Dispersal and recruitment of blue crab larvae in Delaware Bay,U.S.A.

Results of a three-year survey of the occurrence of Callinectes sapidus larvae in the mouth of Delaware Bay indicated that stage I zoea larvae were most abundant insurface water as compared to mid-depths and near bottom. The major peak in abundance of stage I zoea larvae occurred in early August with a secondary peak in early September. Peaks in abundance of megalopae occurred five weeks after the respective peaks in zoeal abundance. Zoea stages II–VIII were not collected in the bay mouth. Results of sampling every 3 h over consecutive tidal cycles showed that stage I zoea larvae were most common in the water column on ebbing tidal currents. Megalopae were most common in the water column on flooding tidal currents, suggesting a tidally related, vertical migration. It was concluded that stage I zoea larvae are flushed from the estuary and undergo development on the continental shelf. Megalopae are then transported back to inshore waters by a combination of winds and currents and invade the estuary by means of migration into the water column on flooding tidal currents and migration to the bottom on ebbing tidal currents.     

基于产卵场环境因子的阿根廷滑柔鱼资源补充量预报模型研究

西南大西洋阿根廷滑柔鱼Illex argentinus是短生命周期种类,其资源量极易受到海洋环境变化的影响。根据2003—2011年我国鱿钓船队在西南大西洋的生产统计数据,以及产卵场海洋表面温度(SST)、海表温度距平值(SSTA),计算分析了阿根廷滑柔鱼在产卵期产卵场各月最适表层水温范围占总面积的比例(用PS表示)以及表征海流强度的SST、SSTA等多种环境变量因子与单位捕捞量渔获量(CPUE)的相关性,建立多种基于主要环境因子的资源补充量预报模型,同时分析比较预报模型的优劣。相关性分析表明:6月份有3片连续区域的SST与CPUE之间存在强相关性,分别为38°~39°S、54°~55°W,40.5°~41.5°S、51°~52°W,39.9°~40.4°S、42.6°~43.1°W。利用6月份此3片连续区域SST与次年CPUE建立的三元线性模型,模型符合统计检验,偏差解释率为82.4%。在此基础上加入7月份PS影响因子建立3种方案下的误差反向传播(EBP)神经网络模型。结果认为,包含了福克兰寒流与巴西暖流表温信息的方案3模型优于其他两种模型,其准确率可以达到90%以上。     

Minimising unsustainable yield: Ten failing European fisheries

Ten European fish stocks recognised by the European Union as “outside safe biological limits” are considered in light of widespread reforms to fisheries legislation in 2013, particularly the legal responsibility to exploit these resources sustainably. Given that some of these stocks are – as of 2013 – fished at over 150% the recommended intensity and many have been outside of these limits for the entirety of their assessment history, the utilisation of traditional fisheries management measures of sustainability are questioned and tougher approaches such as “zero-catch” and long-term, expansive spatial closure scenarios are considered. Finally, the pervasive issue of data-deficiency (the status of 54% of European stocks) is briefly considered, with specific reference to the understudied West of Scotland and North Sea stock of European seabass (Dicentrarchus labrax).     

微信公众号"气象人才"的宣传策略研究

微信用户的迅猛增长催生了基于微信公众号的招聘宣传新模式,阐述了通过微信公众号进行招聘宣传的优势,对相关气象类微信公众号的招聘宣传情况进行分析,并提出"气象人才"微信公众号的招聘宣传工作实施建议。     

Paradigm shifts in community ecology: Open versus closed units,challenges and limits of connectivity studies

Due to the presence of the complex life cycles involving a benthic adult and a pelagic larval phase, the study of benthic community dynamics cannot ignore investigations of the processes occurring in the water column. Current investigations focus mainly on larval dispersal from an evolutionary and a biogeographic perspective, taking into account also population connectivity, conservation planning and coastal management. In the present paper we underline the need to improve knowledge of the main traits of marine invertebrate life cycles, highlighting the limits and challenges of current approaches. Firstly, we summarized the changing approaches within community studies, following the paradigm shifts found in recent marine ecological research, from supply‐side ecology to connectivity, and involving the concepts of open and closed populations. Secondly, we analysed the main larval traits influencing dispersal, paying particular attention to pelagic larval duration in light of the few available data for connectivity studies. The difficulty in estimating many of the main traits of larval ecology make numerical simulation fundamental for a better understanding of the relationship between propagule dispersal and seawater dynamics, both being highly variable. We conclude that some essential biological information is still lacking for the proper integration of the modeling approaches. Thus it is necessary to further investigate the life‐cycle traits and physiological and ecological characteristics of each species, an approach known as autecology or natural history. All too frequently modern ecologists ignore such reductionist approaches, although they are essential for a full understanding of processes, such as connectivity and metapopulation dynamics.     

When plenty is not enough: an assessment of the white stumpnose (Rhabdosargus globiceps) fishery of Saldanha Bay,South Africa

White stumpnose Rhabdosargus globiceps is the main target of the linefishery in Saldanha Bay. Increased fishing pressure over the last three decades, particularly by the recreational sector, has led to concerns regarding sustainability of the local white stumpnose stock. The fishery was exceptionally productive between 2006 and 2008, with an estimated annual catch of 141.2 tonnes (t). Only 3% of boat outings surveyed were commercial boats targeting white stumpnose, yet this sector accounted for 39.3 t (31%) of the average annual catch. The recreational boat sector accounted for most of the catch (70.0 t), and the recreational shore sector the least (31.9 t). Commercial boat catch per unit effort (CPUE; 3.7 fish angler^–1 h^–1) was more than 10 times that of recreational boats (0.3 fish angler^–1 h^–1). White stumpnose catch length-frequency differed significantly (p < 0.01) between the fishing sectors, with the commercial sector retaining larger fish (34.7 cm [SD 5.9]) than the recreational boat (33.9 cm [SD 5.9]) and shore (30.4 cm [SD 5.8]) sectors. A decline in commercial CPUE (2000–2015) of approximately 40% and a concomitant severe decline (>95%) in survey data for juvenile white stumpnose CPUE (2007–2016) indicate that the current rate of exploitation is not sustainable. Recovery of the white stumpnose stock will require a decrease in fishing mortality. Possible management regulations include sector-specific effort limitations, extending the ‘no take’ marine protected area, reducing the recreational-sector bag limit to 5 fish person^–1 day^–1, implementing a commercial-sector bag limit, and increasing the minimum size limit to 30 cm TL.     

Influences of environmental factors on the spawning stock-recruitment relationship of Portunus trituberculatus in the northern East China Sea

Based on the Ricker-type models, the spawning stock-recruitment(S-R) relationship of Portunus trituberculatus was analysed under the impacts of environmental factors(including red tide area(AORT), sea level height(SLH),sea surface salinity(SSS) and typhoon landing times(TYP)) in the northern East China Sea in 2001 and 2014.Besides the traditional Ricker model, two other Ricker-type S-R models were built: Ricker model with ln-linear environmental impact(Ricker-type 2) and Ricker model with ln-quadratic polynomial environmental impact(Ricker-type 3). Results showed that AORT, SLH, SSS and TYP had great influences on the recruitment of P. trituberculatus. When SSS reached 29 and 31, recruitment decreased from 20.7×10~3 million to 8.3×10~3 million individuals. In this case, recruitment declined, whereas AORT and TYP increased. Analysis of the S-R model showed that the Akaike information criterion(AIC) value of the traditional Ricker model was 14.619, which remarkably decreased after addition of the environmental factors. Different numbers of environmental factors were added to the Ricker model, and the best result was obtained when four factors were added to the model together. Moreover, Ricker-type 2 model, with the AIC value of-5.307, was better than Ricker-type 3 model(add above four environmental factors at the same time). The findings indicated that the mechanisms by which various environmental factors affect the S-R relationship are different.     

太湖水华蓝藻底泥中复苏和水柱中生长的比较

为了研究太湖底泥中蓝藻的复苏和水柱中的生长,作者自行设计了原位藻类复苏收集器和生长培养器并安放在太湖梅梁湾监测蓝藻复苏释放和生长.实验在藻类的复苏期(2005年3-6月)进行．结果表明在复苏期太湖蓝藻的复苏呈现波动性增加,4月达到最大量．水柱中蓝藻同步的比生长率和生长量也呈现波动性上升,并在5月初达到最大值．浮游动物的存在并没有对蓝藻的生长造成显著的影响．对底泥蓝藻释放和水柱生长进行比较,底泥释放的蓝藻只占藻类生长量的很小一部分(<2．5％)．所以,水柱中蓝藻的生长对其优势的确立和水华的形成具有重要的作用,今后的研究将主要集中在水柱中蓝藻的动态变化     

贵州红枫湖越冬藻类的空间分布与实验室复苏实验

本文选取贵州省红枫湖这一典型的亚深水型湖泊作为研究对象,在8个代表性湖区开展了为期一年的表层水体藻类浮游植物分布的月定量监测,并在4个采样点采集新鲜沉积物进行了越冬藻类赋存与复苏模拟实验研究.研究表明,红枫湖表层水体藻类种群密度蓝藻绿藻>硅藻>甲藻,蓝藻为优势门类,水体藻类种群密度秋季初期最高,其次是春季初期和夏季,具有明显的季节性演化特征.水体中越冬藻类以蓝藻为主,其次是硅藻和绿藻,水深对水体中藻类的种群密度及组成没有显著影响.沉积物中越冬藻类以硅藻为主,基本不含蓝藻.模拟实验表明,水体中的光照条件对藻类的复苏和生长有重要影响,温度和沉积物中藻类的种群密度与组成同样影响藻类的复苏.     

亚龙湾西岸造礁石珊瑚种类多样性及恢复潜力分析

基于2018年12月在亚龙湾沿岸进行的13个站位的珊瑚礁调查,本文分析了该区域造礁石珊瑚的多样性、分布、覆盖率、死亡率和补充量。结果表明,亚龙湾西岸8个站位共发现造礁石珊瑚12科27属55种和11个未定种,其中蜂巢珊瑚科的种类最多,包括9属25种,其次为鹿角珊瑚科,包括3属17种。亚龙湾西岸各站位造礁石珊瑚种类数为12—33种,平均27种;覆盖率为2.8%—22.9%,平均12.9%;以丛生盔形珊瑚(Galaxea fascicularis)、同双星珊瑚(Diploastrea heliopora)和澄黄滨珊瑚(Poriteslutea)等团块状珊瑚为主要优势种;种类多样性和空间分布异质性都较高。与2010—2011年相比,亚龙湾西岸造礁石珊瑚平均覆盖率显著下降,优势种也有较大的变化,表明该海域的珊瑚礁已大幅衰退,这可能与偏高的悬浮物含量和沉积速率有关。不过,亚龙湾西岸造礁石珊瑚的补充量为1.6ind./m2,与周边海区相比,有相对较高的自然恢复潜力。