我国海洋大型底栖生物多样性研究及展望:以黄海为例

本文综述了我国海洋大型底栖生物生态学和生物多样性研究进展,指出在该领域已有的研究中以胶州湾、长江口、福建和浙江沿岸等海域研究较多,其他海域还需要加强.介绍了常规大型底栖生物群落研究(包括种类组成、栖息密度(丰度)、生物量、生物多样性、次级生产力、能量级等)中的研究方法,环境变化、环境污染、海洋工程建设等对大型底栖生物的影响等方面的主要研究成果和进展,并重点以黄海为例,列举了已有的主要调查项目和研究成果.我国已有的研究表明,渤海海域底栖动物区系简单,大型底栖生物共413种,种数在四个海区中最少,优势种主要是低温、广盐暖水种;年总平均生物量为19.83 g/m2,以软体动物占有绝对优势;年总平均栖息密度474个/m2,多毛类和软体动物为主要贡献类群.黄海大型底栖生物共853种,优势种为狭盐性北温带种;北黄海年总平均生物量为99.66 g/m2,以棘皮动物最高;南黄海年总平均生物量为27.69 g/m2,多毛类贡献量最高;北黄海年总平均密度为2,017.40个/m2,而南黄海只有88.67个/m2差异较大;北黄海大型底栖生物的总平均密度和生物量远高于其他海域.南黄海年平均次级生产力为4.98 g(去灰干重)/m2,两个高生产力区位于黄海冷水团两侧.东海共发现大型底栖生物l,300种,主要优势种类有45种,与黄海优势种生物之间有很大差别;东海平均生物量的季节变化不显著,基本趋势为春季＞冬季＞夏季＞秋季;东海各海域的年总平均生物量浙江海域(28.22 g/m2)＞长江口海域(15.55 g/m2)＞台湾海峡(8.98 g/m2);年总平均栖息密度为164个/m2,呈现由北向南逐渐增加的趋势.南海大型底栖生物共发现1,661种,明显高于渤、黄、东海,部分优势种类与东海相同,与黄海、渤海差别较大;年总平均生物量为20.06 g/m2,基本趋势为春季＞冬季＞秋季＞夏季,软体动物和棘皮动物为主要贡献类群;年总平均栖息密度为198个/m2,夏季＞春季＞冬季＞秋季,多毛类生物为主要贡献者.指出随着人类活动和全球气候变化对海洋环境的影响越来越剧烈,对海洋生物资源和生物多样性的保护显得尤为急迫,而对海洋大型底栖生物长期的变化规律、变化机理、未来变化趋势预测的研究,是探究海洋大型底栖生物生态服务功能,提出资源有效保护和合理开发建议,使之永续利用的基础和迫切任务.     

Mass mortality in Pacific oysters is associated with a specific gene expression signature

Mass mortality events occur in natural and cultured communities of bivalve molluscs. The Pacific oyster, Crassostrea gigas, is a dominant species in many intertidal locations as well as an important aquacultured bivalve species, and for the last 50 years, adult oysters have suffered frequent and extreme mass mortality events during summer months. To investigate the molecular changes that precede these mortality events, we employed a novel nonlethal sampling approach to collect haemolymph samples from individual oysters during the period that preceded a mortality event. Microarray-based gene expression screening of the collected haemolymph was used to identify a mortality gene expression signature that distinguished oysters that survived the mortality event from those individuals that died during the event. The signature was cross-validated by comparing two separate episodes of mortality. Here, we report that near-mortality oysters can be distinguished from longer-lived oysters by the elevated expression of genes associated with cell death, lysosomal proteolysis, and cellular assembly and organization. These results show the potential utility of nonlethal sampling approaches for investigating the environmental causes of mortality in natural populations in the field, and for predicting when such events could occur and which individuals will be affected.     

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.     

Biochemical biomarkers in gills of mangrove oyster Crassostrea rhizophorae from three Brazilian estuaries

Responses of biochemical biomarkers were evaluated in gills of immature adult mangrove oyster Crassostrea rhizophorae collected in three estuarine regions along the Brazilian coast. In each region, ten oysters were collected in one reference site (R) located far from pollution sources, and in two polluted sites (P-I and P-II sites) located in another water body with similar characteristics. P-I site is located close to recognized pollution sources while P-II site is in the same water body, but far from pollution sources. At the Paranaguá Bay (Southern Brazil), polluted sites receive domestic, harbor and phosphate fertilizer plant discharges. High lipid peroxides (LPO) content was observed in winter oysters from the P-I site. In summer, higher catalase activity was observed in these oysters. In the Piraquê region (Southeastern Brazil), polluted sites receive domestic and agricultural effluents. Lower total oxyradical scavenging capacity (TOSC) towards peroxyradicals was observed in summer oysters from both P-I and P-II sites. In the Itamaracá region (Northeastern Brazil), polluted sites receive paper mill and caustic soda and chlorine factories effluents. Increased glutathione S-transferase (GST) activity was observed in oysters from the P-I site in both summer and winter. At Paranaguá Bay (higher latitude), no seasonal differences were observed in oysters from the R site, suggesting that temperature was not an important factor influencing biomarkers levels. Lower GST activity was observed in oysters from the R site of the Itamaracá Bay (lower latitude) in winter and summer. Taken together, data obtained point to responses of biomarkers in oysters from polluted sites of the three estuarine regions analyzed, indicating the need for future monitoring of the biological effects of contaminants in these environments. They also point to the relevance to consider both season and latitude as factors influencing biomarker responses in environmental contamination monitoring programs.     

The biodiversity of macrobenthos from Jiaozhou Bay

The current situation of the animal species biodiversity of macrobenthic fauna in the Jiaozhou Bay (South Shandong Peninsula, Yellow Sea) is reported in the present paper, based on the data from 15 investigation cruises carried out from February 1998 to November 2001. In analyzing the data, the Shannon-Wiener index, and species evenness and richness indices were used to study the trends of variation of the community structure, the species assemblages in the macrobenthic community, the dominant species, and the abundance of macrobenthic fauna in Jiaozhou Bay. A total of 322 species of macrobenthic animals were found in the bay, of which 133 species belong to 44 families of Polychaeta, while 92 species belong to 42 families of Crustacea. The average number of species per sample station ranged from 8 to 26. The Shannon-Wiener indices were very different among the samples, with the highest being recorded from Station 8 in November 2001, and the lowest from Station 9 in August 2001. The number of species, the Shannon-Wiener indices, and the species richness indices from Stations 7 and 9 were generally lower than those from other stations. This is because both the stations are situated at areas with a strong current and where the sediment is coarse sand. Although the richness index of species and the Shannon-Wiener index were high in Station 3, the Pielou evenness index was the lowest of all the sampling stations. This is because the station is located near the culture area of Ruditapes philippinarum, where a high abundance of clams caused low evenness. The results also revealed that the number of species and abundance greatly affected the biodiversity, and some environmental factors such as temperature, salinity, and primary productivity were also closely interrelated with biodiversity. Pollution and overexploitation caused by human activities were very important factors affecting macrobenthic biodiversity. In order to find the best way to enhance and protect living marine resources, the relationship between human activities and the biodiversity of macrobenthos in the Jiaozhou Bay should be studied further.     

The biodiversity of macrobenthos from Jiaozhou Bay

The current situation of the animal species biodiversity of macrobenthic fauna in the Jiaozhou Bay (South Shandong Peninsula, Yellow Sea) is reported in the present paper, based on the data from 15 investigation cruises carried out from February 1998 to November 2001. In analyzing the data, the Shannon-Wiener index, and species evenness and richness indices were used to study the trends of variation of the community structure, the species assemblages in the macrobenthic community, the dominant species, and the abundance of macrobenthic fauna in Jiaozhou Bay. A total of 322 species of macrobenthic animals were found in the bay, of which 133 species belong to 44 families of Polychaeta, while 92 species belong to 42 families of Crustacea. The average number of species per sample station ranged from 8 to 26. The Shannon-Wiener indices were very different among the samples, with the highest being recorded from Station 8 in November 2001, and the lowest from Station 9 in August 2001. The number of species, the Shannon-Wiener indices, and the species richness indices from Stations 7 and 9 were generally lower than those from other stations. This is because both the stations are situated at areas with a strong current and where the sediment is coarse sand. Although the richness index of species and the Shannon-Wiener index were high in Station 3, the Pielou evenness index was the lowest of all the sampling stations. This is because the station is located near the culture area of Ruditapes philippinarum, where a high abundance of clams caused low evenness. The results also revealed that the number of species and abundance greatly affected the biodiversity, and some environmental factors such as temperature, salinity, and primary productivity were also closely interrelated with biodiversity. Pollution and overexploitation caused by human activities were very important factors affecting macrobenthic biodiversity. In order to find the best way to enhance and protect living marine resources, the relationship between human activities and the biodiversity of macrobenthos in the Jiaozhou Bay should be studied further.     

Ecological impacts of non-native Pacific oysters (<Emphasis Type="Italic">Crassostrea gigas</Emphasis>) and management measures for protected areas in Europe

Pacific oysters are now one of the most ‘globalised’ marine invertebrates. They dominate bivalve aquaculture production in many regions and wild populations are increasingly becoming established, with potential to displace native species and modify habitats and ecosystems. While some fishing communities may benefit from wild populations, there is now a tension between the continued production of Pacific oysters and risk to biodiversity, which is of particular concern within protected sites. The issue of the Pacific oyster therefore locates at the intersection between two policy areas: one concerning the conservation of protected habitats, the other relating to livelihoods and the socio-economics of coastal aquaculture and fishing communities. To help provide an informed basis for management decisions, we first summarise evidence for ecological impacts of wild Pacific oysters in representative coastal habitats. At local scales, it is clear that establishment of Pacific oysters can significantly alter diversity, community structure and ecosystem processes, with effects varying among habitats and locations and with the density of oysters. Less evidence is available to evaluate regional-scale impacts. A range of management measures have been applied to mitigate negative impacts of wild Pacific oysters and we develop recommendations which are consistent with the scientific evidence and believe compatible with multiple interests. We conclude that all stakeholders must engage in regional decision making to help minimise negative environmental impacts, and promote sustainable industry development.     

Analysis of Stomach and Gut Microbiomes of the Eastern Oyster (Crassostrea virginica) from Coastal Louisiana,USA

We used high throughput pyrosequencing to characterize stomach and gut content microbiomes of Crassostrea virginica, the Easter oyster, obtained from two sites, one in Barataria Bay (Hackberry Bay) and the other in Terrebonne Bay (Lake Caillou), Louisiana, USA. Stomach microbiomes in oysters from Hackberry Bay were overwhelmingly dominated by Mollicutes most closely related to Mycoplasma; a more rich community dominated by Planctomyctes occurred in Lake Caillou oyster stomachs. Gut communities for oysters from both sites differed from stomach communities, and harbored a relatively diverse assemblage of phylotypes. Phylotypes most closely related to Shewanella and a Chloroflexi strain dominated the Lake Caillou and Hackberry Bay gut microbiota, respectively. While many members of the stomach and gut microbiomes appeared to be transients or opportunists, a putative core microbiome was identified based on phylotypes that occurred in all stomach or gut samples only. The putative core stomach microbiome comprised 5 OTUs in 3 phyla, while the putative core gut microbiome contained 44 OTUs in 12 phyla. These results collectively revealed novel microbial communities within the oyster digestive system, the functions of the oyster microbiome are largely unknown. A comparison of microbiomes from Louisiana oysters with bacterial communities reported for other marine invertebrates and fish indicated that molluscan microbiomes were more similar to each other than to microbiomes of polychaetes, decapods and fish.     

Diversity and Distribution of Sediment <Emphasis Type="Italic">NirS</Emphasis>-Encoding Bacterial Assemblages in Response to Environmental Gradients in the Eutrophied Jiaozhou Bay,China

A gene-clone-library-based molecular approach was used to study the nirS-encoding bacteria–environment relationship in the sediments of the eutrophic Jiaozhou Bay. Diverse nirS sequences were recovered and most of them were related to the marine cluster I group, ubiquitous in estuarine, coastal, and marine environments. Some NirS sequences were unique to the Jiaozhou Bay, such as the marine subcluster VIIg sequences. Most of the Jiaozhou Bay NirS sequences had their closest matches originally detected in estuarine and marine sediments, especially from the Chesapeake Bay, indicating similarity of the denitrifying bacterial communities in similar coastal environments in spite of geographical distance. Multivariate statistical analyses indicated that the spatial distribution of the nirS-encoding bacterial assemblages is highly correlated with environmental factors, such as sediment silt content, NH₄ ⁺ concentration, and OrgC/OrgN. The nirS-encoding bacterial assemblages in the most hypernutrified stations could be easily distinguished from that of the least eutrophic station. For the first time, the sedimentological condition was found to influence the structure and distribution of the sediment denitrifying bacterial community. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Heavy metals in benthic organisms from Todos os Santos Bay, Brazil.

The marine ecosystems of Todos os Santos Bay (TSB, The State of Bahia, Brazil) have been impacted by the presence on its coast of a large metropolitan area as well as of chemical and petrochemical activities. Despite its ecological importance, there is a lack of scientific information concerning metal contamination in TSB marine biota. Thus, we analyzed concentrations of metals in four species of marine benthic organisms (two seaweeds, Padina gymnospora and Sargassum sp. one seagrass, Halodule wrightii and one oyster, Crassostrea rhizophorae) in three sites from the TSB region that have been most affected by industrial activities. The concentrations of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined by Atomic Absorption Spectrophometry. The obtained data indicates that cadmium and copper in seaweeds, oysters and seagrass, as well as Ni concentrations in oysters, were in range of contaminated coastal areas. Cadmium and copper are available to organisms through suspended particles, dissolved fraction of water column and bottom sediment interstitial water. As oysters and other mollusks are used as food sources by the local population, the metal levels found in oysters in TSB may constitute a health risk for this population. Our results suggest implanting a heavy metals biomonitoring program in the TSB marine ecosystems.     

Invasion by a Japanese marine microorganism in western North America

The earliest record in western North America of Trochammina hadai Uchio, a benthic foraminifer common in Japanese estuaries, is from sediment collected in Puget Sound in 1971. It was first found in San Francisco Bay in sediment samples taken in 1983, and since 1986 has been collected at 91% of the sampled sites in the Bay, constituting up to 93% of the foraminiferal assemblage at individual sites. The species is also present in recent sediment samples from 12 other sites along the west coast of North America. The evidence indicates that T. hadai is a recent introduction to San Francisco Bay, and is probably also not native to the other North American sites. Trochammina hadai was probably transported from Japan in ships' ballast tanks, in mud associated with anchors, or in sediments associated with oysters imported for mariculture. Its remarkable invasion of San Francisco Bay suggests the potential for massive, rapid invasions by other marine microorganisms.     

小尺度海域空间评价单元划分技术研究——以福建省东山湾为例

科学合理的海域空间评价单元划分是各类海洋空间监测、评价、规划和管理的基础工作,对于保护海洋生态环境,实现海洋资源的可持续开发利用具有重大现实意义。然而,海洋的流动性、开放性、边界模糊性等特征,导致海洋空间评价单元划分较陆地而言更为复杂、困难。以福建省东山湾为例,提出一种适用于小尺度海域的空间评价单元划分技术方案,通过从化学属性、物理属性、生物学属性三个方面构建海域空间生态属性划分指标体系,进行空间分类评价,运用插值、叠加分析等GIS技术将东山湾划分为67个基本空间评价单元。研究结果不仅能为进一步划定东山湾海洋空间规划提供技术支持,同时为其他小尺度海域生态监测、评价、规划和管理提供科学参考。     

Mortality and herpesvirus infections of the Pacific oyster Crassostrea gigas in Tomales Bay, California, USA

Seed losses of Pacific oysters Crassostrea gigas have been associated with an ostreid herpesvirus-1 (OsHV-1) in Europe, and in 2002, a similar OsHV was detected in Tomales Bay, California, USA. In May of 2003, 5 stocks of seed Pacific oysters were planted at 2 sites (Inner Bay and Outer Bay) in Tomales Bay and monitored for mortality, presence/prevalence of OsHV (using polymerase chain reaction [PCR] and histology), and growth. Temperature (degrees C) and salinity data were collected every half an hour at each site. OsHV was detected at both the Inner and Outer Bay sites on the same sample date and mean temperature predicted OsHV presence (p < 0.005). High levels of mortality occurred 2 wk (Inner Bay site) and 4 wk (Outer Bay site) after OsHV detection. OsHV presence predicted mortality (p = 0.01). Temperature maximums and overall temperature exposure were greater at the Inner Bay site and may explain why mortality affected these oysters sooner than oysters planted at the Outer Bay site. Differences in cumulative mortality were significant among stocks (p < 0.0001), but not between sites (p > 0.05). OsHV prevalence was similar among stocks (p > 0.05) and between sites (p > 0.05). No evidence of herpesvirus-induced Cowdry type A nuclear inclusions or other pathogens were observed. Changes in tissue and cellular architecture including dilation of the digestive tubules and nuclear chromatin margination and pycnosis were observed in OsHV-infected oysters, consistent with previously observed OsHV infections. Stocks with smaller oysters had higher mortality rates than those with larger oysters; growth rate did not correlate with mortalities (p > 0.05). Taken together, these data suggest that the OsHV may cause or act in synergy with temperature to kill Pacific oyster seed in Tomales Bay, but further investigation of OsHV etiology in seed oysters is needed.     

胶州湾浮游植物水华期群落结构特征

根据2001年8月对胶州湾海域进行的为期2d的大面积调查资料,对浮游植物的群落结构进行了初步研究,结果表明,浮游植物群落主要由沿岸暖水性种类组成,以硅藻为主,共34种;还有少量的甲藻7种和绿藻1种,湾中央水域出现的物种数最多,为37种;湾边缘最少,仅出现10种,细胞数量的密集区出现在湾东部边缘水域,最高值为6．96×10⁸个cell·m^-3;低值区出现在湾口,最低值仅为3．18×10⁶个cell·m^-3调查期间浮游植物的物种多样性及其均匀度的最低值均出现在湾东部边缘水域;高值区出现在湾口和湾中央水域,胶州湾海域水团运动和水体富营养化程度是影响浮游植物群落分布的主要环境因素。     

A genetic technique to identify the diet of cownose rays,Rhinoptera bonasus: analysis of shellfish prey items from North Carolina and Virginia

Cownose rays are implicated in the consumption of commercially important shellfish on the U.S. East Coast. We tested this assumption by developing a molecular technique for species identification from cownose ray gut contents. Digestive tracts sampled from 33 rays in Pamlico Sound, NC and Chesapeake Bay, VA contained pieces of partially-digested tissue, well-digested tissue, fluid, and minute shell fragments which made visual identification to the species level nearly impossible. We sequenced the cytochrome oxidase subunit I (COI) for seven locally acquired bivalve species, chosen for their commercial and ecological importance in NC and VA. Sequences were used to design species-specific primers for each bivalve species to amplify polymerase chain reaction (PCR) products. We designed primers such that PCR products were sufficiently different in size to be distinguishable from one another when resolved on an agarose gel, and multiplexing of several species in one reaction was possible. Digestive tract sample testing revealed that cownose rays in Chesapeake Bay ate stout tagelus and soft shell clams. There was no evidence of the rays in the study consuming commercially important oysters, hard clams, and bay scallops. Further sampling over an extended period of time and additional locations is required to confirm these results. Our diagnostic tests could easily be expanded to elucidate the impact of cownose ray predation on prey populations.     

Vibrio–bivalve interactions in health and disease

In the marine environment, bivalve mollusks constitute habitats for bacteria of the Vibrionaceae family. Vibrios belong to the microbiota of healthy oysters and mussels, which have the ability to concentrate bacteria in their tissues and body fluids, including the hemolymph. Remarkably, these important aquaculture species respond differently to infectious diseases. While oysters are the subject of recurrent mass mortalities at different life stages, mussels appear rather resistant to infections. Thus, Vibrio species are associated with the main diseases affecting the worldwide oyster production. Here, we review the current knowledge on Vibrio–bivalve interaction in oysters (Crassostrea sp.) and mussels (Mytilus sp.). We discuss the transient versus stable associations of vibrios with their bivalve hosts as well as technical issues limiting the monitoring of these bacteria in bivalve health and disease. Based on the current knowledge of oyster/mussel immunity and their interactions with Vibrio species pathogenic for oyster, we discuss how differences in immune effectors could contribute to the higher resistance of mussels to infections. Finally, we review the multiple strategies evolved by pathogenic vibrios to circumvent the potent immune defences of bivalves and how key virulence mechanisms could have been positively or negatively selected in the marine environment through interactions with predators.     

Coastal acidification impacts on shell mineral structure of bivalve mollusks

Ocean acidification is occurring globally through increasing CO₂ absorption into the oceans creating particular concern for calcifying species. In addition to ocean acidification, near shore marine habitats are exposed to the deleterious effects of runoff from acid sulfate soils which also decreases environmental pH. This coastal acidification is being exacerbated by climate change‐driven sea‐level rise and catchment‐driven flooding. In response to reduction in habitat pH by ocean and coastal acidification, mollusks are predicted to produce thinner shells of lower structural integrity and reduced mechanical properties threatening mollusk aquaculture. Here, we present the first study to examine oyster biomineralization under acid sulfate soil acidification in a region where growth of commercial bivalve species has declined in recent decades. Examination of the crystallography of the shells of the Sydney rock oyster, Saccostrea glomerata, by electron back scatter diffraction analyses revealed that the signal of environmental acidification is evident in the structure of the biomineral. Saccostrea glomerata, shows phenotypic plasticity, as evident in the disruption of crystallographic control over biomineralization in populations living in coastal acidification sites. Our results indicate that reduced sizes of these oysters for commercial sale may be due to the limited capacity of oysters to biomineralize under acidification conditions. As the impact of this catchment source acidification will continue to be exacerbated by climate change with likely effects on coastal aquaculture in many places across the globe, management strategies will be required to maintain the sustainable culture of these key resources.     

Prevalence of Perkinsus marinus (dermo), Haplosporidium nelsoni (MSX), and QPX in bivalves of Delaware's inland bays and quantitative, high-throughput diagnosis of dermo by QPCR

Restoration of oyster reef habitat in the Inland Bays of Delaware was accompanied by an effort to detect and determine relative abundance of the bivalve pathogens Perkinsus marinus, Haplosporidium nelsoni, and QPX. Both the oyster Crassostrea virginica and the clam Mercenaria mercenaria were sampled from the bays. In addition, oysters were deployed at eight sites around the bays as sentinels for the three parasites. Perkinsus marinus prevalence was measured with a real-time, quantitative polymerase chain reaction (PCR) methodology that enabled high-throughput detection of as few as 31 copies of the ribosomal non-transcribed spacer region in 500 ng oyster DNA. The other pathogens were assayed using PCR with species-specific primers. Perkinsus marinus was identified in Indian River Bay at moderate prevalence ( approximately 40%) in both an artificial reef and a wild oyster population whereas sentinel oysters were PCR-negative after 3-months exposure during summer and early fall. Haplosporidium nelsoni was restricted to one oyster deployed in Little Assawoman Bay. QPX and P. marinus were not detected among wild clams. While oysters in these bays have historically been under the greatest threat by MSX, it is apparent that P. marinus currently poses a greater threat to recovery of oyster aquaculture in Delaware's Inland Bays.     

Wave energy alters biodiversity by shaping intraspecific traits of a habitat-forming species

The role of habitat-forming species in promoting biodiversity is widely acknowledged to vary across environmental gradients according to the extent to which they modify resources and environmental conditions. Population- and individual-level traits of habitat-forming species that influence species interactions may vary across gradients, but the importance of this indirect effect of environmental context is seldom considered. Here, we conducted surveys and field experiments to partition the effects of wave exposure on habitat-provisioning for invertebrates by oysters into direct and indirect effects, arising from morphological variation of the oysters. A survey of nine sites with varying degrees of wave exposure in Port Jackson, Australia revealed a decline in oyster densities and surface area as wave energy increased. Correlated to declining oyster surface area was a decrease in the richness and abundance of associated invertebrates. By contrast, taxon diversity increased with increasing wave energy. Experimental deployments of oysters at high and low wave energy sites confirmed that variations in oyster morphology was a phenotypically plastic response to environmental conditions. Oyster recruitment was also lower at high as compared to low wave energy sites, further contributing to the variation in oyster habitat among sites. A colonisation experiment in which exposed and sheltered morphologies of oysters were deployed under high and low wave energy conditions in a fully orthogonal design found that invertebrate communities were influenced by both the wave energy of sites and by habitat structure. Our study suggests that in some instances the indirect effects of environment on habitat availability, arising from changes in habitat-forming species density and morphology, may be as, or even more, important than the direct effects. Understanding how traits of habitat-forming species respond to environmental conditions, and how intraspecific trait-variation cascades to influence associated communities is critical to predicting when and where positive species interactions will be greatest.     

胶州湾潮下带大型底栖动物群落的季节变化

胶州湾位于山东半岛南岸, 是黄海深入内陆的半封闭天然海湾, 底栖动物种类丰富。本文根据2014年2、5、8和11月4个航次(冬、春、夏、秋)的调查资料, 采用优势度指数, 物种多样性指数、丰富度指数、均匀度指数, Bray-Curtis相似性聚类和非参数多维标度排序(NMDS)方法, 分析了胶州湾大型底栖动物群落的季节变化特点。各航次共采集大型底栖动物199种, 其中多毛类79种, 甲壳动物47种, 软体动物40种, 棘皮动物17种, 其他类群16种。各季度优势种有变化亦有重叠, 以多毛类为主。2014年度胶州湾大型底栖动物的年平均丰度为209.85 ind./m², 最高丰度出现在秋季, 最低出现在春季; 年平均生物量为79.22 g/m², 最高生物量出现在夏季, 最低出现在春季。物种多样性指数(H')变化范围为2.16-2.86, 物种丰富度指数(D)变化范围为2.79-3.72, 物种均匀度指数(J)变化范围为0.58-0.82。聚类分析结果显示, 4个航次的群落相似性系数均较低, 分布格局存在季节性变化。近年来, 伴随海岸带开发及人类活动的持续影响, 胶州湾底栖生境的稳定性受到一定的威胁, 建议继续开展长期连续的监测, 探索有效的综合治理措施, 使胶州湾海洋生态系统能够持续健康的发展。