Infestation of the surf clam Mesodesma donacium by the spionid polychaete Polydora bioccipitalis   总被引：1，自引：0，他引：1  

Jos M. Riascos  Olaf Heilmayer  Marcelo E. Oliva  Jürgen Laudien  Wolf E. Arntz 《Journal of Sea Research》2008,59(4):217-227

The surf clam Mesodesma donacium is an economically important species for Chilean and Peruvian shellfisheries. This clam is often infested by Polydora bioccipitalis, a species belonging to the Spionidae, the most common parasitic polychaete group. To study this association, clams were sampled monthly over a one-year period in northern Chile. Collected clams covered the entire available size range and were classified into four infestation levels in order to study: (1) the relationship between prevalence of infestation (PI) and host size, (2) the temporal pattern of infestation events related to seasonal temperature changes, and (3) the relationship between infestation, body condition index (BCI) and gonado-somatic index (GSI). Additionally, growth rate and digging ability of clams with different infestation levels was studied. A logistic regression model best explained the relationship between PI and host size, with the smallest infested clam being 34 mm long and PI increasing steeply thereafter. Ontogenetic shifts in the habitat of the clam and ontogenetic changes, mainly in shell morphology, seem to explain the sigmoid pattern. Periods of increased shell blistering after infestation by P. bioccipitalis showed a similar seasonal pattern with GSI and BCI of non-infested clams, suggesting either an association between infestation ability and low condition of the clam or common environmental triggers for those factors. Heavily infested clams showed a significant lower BCI, growth rate and digging ability; however, given its low number, they are unlikely to be significant in terms of the local population survival. However, the infestation could play a key role in explaining mass mortality of northern populations during El Niño events, given the latitudinal differences in PI and the fact that infestation ability could be enhanced by increased temperature and facilitated in stressed clams.  相似文献   

Regulation of the fishing activities in the lagoon of Venice,Italy: Results from a socio-economic study     

Paulo A.L.D. Nunes  Silvia Silvestri  Michele Pellizzato  Vasco Boatto 《Estuarine, Coastal and Shelf Science》2008

In the last years, the overall fish industry in the lagoon of Venice has shown a gradual decline. In order to better understand this process, we carry out a socio-economic questionnaire next to the fisherman population. Questionnaire contains significant qualitative and quantitative data that allow us to evaluate the social and the cultural profile of the respondents, including information with respect to the different technological fishing characteristics involved, type and amount of the species harvested as well as the overall productivity of the activity. Furthermore, the questionnaire contains an economic valuation exercise so as to assess in monetary terms the preferences of the fishermen with respect to different alternative policy options that may characterize a future regulation of this economic activity. Estimation results show that fishermen welcome any regulation initiative that is characterized by: (1) banning all fishing activities during the night, (2) allocating fishing concessions areas to each fishermen in a way that minimize the distance between the fishing area and the harbor, and (3) by introducing of a labeling mechanism that certifies the origin of the product. Moreover, the underlying economic valuation mechanism reveals to sensitive to respondent's motivational profile, including the overall trust and confidence that fisherman community places on the current institutional bodies. This result reveals to be of particular significance when attempting the design of an efficient, widely supported regulation of the fishing activity in the lagoon of Venice.  相似文献   

Influence of beach morphodynamics on the bivalve Donax hanleyanus and Mesodesma mactroides populations in Argentina     

Gustavo A. Thompson  & Mariana F. Sánchez De Bock 《Marine Ecology》2009,30(2):198-211

Five exposed microtidal sandy beaches of North-eastern Buenos Aires (Argentina) were analysed to evaluate the influence of coastal dynamics on the abundance of the intertidal clams Donax hanleyanus and Mesodesma mactroides over a 1-year period. The physical characterisation of each beach was performed using 15 environmental variables and six morphodynamic indices. The population densities of both clam species were estimated by the number of individuals per strip-transect. Analysis of similarities revealed a significant multivariate environmental difference among beaches, which could be aggregated into a northern and a southern group. The former group was characterised by an intermediate morphodynamic state and by having, in general, high density values for both clam species. The latter was composed of beaches with an intermediate reflective state and showed, in general, low density values. Beach Index and Area showed the lowest temporal variation. Total density values, as well as density values of recruits and adults of D. hanleyanus and M. mactroides did not follow a north–south latitudinal gradient. Spatial and temporal fluctuations of density values were best explained by changes in individual physical variables rather than by changes in composite indices.  相似文献   

泥蚶(Tegillarca granosa)6个微卫星引物的分离和鉴定   总被引：3，自引：0，他引：3       下载免费PDF全文

顾晓英  曾庆国  尤仲杰  林志华 《海洋与湖沼》2008,39(6):661-664

应用6个微卫星标记在奉化泥蚶种群上进行扩增，以检测其遗传信息。扩增结果表明，引物所扩增出的等位基因数目变化从3个到7个，平均等位基因数目为5．4。引物的多态性信息含量范围为0．111-0．814。最大的观察杂合度风为0．690，最小为0．121。期望杂合度风范围为0．117-0．848。位点TMP22显著偏离了哈代-温伯格平衡。6个引物在18个马来西亚泥蚶上进行扩增，结果只有TMP18和TMP36在马来西亚模板上有扩增产物。  相似文献   

Indenter-tectonics in the Philippines: Example from the Palawan Microcontinental Block - Philippine Mobile Belt Collision     

Graciano P. Yumul  Jr  Carla B. Dimalanta  Rodolfo A. Tamayo  Jr 《Resource Geology》2005,55(3):189-198

Abstract. The aseismic Palawan microcontinental block is an oceanic bathymetric high that has collided with the seismically-ac-tive Philippine Mobile Belt since the Early Miocene. Consequently, tectonic microblocks immediately north (Luzon) and south (Western Visayas Block) of the collision front rotated in opposite senses. The rotation led the microblocks to onramp adjacent strike-slip faults, and converted these to subduction zones, namely, the current Manila and Negros Trenches. In addition, the collision also initiated the southward propagation of a major left-lateral strike slip fault, the Philippine Fault Zone, and the Philippine Trench, which bounds the Philippine archipelago along its eastern boundary. Based on onshore and offshore data, the Philippine Fault Zone and the East Luzon Trough - Philippine Trench appears to also propagate northward. Furthermore, the opposite direction of propagation is also noted for the Manila and Negros Trenches from the locus of the collision in the Central Philippines to their northern and southern extensions, respectively. The ages of initiation of the Manila Trench (Early Miocene), Philippine Fault Zone (Middle Miocene) and Philippine Trench (Pliocene) as encountered along a west to east transect in the Central Philippines are consistent with the collision and subsequent indentation of Palawan with the rest of the Philippine Mobile Belt.  相似文献   

青岛近海魁蚶群体等位基因酶遗传变异研究   总被引：7，自引：1，他引：7  

喻子牛  刘必谦 《海洋湖沼通报》1997,(3):33-39

采用淀粉凝胶电泳技术研究了青岛近海魁蚶自然群体的等位基因酶遗传变异。在十种等位基因酶中共检测到了二十二个基因座位，多态位点比例为45．5％，位点有效等位基因数分布从1．000～2．469（平均值1．415），位点杂合度观察值分布为0．000～0．595（平均杂合度0．105±0．023），在六个基因座位上存在相当明显的杂合子缺失现象。文中讨论了杂合子缺失的原因。  相似文献   

文蛤净化技术的研究   总被引：4，自引：0，他引：4  

许永安  廖登远  陈月忠 《台湾海峡》2004,23(1):94-100

本文探讨了用食品级二氧化氯消毒海水净化文蛤,通过L9(33)的3次重复正交试验,以菌落总数的杀菌率为指标,摸索出用4倍的消毒海水[二氯化氯浓度10×10-6(m m)]在充氧状态下净化文蛤,8h换水1次,净化时间共24h的净化工艺.该工艺经中试能使文蛤肠道的细菌总数杀菌率达到70%～93%,大肠菌群的杀菌率达99%左右,卫生指标达到SC T3013 2002和GB2744 1996的规定.研究表明其净化时间必须随着文蛤污染度的增加而延长.同时进行余氯的定性和定量检测,证明净化文蛤未检出余氯的残留.  相似文献   

菲律宾蛤仔(Ruditapes philippinarum)对潮间带水层-沉积物界面颗粒通量影响的研究   总被引：2，自引：0，他引：2  

韩洁  张志南  于子山 《中国海洋大学学报(自然科学版)》2001,31(5):723-729

研究利用中型生物扰动系统 (AFS)对胶州湾薛家岛潮间带菲律宾蛤仔 (Ruditapesphilippinarum)养殖断面和非养殖断面的中潮和低潮 4个站位的生物沉降和沉积物的再悬浮过程进行测定。结果表明生物沉降作用与大型滤食性双壳类动物 -菲律宾蛤仔的丰度呈显著的正相关关系 (r=0 .984 ,P<0 .0 5 ) ,养殖断面的生物沉降作用要明显地大于非养殖断面。在菲律宾蛤仔的低密度区 ,生物沉降的作用小于自然沉降 ,而在其养殖的高密度区 ,生物沉降率约为自然沉降率的4倍。薛家岛潮间带沉积物的临界侵蚀速率为 17.4～ 2 0 .4 cm/ s。沉积物的稳定性与所测生物因子的关系不密切 (P>0 .0 5 )。作者推测两个断面中潮站位沉积物的相对易侵蚀性 ,可能是由于此处环境受到某些大型动物及高潮带人工养殖带来的扰动所致  相似文献   

Contribution of benthic and epiphytic diatoms to clam and oyster production in the Akkeshi-ko estuary   总被引：1，自引：0，他引：1  

Ma’ruf Kasim  Hiroshi Mukai 《Journal of Oceanography》2006,62(3):267-281

The species composition and dynamics of phytoplankton in the water column and its contribution to clam, Ruditapes philippinarum, and oyster, Crassostrea gigas, production were studied in the Akkeshi-ko estuary, eastern part of Hokkaido, Japan. A total 128 taxa of diatoms were identified, with 103 and 102 species occurring on the surface sediments and in the water column, respectively. Amphora sp., Bacillaria paradoxa var paxilifer, Cocconeis scutellum, Navicula sp., Nitzschia sigma, Paralia sulcata, Rhoicosphenia curvata, Synedra ulna and Thalassiosira sp. were most common and dominant in all stations in both water column and surface sediment. Benthic diatoms were most dominant in both water column and surface sediment. The species composition of epiphytes was, in part, similar to diatom assemblage of the water column and also to that of the surface sediment. The benthic and pelagic ratio in the diatom assemblage of the water column was very high. Benthic diatoms were able to resuspend into water column by turbulence stimulated by wind. Chlorophyll a concentration in the water column increased as wind speed increased. Seventy and 67% of the gut contents oysters consisted of benthic diatoms in 2003 and 2004 and also 78 and 87% of clams in 2003 and 2004, respectively. The availability of benthic and epiphytic diatom assemblages contributes significantly to food resources for clam and oyster mariculture due to resuspension by disturbance in the Akkeshi-ko estuary.  相似文献   

利用虾池排出水养殖菲律宾蛤仔的研究   总被引：3，自引：0，他引：3  

沈国英  黄凌风 《台湾海峡》1992,11(2):180-184

本文报道了福建泉州市晋江县金井垦区利用虾池排出水试养匪律宾蛤仔(花蛤)的结果。垦区排水渠道具有丰富的饵料生物和适宜的流水条件,饲养3个月的花蛤个体平均重量从1.5g增至6g。每亩毛产量可达2756kg。体重(W)相对月增长率与体重呈负相关(R_fW=1.028—0.405lnW)。调查结果还表明,这种花蛤养殖方式可大大地降低虾池排出水的有机质含量,从而减轻其邻近内湾的有机质污染压力。  相似文献