Intertidal biogenic reefs built by the polychaete Boccardia proboscidea in sewage‐impacted areas of Argentina,SW Atlantic

The rocky intertidal zone around the city of Mar del Plata (SW Atlantic, 38° S–57° W) is characterized by dense mussel beds of Brachidontes rodriguezii. This intertidal community develops on natural and artificial hard substrates, including abrasion platforms in sewage‐impacted areas. A monitoring program, designed to assess the effect of sewage discharge on intertidal macrobenthic communities, has been conducted since 1997. During the spring season of 2008, a new spionid polychaete (Boccardia proboscidea) was found near the sewage outfall, forming large biogenic reefs. This is the first report of biogenic reefs being built by a non reef‐forming spionid polychaete in areas organically impacted by sewage discharges. The aim of this work was to evaluate the spatial–temporal dynamics (% cover and density of B. proboscidea) of these reefs. These biogenic reefs covered almost the entire impacted site, reaching a density of 650,000 ind·m^?2. This phenomenon is unique in that there is no other record available worldwide of any other biogenic polychaete reefs that could be sewage‐induced. The presence and stability of these biogenic reefs is discussed in relation to increased organic contamination as a structuring factor.     

东海浮游介形类(Ostracods)分布特征

根据1997~2000年东海(23°30'~33°00'N,118°30'~128°00'E)海域四季海洋调查资料,探讨了东海浮游介形类分布特征及与环境的关系.结果表明:东海浮游介形类丰度占浮游动物总丰度的3.47%;春、夏、秋和冬四季平均丰度分别为0.70,1.72,2.57和0.90个/m3;冬春季的短棒真浮萤(Euconchoecia chierchiae),夏季的后圆真浮萤(Euconchoecia maimai)和秋季的齿形海萤(Cypridi-na dentata)分别是各季的主要优势种;夏、秋季介形类总丰度与水文环境因子的线性相关性不显著,春季与表层盐度相关,冬季与表层温度相关.东海北部外海四季均有介形类高丰度区出现,但在东海北部近海长江口及其邻近舟山水域,介形类数量相对较低.在东海南部,冬春季高丰度区位于外海,夏秋季在近海.东海浮游介形类基本上是一大类较为典型的暖水性且具有集群行为的海洋浮游动物.介形类秋季高丰度区和较高丰度区的分布与太平洋褶柔鱼(Todarodes pacificus)、绿鳍马面鲀(Navodon Septentrionalis)、鲐鯵鱼类等渔场的位置基本一致,在渔业上有重要的意义.     

中国远洋作业渔场海表温度异常年际变动分析

基于美国国家海洋大气局(NOAA)气候预测中心月平均SST资料,利用时间序列的统计学特征分析了中国7个主要远洋作业渔场1982~2011年海表温度异常(SSTA)年际变动,用功率谱方法计算时间序列的显著变动周期,并用相关分析探讨了去除趋势项后的SSTA与南方涛动指数(Southern Oscillation Index,SOI)的相关性。结果表明,1982~2011年中国主要远洋作业渔场SSTA为–0.3~0.3℃,波动周期约为3~4 a,平均SSTA总体呈现上升趋势,与SOI存在显著的相关性(r=–0.509),说明渔场的SSTA与ENSO事件有着密切联系;从渔场SSTA升降趋势来看,除了东太平洋和东南太平洋SSTA出现下降趋势,其余渔场的SSTA均有一定程度的上升,其中西北太平洋SSTA上升最为显著;从渔场SSTA的变化周期来看,东太平洋和西南大西洋的SSTA变化周期为3~4 a,东南太平洋为4 a,西太平洋为5 a,其余的短期周期性较不明显,约为10 a;与SOI时间序列进行相关分析得到,东太平洋、中大西洋以及西南大西洋均与SOI存在显著的相关性,相关系数分别为–0.895、0.471和–0.598,其余渔场与SOI无显著相关。通过各渔场间的对比得到以下特征:赤道附近海域东太平洋SSTA变化往往与西太平洋和中大西洋反相,而与印度洋同相;中纬度海域的3个渔场中,南半球中纬度渔场温度变化要比北半球中纬度渔场小;东、西印度洋SSTA存在显著相关性,印度洋内部SSTA正负变化情况基本一致。     

南沙海域虫戎群落特征与季风、管水母关系分析

根据2013年3-4月、6-7月、9月和11-12月4个航次的调查资料;分析南沙海域浮游虫戎亚目的种类组成、优势种、栖息密度和群落结构特征;并探讨季风转换对其影响及其与管水母的关系。研究海域内共鉴定浮游虫戎亚目12科26属63种。生态类群结构属于热带大洋性。优势种较少;共出现7种;其中;孟加拉蛮虫戎（Lestrigonus bengalensis）为唯一的年度优势种;优势地位显著。物种组成存在季节性变化;分为春季、夏季与秋-冬季3个群落。虫戎年均栖息密度为18.30×10-2 ind/m3;高数量区主要分布于近岸水域;数量季节变化不明显;但平面分布季节差异明显。虫戎年均丰富度、多样性、均匀度指数和多样性阈值各是1.23、1.28、0.33、0.48。虫戎物种组成随季风转换左右近岸低盐水影响程度而变化;群落结构、生物多样性和栖息密度平面分布随季风转换所驱动的表层环流结构改变而变化。虫戎群落分布与管水母间的相关性证实研究海域两类群物种间的寄宿关系。这种关系促使孟加拉蛮虫戎在沿岸低盐水影响下更易形成高优势度;而表现出类似近岸海域优势种优势地位显著的特点。     

Contribution of benthic and epiphytic diatoms to clam and oyster production in the Akkeshi-ko estuary

The species composition and dynamics of phytoplankton in the water column and its contribution to clam, Ruditapes philippinarum, and oyster, Crassostrea gigas, production were studied in the Akkeshi-ko estuary, eastern part of Hokkaido, Japan. A total 128 taxa of diatoms were identified, with 103 and 102 species occurring on the surface sediments and in the water column, respectively. Amphora sp., Bacillaria paradoxa var paxilifer, Cocconeis scutellum, Navicula sp., Nitzschia sigma, Paralia sulcata, Rhoicosphenia curvata, Synedra ulna and Thalassiosira sp. were most common and dominant in all stations in both water column and surface sediment. Benthic diatoms were most dominant in both water column and surface sediment. The species composition of epiphytes was, in part, similar to diatom assemblage of the water column and also to that of the surface sediment. The benthic and pelagic ratio in the diatom assemblage of the water column was very high. Benthic diatoms were able to resuspend into water column by turbulence stimulated by wind. Chlorophyll a concentration in the water column increased as wind speed increased. Seventy and 67% of the gut contents oysters consisted of benthic diatoms in 2003 and 2004 and also 78 and 87% of clams in 2003 and 2004, respectively. The availability of benthic and epiphytic diatom assemblages contributes significantly to food resources for clam and oyster mariculture due to resuspension by disturbance in the Akkeshi-ko estuary.     

Scaeurgus unicirrhus (Orbigny, 1840) (Cephalopoda,Octopodidae): first record from the South-East Atlantic

The first recorded specimens of Scaeurgus unicirrhus from the South-East Atlantic are described. Five males and two females were captured on the Valdivia Bank, Walvis Ridge, between 24 and 27°S, 400 miles off the Namibian coast. They are compared with specimens caught from other areas, and historical and geographic surveys of the species are made.     

Surviving off junk: low-energy prey dominates the diet of African penguins Spheniscus demersus at Mercury Island,Namibia, between 1996 and 2009

The diet of African penguins Spheniscus demersus in Namibia consisted mainly of sardine Sardinops sagax in the 1950s. Since the collapse of pelagic fish stocks in the 1970s, birds fed mainly on bearded (pelagic) goby Sufflogobius bibarbatus, a low-energy prey species. We present diet data for African penguins breeding at Mercury Island, the largest colony for this species in Namibia, between 1996 and 2009. Bearded goby was the main prey item throughout the study period, both in terms of frequency of occurrence (67.8%; SD 31.2) and in terms of mass (59.2%; SD 31.5). Diet composition varied throughout the year as well as between years; birds occasionally fed on a variety of fish species other than bearded goby. In Namibia, poor prey abundance is considered as a major factor contributing to the decline of penguin numbers after the collapse of the sardine stocks. However, bearded goby appears to be relatively abundant along Namibia's southern coast and low prey quality rather than low abundance appears to be a key factor influencing population dynamics of African penguins and other marine top predators in southern Namibia.     

St Helena Bay (southern Benguela) then and now: muted climate signals,large human impact

The development of suitable reference states for ecosystem-based management requires documentation of changes in structure and functioning of marine ecosystems, including assessment of the relative importance of bottom-up and top-down processes as drivers of change. We used monitoring data available from St Helena Bay, the most productive bay and an important nursery area situated on the west coast of South Africa, during 1950–2010 to reveal changes in the abiotic and biotic components. St Helena Bay in the 1950s showed similarities to 2000–2010 in terms of wind patterns, hydrology and phytoplankton. Upwelling, oxygen and nutrient concentrations in subthermocline water displayed pronounced decadal-scale variability. Primary production in St Helena Bay is variable, but consistently higher than that on the adjacent Namaqua shelf. Zooplankton size composition and biomass in August have changed markedly since the 1950s. During 2001–2010, mesozooplankton biomass in autumn was considerably lower than in summer, probably due to predation by small pelagic fish. Pelagic fish catch patterns and distributions have altered dramatically. Conservation measures, implemented to reverse past negative human impact, have benefitted marine mammals, the abundance of which has increased in the area, but additional conservation measures are necessary to reverse the decline in African penguins Spheniscus demersus. St Helena Bay shows a muted response to long-term change in the southern Benguela, with marked decadal variability but no clear long-term trend in oceanography and biogeochemistry. Changes in ecosystem boundary conditions and fishing pressure cannot be ignored as important drivers of change in the southern Benguela since the 1950s.