Movements of beluga whales (Delphinapterus leucas) in Bristol Bay,Alaska

We describe the annual distribution of beluga whales (Delphinapterus leucas) in Bristol Bay, Alaska, using data from 31 satellite‐linked transmitters during 2002–2011. Bristol Bay has one of the largest and best studied Pacific salmon (Oncorhynchus spp.) fisheries in the world, allowing us to link the seasonal distribution of belugas to that of salmon. During salmon migrations, beluga movements were restricted to river entrances. Belugas generally did not relocate to different river entrances or change bays during peak salmon periods. However, the location of belugas was not related to the number of salmon passing counting towers, suggesting that belugas were either selecting locations that were good for catching salmon or there were simply more salmon than belugas needed to supply their nutritional needs. The distribution of belugas expanded after salmon runs ended, and was greatest in winter when belugas ranged beyond the inner bays, traveling as far west as Cape Constantine. Belugas continued to frequent the inner bays in winter whenever sea ice conditions allowed, e.g., when winds moved sea ice offshore; however, they were never located south of the southern ice edge in open water or outside of Bristol Bay.     

太湖贡湖湾食物网特征研究

应用稳定性同位素技术(13C和15N)研究了太湖贡湖湾食物网特征, 结果显示由于食物来源变化多样性影响, 导致贡湖的食物网结构和营养级关系变化较为复杂, 贡湖主要生物类群13C、15N值表现出较大的种间差异。消费者13C值从摇蚊幼虫的-32.3到锯齿米虾的-22.1, 其值大小与营养级的关系没有规律性。消费者平均15N值从褶纹冠蚌的10.3到位于顶端间下鳙的19.0, 随营养级位置而升高。群落中所有种类的15N、13C值之间没有相关性(r=0.1835, P0.05), 表明该食物网是非线性食物网。研究结果验证了杂食性生物有机体普遍存在于富营养化的贡湖水域生态系统中, 且13C结果表明, 浮游植物、固着藻类以及沉水植物为贡湖食物网中大多数生物有机体的主要碳源。贡湖食物链长度为4.44营养级。     

Distribution of Karlodinium veneficum in the coastal region of Xiangshan Bay in the East China Sea,as detected by a real-time quantitative PCR assay of ribosomal ITS sequence

Athecate dinoflagellate Karlodinium veneficum is a universal toxic species possessing karlotoxins recognized especially as ichthyotoxic as well as cytotoxic and hemolytic. Blooms of K. veneficum, both single-species or accompanied with other species, occurred more frequently worldwide in recent years, including the coastal region of China. Normally, K. veneficum present in relatively low abundance in phytoplankton communities in estuary regions. Being small and difficult to identify with light microscopy, it has been ignored for a long time till its blooming and toxins being confirmed. How it presents in background level and what is its relationship with critical geological and hydrological environment factors are basically not clear. In this study, the paper reports the application of a real-time quantitative PCR (qPCR) method to investigate the abundance and distribution of K. veneficum in the coastal waters of Xiangshan Bay in the East China Sea (ECS), a typical bay area of harmful algae blooms and heavily affected by anthropogenic activities. The real-time qPCR assay came out being an efficient method at detecting even low cell densities of K. veneficum of different genotypes. A total of 38 field samples of surface (0.5 m) and bottom water (9–100 m in depth) were analyzed and 12 samples were found positive for K. veneficum. At least 3 genotypes of K. veneficum present in this region. Temperatures in sites of K. veneficum positive ranged from 21.7 to 23.4 °C, and salinity levels were between 21.1 and 26.3. The K. veneficum distributed quite extensively in the waters of Xiangshan Bay, cell abundance varied from a low of 4 cells/L to a maximum of 170 cells/L. Most of the samples containing K. veneficum were collected from bottom water in different sites. At three of the 19 sampling sites, K. veneficum was detected in both surface and bottom water samples. Especially at sampling site near Beilun port, where the water is typically muddy with low transparency, relative high cell numbers of K. veneficum were found in both surface and bottom waters. Mixotrophy and vertical migration of K. veneficum could be important eco-physiological factors to consider in terms of understanding these distribution characteristics. The ideal conditions for K. veneficum growth and aggregation in this area still needs further study.     

Trends in Dinophysis abundance and diarrhetic shellfish toxin levels in California mussels (Mytilus californianus) from Monterey Bay,California

Diarrhetic shellfish toxins (DSTs) are produced by the marine dinoflagellate, Dinophysis, as well as select species of benthic Prorocentrum. The DSTs can bioaccumulate in shellfish and cause gastrointestinal illness when humans consume high levels of this toxin. Although not routinely monitored throughout the U.S., recent studies in Washington, Texas, and New York suggest DSTs may be widespread throughout U.S. coastal waters. This study describes a four-year time series (2013–2016) of Dinophysis concentration and DST level in California mussels (Mytilus californianus) from Santa Cruz Municipal Wharf (SCMW) in Monterey Bay, California. Results show a maximum Dinophysis concentration of 9404 cells/L during this study and suggest Dinophysis persists as a member of the background phytoplankton community throughout the year. In California mussels, DSTs were found at persistent low levels throughout the course of this study, and exceeded the FDA guidance level of 160 ng/g 19 out of 192 weeks sampled. Concentrations of Dinophysis alone are a positive but weak predictor of DST level in California mussels, and basic environmental variables (temperature, salinity, and nutrients) do not sufficiently explain variation in Dinophysis concentration at SCMW. This study demonstrates that Dinophysis in Monterey Bay are producing DSTs that accumulate in local shellfish throughout the year, occasionally reaching levels of concern.     

Stratigraphic record of U37K in Sanmen Bay: the effect of SST and EI Niño on life activity in macrobenthos communities

Sea surface temperature (SST) from 1916–2003 was estimated by using the index of U₃₇^K of organic compounds in Sanmen Bay (SMB) sediment. It fluctuated between 15.97°C and 18.00°C with an average of 17.03°C. The estimated SST was 3.52°C lower than the annual average temperature measured in the same year but was close to the temperature measured in fall. The research suggested that the climate events (EI Ni?o) on large scale in Sanmen Bay were affected by the climate, similar to that in the East Pacific Ocean (EPC). The change scale was also affected by geographical location and local climate such as monsoon. According to the chronological basis, the events in SMB corresponded to those in EPC, but the scale of variation is not so strong as that in EPC. By comparing the community, biomass, individual density and biodiversity of macrobenthos during EI Ni?o (between 2002 and 2003) and non-EI Ni?o (between 2005 and 2006) periods, it was indicated that certain macrobenthos communities in SMB responded to EI Ni?o events. During the EI Ni?o period, Taiwan warm current (TWC) is much stronger than that in normal years. The diversity of macrobenthos during 2002 and 2003 was relatively low owing to invasion of the warm current that caused salinity change. The macrobenthos and zooplankton in Sanmen Bay responded to EI Ni?o events significantly. The diversity of macrobenthos decreased significantly because TWC invaded into the shallow bay from the floor and thus changed the temperature and salinity in the bay. On the other hand, zooplankton species, biomass and abundance increased in the period of EI Ni?o since the invaded warm current brought abundant species of zooplankton.     

Characteristics of macrofauna and their response to aquiculture in Yueqing Bay, China

Four seasons of investigations on macrofauna in Yueqing Bay, China were carried out from August 2002 to May 2003. One hundred and twenty four species of macrofauna were identified, including 41 species of polychaeta, 37 species of mollusc, 22 species of crustacea, 10 species of echinoderm and 14 others. The average biomass was 41.95 g·m⁻² and the average density was 85 ind·m⁻². The echinoderm contributed the highest proportion (about 60%) to the total biomass, and the mollusc contributed the maximum proportion (about 35%) to the total density. Biomass and density in spring were higher than those in other seasons. This article analyzes the macrofauna distribution, compares the study results with the history data of Yueqing Bay and adjacent bays, and discusses the response of macrofauna community to the aquiculture in Yueqing Bay.     

Monthly change of community structure of zoobenthos in Xiangxi Bay after impoundment of the Three Gorges Teservoir, China

Xiangxi Bay, a typical bay of the Three Gorges Reservoir (TGR) in China, was formed in June 2003 after the impoundment of the TGR. We investigated the community structure of zoobenthos in Xiangxi Bay from August 2003 to August 2004. Benthic abundance and biomass were calculated per unit area of sediment. A total of 26 taxa were identified. They included two families of Lamellibranchia (7.7% of the total taxa number), two families of Oligochaeta (50%), Chironomidae (38.5%), and one other animal (3.8%). The average density and biomass were 276 ind./m² and 0.301 g/m², respectively. Oligochaetes and chironomids constituted the major groups, and Limnodrilus hoffmeisteri, Procladius sp., Branchiura sowerbyi, Tubificidae sp1. and Polypedilum scalaenum group sp. were the common taxa in this reservoir system. Among them, L. hoffmeisteri and Procladius sp. were the dominant species, and contributed 37.0% and 28.3% of the total density, respectively. The standing crop of zoobenthos in Xiangxi Bay was relative low, compared with other similar reservoirs. Our studies demonstrate that the standing crop increased gradually with time. The total density and biomass in August 2004 were 8.8 and 14.3 times those of the initial impoundment, separately. Oligochaetes did not become the sole dominant group, indicating that the sediment loading in Xiangxi Bay may be not serious. __________ Translated from Acta Hydrobiologica Sinica, 2006, 30(1): 64–69 [译自: 水生生物学报]     

The first description of the potentially toxic dinoflagellate, Alexandrium minutum in Hunts Bay, Kingston Harbour, Jamaica

The occurrence and morphology of the potentially toxic dinoflagellate species Alexandrium minutum found for the first time in Jamaica, were examined and described by light and scanning electron microscopy. Classical morphological examinations of whole cells, the thecal plate pattern of intact cells and more importantly the structure of individual thecal plates of squashed cells, were conducted in an attempt to positively identify the species. Characteristics such as a tear-drop shaped apical pore plate with a comma-shaped apical pore and no anterior attachment pore; a narrow sixth precingular plate; a narrow anterior sulcal plate longer than or approximately as long as it is wide; and a posterior sulcal plate wider than long, confirmed the Jamaican species as A. minutum. This dinoflagellate which produces potent neurotoxins responsible for paralytic shellfish poisoning (PSP) in humans in many parts of the World, as well as mass mortality of various marine flora and fauna, was identified in water samples collected during an extensive bloom of the species in the brackish to saline water body of Hunts Bay, an estuarine arm of Kingston Harbour, Jamaica in August 1994. The highest cell concentration was 4.6 × 10⁵ cells l⁻¹, a concentration which far exceeds acceptable concentrations (<10³ cells l⁻¹) of PSP-toxin producing A. minutum in several countries including: Spain and Denmark. No PSP human symptoms were reported during the bloom; however it was accompanied by a large kill of small pelagic fish extending across a third of the bay. Since then, smaller blooms of A. minutum have occurred with the most recent in February and April 2004. Hunts Bay is an important fishing, shrimping and to some extent oyster/mussel collection area and provides an important source of livelihood and food for many fishermen in nearby fishing communities as well as an important source of food for members of other communities. Although there are no known records of human illness due to PSP in Jamaica, the occurrence and blooming in Jamaican waters of this potentially toxic dinoflagellate, is great cause for concern.     

海州湾春季短蛸的栖息分布特征及其与环境因子的关系

近年来,我国近海多种重要渔业资源处于不同程度的衰退状态,而短蛸具有生命周期短、生长迅速的特点,在我国近海经济渔获产量中占重要地位。然而,有关短蛸的栖息分布特征及其与环境因子的关系尚缺乏研究,不利于更好地保护和利用其资源。本研究根据2011年和2013—2017年春季海州湾的渔业资源和环境因子调查数据,采用随机森林模型、人工神经网络模型和广义提升回归模型3种机器学习方法分析了短蛸的栖息分布特征及其与环境因子的关系。结果表明: 随机森林模型的拟合效果和预测能力在3种模型中优势较大,选择该模型进行分析表明,底层水温、水深和底层盐度对短蛸的栖息分布有较大影响。短蛸的相对资源密度随底层水温、水深和底层盐度的增加均呈先上升后下降趋势。根据FVCOM模型模拟的环境数据,应用随机森林模型预测了短蛸在海州湾海域的栖息分布,发现短蛸主要分布在34.5°—35.8° N、119.7°—121° E之间的海域。