Historical distribution of the otter (Lutra lutra) in north‐east China according to historical records (1950–2014)

1. The Eurasian otter (Lutra lutra) has undergone a dramatic decline throughout the 20th century in China, especially in the North East. However, the dynamics responsible for the reduction in the distribution of otters in this region since the 1950s is still unclear. Such uncertainty and insufficient information can hinder effective conservation strategies. 2. A study was conducted using historical documents to attempt an evaluation of the status of otter populations in north‐east China between 1950 and 2014. The data suggest that otters were widely distributed with abundant populations in north‐east China in the 1950s, particularly in the area of the Songhua River basin and the Ussuli River basin. 3. Compared with the 1950s, the number of records in 2014 has fallen by 92%. Otter populations are fragmented and mainly restricted to national nature reserves, leaving little optimism for their future. 4. More broadly, this research demonstrates that recovering information from local historical documents can be a useful and reliable way to overcome the limits caused by lack of data. Copyright © 2016 John Wiley & Sons, Ltd.     

Conservation of otter (Lutra lutra) in a Mediterranean area: the importance of habitat quality and temporal variation in water availability

1. This study analyses quantitatively the association between habitat characteristics and annual variation in water availability on otter (Lutra lutra L.) distribution in a large Mediterranean area (13 717 km²) in southern Spain. 2. There was a strong positive correlation between habitat quality, estimated after the two first components of a principal component analysis of a matrix of habitat variables×sites, and an index of otter presence/absence, otter presence being most commonly associated with unpolluted and undisturbed sites surrounded by woodland. 3. After univariate analysis, the main freshwater habitat features were statistically different between sites with otters and sites lacking them. In general, otters occurred in medium‐sized fluvial habitats, with high bankside vegetation cover, unpolluted, with low or very low human disturbance and surrounded by forests or dehesas (Mediterranean‐like savannah). 4. Water availability, inferred from the water balance, strongly influenced otter distribution and the type of water body used the most. As water availability increased so did the otter distribution range and during these periods they tended to colonize low‐order streams. During periods of water shortage, otters were usually found in high‐order streams and reservoirs, the only sites that kept water. 5. This work shows that otter distribution in Mediterranean areas is strongly influenced by two factors — man‐induced habitat degradation and natural variability in water availability. The addition of the second factor to the first one introduces additional risks to the survival of otter populations in Mediterranean areas compared with more northerly and humid areas. Copyright © 2001 John Wiley & Sons, Ltd.     

Diet of the Eurasian otter (Lutra lutra) on the River Gradac,Serbia: Predation in a brown trout‐dominated stream

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长白山自然保护区水獭种群数量变动与资源保护

1980-2010年,对长白山自然保护区3条主要河流的水獭种群数量和栖息地食物资源进行了长期监测;2006-2008年冬季采用路线直接计数法对18条河流进行野外定点调查;2004-2010年5-8月对头道白河流域的水獭活动情况进行了定点全天观察;2006-2008年冬季对水獭栖息地8条河流的无冰水面进行了调查。结果表明,长白山自然保护区及其周边水域水獭种群数量从1990年开始显著下降,到2010年其种群数量比1975年下降了99.3%;2006-2008年冬季和2004-2010年5-8月的定点观察都没有发现水獭活动,水獭种群基本处于区域性消失状态。水獭种群数量的变化与河流中水生动物生物量的变化有显著的关系(n=8,r=0.977,P<0.01)。由于过渡捕捞、使用农药和筑坝等人类活动影响,鱼类数量减少,许多种类已经消失,致使水獭的食物严重不足;当地大量使用含有机氯和多氯联苯等成分的杀虫剂和除草剂,导致河流被污染,水生动物生物量急剧下降,这与水獭种群数量锐减关系密切;水獭栖息地冬季的河流无冰水面因修建电站、建设河坝和修引水渠等人类活动而呈逐年减少的趋势,一定程度上影响了水獭的取食活动。     

Range and diet of Eurasian otters Lutra lutra (L.) in the catchment of the River Lee (south‐east England) since re‐introduction

• 1. After re‐introduction in 1991 of Eurasian otters Lutra lutra (L.) to the River Lee catchment (England), changes in range were assessed from spraint collections in the periods 1991–1994, 1995–1997 and 1998–2000. Diet, assessed from concerted spraint sampling within the first two periods, was compared between 1992–1994 and 1996–1997, with dietary preferences assessed for the initial phase using available fish stock data for that period.
• 2. In 1991–1994, range encompassed much of the catchment, but reduced in 1995–1997 to a small area around the initial release site, when the otters were joined/replaced by natural immigrants presumed to come from a contiguous catchment. Range expanded in 1998–2000 to upper reaches of the catchment's major tributaries.
• 3. Fish, mainly cyprinids, were the major prey taken in 1992–1994 and 1996–1997. In 1996–1997, fish abundant near the initial release site became more prominent, in particular chub Leuciscus cephalus, and (upstream) species characteristic of the initial range decreased in importance.
• 4. Despite confirmed and unconfirmed sightings of females with cubs, it remains unclear whether the presence and apparent expansion of otters in the Lee catchment is the result of the re‐introduction or of natural immigration/recolonization.

Copyright © 2003 John Wiley & Sons, Ltd.     

广东大鹏湾海域糙齿海豚体内多氯联苯的分布特征与毒性评价

以广东大鹏湾海域糙齿海豚(Steno bredanensisLesson)为研究对象,采用气相色谱法分析了海豚8种组织中多氯联苯(PCBs)的含量。将海豚8种组织分别经皂化、萃取、净化、浓缩等处理后,用Agilent 6890N型气相色谱仪、DB-XLB型毛细管气相色谱柱(30 m×0.32 mm×0.50μm)、ECD检测器测定。共检测出43种PCBs同系物。结果表明,PCBs在海豚8种不同组织中的含量范围为19.6~1 326.3 ng/g组织,皮肤中比其余7种组织的PCBs含量(19.6~90.4 ng.g-1)高2个数量级,各组织中含量由大到小依次为皮肤、心脏、肌肉、肝脏、睾丸、胃、肾脏、肺。PCBs同系物和同族物在海豚不同组织中的分布特征相似,同系物中以PCB153所占总量的百分比最大,在18.7%~21.1%之间,其次分别为PCB180、PCB187,分别占9.65%~12.02%和4.08~9.26%,PCB138、PCB157、PCB151、PCB110和PCB145等5种同系物所占百分比相对较低,范围为0.87%~5.80%;在同族物中以含6个氯原子的PCBs百分比最大,为48.2%~58.2%,其次分别是含7个和5个氯原子的,所占百分比分别为18.76%~24.81%和12.10%~18.10%。应用二英毒性当量(TEQ)评价了糙齿海豚不同组织中PCBs的毒性,其TEQs范围为45.04~2 896.67 pg/g,其中皮肤的毒性当量最高,比肺的高2个数量级,比心脏、睾丸、肌肉、肝脏、胃和肾脏的高1个数量级。TEQs主要来自非邻位取代的PCBs,占总量的98.5%~99.3%,其中来自PCB126的占86.3%~93.7%,是海豚体中TEQs的主体。与世界其他海域海豚的PCBs污染水平相比,大鹏湾海域糙齿海豚的PCBs污染处于相对严重水平。     

Morphological and ecological responses to a conservation translocation of powan (Coregonus lavaretus) in Scotland

• 1. The establishment of refuge populations has become a common management tool for threatened fish species in recent years, yet the effects of translocation are not fully understood in a conservation context.
• 2. This paper examines the hypothesis that phenotypic changes have occurred during the formation of two refuge populations of the nationally rare powan (a freshwater fish species) which were established in Loch Sloy and Carron Valley Reservoir in Scotland.
• 3. Significant differences in head morphology, size and growth between the founder and refuge populations and between the two refuge populations were demonstrated. These changes are probably due to a combination of founder effects, intense selection and phenotypic plasticity. These changes can undermine the rationale behind the establishment of refuge populations.
• 4. The results call into question the usefulness of translocation as a conservation measure; however, there are times when this is the only viable management option available. The future of translocation and the validity of establishing refuge populations for powan conservation are discussed. Copyright © 2010 John Wiley & Sons, Ltd.

     

应用聚类分析评价珠江口翡翠贻贝和环境水域有机氯农药与多氯联苯污染情况

选用皮尔逊相关度量和最长距离法，对珠江河口区翡翠贻贝体内有机氯农药和多氯联苯的含量进行了聚类分析。结果显示，13个采样点的样品可分为3类：一类污染物含量最低，二类中多氯联苯含量最高，三类中有机氯农药含量最高，这些污染物的含量与分布及样品所处地理位置、地方经济结构有关。将贻贝品质分为较好、合格、较差3个等级。     

Crayfish in central and southern Ukraine with special focus on populations of indigenous crayfish Astacus pachypus (Rathke, 1837) and their conservation needs

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Changes in the distributions of freshwater mussels (Unionoida: Hyriidae) in coastal south‐eastern Australia and implications for their conservation status

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Variation in DVM behaviour of juvenile and adult pearlside (Maurolicus muelleri) linked to feeding strategies and related predation risk

In the Norwegian fjord Masfjorden, different developmental stages of the mesopelagic planktivore Maurolicus muelleri form vertically separate sound scattering layers (SSLs) and in late autumn display different diel vertical migration (DVM) behaviour. Post‐larvae and juvenile fish perform normal crepuscular DVM, whereas the large majority of adults remain at depth throughout the diel period. In this study we examined the stomach contents of juvenile and adult fish caught at different times and depths during a 24‐h period in autumn. The different DVM behaviour of these two SSLs in addition to a shallow layer believed to be composed of post‐larvae is explained with a model for visual foraging in aquatic environments that uses gradients in vertical light intensity and copepod density and size as input variables. Field data revealed that vertically migrating juveniles distributed at a higher ambient light intensity and on average consumed 25 times more copepods than non‐migrating adult fish. The model showed that juveniles experienced a 15 times higher prey encounter rate and a higher level of predation risk than non‐migrating adults, and that the energetic benefits for post larvae and juveniles from prolonged feeding in a nearly constant and brighter environment outweigh the associated predation risk. The model also suggests that the visual detection range of piscivore predators is relatively more limited by the turbid surface water than that of their prey, which provide the post‐larva and juvenile life‐stages of M. muelleri a window of reduced visual predation near the surface.     

Evaluating the upper thermal limits of glochidia for selected freshwater mussel species (Bivalvia: Unionidae) in central and east Texas,and the implications for their conservation

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Biological and ecological traits of Bathynomus giganteus and Bathynomus miyarei (Crustacea: Isopoda): Contribution to the conservation of deep-sea in southern Brazil

1. This study aimed to determine biological and distributional aspects of deep-sea giant isopods Bathynomus giganteus and Bathynomus miyarei to assess their extinction risk.
2. Bathynomus giganteus (663 specimens) and B. miyarei (649 specimens) were collected during five research cruises involving 265 h of sampling effort during 32 fishing operations of circular pots, baited traps, ranging from 400 and 1,000 m deep, between 26 and 29°S adjacent to the Brazilian coast.
3. A trend towards larger, sexually mature animals in shallower regions was observed for both species, and depth was the most important environmental variable influencing the animals’ distribution.
4. Bathynomus giganteus were collected between 600 m and 1,000 m depth, while the highest densities of B. miyarei were at shallower depths, between 400 and 600 m.
5. The sex ratio was equal for both B. giganteus and B. miyarei for different seasons, latitudes and bathymetries.
6. The sexual maturity of B. giganteus was estimated at 340–345 mm total length for males and between 280–290 mm for females. Bathynomus miyarei males’ sexual maturity was estimated in the 225–230 mm size class.
7. Bathynomus giganteus showed reproductive activity throughout the year.
8. The longevity of B. giganteus was estimated at 6 years for males and 7.7 years for females. The longevity of B. miyarei was estimated at 9 years for males and 6 years for females.
9. Extinction risk assessment for B. giganteus, which has a greater latitudinal and bathymetric distribution, was evaluated as Least Concern. However, B. miyarei was evaluated in the Data Deficient category.

     

Size,permeability and buoyancy of anchovy (Engraulis Encrasicolus) and sardine (Sardina Pilchardus) eggs in relation to their physical environment in the Bay of Biscay

The size and specific gravity of eggs of marine pelagic fish partly determine their dispersal and survival. Using an original dataset of anchovy and sardine eggs, sampled in spring over the last decade in the Bay of Biscay, we provide a parameterization of these properties on ambient water temperature and salinity. We used the density gradient column for measurement of egg specific gravity. The column was also filled with homogeneous water for sinking velocity experiments. For anchovy, these experiments confirm that the effect of egg permeability through the chorion could be neglected when modelling sinking, while it has to be considered for sardine, its perivitelline space representing 78.6% (±6.2%) of the total egg volume, as opposed to 5–10% for most teleosts species. We estimated a coefficient of permeability of the chorion of 0.0038 mm s^?1. However, permeability should not affect the measurement of sardine egg specific gravity in a gradient column, provided a minimum duration before reading is respected for equilibrium to be reached. In relation to their environment, we found that the egg specific gravity is largely determined by sea surface salinity for both species, whereas egg size is weakly but significantly impacted by temperature, for sardine only. On average, the estimated difference in specific gravity between egg and surface water is ?0.92 σ_T for anchovy and ?1.06 σ_T for sardine. The detailed parameterization of the relationship between eggs and water properties should prove useful, in particular to modellers dealing with the dispersal of fish early life stages.     

Ultrastructural study of epitheliocystis organisms from gill epithelium of the fish Sparus aurata (L.) and Liza ramada (Risso) and their relation to the host cell

Abstract. Ultrastructural study of epitheliocystis organisms from gills of Sparus aurata (L.) and Liza ramada (Risso) revealed in each fish a new form of the organism which differed from epitheliocystis organisms previously described. In their size range, the presence of a plasma membrane, a trilaminated cell wall and a central nucleoid, these organisms resembled chlamydial organisms (PLT). However they differed from them in the following respects: in both species several morphological forms were recognized; hyphae or mycelium-like forms and individual units, not comparable to any of the successive units described for Chlamydia organisms. Both organisms were contained within an inclusion in the host cell, but in epitlieliocysts from S. aM7-ata apparently intracytoplasmic forms were also observed. Ultrastructural studies of the cytoplasmic wall of the epitheliocystis inclusion in S. aurata suggest that the epitheliocystis cyst remains contained in a single unruptured hypertrophied cell, while in i. ramada the final cyst is formed through the coalescence of several epithelial cells.     

Using occupancy and species distribution models to assess the conservation status and habitat use of the goldline darter (Percina aurolineata) in Georgia,USA

The goldline darter (Percina aurolineata) is threatened by recent increases in urbanisation in the Coosawattee River watershed, but no studies have addressed their current status. Similarly, limited data on habitat use make it difficult to understand factors that may impact this species. We compared occurrence data before (1996–2000) and after (2009–2011) a period of rapid development and population growth within the watershed. Single‐season occupancy models were built to account for imperfect species detection and to identify habitat covariates. MaxEnt was used to identify important stream reaches for conservation and to understand landscape scale factors correlated with the distribution of goldline darters. Our results indicate a high proportion of sites occupied upstream of Carters Lake during the historic and recent time periods, with no evidence of decline. However, occurrences of goldline darters for sites in Talking Rock Creek and the lower Coosawattee River were sparse in the historic period and absent during the recent period. The probability of detecting goldline darters is low and was positively associated with the occurrence of small substrate. Species distribution models were strongly influenced by watershed area and elevation and indicated a high probability of suitable habitat within the Coosawattee River and large tributaries upstream of Carters Lake. While goldline darter occupancy is currently stable upstream of Carters Lake, continued urbanisation is a threat to long‐term persistence. We recommend additional monitoring and describe a protocol that allows for precise estimates of species occupancy while minimising the risk of sampling‐related mortality.     

海洋鱼类种群划分的研究方法及其在小黄鱼上的应用进展

综述了标记重捕法、渔获量分析法、寄生虫标记法、形态表型量度特征法、分子生物学法、钙质结构元素指纹法等6种方法在海洋鱼类种群划分上的应用进展,并探讨了这些方法各自的可靠性和局限性。并以我国重要经济鱼类小黄鱼(Larimichthys polyactis)为例,归纳了自20世纪40年代以来应用上述方法开展小黄鱼种群研究的脉络,剖析了我国近海小黄鱼种群(特别是黄海南部种群)划分存在较大分歧的现状。通过比较分析各种方法的研究效果,指出基于钙质组织中元素指纹的方法在鱼类种群判别研究中将具有更大优势。最后,展望了海洋鱼类种群研究方向,以及在今后小黄鱼种群划分研究中上述方法的应用特征。