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1.
We determined that growth differences among coral fragments transplanted for restoration were influenced by both source population and environmental factors. In two common garden experiments, storm‐generated fragments of Acropora palmata were transplanted from two source populations in the British Virgin Islands to a restoration site (a ‘common garden’) that lacked A. palmata. In the first experiment, colonies from different sources grew at different rates in the first year after transplanting, suggesting either genetic differences among source populations or enduring acclimation to conditions at the source site. No differences in growth among source populations were detected in the second common garden experiment. To isolate environmental effects on growth, we subdivided fragments from three source populations to create genetically identical pieces that were attached separately at both source and restoration sites. Genetically identical pieces from all source populations grew slightly faster at their source than at the restoration site, implying a subtle home‐site advantage. Overall, our results suggest that matching environmental conditions at source and restoration sites may increase the success of restoration projects.  相似文献   

2.
Species traits that carry adaptive advantages such as reproductive timing and stress resilience may differ among populations. Knowledge and consideration of these traits should, therefore, be integrated into conservation efforts that include long‐term persistence of species. To test for adaptive differences between Olympia oyster, Ostrea lurida, populations a reciprocal transplant experiment was carried out monitoring survival, growth and reproduction using three established populations of O. lurida within Puget Sound, WA, USA. Performance differed for each population. Ostrea lurida from Dabob Bay had the highest survival at all sites but the lowest reproductive activity and growth. Oysters from Oyster Bay demonstrated the greatest proportion of brooding females at a majority of sites with moderate growth and survival. Together these data suggest the existence of O. lurida population structure within Puget Sound and provide information on how broodstock should be selected for restoration purposes.  相似文献   

3.
A comparison was made of population of the economically important cockleAnadara (=Scapharca)broughtoni (Bivalvia, Arcidae) inhabiting different areas of the Razdolnaya River estuary at the head of Amurskii Bay (Peter the Great Gulf, East Sea). Also, changes in cockle population density and structure, as well as in cockle growth rates during the last 20 years were studied. In all years of investigation, the morphometrical parameters and growth rates of cockles were smaller at the sites located close to the River mouth than farther down-estuary. The differences can be attributed to higher concentration of suspended particulate matter, decreased salinity and water temperature, as well as a longer exposure to these unfavorable environmental factors at sites located close to the River mouth, compared to farther sites. For two decades, cockle population density had decreased by almost 30 times at some sites in the River estuary. The main reason for this population decline is commercial over-fishing of the cockle. Besides, for the last 20 years, linear parameters of the cockles in the population decreased approximately by 30% and weight parameters, almost two times. Cockle growth rates also decreased for this period. Evidently, these facts are due to the damaging effect of dredging.  相似文献   

4.
Suction dredging for cockles removes large cockles from tidal flats and may also cause mortality of non-target fauna and make the habitat less suitable for some species. This study examines whether suction dredging for cockles on tidal flats of the Dutch Wadden Sea had affected densities of non-target fauna, directly after fishing and one year later. Densities of non-target fauna in two randomly chosen undredged locations were compared to densities at the surrounding heavily commercially dredged area. A significant negative effect of cockle dredging on densities of 0-group Macoma balthica was observed and this effect persisted one year after dredging. The dredged area appeared to be less suitable for settlement of mussels Mytilus edulis. No significant effects of dredging on the mudsnail Hydrobia ulvae and on 0 and 1-group C. edule were found. For the mobile young Macoma balthica it seems unlikely that the effect found after one year was still due to the mortality caused by dredging and this suggests that the habitat was less suitable as a consequence of dredging. Thus, even in the highly dynamic ecosystem of the Wadden Sea, effects of bottom disturbance by cockle dredging may persist after one year.  相似文献   

5.
The cordgrass Spartina anglica is an introduced species that tends to invade sheltered sand and mudflats, at the upper low marsh level. In Arcachon Bay, a lagoon in South West of France, the cordgrass can also replace Zostera noltii beds. The consequence of cordgrass presence on macrobenthic fauna was estimated and compared to adjacent habitats (bare sands, Z. noltii sea grass beds) during one year. The communities of the three habitats were characterised by low species richness, low abundance and biomass (when Hydrobia ulvae, 90% of abundance, is not considered) and high seasonal stability. The infaunal assemblages were particularly homogeneous between habitats without any characteristic species.Cordgrass eradication experiments were performed and zoobenthic recolonisation was observed the following year. Modifications in benthic fauna were observed on epifauna only.These results highlight the limited structuring effect of habitat heterogeneity at high tidal levels and in soft-bottom sediments where desiccation becomes the dominant factor determining infauna community structure.  相似文献   

6.
Paphies donacina (Spengler, 1793) populations were surveyed at 11 low tide sites on surf beaches along Pegasus Bay, Canterbury, New Zealand, during summer 1998. Random sampling was not feasible. At the non‐random sites chosen the average number of tuatua per 5 m of shoreline ranged between 0.1 and 62. Total wet weight biomass m‐2 was highest at the southern sites in the Bay. There were site‐related differences in length frequency distributions of tuatua populations. Northern populations included a wide length range and southern populations were dominated by larger bivalves. Average shell length increased significantly with distance south, being close to 40 mm at Waikuku and 80 mm at Taylors Mistake. The shell length: width and weight relationships were similar for tuatua collected over the whole geographic range. Average dry weight condition index varied significantly between sites (ANOVA F= 23.3, d.f. = 10, 329) depending on the length distribution of the contributing population. Where populations included a wide length range the condition index was positively correlated with shell length but in populations dominated by larger bivalves there was either no relationship or a negative relationship with shell length. Juvenile tuatua were found at average densities between 81 and 1200 m‐2 at all sites except Taylors Mistake. The mean length of recruits ranged from 2.2 to 3.1 mm and shell length was independent of both juvenile and adult density. These results are discussed in relation to the environmental and other factors thought to influence population structure and recruitment of tuatua in Pegasus Bay.  相似文献   

7.
Seasonal dynamics of Zostera noltii was studied during 1984 in Arcachon Bay, France. In this Bay, Z. noltii colonizes 70 km2, i.e. approximately 50% of the total area, while Z. marina occupies only 4 km2. Densities and length of vegetative and generative shoots and above-ground and below-ground biomasses were monitored in four meadows which differed according to their location in the Bay, tidal level and sediment composition. Three of these meadows were homogeneous, well-established beds whilst the fourth was under colonization and patchy. Shoot densities and maximal below-ground biomass were lower in the inner silty seagrass bed than in the sandy meadows located in the centre of the Bay. Maximal above-ground biomasses were similar in the two population types. In the well-established beds, vegetative shoot densities, above-ground and below-ground biomasses showed a unimodal pattern with minima in winter (4000 to 9000 shoots·m−2, 40 to 80 g DW·m−2, and 40 to 60 g DW·m−2, respectively) and maxima in summer (11000 to 22000 shoots·m−2, 110 to 150 g DW·m−2, and 140 to 200 g DW·m−2, respectively). Reproductive shoots were observed from the beginning of June until the end of September, except in the colonizing bed where they persisted until December. Furthermore, in the latter, maximal reproductive shoot density was higher (2600 shoots·m−2) than in the established beds (650 to 960 shoots·m−2). The total production of Z. noltii in Arcachon Bay was estimated to approximately 35.6·106 kg DW·y−1 (19.4·106 kg DW·y−1 for above-ground parts and 16.2·106 kg DW·y−1 for below-ground parts).  相似文献   

8.
The venerid clam Ruditapes philippinarum is the most prominent suspension-feeding bivalve inhabiting muddy intertidal seagrass beds in Arcachon Bay (SW France). It is exploited by fishermen, and Arcachon Bay ranks number one in France in terms of production and total biomass of this species. Previous studies revealed a decrease in the standing stock of R. philippinarum since 2003 and unbalanced length–frequency distributions with a lack of juveniles and of adults > 40 mm. Consequently, the population dynamics of this bivalve were studied at four intertidal sites and one oceanic site in Arcachon Bay. As clam size structure did not allow classical dynamics computations, field monitoring was coupled with field experiments (tagging–recapture) over two years. Monitoring of condition index and gonadal maturation stages highlighted a high variability in spawning number and intensity between sites. Recruitment events in the exploited area varied spatially but with uniformly low values. Von Bertalanffy Growth Function (VBGF) parameters (K, L∞) were determined using Appeldoorn and ELEFAN methods. In the exploited sites in the inner lagoon, K was relatively high (mean = 0.72 yr? 1) but L∞ was low (mean = 41.1 mm) resulting in a moderate growth performance index (Φ′ = 2.99). Growth parameters were not correlated with immersion time and L∞ was different between sites. Comparison of mortality coefficients (Z) between cage experiments and field monitoring suggested that fishing accounts for 65–75% of total adult mortality. Low recruitment, a low growth rate and a normal mortality rate led to low somatic production (4.1 and 8.7 g Shell-Free Dry Weight (SFDW) m? 2 yr? 1) and an annual P/B ratio from 0.44 to 0.92 yr? 1. Under current conditions, the possibility of a sustainable population in Arcachon Bay will strongly depend on recruitment success and fishing management.  相似文献   

9.
基于线粒体COI序列莱州湾单环刺螠遗传多样性分析   总被引：1，自引：1，他引：0  
为系统地了解莱州湾单环刺螠(Urechis unicinctus)遗传多样性,作者基于线粒体COI序列利用基因测序技术研究了莱州湾3个单环刺螠不同群体的遗传多样性。实验结果显示,84个莱州湾单环刺螠样本有变异位点数125个,其中包括43个单一变异位点,82个简约信息位点;48个单倍型,单倍型多样性0.977;核苷酸多样性指数0.01048;平均核苷酸差异数量13.725;莱州湾单环刺螠遗传多样性水平较高;个体聚类并没有体现出和地理位置相关。  相似文献   

10.
Bivalve populations from inshore waters often accommodate a diverse trematode fauna that may have a variety of effects on host specimens. In particular, larval trematodes that grow or reproduce within their host are known to be severe pathogens, whereas trematodes utilising bivalves only for encystment are thought to be relatively benign. Yet this may depend on the environmental conditions, and it can be expected that such trematodes in concert with other stress agents can be detrimental to host organisms. To examine the impact of such larval trematodes on hosts subjected to stress, we studied the digenetic trematode Himasthla elongata and one of its second intermediate hosts, the bivalve Cerastoderma edule. Experimentally infected cockles and non-infected cockles were exposed to oxygen depletion, whereupon we measured their burrowing ability and survivorship. After 30 h of hypoxia, the survival of infected cockles was significantly reduced compared to non-infected cockles, whereas no effect of parasites on cockles under normoxic conditions was found. In addition, parasites tended to reduce the burrowing ability of cockles exposed to hypoxia but the effect was not clear. The effect of parasites and possible ecological consequences are discussed and it is suggested that the combined effects of parasites and oxygen deficiency may explain some hitherto unexplained cases of mass mortalities in bivalve populations.  相似文献   

11.
Abstract. The population densities, spatial distributions, size frequencies, growth rates, longevity and reproductive activities of sub‐populations of the sea urchin Lytechinus variegatus were investigated over a two‐year period. Sea urchins were examined in three habitats in Saint Joseph Bay, Florida, which is within the northern limits of their distribution. Densities of sea urchins, which ranged as high as 35 individuals ·?2, fluctuated seasonally at all sites and were higher in seagrass beds comprised of Thalassia testudinum than Syringodium filiforme or on a sand flat. A cold front caused large‐scale, catastrophic mortality among adult, and especially juvenile, sea urchins in nearshore habitats of the Bay in the spring of 1993, leading to a dramatic decline in sea urchin densities at the Thalassia seagrass site. The population recovered over 6 months at this site and was attributable to immigration of new adults. Juvenile recruitment displayed both interannual and site‐specific variability, with recruitment being highest in seagrass habitats in fall and spring. The most pronounced recruitment event occurred in fall 1993 at the Thalassia site. Spatial distributions of adult individuals ascertained monthly never varied from random in the seagrass beds (T. testudinum and S. filiforme) or during spring, summer or fall months on the sand flat. Nonetheless, aggregations of adult sea urchins were observed on the sand flat in the winter months and were associated with patchy distributions of plant food resources. Juvenile sea urchins (< 25 mm test diameter) exhibited aggregations at all sites and 67 % of all juveniles under 10 mm test diameter (91 of 165 individuals observed) were found under the spine canopies of adults. Measurements of the inducibility of spawning indicated peak gametic maturity in all three sub‐populations in spring and summer. Gonad indices varied between habitats and years, but distinct maxima were detected, particularly in spring 1993 and late summer 1994. The mean gonad index of individuals at the Syringodium seagrass site was 2‐ to 4‐fold higher than the other sites in spring 1993 and gonad indices were much higher at all sites in spring of 1993 than 1994. Estimates of growth based on changes in size frequency cohorts coupled with measurements of growth bands on lantern demipyramids indicated that L. variegatus in three habitats of Saint Joseph Bay have similar growth rates and attain a mean test diameter of approximately 35 mm in one year. In contrast to populations within the central biogeographical range of the species, which may attain test diameters up to 90 mm, the largest individuals recorded in Saint Joseph Bay were 60 mm in test diameter, and almost all individuals were no more than 45 mm in test diameter or two years of age. The demographics of L. variegatus in the northern limits of their distribution appear to be strongly influenced by latitudinally driven, low‐temperature events and secondarily by local abiotic factors, especially springtime low salinities, which may negatively impact larval development and recruitment.  相似文献   

12.
The benthic bivalve, Anadara trapezia, was collected from a 'clean' reference site and transplanted along a suspected trace metal contamination gradient in Lake Macquarie, NSW. At monthly intervals, Zn, Se, Cd and Pb concentrations were measured in the surficial sediments and whole tissues of the cockle as well as their physiological condition (Scope for Growth). Zinc, Cd and Pb concentrations in sediments decreased together, southward, with the highest concentrations in the Cockle Bay area, suggesting that this is the main source of contamination. Zinc, Cd and Pb concentrations were near or above [ANZECC/ARMCANZ, 2000. National water quality management strategy paper 4. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand. pp. 3.5.-1-3.5-10] sediment quality guidelines at Cockle Creek, Warners Bay and Koorooa Bay. Significant differences in trace metal concentrations could not be attributed to grain size or Fe concentration differences. Se concentrations were highest in fine grain Fe rich sediments of Whiteheads Lagoon, and likely to be associated with power generation operations. Trace metal concentrations did not vary significantly over time. Zinc, Cd and Pb concentrations in the tissues of A. trapezia followed a similar pattern to that of sediments. Zinc and Pb concentrations in cockles and sediments were highly correlated, indicating significant exposure-dose relationships. Selenium concentrations in the tissues of A. trapezia were higher after transplantation to the lake, however, Se concentrations were similar in all transplanted cockles, indicating that Se in contaminated sediments is not the major source of Se to organisms. There was a decline in the physiological condition of A. trapezia transplanted to Lake Macquarie after a 90-day-period with marked differences in clearance rates and respiration rates at some locations and absorption efficiencies at all locations. The mean Scope for Growth value at the most contaminated location, Cockle Bay, was markedly lower than at other locations. A significant Zn exposure-dose response relationship indicates that Zn bioaccumulation is occurring in response to sediment contamination. A significant Cd exposure-response relationship indicates that Cd may be influencing the health of cockles. Significant Pb exposure-dose, exposure-response and dose-response relationships indicate that Pb probably is affecting the health of cockles in Lake Macquarie. Therefore, Zn, Cd and Pb concentrations in sediments are likely to be affecting the health of cockles in Lake Macquarie.  相似文献   

13.
Seasonal and spatial variations of phytoplankton primary production were studied using a high frequency sampling strategy in the external (ENW) and internal (INW) part of Arcachon Bay, during 2002 and 2003. In order to better assess the availability of nutrients and their relationship with phytoplankton primary production, nutrient variability was studied in relation to environmental conditions and phytoplankton production. During winter, when primary production rates were the lowest, nutrient concentrations were maximal but did not show excessive levels compared to highly urbanised areas. Seasonal and spatial variations of nutrient concentrations (especially DIN-nitrate + nitrite + ammonium- and Si) were largely influenced by Leyre River loads coupled with high tidal exchange with the Atlantic Ocean creating a nutrient gradient between the INW and ENW. By February, diatom growth leads to an early severe nutrient depletion in the entire bay. Examination of nutrient ratios showed that the potential limiting nutrient during spring was P in 2003, and Si in 2002. During summer 2003, N and Si concentrations reached their lowest values, and nutrient ratios revealed a N-deficient environment, more pronounced in the INW. The high Si:N ratios during this period might be explained by (1) important N-uptake by all autotroph communities and (2) benthic-pelagic coupling with high Si regeneration. This study shows that nutrient levels in Arcachon Bay seem to play an important role in the control of phytoplankton primary production rates during the productive period and explain their spatial, seasonal and inter-annual variability. Our estimates of annual integrated phytoplankton primary production (103 g C m−2 y−1) place this bay within the low to moderate phytoplankton primary production systems.  相似文献   

14.
Tidal conditions differently influence inter‐tidal organisms in terms of general physiological and metabolic responses. In this study we investigated the morphological response in shells of Mytilus galloprovincialis native to different micro‐tidal coastal environments in the Northern Adriatic Sea. Our purpose was to highlight the ecophenotypic variability across tidal levels and to elucidate how tidal currents and waves produced by anthropogenic activities may play a part in modulating shell morphology. Three sampling sites were selected: an open‐sea area 15 km off‐shore and two sites within the lagoon of Venice, the first near one of its three inlets, and the other one in the proximity of Venice city centre. At each sampling site, organisms were seasonally collected at different depths within their vertical zonation, either in the inter‐tidal zone – i.e. at both the highest and lowest tide zonation limits, and subtidally. The mussel shells were analysed by investigation of their morphometric relationships (height/length and width/length ratios) and by elliptic Fourier analysis of the shell contours. Shell thickness and condition index were also evaluated for a better comprehension of energy allocation/partitioning. Estimates based on long‐term measurements, visual observation, wind statistics and wave growth laws allowed an evaluation of the forces acting on shells. At the open‐sea site, the observed phenotypic variability of both shell shape and thickness was clearly related to the tidal vertical zonation. At the two lagoon sites, the currents generated by tidal flow through the inlet and the waves caused by the frequent passage of boats influenced both shell shape and thickness. A trade‐off between protection and growth was apparent along the tide gradient, as emphasized by the differences in the partitioning and allocation of energy between shell and flesh production.  相似文献   

15.
采用PCR扩增和序列测定等技术,对脊尾白虾3个野生群体共计58个个体的线粒体16SrRNA基因片段进行初步研究。结果表明,在获得的长度为509bp核苷酸序列中,共检测到7个变异位点、8种单倍型,除象山湾群体外其它两个群体遗传多样性水平都较低。AMOVA分析表明,象山湾与莱州湾群体有显著的遗传差异,其余群体间的遗传差异不显著。另外,将本研究所得序列与GenBank中长臂虾科11个种的16SrRNA基因片段序列进行比较后,发现其聚类关系与传统分类略有不同,并依据16SrRNA序列变异百分比推测了长臂虾科12个种的大致分化时间。  相似文献   

16.
秦皇岛海域海流特征及规模化养殖对其影响的观测研究   总被引：1，自引：1，他引：0  
秦皇岛海域是辽东湾与渤海中部及渤海湾进行物质和能量交换的重要通道。本文基于海床基观测平台获取的夏秋季海流连续观测资料，运用调和分析和滤波等方法对该海域的海流特征及其对规模化养殖的响应进行了研究。结果表明:秦皇岛海域最显著的潮流是M2分潮流，其最大流速介于20.0~36.9 cm/s之间，远小于辽东湾东部海域M2分潮流最大流速；秋季秦皇岛海域余流流速介于0.2~2.5 cm/s之间，整体上较辽东湾东侧海域余流弱，辽东湾底层可能存在逆时针的弱环流系统；夏季秦皇岛海域M2和K1分潮流的最大流速均大于秋季；养殖活动对余流影响较大，养殖区中部A7、A8站余流的垂向平均流速比养殖区边缘A6站分别减小76%和18%左右。  相似文献   

17.
采用聚丙稀酰胺凝胶电泳技术对福建平潭岛、浙江象山港、江苏海州湾和辽宁辽东湾4个海区菲律宾蛤仔(Ruditapes philippinarum)野生群体的生化遗传特征进行了分析.结果表明,菲律宾蛤仔4个群体的多态位点比例为62.5%～75.0%,平均杂合度观测值在0.274 3～0.338 7之间,与平均杂合度期望值相近;平均有效等位基因数在1.489 1～1.632 5之间,遗传变异水平较高;杂合子缺失不显著.比较群体间的遗传分化指数和群体每代迁移数发现,平潭岛、象山港和海州湾3个群体间的遗传分化不显著,而辽东湾群体与3个群体间出现遗传差异.聚类分析同样表明,平潭岛群体首先与象山港群体聚类,再与海州湾群体相聚,最后与辽东湾群体相汇.讨论了杂合子缺失不显著原因和群体间遗传分化机制.  相似文献   

18.
为研究东海区厚壳贻贝(Mytilus coruscus)遗传多样性,以厚壳贻贝F mtDNA D-loop为标记,对浙江省舟山嵊山岛、宁波渔山岛、温州南麂岛、福建省宁德湾和莆田南日岛五个海区的厚壳贻贝群体进行了遗传分析。结果表明,厚壳贻贝各群体的遗传多样性差异不明显,在5个群体中,宁德群体的遗传多样性相对最丰富;将5个群体作为一个整体时,呈现出较高的单倍型多样性和较低的核苷酸多样性。对厚壳贻贝5个群体间的遗传分化系数(Fst)和基因流(Nm)进行检测,结果显示群体间Fst值都很低,但Nm值都很高(Nm绝对值1),表明5个群体间存在丰富的基因交流。但宁德群体与浙江沿海的3个群体(嵊山、渔山、温州)的Fst值相对较高,且差异显著(P0.5),表明宁德群体与这3个群体间出现遗传分化。本研究旨在为海洋经济贝类资源的保护管理提供理论依据。  相似文献   

19.
The effects of tidal flushing on the abundance, productivity, and community structure of phytoplankton in response to eutrophication were examined every 2–3 months for more than 2 years in Tapong Bay, a tropical lagoon with only 1 tidal inlet connecting it to the sea in southern Taiwan. Water flushing time ranged from 4–12 d (8–25% d−1) in the outer region subject to fast flushing to 8–24 d (4–12% d−1) in the inner region subject to poor flushing. Chlorophyll a, cell number, and gross production (GP) rate of phytoplankton were significantly greater in the inner region than in the outer region. However, while GP rate was normalized by chlorophyll a (PB) and was expressed as photosynthetic intensity, no significant differences were detected among the study sites. These parameters exhibited a unimodal seasonal pattern across all study sites, with greater values in summer and lower values in winter. No significant differences in species richness or Shannon–Wiener diversity were detected among the study sites. Nevertheless, diversity indices were significantly higher in winter and lower in summer. Classification of phytoplankton communities showed that the grouping patterns were primarily determined by sampling time. Ordination by non-metric multidimensional scaling (MDS) revealed a clear temporal continuum of changes in species composition across all study sites, suggesting that the communities were primarily structured by time, but that it was little affected by study site. Analyses of similarities (ANOSIM) showed that phytoplankton communities sampled in winter could be separated from those in summer, but others were barely separable at all. In summer, the most frequently observed species were the diatom Skeletonema costatum and the cyanobacterium Oscillatoria sp., and these shifted to the diatoms S. costatum and Cylindrotheca closterium in winter. Our results suggest that tidal flushing is an important factor for regulating responses of phytoplankton abundance and productivity to eutrophication in tropical lagoons, but the community structure was little affected due to horizontal mixing by the tidal circulation.  相似文献   

20.
采用二维非线性运动方程和连续方程组，以多个分潮同步输入，做耦合数值模拟，进行潮汐数值预报。结果表明，K1潮波等振幅线分布与历史潮波图明显不同，此线呈舌状向北伸展，特别在湾的南部海域，其中央区振幅很小，10cm等振幅线可以伸至北纬19°以北。O1分潮的分布与K1分潮类似；北部湾北部以全日潮为主，湾的南部潮汐性质指标数2．0的等值线呈舌状向湾内神，两侧为不正规日潮，中间为不正规半日潮。4．0等值线向北推移，在19°N以南中央海区预报结果与前人的结果不同；南部海区中央一带潮差很小，最大可能潮差不超过2m，这种分布与前人结果有较大差异。  相似文献   

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