extinction data from Singapore to our regression analyses, we found there were proportionally fewer forest bird extinctions in areas with greater remaining forest cover. Nevertheless, the statistical evidence to support this relationship was weak, owing to our unavoidably small sample size. Bird species that are restricted to the Indomalayan region, lay few eggs, are heavier, and occupy a narrower habitat breadth, were most vulnerable to extinction on Pulau Bintan. This was the only island where sufficient data existed to analyze the correlates of extinction. Forest preservation and restoration are needed on these islands to conserve the remaining forest avifauna. Our study of landbridge islands indicates that deforestation may increasingly threaten Southeast Asian biodiversity.     

Significance of Specimen Databases from Taxonomic Revisions for Estimating and Mapping the Global Species Diversity of Invertebrates and Repatriating Reliable Specimen Data

Abstract:  We argue that the millions of specimen-label records published over the past decades in thousands of taxonomic revisions are a cost-effective source of information of critical importance for incorporating invertebrates into biodiversity research and conservation decisions. More specifically, we demonstrate for a specimen database assembled during a revision of the robber-fly genus Euscelidia (Asilidae, Diptera) how nonparametric species richness estimators (Chao1, incidence-based coverage estimator, second-order jackknife) can be used to (1) estimate global species diversity, (2) direct future collecting to areas that are undersampled and/or likely to be rich in new species, and (3) assess whether the plant-based global biodiversity hotspots of Myers et al. (2000) contain a significant proportion of invertebrates. During the revision of Euscelidia , the number of known species more than doubled, but estimation of species richness revealed that the true diversity of the genus was likely twice as high. The same techniques applied to subsamples of the data indicated that much of the unknown diversity will be found in the Oriental region. Assessing the validity of biodiversity hotspots for invertebrates is a formidable challenge because it is difficult to decide whether species are hotspot endemics, and lists of observed species dramatically underestimate true diversity. Lastly, conservation biologists need a specimen database analogous to GenBank for collecting specimen records. Such a database has a three-fold advantage over information obtained from digitized museum collections: (1) it is shown for Euscelidia that a large proportion of unrevised museum specimens are misidentified; (2) only the specimen lists in revisionary studies cover a wide variety of private and public collections; and (3) obtaining specimen records from revisions is cost-effective.     

Prioritising catchment management projects to improve marine water quality

Runoff from human land-uses is one of the most significant threats to some coastal marine environments. Initiatives to reduce that runoff usually set runoff reduction targets but do not give guidance on how to prioritize the different options that exist to achieve them. This paper demonstrates an easy to interpret economic framework to prioritise investment for conservation projects that aim to reduce pollution of marine ecosystems caused by runoff from agricultural land-uses. We demonstrate how to apply this framework using data on project cost, benefit and feasibility with a subset of projects that have been funded to reduce runoff from subcatchments adjacent to the Great Barrier Reef. Our analysis provides a graphical overview of the cost-effectiveness of the investment options, enables transparent planning for different budgets, assesses the existence of trends in the cost-effectiveness of different categories, and can test if the results are robust under uncertainty in one or more of the parameters. The framework provided solutions that were up to 4 times more efficient than when omitting information on cost or benefit. The presented framework can be used as a benchmark for evaluating results from a range of prioritisation processes against the best possible conservation outcomes.     

The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae)

Giant clams, the largest living bivalves, live in close association with coral reefs throughout the Indo-Pacific. These iconic invertebrates perform numerous important ecological roles as well as serve as flagship species—drawing attention to the ongoing destruction of coral reefs and their associated biodiversity. To date, no review of giant clams has focussed on their behaviour, yet this component of their autecology is critical to their life history and hence conservation. Almost 100 articles published between 1865 and 2014 include behavioural observations, and these have been collated and synthesised into five sections: spawning, locomotion, feeding, anti-predation, and stress responses. Even though the exact cues for spawning in the wild have yet to be elucidated, giant clams appear to display diel and lunar periodicities in reproduction, and for some species, peak breeding seasons have been established. Perhaps surprisingly, giant clams have considerable mobility, ranging from swimming and gliding as larvae to crawling in juveniles and adults. Chemotaxis and geotaxis have been established, but giant clams are not phototactic. At least one species exhibits clumping behaviour, which may enhance physical stabilisation, facilitate reproduction, or provide protection from predators. Giant clams undergo several shifts in their mode of acquiring nutrition; starting with a lecithotrophic and planktotrophic diet as larvae, switching to pedal feeding after metamorphosis followed by the transition to a dual mode of filter feeding and phototrophy once symbiosis with zooxanthellae (Symbiodinium spp.) is established. Because of their shell weight and/or byssal attachment, adult giant clams are unable to escape rapidly from threats using locomotion. Instead, they exhibit a suite of visually mediated anti-predation behaviours that include sudden contraction of the mantle, valve adduction, and squirting of water. Knowledge on the behaviour of giant clams will benefit conservation and restocking efforts and help fine-tune mariculture techniques. Understanding the repertoire of giant clam behaviours will also facilitate the prediction of threshold levels for sustainable exploitation as well as recovery rates of depleted clam populations.     

己烯雌酚在斑马鱼胚胎中的生物蓄积及毒性机制研究

采用HPLC和斑马鱼胚胎发育方法,测定了己烯雌酚（DES）在标准模式种斑马鱼胚胎体内的蓄积规律及胚胎毒性效应,并利用定量活性-结构分析（QSAR）和基因芯片技术,探讨了DES对斑马鱼胚胎的致毒机制.结果表明,在0.2 mg/L DES中暴露24、 48和72 h后,胚胎体内的DES含量分别为（25.78±4.95）、（54.88±7.10）和（71.93±10.55）μg/g;不同起始染毒时间（0 hpf和8 hpf）条件下,亚致死最敏感指标均为72 h孵化率抑制,EC₅₀分别为（0.14±0.09）和（0.33±0.14） mg/L,说明胚胎在发育囊胚期（发育8　h）前对DES暴露更为敏感.QSAR研究发现,DES相对其它酚类类雌激素对斑马鱼胚胎具有较高的毒性,这与它具有较高的TE值（51.121 7　eV）相关;基因芯片研究发现,5　μg/L DES暴露21　d后能导致斑马鱼成鱼部分基因表达异常.DES对斑马鱼具有一定的胚胎毒性和遗传毒性,而生化反应是致毒的关键步骤.     

Lichens as Bioindicators of Atmospheric Heavy Metal Pollution in Singapore

Lichens have been used as bioindicators in various atmospheric pollution assessments in several countries. This study presents the first data on levels of heavy metals (As, Cd, Cu, Ni, Pb, and Zn) in lichens at different locations in Singapore, Southeast Asia. Singapore is a fully industrialised island nation, with a prevailing tropical climate and a population of 4 million people within a confined land area of less than 700 km². The ubiquitous lichen species, Dirinaria picta was collected from six sample sites across Singapore and analysed for heavy metals using inductively coupled plasma mass spectrometry (ICPMS). No significant relationship existed between metal levels in lichen and soil, indicating that accumulated metals in lichen are primarily derived from the atmosphere. Peak concentrations of zinc (83.55 μg g⁻¹), copper (45.13 μg g⁻¹) and lead (16.59 μg g⁻¹) in lichens were found at Sembawang, Jurong and the National University of Singapore campus which are locations associated with heavy petroleum and shipping industries, and road traffic respectively. The mean heavy metal levels of lichen samples in Singapore were found to be at the upper range of values reported in the literature for temperate countries.     

Animal abundance estimation in independent observer line transect surveys

The theory of conventional line transect surveys is based on an essential assumption that 100% detection of animals right on the transect lines can be achieved. When this assumption fails, independent observer line transect surveys are used. This paper proposes a general approach, based on a conditional likelihood, which can be carried out either parametrically or nonparametrically, to estimate the abundance of non-clustered biological populations using data collected from independent observer line transect surveys. A nonparametric estimator is specifically proposed which combines the conditional likelihood and the kernel smoothing method. It has the advantage that it allows the data themselves to dictate the form of the detection function, free of any subjective choice. The bias and the variance of the nonparametric estimator are given. Its asymptotic normality is established which enables construction of confidence intervals. A simulation study shows that the proposed estimator has good empirical performance, and the confidence intervals have good coverage accuracy.