Phylogeography of the East Asian polymitarcyid mayfly genus Ephoron (Ephemeroptera: Polymitarcyidae): a comparative analysis of molecular and ecological characteristics

In East Asia, the mayfly genus Ephoron, a member of Polymitarcyidae, has been classified into three species: Ephoron eophilum, Ephoron limnobium, and Ephoron shigae. Using the nuclear histone 3 and internal transcribed spacer 1 and mitochondrial 16S rRNA and cytochrome c oxidase subunit I genes, we investigated the phylogenetic relationships of these mayflies. Ephoron limnobium formed polyphyletic relationships within the clade of Japanese E. shigae and shared identical sequences with E. shigae, suggesting that E. limnobium is a synonym of E. shigae. Monophyly was supported in E. eophilum, Korean E. shigae, and E. limnobium + Japanese E. shigae. Ephoron eophilum that co‐occurs with the other Ephoron species has several peculiar traits in its adult swarming period and karyotype. This suggests that both pre‐ and post‐zygotic isolation are likely to have promoted speciation of these Ephoron species. The divergence between E. eophilum and E. shigae would have occurred from the late Late Miocene to Early Pliocene according to the Bayesian relaxed clock model calibrated using the mitochondrial substitution rate. The area currently inhabited by E. eophilum emerged above sea level some 0.1 Mya, suggesting that E. eophilum moved into this area from other areas that it occupied prior to this time. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 181–202.     

Application of an Ecological Risk Assessment for Evaluation of Alternatives Considered for Restoration of Oysters in Chesapeake Bay: Background and Approach

Oyster populations in Chesapeake Bay, USA, declined precipitously over the past three decades, and on-going efforts to restore the native oysters to former abundance were considered to be ineffective. Maryland and Virginia natural resource agencies proposed the introduction of a non-native Asian oyster (Crassostrea ariakensis) that is resistant to diseases affecting the native oyster and well adapted to the Chesapeake Bay environment. Numerous stakeholders raised concerns about potential adverse consequences of an introduction of a non-native species into a new environment. In response, state and federal agencies determined that an Environmental Impact Statement (EIS) should be prepared to address the environmental consequences of such an introduction as well as of seven other oyster restoration alternatives, including several involving only the native oyster. Preparation of an Ecological Risk Assessment (ERA) of the proposed action as well as all alternatives was an integral element of EIS preparation. This series of articles describes several different analyses that contributed to and collectively comprised the ERA conducted as input to the EIS. The final article of this series in HERA describes how the ERA and EIS findings were taken into account in the final decision on the preferred restoration alternative by state and federal agencies.     

New species and records of Pelycidion P. Fischer in de Folin & Périer, 1873 (Gastropoda: Pelycidiidae) from temperate Australia

Four new species of Pelycidion P. Fischer in de Folin & Périer, 1873 are described from temperate Australia on the basis of shells: Pelycidion eukyrtos n. sp. from central Victoria, P. caperovertex n. sp. and P. kratycylindros n. sp. from southwest Australia and P. meizonarchei n. sp. from southern Tasmania. Two additional congeneric specimens are known from the region and discussed; one of these, from the Tasman Sea, is illustrated and likely represents a new species. Collectively, these specimens are the first members of the genus and family to be recorded from temperate Australia. A brief overview of the described species of Pelycidion is given.     

New records and uncommon occurrences of deep-water fishes in the Turkish Mediterranean Sea (Osteichthyes)

In monthly surveys carried out between September 2009 and July 2011 in Antalya Bay, five species of fish were found which have hitherto been unknown from the Antalya Bay: Notacanthus bonaparte, Diaphus metopoclampus, Gadella maraldi, Benthocometes robustus and Evermannella balbo. For the latter species it is the first record for the Turkish Seas.     

Diet composition of the Thornback Ray,Raja clavata Linnaeus, 1758 (Elasmobranchii: Rajidae) in the Turkish Aegean Sea

The diet of Raja clavata (Thornback Ray) was studied in 2008–2009 in S??ac?k Bay in the eastern Mediterranean, based on 187 stomach contents obtained by commercial trawl operations. 40 different prey species were found. Mysidacea, Parapenaeus longirostris and Plesionika sp. were the most abundant prey items. The results indicate that the main prey varies considerably depending on the ecological characteristics of the habitat.     

四十里湾营养状况与浮游植物生态特征

研究了2006-2010年5月、8月和10月四十里湾的营养盐结构、海水营养级、有机污染状况、浮游植物数量及多样性变化特征,并对上述因子进行了相关性分析.结果表明,近5年N/P值先增加后降低,5月和8月海水多为贫营养和磷限制中度营养,而10月多呈磷限制潜在性富营养;除2006年和2007年10月水质分别达到轻度和中度污染外,其他时期基本未受有机污染,四十里湾有机污染状况有向好趋势.浮游植物多样性指数年际变化显示,总体呈先降低后增加的趋势,与其数量变化趋势相反.相关性分析显示,有机污染指数A与无机磷(IP)浓度呈显著正相关(P＜0.01),与DIN相关不显著(P＞0.05),这说明IP是影响四十里湾有机污染水平的首要因素;浮游植物多样性指数与其数量呈负相关,而与Si/P和IP浓度分别呈正相关(P＞0.05),浮游植物多样性指数与Si/P和IP的Pearson相关系数分别达到0.446和0.413.IP是四十里湾海水营养状况、有机污染及浮游植物多样性的主要影响因子之一.     

海湾生态系统健康评价方法构建及在大亚湾的应用

根据海洋生态系统的压力-结构-响应框架模型,从压力指标、结构指标、响应指标等几个方面构建了海湾生态系统健康评价的指标体系,提出了基于GIS的海湾生态系统健康综合指数法.以春季大亚湾海洋生态系统为例进行实证研究.结果表明:大亚湾海湾生态系统春季的健康综合指数平均值为0.57±0.08,从总体看来,生态系统健康状态处于“较好”水平,浮游植物丰度、浮游植物多样性和生态缓冲容量是其主要健康负面因子,健康状况可能面临着向“临界”状态转化的危险.实证研究表明该方法适用性强、结果客观准确、形象生动,是一种值得推广的定量评价方法.     

辽东湾北部近海沙蜇的动态分布

通过分析2008-2011年5月下旬至7月下旬辽东湾北部近海的大型水母锚流网监测数据并结合8月份的渔业资源拖网调查和渔港访问的数据,探讨辽东湾北部近海沙蜇的动态分布移动规律并着重分析了沙蜇幼水母的生态类型,为渔业资源生产和灾害性预警预报提供科学依据.结果显示:6月份,辽东湾北部近海发现大量沙蜇幼水母,并且在双台子河河口近海5 m等深线两侧水域形成密集区,6月上中旬沙蜇海区平均渔获密度52.8条·网-1·h-1,6月下旬海区平均渔获密度46条·网-1·h-1,最高渔获密度可达667条·网-1·h-1,出现在双台子河口5 m等深线内;7月份,沙蜇个体增大,逐渐进入成体阶段,调查海区沙蜇渔获数量比6月份大幅度减少,并且渔获密度的中心区向5-10 m等深线内偏深水域移动,7月上旬海区平均渔获密度5.1条·网-1,h-1,7月中下旬海区平均渔获密度1.8条·网-1·h-1;8月中旬辽东湾北部近海5 m等深线内沙蜇数量极少,在10-20 m等深线内海域往往出现成体沙蜇的密集区并形成渔汛.沙蜇幼水母生存的海水表层温度为17.7-27.3 ℃,表层盐度为24.3-31.9;渔获密度300条·网-1·h-1以上的沙蜇幼水母密集分布区海水表层温度为20.4-24.4℃,表层盐度为27.1-31.6.辽东湾北部河口区是沙蜇的可能发生地之一,相对于沙蜇成体阶段表现出来的低温高盐的生态属性而言,河口近海相对高温低盐水域往往出现沙蜇幼水母渔获的中心,沙蜇幼水母阶段表现出相对高温低盐的生态特性.沙蜇自幼水母至成体阶段,海区分布密集区自浅水位移至深水.     

胶州湾近岸浅水区鱼类群落结构及多样性

根据2009年3月-2010年2月在胶州湾西北部近岸浅水区进行的鱼类逐月定置网调查数据,采用生态多样性指数和多元统计分析等方法研究了该海域的鱼类群落结构及多样性特征.结果表明:调查共鉴定出44种鱼类,其中海洋性27种,河口性鱼类17种.鱼类种类组成与底层水温和盐度有密切关系.胶州湾近岸浅水区鱼类群落Margalef种类丰富度指数(R)变化范围为0.33-3.50,Shannon-Wiener多样性指数(H’)为0.42-2.25,Pielou均匀度指数(J’)为0.23-0.93.聚类分析(CLUSTER)和多维标度排序(MDS)分析表明,不同鱼类种类组成的各月份样品可划分为3个组分:水温较低的冬季组G1(12月-翌年4月)、水温次高的春秋季组G2(5-6月、10-11月)和水温最高的夏季组G3(7-9月).其中G1的典型种主要为尖海龙(Syngnathus acus)、方氏云鳚(Enedrias fangi)和玉筋鱼(Ammodytes personatus)等冷温性常栖类群种类,G2的主要典型种为鳀鱼(Engraulis japonicus)和尖海龙,G3的主要典型种为鲐鱼(Scomber japonicus)、细条天竺鱼(Apogonichthys lineatus)和普氏缰虾虎鱼(Amoya pflaumi)等洄游性鱼类.单因子相似性分析(ANOSIM)表明,3个月份组间鱼类群落结构差异显著,不同月份组间两两差异均显著.生物-环境分析(BIOENV)表明,底层水温是影响胶州湾近岸浅水区鱼类群落结构时间变化的主要环境因子.在胶州湾内近岸浅水区发现40余种幼鱼,但占优势的主要为低值鱼类,表明胶州湾的产卵、肥育场功能有所下降,应加强胶州湾近岸水域生态环境和渔业资源的保护及修复.     

流沙湾食物网结构的初探——基于稳定同位素方法的分析结果

海洋食物网的传统研究方法是胃含物分析法,即通过胃肠道的解剖,直接分析残留物的组成来计算生物体的营养层次。它反映的是捕食者的瞬时摄食情况,不能提供动物长期的摄食信息以及食性变化情况,存在很大的局限性[1]。