中西太平洋鲣鱼的年龄鉴定和生长特性

鱼类的年龄和生长等生物学参数对于准确评估渔业资源非常重要.本文于2007年10月至2008年1月,利用围网渔船在中西太平洋海域采集了262尾鲣鱼样本,现场测定其叉长（278～746 mm）和体质量（345～9905 g）,并搜集第一背鳍鳍棘用于鉴定其年龄和生长状况.结果表明：鲣鱼叉长（L, mm）与体质量(M,g)的关系式为M=3.612×10^-6L^{3. 278} （R²=0.9782）,性别对其影响不显著（F=2.002,P>0.05）;经赤池信息量标准（AIC）评估,在幂函数、线性及指数3种回归关系中,线性回归模型最好地拟合了鲣鱼叉长与鳍棘截面半径之间的关系(AIC=2257.4);采用Fraser-Lee法求得的鲣鱼1～5龄平均逆算叉长分别为398.4、494.2、555.4、636.8和728.8 mm;经残差平方和分析,雌雄鲣鱼的生长状况间不存在显著性差异(F=0.670;df=182;P>0.05),推得鲣鱼von Bertalanffy生长方程为L_t=706.51(1-e^{-0.64(t+0.037)}).     

Effect of Body Size on Reef Fish Tolerance to Extreme Low and High Temperatures

Understanding the thermal physiology of tropical marine organisms has become an issue of major interest due to the potential impact of current global changes in temperature. In this study we report the effect of body size on the thermal tolerance (as critical thermal maximum (CTMax) and minimum (CTMin)) of seven reef fish species from Gorgona Island (tropical eastern Pacific Ocean). Within the studied species we found little variation in CTMax and CTMin among fishes ranging from juveniles to adults. This suggests that thermal tolerance of small tropical reef fishes is not significantly affected by differences in body size. The reduced intra-specific variation in thermal tolerance found in these species also suggests a limited capability to adapt to extreme thermal conditions and raises concerns regarding current global changes in temperature.     

印度洋中西部和大西洋西部水域大眼金枪鱼的食性比较

根据2004年8月至2005年3月大西洋西部水域及2003年12月份至2004年5月份在印度洋中西部水域金枪鱼延绳钓渔业所获取的大眼金枪鱼数据,对两个诃查区域内的大眼金枪鱼食性进行了研究。结果表明,印度洋中西部水域大眼金枪鱼的食物组成包括沙丁鱼、鱿鱼、乌贼等13个饵料类群,其中主要摄食鱿鱼和沙丁鱼;大西洋西部水域大眼金枪鱼主要摄食沙丁鱼、鱿鱼、虾类等13种饵料类群,主要以沙丁鱼为饵,其次为鱿鱼。印度洋中西部水域大眼金枪鱼空胃率非常高,基本上维持在60％以上;大西洋西部水域大眼金枪鱼空胃率相对较低,基本上都在30％以下。印度洋中西部水域大眼金枪鱼平均饱满指数变化不大,基本上维持在0．40～0．55之间。大西洋西部水域大眼金枪鱼平均饱满指数变化也不太大。印度洋中西部水域大眼金枪鱼各月平均饱满指数高于大西洋西部水域,且各月空胃率高于后者。印度洋中西部和大西洋西部水域大眼金枪鱼Shannon-Weiner多样性指数H’基本上都1．50～2．00之间变化。相同调查月份内,印度洋中西部水域大眼金枪鱼食物Pielou均匀度指数J’均高于大西洋西部水域。     

Implications of global warming for the climate of African rainforests

African rainforests are likely to be vulnerable to changes in temperature and precipitation, yet there has been relatively little research to suggest how the regional climate might respond to global warming. This study presents projections of temperature and precipitation indices of relevance to African rainforests, using global climate model experiments to identify local change as a function of global temperature increase. A multi-model ensemble and two perturbed physics ensembles are used, one with over 100 members. In the east of the Congo Basin, most models (92%) show a wet signal, whereas in west equatorial Africa, the majority (73%) project an increase in dry season water deficits. This drying is amplified as global temperature increases, and in over half of coupled models by greater than 3% per °C of global warming. Analysis of atmospheric dynamics in a subset of models suggests that this could be partly because of a rearrangement of zonal circulation, with enhanced convection in the Indian Ocean and anomalous subsidence over west equatorial Africa, the Atlantic Ocean and, in some seasons, the Amazon Basin. Further research to assess the plausibility of this and other mechanisms is important, given the potential implications of drying in these rainforest regions.     

The enigmatic,deep‐sea,organic‐walled genera Chitinosiphon,Nodellum and Resigella (Protista,Foraminifera): A taxonomic re‐evaluation

Abstract

Using a morphology‐based approach, we explore the relationships between three poorly understood species of organic‐walled Foraminifera. Thalmann and Bermudez (1954) described Chitinosiphon rufescens as the type species of a new monotypic genus which they compared to the tubular agglutinated foraminiferan Bathysiphon. Loeblich and Tappan (1964), however, considered C. rufescens to be identical to Reophax membranacea Brady 1879, type species of another organic‐walled genus, Nodellum. Based on a re‐examination of the type specimens of both species, new material of C. rufescens from the Lost City hydrothermal field, and new material of N. membranacea from the NE Atlantic and Pacific Oceans, we show that these two deep‐sea species are distinguished by the following features. (1) Chitinosiphon rufescens lacks the distinct, regular constrictions that divide the tubular test of N. membranacea into a series of segments. (2) The proloculus is spindle‐shaped in C. rufescens but sub‐cylindrical in N. membranacea. (3) A distinctive, pocket‐like invagination is developed at the base (proximal end) of the proloculus in N. membranacea but not in C. rufescens. However, a series of undescribed species which occur in deep‐sea sediments blur the distinction between the two genera. We therefore adopt a conservative position and regard Chitinosiphon as a junior synonym of Nodellum. We also examined the holotype and new material of Nodellum moniliforme Resig, 1982, the type species of Resigella Loeblich and Tappan, 1984, in which the organic‐walled test comprises a series of bulbous chambers. This species exhibits a basal invagination, identical to the feature present in Nodellum membranacea. These three remarkable species are united by the basically tubular test and the nature of the test wall which is largely organic, brownish in colour, and exhibits no internal structure when broken sections are examined by SEM. The surface of the organic test of Nodellum rufescens from Lost City is strewn with tiny (≤1μm), needle‐shaped mineral particles, visible only by SEM. More equidimensional, micron‐sized particles are present in the other two species. We agree with Thalmann and Bermudez (1954) that N. rufescens is related to tubular agglutinated taxa such as Bathysiphon. Resigella may have similar affinities, although this needs to be tested using molecular approaches.     

Multiple population structure of the giant mottled eel, Anguilla marmorata

The population structure of the giant mottled eel, Anguilla marmorata, was investigated with mitochondrial and microsatellite DNA analyses using 449 specimens from 13 localities throughout the species range. Control region F-statistics indicated the North Pacific (Japan, Taiwan, Philippines, Sulawesi), South Pacific (Tahiti, Fiji, New Caledonia, Papua New Guinea), eastern Indian Ocean (Sumatra), western Indian Ocean (Réunion, Madagascar), Ambon, and Guam regions were significantly different (Phi(ST) = 0.131-0.698, P < 0.05) while only a few differences were observed between localities within the South Pacific. These regions were roughly clustered in the neighbour-joining tree, although Ambon individuals were mainly divided into North and South Pacific groups. Analysis with eight microsatellite loci showed almost identical results to those of the control region, except no genetic difference was observed between the western and eastern Indian Ocean (F(ST) = 0.009, P > 0.05). The Bayesian cluster analysis of the microsatellite data detected two genetic groups. One included four North Pacific localities, and the other included eight localities in the South Pacific, Indian Ocean, and Guam, but Ambon individuals were evenly assigned to these two groups. These results showed that A. marmorata has four genetically different populations (North Pacific, South Pacific, Indian Ocean, Guam region). The North Pacific population is fully panmictic whereas the South Pacific and Indian Ocean populations have a metapopulation structure. Interestingly, Guam was suggested to be inhabited by a reproductive population restricted to that region, and the individuals from the North and South Pacific populations co-exist in Ambon.     

What can metazoan parasites reveal about the taxonomy of Scomber japonicus Houttuyn in the coast of South America and Madeira Islands?

The metazoan parasites of four populations of the chub mackerel Scomber japonicus were analysed from two localities in the Atlantic Ocean (Madeira Islands, Portugal, and Rio de Janeiro, Brazil) and two localities in the Pacific Ocean (Callao, Peru, and Antofagasta, Chile), collected during 2002 and 2003. A total of 373 fish specimens were studied and 34 metazoan parasite species were obtained. Parasites identified from the populations of chub mackerel studied could be separated into three categories: parasites with a wide distribution, present in the Pacific and Atlantic, parasites proper of the Pacific Ocean and parasites proper of the Atlantic Ocean. The analyses of some highly specific parasites of the genus Scomber ( i.e. monogeneans of the genus Kuhnia and didymozoid digeneans) strongly suggest the need for a revision of the taxonomic status of chub mackerels from the Atlantic and Pacific coast of America. The results demonstrated the usefulness of parasites as adequate tools to clarify the taxonomic status of their hosts.     

Developing 23 new polymorphic microsatellite markers and simulating parentage assignment in the Pacific bluefin tuna, Thunnus orientalis

Twenty-three new polymorphic microsatellite markers were isolated in the Pacific bluefin tuna, Thunnus orientalis. Each locus comprised three to 34 alleles. The expected and observed heterozygosities ranged between 0.46 and 0.96 and between 0.44 and 0.97, respectively. The Kto9, Kto11, and Kto42 markers demonstrated significant deviation from Hardy-Weinberg equilibrium; high null allele frequencies (0.08-0.14) were observed in the deviating group. From the results of simulation of parentage assignment, a combination of four loci (i.e. Kto15, Kto23, Kto38, and Kto39) was considered the best for parentage assignment.     

Stolidobranch ascidians from the tropical western Indian Ocean

Coastal ascidians collected over two centuries from Suez to Mozambique have been successively deposited in the MNHN and are now described and figured. Some of them were already known from the Indian Ocean, others are common to the Pacific, and some others are new species. Even though the present taxonomic work notably increases our knowledge of the tropical eastern African coast, it comprises so many miscellaneous collections from such distant points that it can only begin to suggest the diversity of ascidians there. © 2002 The Linnean Society of London. Zoological Journal of the Linnean Society , 2002, 135 , 65–120.     

More,smaller bacteria in response to ocean's warming?

Heterotrophic bacteria play a major role in organic matter cycling in the ocean. Although the high abundances and relatively fast growth rates of coastal surface bacterioplankton make them suitable sentinels of global change, past analyses have largely overlooked this functional group. Here, time series analysis of a decade of monthly observations in temperate Atlantic coastal waters revealed strong seasonal patterns in the abundance, size and biomass of the ubiquitous flow-cytometric groups of low (LNA) and high nucleic acid (HNA) content bacteria. Over this relatively short period, we also found that bacterioplankton cells were significantly smaller, a trend that is consistent with the hypothesized temperature-driven decrease in body size. Although decadal cell shrinking was observed for both groups, it was only LNA cells that were strongly coherent, with ecological theories linking temperature, abundance and individual size on both the seasonal and interannual scale. We explain this finding because, relative to their HNA counterparts, marine LNA bacteria are less diverse, dominated by members of the SAR11 clade. Temperature manipulation experiments in 2012 confirmed a direct effect of warming on bacterial size. Concurrent with rising temperatures in spring, significant decadal trends of increasing standing stocks (3% per year) accompanied by decreasing mean cell size (−1% per year) suggest a major shift in community structure, with a larger contribution of LNA bacteria to total biomass. The increasing prevalence of these typically oligotrophic taxa may severely impact marine food webs and carbon fluxes by an overall decrease in the efficiency of the biological pump.