The Palaeozoic, Mesozoic and Early Cenozoic fishes of Africa

Africa has provided many fossil fishes from sediments laid down over a 400 million year period. The large array of fossil fishes come from diverse localities throughout the continent, representing a variety of environments. The marine fossil fishes of Africa have not been reviewed as a whole, while the freshwater Cenozoic fishes of Africa were last reviewed over 25 years ago. Since that time, many new finds have increased our knowledge of the history of African fishes. This paper summarizes the known fish fossils, excluding otoliths, from marine and freshwater deposits throughout Africa from the Palaeozoic, Mesozoic and first part of the Cenozoic (Palaeogene). Much new work is ongoing, in areas such as Mali and South Africa, from which more information on the ichthyofaunas should come to light. New information presented here includes the Eocene site of Mahenge, Tanzania, from which have come the oldest known members of the family Cichlidae.     

Present state and perspectives for the southern Brazil shelf demersal fisheries

The demersal fish stocks in southern Brazil were assessed from landings and catchper-unit effort data trends between 1975 and 1994, available information on the life history patterns, and population dynamics of the most important species. The fishing gears, mostly otter and pair bottom trawls in the 1970s, diversified towards double-rig trawls for fish and shrimp and bottom gill nets in the mid 1980s, and bottom longlines in the upper slope in the early 1990s. There were also some less successful attempts with traps for fish and crabs. The demersal fisheries are more intensive in winter when migratory species move northward, associated with the seasonal displacement of the western boundary of the Subtropical Convergence. Landings between 1975 and 1994 were mostly of sciaenid fishes (>70%) and elasmobranchs (10%) and oscillated around 59 000 t. There was not a decrease in total landings but a shift from more to less exploited stocks. Since 1989, 4% of the landings came from depleted stocks of Pagrus pagrus (L.), Netuma barba (Lacépède), Pogonias cromis (L.) and Rhinobatos horkelli (Muller & Henle); 37% from overexploited stocks: Micropogonias furnieri (Desmarest), Paralichthys patagonicus Jordan, Squatina guggenheim Marini, and Galeorhinus galeus (L.); 24% from heavily exploited stocks of Umbrina canosai Berg, and Macrodon ancylodon (Bloch & Schneider); and 35% of Cynoscion guatucupa (Cuvier) and small stocks with unclear status. The demersal fisheries are virtually unmanaged and future landings are expected to decrease if fishing pressure remains high. Effective management will require the participation of all three countries in the region because most of the stocks fished in southern Brazil are shared with Uruguay and Argentina.     

Egg size and its relationship with fecundity,newborn length and female size in Cuban poeciliid fishes (Teleostei: Cyprinodontiformes)

Abstract – This study describes the relationship between egg size (ES) and brood size (BS), newborn length (NL) and female total length (FTL) in ten species of Cuban poeciliids. Variability and the level of association among variables are analysed and comparisons of ES among species established. Egg size has the lowest variability among the analysed variables and in most species is not correlated with BS, when the effect of FTL is controlled. Cuban poeciliids, thought to be primarily lecithotrophic, can be separated in two groups according to ES, NL and BS relative to FTL. One such group inhabits mountain streams and produces large eggs and small broods. The other group is distributed in lowland wetlands and produces small eggs and large broods. In Cuban poeciliids, ES and NL are highly correlated, which suggests adaptive value for ES.     

浙江海洋鱼类种类组成、区系分布及资源特征研究

经近10年的实地采集,结合相关文献查阅,总结出浙江海域鱼类共734种,分属于3个纲、42目、220科、488个属。本文在重点分析了浙江海域鱼类水平分布区系特点,并根据资源特征,将其划分为记录种、罕见种、少见种、习见种及优势种,并对习见种及优势种进行了现状分析。     

Dams in the Amazon: The importance of maintaining free-flowing tributaries for fish reproduction

1. Free-flowing tributaries are important for the maintenance of fish diversity in dammed systems. In relation to the reproduction of fish species, the role of a free-flowing tributary was evaluated and compared with that of a dammed tributary downstream of large dams in the Madeira River, one of the main tributaries of the Amazon River.
2. Two hypotheses were tested: (i) the densities of the ichthyoplankton differ between the dammed and the free-flowing tributaries; and (ii) the free-flowing tributary contributes a greater diversity of fish larvae species to the assemblage structure of the main stem than the dammed tributary.
3. Fish eggs and larvae were sampled at five sites: one in each tributary (Jamari – dammed – and Machado – free-flowing) and three in the main stem (Madeira River), upstream and downstream from the mouth of each tributary.
4. Fitted Bayesian models showed that the densities both of eggs and larvae were more than twice as high in the free-flowing tributary than in the dammed tributary. The results also indicated that the free-flowing tributary makes a major contribution to the fish assemblage structure of the Madeira River, whereas the dammed tributary does not have a significant influence on the main stem assemblage structure.
5. The results demonstrate the importance of conservation and maintenance not only of the Machado River but also of other free-flowing tributaries in dammed basins, especially those basins with high biodiversity, such as the Amazon. Moreover, this study helps inform the decision-making process regarding the location of new dams, which is critical in fish diversity conservation.

     

几种近海底层鱼类和中上层鱼类隐蔽伪装色的比较

为了探明近海不同生态类型鱼类隐蔽伪装色的差异,研究了6种中上层鱼类和5种底层鱼类的隐蔽伪装色,结果表明:无论近海中上层鱼类(包括大甲鲹Megalaspis cordyla、斑■Hemiramphus far、五条■Seriola quinqueradiata、竹■鱼Trachurus japonicus、蓝圆鲹Decapterus maruadsi、蓝点马鲛Scomberomorus niphonius)还是近海底层鱼类(海鳗Muraenesox cinereus、斑尾复虾虎鱼Synechogobius ommaturus、带鱼Trichiurus japonicus、单角革鲀Aluterus monoceros、龙头鱼Harpadon nehereus),黑色素细胞和黄色素细胞均为背部多腹部少,差异显著;相比近海底层鱼类,近海中上层鱼类背腹部体色差异更加明显,中上层鱼类黑色素细胞和黄色素细胞差异更大;虹彩细胞在背腹部皮肤中都存在,而近海底层鱼类的腹部主要为虹彩细胞;红色素细胞在近海底层鱼类中很少存在,但在中上层鱼类中较多。上述结果显示,鱼类背部体色的深浅主要与皮肤中黑色素细胞和黄色素细胞的数量有关,腹部体色的形成主要与虹彩细胞的多少有关。     

黄河水系鱼类分布的模糊聚类分析

应用模糊聚类法对黄河水系鱼类分布进行研究,结果表明,当λ＝０．５２时,黄河水系鱼类分布可分为８类：黄河上游干流、星宿海、黑河、鄂陵湖为一类;黄河中游干流、渭河为一类;乌梁素海、哈素海、陕北高原河流为一类;冯家山水库、陆浑水库为一类;黄河下游干流、东平湖为一类;洮河、伊洛河、河口干流各为一类。     

Indicators of mangrove zonality: the Normanby river, N.E. Australia

Mangrove species distributions within the tidal sector of the Normanby river are described. The relationships of centres of distribution to along transect distances and topographic height at various locations along river are defined. At local scales, evidence is presented to show that the detail of zonal expression, within limits, is subject to chance.     

三峡库区鱼类环境和污染状况

三峡库区的自然环境适合于多种鱼类的生长,库区水质表现一定的季节变化,水体中大肠杆菌和铜等超标;鱼体内主要污染物为Ｃｄ,Ｃｒ,Ａｓ等,但未超标,食用品质较好;鱼样外周血红细胞微 ０．８２‰－４．２８‰,表明水质对鱼体细胞具诱变作用。     

Hydrological connectivity in coastal inland systems: lessons from a Neotropical fish metacommunity

de Macedo-Soares PHM, Petry AC, Farjalla VF, Caramaschi EP. Hydrological connectivity in coastal inland systems: lessons from a Neotropical fish metacommunity.
Ecology of Freshwater Fish 2010: 19: 7–18. © 2009 John Wiley & Sons A/S
Abstract –  We assessed the influence of hydrological connectivity in structuring fish communities through seasonal samplings of environmental variables and fishes in a coastal lagoon and associated pools in the Restinga de Jurubatiba National Park, Brazil. Community structure attributes such as species richness, numerical density and biomass, Shannon–Wiener diversity index and evenness were compared between periods of the lowest and highest hydrological connectivity, while the environmental gradient and fish zonation were explored through ordination techniques. The greater hydrological connectivity established in the rainy season promoted the homogenisation of most environmental variables and fish species, which differed markedly from the arrangement observed in the dry season. Despite variation in fish species composition, community attributes showed non-significant differences between the dry and rainy seasons. The patterns of composition and numerical density in pools were strongly influenced by local factors, especially salinity, dissolved oxygen, total phosphorous concentration and water colour in the dry season, in addition to total nitrogen concentration and depth in the rainy season. Comparable to the role played by flood pulses in river-floodplain systems, the hydrological connectivity in these tropical coastal waterbodies seems to strongly influence fish community structure, and, therefore to determine regional biodiversity.