Unravelling the diversity and assemblage of phytoplankton in homestead ponds of central coastal belt,Bangladesh

Homestead ponds may offer an ideal opportunity in contribution to household income, fish consumption through fish culture. Phytoplankton plays a key indicator in pond productivity. However, the phytoplankton communities in the homestead ponds are nearly undetermined in Bangladesh. This study summarizes the phytoplankton diversity, assemblage and ecological parameters of the homestead ponds in central coastal belt, Bangladesh, based on two seasons. The results revealed that significant differences (p < .05) were found in pH, DO, conductivity, TDS, nitrates, phosphates and sulphates except temperature in monsoon, and transparency in both seasons. A total of 34 phytoplankton genera representatives of five major groups were recorded such as Euglenophyceae (41.5%), Chlorophyceae (30.5%), Cyanophyceae (13%), Dinophyceae (10%) and Bacillariophyceae (5%). A significant difference (p < .05) in phytoplankton abundance was found in both seasons with the highest mean of 186.13 ± 129.34 × 10⁴ cells L^?1 in monsoon and the lowest mean of 144.40 ± 107.26 × 10⁴ cells L^?1 during winter. The diversity (H'), evenness (J'), richness (d) and dominance (D) ranged from 1.62 to 2.47, 0.52 to 0.97, 0.37 to 1.15 and 0.10 to 0.28 respectively. Based on SIMPER, the most dominant (>10%) genera for dissimilation within stations and seasons were Euglena spp., Phacus spp., Chlorella spp., Strombomonas spp. and Peridinium spp. ANOSIM results stated that 12 genera of phytoplankton were significant contributors based on average dissimilarity. Pearson's correlation coefficient and canonical correspondence analysis (CCA) revealed that phytoplankton abundance, diversity and community were mainly governed by transparency, dissolved oxygen and nitrates.     

Life-history variation in relation to nest site abundance in males of the freshwater goby Tridentiger brevispinis

Abstract –  Age at maturity in males of the freshwater goby Tridentiger brevispinis , a species with exclusive paternal care, was investigated in two populations in Lake Biwa, Japan, that differed markedly in nest site abundance. At Ohmi-maiko, where nest sites were scarce, most males matured at age 3, and mean body size of males guarding eggs in nests was larger than that of males sampled randomly (including both guarding and nonguarding males) in the population. Conversely, at Minamihama, where nest sites were abundant, many males matured at age 1, and there was no difference in body size between guarding males and males collected randomly. The slope of regression lines between body size of the guarding male and the number of eggs in his nest was greater in Ohmi-maiko than in Minamihama. These results suggest that the shortage of nest sites enhances reproductive success in larger males, probably through male–male competition for nest sites and female mate choice for larger males. I conclude that in nest spawners, the availability of nest sites should strongly affect life-history traits of males through sexual selection.     

Processes of collating a European fisheries database to meet the objectives of the European Union Water Framework Directive

Abstract  FIsh Database of European Streams, a common database for the FAME project, was merged using existing data on electric fishing and environmental data. FIsh Database of European Stream is a relational database with eight tables. Metrics based on classification of fish species into guilds were calculated, and provided in separate tables. FIsh Database of European Stream contained information about 150 freshwater fish species, from 12 countries, 17 ecoregions, 40 main river regions, 2651 rivers and 8228 sites. Examples of data coverage and use are given. Relationships between environmental variables were illustrated using principal component analysis, which resulted in three environmental components – latitude, size and altitude. Environmental component scores were correlated with fish metrics used in the European Fish Index. Results exemplify how fish guilds reflect gradients in environmental variation. Benefits and problems concerning standardisation and data availability at the global level are discussed.     

Decadal trends in abundance,size and condition of Antarctic toothfish in McMurdo Sound,Antarctica, 1972–2011

We report the analyses of a dataset spanning 39 years of near‐annual fishing for Dissostichus mawsoni in McMurdo Sound, Antarctica, 1972–2011. Data on total length, condition and catch per unit effort (CPUE) were derived from the > 5500 fish caught, the large majority of which were measured, tagged and released. Contrary to expectation, the length frequency of the McMurdo Sound catch was dominated by fish in the upper two‐thirds of the overall distribution exhibited in the industrial catch for the Ross Sea shelf. Fish length and condition increased from the early 1970s to the early 1990s and then decreased. Fish length positively correlated with Ross Sea ice extent in early spring, a relationship possibly caused by more ice encouraging larger fish to move farther south over the shelf and into the study area. Fish condition positively correlated with the amount of open water in the Ross Sea during the previous summer (Feb), perhaps reflecting greater availability of prey with the higher productivity that more open water brings. Decreasing fish size corresponds to the onset of the fishery, which targets the large individuals. CPUE was constant through 2001 and then decreased dramatically. We hypothesize that this decrease is related to the industrial fishery, which began in the 1996–97 austral summer, and concentrates effort over the ice‐free Ross Sea continental slope. As a result of limited prey choices and close coupling among mesopredators of the region, Antarctic toothfish included, the fishery appears to be dramatically altering the trophic structure of the Ross Sea.     

果胶酶对铜绿微囊藻蛋白表达的影响

为研究果胶酶对铜绿微囊藻蛋白表达的影响并寻找有价值的蛋白质分子水平上的差异,分别在光照和黑暗条件下采用果胶酶处理铜绿微囊藻,获取藻细胞全蛋白。采用SDS-PAGE电泳分离藻细胞全蛋白,比较光照和黑暗条件下的藻蛋白表达差异。结果显示,一类分子量约42ku的蛋白丰度存在显著差异,光照条件是果胶酶对铜绿微囊藻起抑制作用的一个敏感条件。MALDI串联飞行时间质谱仪分析和SwissPort数据库检索结果表明,该蛋白为功能未知的新蛋白且与真核生物actin蛋白有可信的匹配分值。     

Effects of climate on temporal variation in the abundance and distribution of the demersal fish assemblage in the Tsushima Warm Current region of the Japan Sea

In the present study, we examined the effects of climate on temporal variation in the abundance and geographical distribution of demersal fishes at both interannual and decadal scales in the Tsushima Warm Current region of the Japan Sea using single‐trawler fishery data (1972–2002). This single‐trawler fishery targeted multiple species with different geographical affinities and life history traits. Thus, these data were suitable for examining the biological mechanisms that underlie how species respond to climate variability. Our results indicate that the distributional changes of species in response to decadal climate variability are best explained by asymptotic length, which indicates that warming has greater negative effects on larger fishes in the Japan Sea. However, none of the variables examined (including geographical affinity, asymptotic length and age at maturation) could explain the shift in abundance at interannual or decadal scales. It should be noted that life history traits and geographical affinities only provide partial explanations of the responses of species to environmental variability, thereby suggesting that other factors, such as interactions among species, may be involved in mediating species responses.     

The Role of Mangroves in Retaining Penaeid Prawn Larvae in Klang Strait,Malaysia

The mangrove-fringed Klang Strait, Malaysia, retains approximately 65 billion penaeid prawn larvae annually prior to their settlement in coastal nursery grounds. This phenomenon appears to be due principally to tidal currents and lateral trapping in mangrove-fringed channels, the wind playing an insignificant role.     

阳东县水稻测土配方施肥氮素指标体系初步研究

通过2007―2009年3年来阳东县各地区的水稻"3414"田间肥效试验结果进行统计分析,建立了阳东县水稻土壤有效氮素养分极低、低、中、高四级养分丰缺指标,提出了不同肥力水平下水稻土壤的推荐施氮肥量。结果表明,建立的水稻土壤有效氮丰缺指标的数学模型为y=19.058Ln(x)+23.797,水稻土壤有效氮含量与推荐施氮量的数学模型为y=-0.0064x+3.09。根据模型获得的推荐施氮量仍需在生产中进一步验证。     

勤得利湾浮游植物群落结构特征

2003年5、7、9、11月对勤得利湾浮游植物的种类组成结构特征进行了研究。结果表明:浮游植物共计7门69种,以绿藻、硅藻为主,分别占52.36%和20.11%。近亲鱼腥藻、铜绿微囊藻、普通小球藻、柱形栅列藻、四尾栅列藻、颗粒直链藻、细长锥囊藻、四角十字藻、浮球藻、含糊囊裸藻、针形纤维藻、尺骨针杆藻等为优势种。浮游植物数量为1750.8×104ind./L,以硅藻为主,数量为517.3×104ind./L,占29.55%;生物量为16.082mg/L,硅藻最高,为7.285mg/L。浮游植物季节变化比较明显,数量夏季最高为2801.4×104ind./L,生物量以夏季最高28.235mg/L;水平分布采样点Ⅲ最高,平均为2158.6×104ind./L,采样点Ⅳ生物量最高为12.296mg/L。多样性指数变化是夏季>秋季>冬季>春季。均匀度指数变化是秋季>夏季>冬季>春季。     

Evaluating the relationship between yearling walleye,Sander vitreus,electrofishing catch‐per‐unit‐effort and density in northern Wisconsin lakes

Recruitment declines of walleye, Sander vitreus (Mitchill), observed in some northern Wisconsin lakes have resulted in management actions to evaluate and rehabilitate populations. An effective index for estimating relative abundance of yearling walleye is required. The objectives herein were : (a) to evaluate the relationship between yearling walleye electrofishing CPUE and density in northern Wisconsin lakes; (b) to test for the influence of lake‐specific factors on electrofishing catchability of yearling walleye; and (c) to develop an index whereby electrofishing CPUE can be used to quantify yearling walleye relative abundance. Yearling density was significantly positively related to electrofishing CPUE on a long‐term dataset from Escanaba Lake as well as a dataset including several lakes combined. Electrofishing catchability of yearling walleye was negatively related to lake‐surface area but was not related to other lake‐specific variables. This index can provide an efficient method to continue monitoring natural recruitment and also to evaluate survival of stocked walleye.