Modeling the risk of spread and establishment for Asian longhorned beetle (Anoplophora glabripennis) in Massachusetts from 2008-2009

Land managers responsible for invasive species removal in the USA require tools to prevent the Asian longhorned beetle (Anoplophora glabripennis) (ALB) from decimating the maple-dominant hardwood forests of Massachusetts and New England. Species distribution models (SDMs) and spread models have been applied individually to predict the invasion distribution and rate of spread, but the combination of both models can increase the accuracy of predictions of species spread over time when habitat suitability is heterogeneous across landscapes. First, a SDM was fit to 2008 ALB presence-only locations. Then, a stratified spread model was generated to measure the probability of spread due to natural and human causes. Finally, the SDM and spread models were combined to evaluate the risk of ALB spread in Central Massachusetts in 2008–2009. The SDM predicted many urban locations in Central Massachusetts as having suitable environments for species establishment. The combined model shows the greatest risk of spread and establishment in suitable locations immediately surrounding the epicentre of the ALB outbreak in Northern Worcester with lower risk areas in suitable locations only accessible through long-range dispersal from access to human transportation networks. The risk map achieved an accuracy of 67% using 2009 ALB locations for model validation. This model framework can effectively provide risk managers with valuable information concerning the timing and spatial extent of spread/establishment risk of ALB and potential strategies needed for effective future risk management efforts.     

南沙群岛海域长腹剑水蚤(Oithona spp.)的种类组成、数量分布及其与环境因子的关系

中小型桡足类是海洋食物网中重要的中间环节,在碳循环里细菌碳和藻类碳向高营养级转化的过程中扮演重要角色。本文通过分析2013年3—4月、6—7月、9—10月和11—12月南沙群岛海域(111°30′E—112°30′E,4°30′N—11°30′N)的生态环境调查数据,对长腹剑水蚤属(Oithona)的种类组成、数量分布及其与环境因子的关系进行了研究。结果表明:(1)南沙群岛海域共出现长腹剑水蚤15种(包括1个未定种),其中线长腹水蚤(Oithona linearis)、粗长腹剑水蚤(O.robusta)和长刺长腹剑水蚤(O.longispina)为南沙群岛海域首次记录,长腹剑水蚤属种类组成沿水深变化的现象较为明显,该属虽然在南沙群岛海域广泛分布,但单种的出现频率较低,其种类出现的季节性较强;(2)南沙群岛海域的长腹剑水蚤可以划分为常见广布组群Ⅰ和低频组群Ⅱ;(3)长腹剑水蚤年均栖息密度为30ind./m3,季节变化呈单峰型,秋季最高、冬季最低,高数量区主要出现在受南沙西部沿岸流和东部沿岸流影响的近岸海域;(4)在0—750m水深范围内,长腹剑水蚤数量沿水深梯度的垂直变化明显,呈现由浅至深数量明显减少的趋势,长腹剑水蚤主要集中分布在0—75m的水层中,75—500m数量急剧降低至最低后,在500—750m基本维持不变;(5)GAM分析表明,纬度、海水温度、盐度和叶绿素a浓度对长腹剑水蚤数量均有影响,以纬度的影响最为显著,其中长腹剑水蚤属最适温度为28.6—29.2℃,最适盐度为32.6—33.2,最适叶绿素a浓度为5—10μg/L;(6)长腹剑水蚤属更适栖息于低温和低盐,且受沿岸流影响的环境中。因此,其数量分布的季节变化与季风驱动的沿岸流势力强弱密切相关。     

Sexual reproduction and early life‐history traits of the Mediterranean soft coral Alcyonium acaule

Understanding processes that contribute to a better comprehension of the population dynamics of long‐lived species is critical for the maintenance and potential recovery of such species. Despite the abundance of soft corals in Mediterranean rocky reefs, little information exists on their life histories and reproductive patterns. In this study, we assessed the main reproductive characteristics and early life‐history traits of the long‐lived soft coral Alcyonium acaule. The sex ratio was 1:1; the smallest fertile colonies were one finger in size (2.1 ± 0.6 cm in height), and both colony and polyp fertility increased with colony size. Likewise, the number of eggs and spermary sacs per polyp increased significantly with colony size, whereas the diameter of the female and male sexual products did not. Over 6 years of observations (2007–2012), spawning occurred primarily in July, after the seawater reached 20 °C, in a single spawning episode per year. Approximately 80% of female colonies released eggs, which were retained on the surface of the mother colony by mucous strings for up to a few days. High fertilization rates were observed during spawning in 2008 and 2009 (94.9% and 87.0%, respectively). The timing of development was ~24 h for the blastulae, ~48–72 h for the planulae and 8–22 days for metamorphosis into primary polyps. Survivorship of planulae was relatively high (~50% at 45 days after release), but only 24% of larvae metamorphosed into primary polyps, and their survivorship was moderate after 2 months (65% in 2008 and 74% in 2009). Asexual reproduction was negligible, indicating that sexual reproduction is the main mechanism supporting the maintenance and recovery of populations.     

Differentiation in reproductive traits of geminate mangrove crabs of the genus Aratus (Decapoda: Brachyura) across the Central American Isthmus

The mangrove crab Aratus pisonii was considered to have an amphi‐American distribution; however, a recent study revealed that the Eastern Tropical Pacific populations were genetically distinct, thus representing a new species: Aratus pacificus. These species separated by the Isthmus of Panama have diverged under different environmental conditions that may have influenced their reproductive biology. As the available information about this genus concerns almost exclusively the Caribbean species, the aim of the present study was to analyse and compare reproductive aspects of A. pacificus and A. pisonii obtained from both the Pacific and Caribbean coasts of Costa Rica. Females were collected from April 2011 to April 2012, and reproductive features such as breeding season, size distribution of ovigerous females, fecundity, reproductive output, embryo volume and embryo water content were assessed. Both species produced embryos during the entire sampled period. Most females of A. pacificus carrying embryos close to hatching were found during the rainy season. Ovigerous females of A. pisonii were substantially larger and reached sexual maturity at a larger size than females of A. pacificus. Embryo production started in A. pacificus at a smaller female size than in A. pisonii. As fecundity increased with female size, the average fecundity was lower in A. pacificus. Females of A. pisonii produced larger embryos, which might be related to lower food availability: higher energy content in the embryo enhances the chances of larval survival. These data regarding reproductive features of the Pacific and Caribbean species support the conclusion to separate A. pacificus from A. pisonii.     

Population genetic diversity and structure of a dominant tropical seagrass,Cymodocea rotundata,in the Western Pacific region

Cymodocea rotundata is an ecologically important tropical pioneer seagrass species distributed in the Indo‐Pacific region. The population genetic diversity and structure of this species were analysed at 46 sites spanning the Philippines, Ryukyu Islands (northern limit) and Hainan Island, by using microsatellite simple sequence repeat (SSR) markers. Analyses revealed the persistence of C. rotundata likely relies on local population dynamics and fitness influenced by environmental gradients, with sexual reproduction prevalent in the Philippines while the Ryukyu and Hainan populations were predominantly established by clonal spread. Analysis of molecular variance showed significant genetic differentiation (P < 0.001) among three geographic regions: the Philippines, Ryukyu and Hainan. Furthermore, the mean fixation index value was very high (F_ST = 0.36), indicating poor dispersal potential or limited gene flow. Allelic richness and heterozygosity of C. rotundata was comparable in the Philippines and Ryukyu Islands populations. More private alleles were found in the Philippines and excess heterozygotes in the Ryukyu Islands. STRUCTURE analysis revealed that the Ryukyu and Hainan populations were mosaics of admixed alleles of individuals from the Philippines. An assignment test suggested that recruitment occurs from the Northeast Philippines to Ryukyu Islands. These results suggest that the Philippine populations are tropical seagrass hotspots and perhaps the origin of the populations in the Ryukyu and Hainan Islands. This scenario is most likely driven by the Kuroshio Current and island integration events during plate tectonic activities. The Philippine Archipelago is considered of high importance for conservation objectives and management plan of seagrasses. Likewise, the Ryukyu Islands are also important in terms of conserving regional diversity because locally adapted genotypes have important evolutionary potential in the face of environmental change.     

2014年春季季风间期东印度洋赤道及其邻近海域硅藻群落

2014年4月10日至5月13日在东印度洋赤道区及其邻近海域(10.08°N-6.00°S,80.00°~96.10°E)进行硅藻物种组成和群落结构的调查。分析了45个网采样品,共鉴定出浮游硅藻34属113种(包括变种、变形及未定名种),大部分物种为热带外洋性种以及暖海外洋性种,与该海区的热带及亚热带的环境特征一致。优势种为佛氏梯形藻(Climacodium frauenfeldianum)、地中海细柱藻(Leptocylindrus mediterraneus)、密聚角毛藻(Chaetoceros coarctatus)、美丽漂流藻(Planktoniella foromsa)、大西洋角毛藻那不勒斯变种(Chaetoceros atlanticus var. neapolitanus)、距端假管藻(Pseudosolenia calcar-avis,即距端根管藻Rhizosolenia calcaravis)、圆柱几内亚藻(Guinardia cylindrus)、达蒂角毛藻(Chaetoceros dadayi)、伏氏海线藻(Thalassionema frauenfeldii)、离心列海链藻(Thalassiosira excentrica)、瘤面角毛藻(Chaetoceros bacteriastroides)以及笔尖根管藻粗径变种(Rhizosolenia styliformis var. latissima)等。硅藻的平均细胞丰度为1.855×103个/m3,其平面分布不均匀,赤道断面细胞丰度较低,高值区出现在海区北部。聚类分析发现有7种生态类群,这些硅藻的种类和丰度平面分布与上层水体(200 m以浅)温度、盐度及营养盐的水柱平均值有较好的对应关系。     

Interactions between whale sharks,Rhincodon typus Smith, 1928 (Orectolobiformes,Rhincodontidae), and Brazilian fisheries: The need for effective conservation measures

This study reports three interaction events between the whale shark (Rhincodon typus) and fisheries in Brazilian waters. Two events were described as incidental captures in a gillnet fishery on the northern coast of Rio de Janeiro State, in southeastern Brazil. The last event took place at the Royal Charlotte Oceanic Bank (RCOB), in the southern region of Bahia State, where five fishermen filmed their interaction with a juvenile specimen. For one of the incidental captures, the fish was landed and consumed by locals, and for the other, the shark was released. In the RCOB, the fishermen touched the whale shark with their hands, wooden sticks and even rode on it. In addition, 74 interviews were conducted with fishermen from Bahia about sightings and possible interactions with R. typus. According to statements made by the fishermen, although not frequent, the conduct reported for the RCOB occasionally takes place in the region. Evaluating information of this nature is important to support government plans that regulate fishing activities in order to reduce incidental captures and the harassment of whale sharks. Encouraging the participation of fishermen in a collaborative monitoring program for R. typus may be a good way to better understand the threats to the species at a reduced cost, particularly for developing countries, such as Brazil.     

Seeing the ocean through the eyes of seabirds: A new path for marine conservation?

Seeing the ocean through the eyes of seabirds could help meet the challenges of managing common-pool marine resources both in protected and unprotected areas. First, seabirds are top-predators, exposed to all threats affecting the oceans, and this makes them ideal sentinel organisms for monitoring changes within marine ecosystems. Second, seabirds cross both ecological and political boundaries, and following their movements should help making interdependencies within and between marine ecosystems more visible. Third, seabirds are conspicuous and often charismatic animals, which interact differently with different groups of stakeholders and provide the opportunity to acknowledge and discuss each other's values and interests. In this paper, we present these research avenues using a seabirds’ view, for tackling marine conservation and management issues, and we give operational examples of implementation based on our work in the English Channel.     

夏季辽东湾西部海域大型底栖动物群落结构与多样性

为了解夏季辽东湾西部海域大型底栖动物群落结构与多样性,作者于2009年8月对六股河口外海域15个站位进行了大型底栖动物调查。整个研究海域共采到大型底栖动物124种,其总平均丰度为(2824±1537)个/m2,总平均生物量为(22.01±38.58)g/m2。利用相对重要性指数和优势度指数所确定的前三位优势种一致,分别为二齿半尖额涟虫(Hemileucon bidentatus)、深钩毛虫(Sigambra bassi)和独指虫(Aricidea fragilis),其余优势种存在细微差异。各站位香农-维纳多样性指数、Pielou均匀度指数和Margalef丰富度指数均呈现河口和中部海域低,近岸和外围海域高的分布规律。在50%相似度水平上,可将研究海域划分为4个群落。研究结果表明:研究海域底栖环境整体清洁,底层水环境因子对大型底栖动物群落的影响较弱。     

不同饵料种类、投喂方式及环境条件对凡纳滨对虾相对摄食量的影响

为提高对虾养殖过程中的饵料利用率并减少养殖废水的排放,作者以凡纳滨对虾(Litopenaeus vannamei)为实验对象,研究了不同饵料种类、投喂方式、体质量、充气量、光照强度、水温及盐度对其相对摄食量的影响。结果表明:配合饲料组对虾的相对摄食量显著高于冰鲜虾肉组;连续单颗投喂时对虾的相对摄食量较高;相对摄食量随对对虾体重升高而显著(P0.01)下降,而且不同规格的对虾在竞争条件下平均相对摄食量会降低;充气量6 L/min组对虾的相对摄食量明显高于另外两组;弱光环境下对虾的相对摄食量较高;水温和盐度对相对摄食量的影响极显著(P0.01),在32℃时对虾获得最大相对摄食量,在盐度为5时相对摄食量最小,高盐度下组间差异不显著(P0.05)。因此,在实际生产中应采取少量多次的投饵策略,并根据环境条件的变化合理的调整投饵量。