Population biology of bryozoans: correlates of sessile,colonial life histories in freshwater habitats

Bryozoans are common, often abundant, sessile, colonial invertebrates of freshwaters. By reviewing what is known of their general ecology and considering in further detail the population biology of specific groups, we provide evidence that 1) populations are locally ephemeral and regional persistence is attained via a dynamic equilibrium between dispersal and colonization, and 2) sex may often be infrequent and a high degree of clonality obtains at both local and regional scales. On the basis of these characteristics we discuss how the group offers exceptional opportunities for investigating a number of fundamentally important ecological and evolutionary questions.The highly curious modification of the Molluscan type which the Polyzoa [=Bryozoa] present... the great beauty of their forms, and the facility with which they can in general be observed in a living state, cannot but render them special favorites for every lover of Nature; and for the more profound student must confer on them a peculiar significance, and invest their study with a scientific interest which is scarcely surpassed by that of any other group of animals.... (Allman 1856)     

东海北部拖虾渔业的现状与设立拖虾休渔期的建议

本文根据近１０年来拖虾调查和虾类资源动态监测资料，分析了拖虾渔业发展的现状和存在问题，并根据虾类资源种类多，分布区域性明显，主要种类的渔场渔期不同，繁殖期、幼虾的时空分布不同等特点，提出设立拖虾休渔期的建议方案。     

浙江海洋渔业可持续发展战略研究

海洋渔业作为浙江国民经济的支柱产业和发展海洋经济的先导产业,在未来5年,面临着从未有过的严峻挑战和一系列新的问题,在这样的情势下,如何审时度势,采取相应的战略措施、发展对策,以实现海洋渔业可持续发展.本文结合浙江海洋渔业实际,作了较深入的探讨.     

2016年春季日照港岚山港区近岸海域渔业资源浅析

[目的] 了解岚山港区近岸海域渔业资源的种类组成及分布情况,探明该海域渔业资源变化及人类活动对该海域渔业资源的影响。[方法] 以2016年5月日照港岚山港区进行的渔业资源底拖网调查资料分析该海域的渔业资源状况,并结合2012年5月调查数据分析该海域渔业资源的变化情况。[结果] 2016年5月该海域共捕获渔业资源种类46种,平均渔获量为27.63 kg/h。优势种为戴氏赤虾(Metapenaeopsis dalei)、双斑蟳(Charybdis bimaculata)、绯魚銜(Callionymus beniteguri)、口虾蛄(Oratosquilla oratoria)等。比较2012年调查数据分析日照港岚山港区海域渔业资源种类和渔获量变化均不大。[结论] 近几年该海域渔业资源群落结构变化不大,受人为影响较小。     

Allozyme electrophoresis demonstrates the presence of a species boundary in freshwater crabs (Decapoda: Potamonautidae)

Potamonautes granularis, P. perlatus and P. sidneyi are morphologically similar species of freshwater crab occurring in the middle to lower reaches of rivers. Potamonautes perlatus and P. sidneyi are known to exhibit clinal morphological differentiation between two distinct morphotypes and their specific status has remained obscured. This study investigates the species boundaries between these three species, as well as genetic differentiation and gene flow between populations within each species, using allozyme electrophoresis. Twenty-five populations (including two P. granularis, 10 P. perlatus and 13 P. sidneyi populations) were utilized, collected along a transect of 2300 km. Individuals were screened for 11 presumptive loci, using a horizontal starch-gel electrophoresis protocol. Mean genetic identities obtained in pair-wise comparisons of populations of different species (I =0.748-0.846) were typical of interspecific comparisons. Diffuse species boundaries (over which gene flow and hybridization may be possible) were observed between P. granularis and P. perlatus, and between P. perlatus and P. sidneyi. A fixed allele difference at the ME locus distinguished P. granularis and P. sidneyi. Hierarchical F -statistics revealed significant genetic sub-structuring between populations within each species and within the entire sample, illustrating low-levels of gene flow. Although some regional groupings were evident from the genetic data, no distinct distance-related patterns, or patterns of clinal variation could be observed. Patterns of genetic differentiation resemble a patchwork that is probably the product of mutations, genetic drift, balanced by low levels of gene flow, and natural selection. The extensive morphological variation must now be seen against the backdrop of three genetically defined species.     

A new species of Hyalella from Colombia,and the redescription of H. meinerti Stebbing, 1899 from Venezuela (Crustacea: Amphipoda)

The new species H. quindioensis is described from Colombia. This species is close to H. paramoensis Andres, 1988 also in Colombia. Hyalella meinerti Stebbing, 1899 is figured and redescribed. The type locality for this species is Venezuela. However, it has a wide distribution including Colombia, Peru, Ecuador and Brazil.     

我国海洋渔业资源产权化管理模式研究

随着世界人口的增长和科学技术的发展,渔业资源从一度被称之为“不可枯竭”的资源变为日益稀缺的资源。如何分配准入权或其它权利也就成为渔业管理者无法回避的一个中心问题。不同国家可能会采取不同的方法来处理这一问题,明确界定和有效实施的渔业产权,被多数经济学家视为最有效率的制度安排之一。介绍了海洋渔业产权的基本理念、类型及其特征,并指出确保我国渔业可持续发展的关键在于构建基于产权的渔业管理机制,进而结合我国的具体情况,提出了我国海洋渔业产权制度应采取的可选路径。     

徐州淡水枝角类的调查

在徐州市郊调查,共获淡水枝角类31种,其中有6种为江苏省新记录。对这些枝角类进行分析,可以认为,徐州的淡水枝角类的区系组成,具有南方种与北方种过渡地区的特点,但又偏重于南方种。     

Rediscovery of Gastrostyla setifera (Engelmann, 1862) Kent, 1882: morphology and divisional morphogenesis (Ciliophora,Hypotrichida)

The morphology and morphogenesis of the poorly known hypotrichous ciliate Gastrostyla setifera, isolated from a freshwater pond near Harbin, China, are described from both living and protargol silver-impregnated specimens. The Harbin population of this species is characterized thus: medium-sized freshwater Gastrostyla, 150-205 × 70-95 μm in vivo, ellipsoid in shape but somewhat narrowed posteriorly. Contractile vacuole located in left half of mid-body region. On average 48-56 (mean 52) adoral membranelles; 10 frontal and 9-11 ventral cirri; 23-26 left and 30-34 right marginal cirri; usually with four complete dorsal kineties and two dorsomarginal kineties; three caudal cirri present at posterior margin; invariably two macronuclear nodules and two micronuclei. Its morphogenesis reveals the following characteristics: (1) adoral zone of membranelles (AZM) in the opisthe arises from the new oral primordium while the proter inherits the entire parental structure; (2) 10 frontal, 9-11 ventral and five transverse cirri are derived from five frontoventral transverse cirral anlagen together with the undulating membrane anlage; (3) left and right marginal cirri are derived from new anlagen which originate within the old marginal rows; (4) the generation of the dorsal kineties is of the 'two-group-mode'; three left primary dorsal anlagen and two dorsomarginal anlagen appear as two groups in both dividers from which all dorsal kineties are derived (the fourth kinety is formed due to the fragmentation of the third anlage); (5) one caudal cirrus is formed at the ends of each of the first, second and fourth dorsal anlagen.     

Two new Mastigodiaptomus (Copepoda,Diaptomidae) from southeastern Mexico,with a key for the identification of the known species of the genus

Two new species of the freshwater planktonic copepod genusMastigodiaptomus—M. maya and M. reidae—are described from material collected in southeastern Mexico. This neotropical genus is known to be distributed mainly in the southern part of the United States, Mexico and Central America, and now embraces eight species. Of these, six occur in Mexico. Both new species seem to be closely related to M. texensis and M. albuquerquensis. It is probable that this group of Mexican species represents a northwards radiation from the Proto-Antilles-Central America region into the continent, eventually reaching North America. A key for the identification of the known species of the genus is provided.