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1.
Rhabdosargus holubi is a small (maximum weight=2.4?kg) yet important fishery species in the estuaries of the south-east coast of South Africa. Little is known of its biology and specifically its growth rate, which is essential for sustainable management of the fishery. We examined and counted the opaque zones in the sectioned otoliths of 134 R. holubi to determine its age and growth parameters. The otoliths from two recaptured fish marked with oxytetracycline confirmed that one opaque zone was deposited annually. The species reached a maximum age of 18 years and growth was adequately described by a von Bertalanffy growth function of the form: Lt = 358.1 (1 – e?0.24(t+0.77)) mm fork length. There were no significant differences between any of the male and female growth parameters (likelihood ratio test: p = 0.3). The growth was slow (omega index: ω = 86.56); however, despite this, the unique life history of R. holubi may provide a degree of resilience to heavy fishing pressure in estuaries. 相似文献
2.
选择珠江口南沙区两处典型的以大面积人工种植红树植物无瓣海桑(Sonneratia apetala)为主的感潮河涌,进行湿地区域中的浮游动物研究。于2011年5月和11月对开放性河涌湿地14涌(A区)和封闭性河涌湿地19涌(B区)中的浮游动物进行调研,从种类数和丰度、污染指示种和优势种、营养指数E和污染指数A等方面对浮游动物进行群落结构和功能的分析,并以此对湿地水质和无瓣海桑的净化能力进行评价。结果表明,B区林内原生动物总丰度可达106ind/L数量级,7种丰度优势种均为纤毛虫类,优势种哑铃中缢虫(Mesodinium rubrum),1种赤潮原生动物种类,单种丰度在春秋两季可达1.8×105ind/L、5.1×105ind/L。桡足类、枝角类在春季B区林内丰度最高,分别可达576ind/L和46ind/L,显示春季可能为其繁殖季节。轮虫相对不耐污染生境。指数E和指数A均远高于判断阈值。提出了二项浮游动物的富营养判断标准和二条原则。据此判断,B区湿地存在极重的有机污染现象,主要可能与无瓣海桑林内凋落物量较大或根系分泌物的作用且林内水流不畅有关。 相似文献
3.
《African Journal of Marine Science》2013,35(1):15-19
Eight spotted ragged-tooth sharks Carcharias taurus (95–248,4 cm total length TL), ranging in known age from 0 to 16,6 years, were used to investigate the growth of the species in captivity. Total length was measured by a standard technique in some cases and estimated from photographs in others. The accuracy of the photographic technique was evaluated and found adequate for captive growth studies in sharks. Parameters of various growth models were estimated by non-linear regression and the special Von Bertalanffy growth model provided the best fit to the age-length data of the combined sexes. The parameters of the special Von Bertalanffy model are L ∞ = 249,8 cm TL, K = 0,233·year?1, t 0 = ?2,238 years. Longevity of captive C. taurus is greater than 16,6 years. 相似文献
4.
本文基于2018年5月（春季）、8月（夏季）、11月（秋季）和2019年1月（冬季）季度航次调查,采用冗余分析（RDA）和Bray-Curtis相似性聚类分析方法,讨论了烟台四十里湾及其邻近海域网采浮游植物丰度、优势种组成、多样性指数、均匀度指数的分布特征以及浮游植物与环境因子的关系。本年度调查共发现浮游植物4门69属116种,其中硅藻门50属85种,甲藻门15属27种,着色鞭毛藻门3属3种,未定类1种（三深碎裂藻,Ebria tripartita）。浮游植物丰度在8月份达到年度最高值,为2.89×108cells/m3,秋季次之,春季最低,春、秋、冬季浮游植物丰度均为~105cells/m3。硅藻门在4个季节中均占绝对优势,除春季出现甲藻门（夜光藻）优势种外,其余季节浮游植物优势种均为硅藻门。相邻季节浮游植物优势种更替明显,未出现4个季节共有的优势种。浮游植物多样性和均匀度指数均在夏季达到最低值,分别为1.58和0.31。RDA排序分析显示,不同季节影响浮游植物群落分布的环境因子不同,总体来讲,温度、溶解氧浓度、SiO32-浓度和NO3-浓度对浮游植物的丰度和平面分布有显著影响。Bray-Curtis相似性聚类结果显示,2018年每个季节浮游植物群落分布均可分为两个类群,其分布受营养盐分布的影响较为明显。 相似文献
5.
MW Farthing AC Winkler K Anderson S Kerwath C Wilke WM Potts 《African Journal of Marine Science》2018,40(2):187-196
The hottentot seabream Pachymetopon blochii is a small-sized (maximum 2.67 kg) sparid endemic to southern Africa. It is an important target in South Africa's Western Cape traditional linefishery, particularly in the absence of more valuable pelagic species (such as Thyrsites atun and Seriola lalandi). In 2000, South Africa's linefishery was declared to be in a state of emergency, and commercial fishing effort was consequently reduced by 70%. A subsequent increase in stock biomass and intraspecific competition, coupled with environmental changes, were hypothesised to have thereafter altered the growth rate of hottentot, from 2000 to 2010. This study aimed to revise outdated age–growth models for the hottentot by using modern techniques (sectioned otoliths), and to compare age–growth relationships before and after the declared linefish state of emergency. The maximum age observed was 19 years, with no difference in the growth rate between sexes (p = 0.39–0.43) or time-periods (p = 0.96). Although the growth rate did not change, there is evidence that the age structure of the stock changed between time-periods as a result of changes in fishing pressure between 2000 and 2010. The enhanced recent growth model for hottentot, described as Lt = 418.063 (1 – e?0.104(t – [?4.709])) (pooled sexes; n = 206), indicates a considerably slower growth rate for this species than was proposed previously using whole otoliths and has major implications for effective stock management. 相似文献
6.
研究了热带西太平洋雅浦Y3海山冬季和马里亚纳M2海山春季网采浮游植物群落结构,对调查区浮游植物的物种组成、优势种类、细胞丰度以及多样性指数进行了分析。结果表明,两个海山区共鉴定浮游植物4门50属219种,其中硅藻门30属106种,甲藻门17属112种,蓝藻门1属2种,金藻门2属3种。两个航次研究区浮游植物优势种均以链状硅藻如根管藻(Rhizosolenia)、半管藻(Hemiaulus)和角毛藻(Chaetoceros)等属的种类为主,此外太阳漂流藻(Planktoniella sol)、铁氏束毛藻(Trichodesmium thiebautii)以及部分角藻(Ceratium)物种优势度也比较明显。Y3海山区浮游植物细胞丰度介于1.60～16.61 cells/L,平均值为5.02 cells/L; M2海山区浮游植物细胞丰度介于1.36～10.20 cells/L,平均值为4.12cells/L。两个海山区浮游植物细胞丰度的分布趋势均受硅藻影响较大,甲藻细胞丰度相对较低。在属的水平上,角毛藻、根管藻、角藻和半管藻等属的细胞丰度对两个海山区浮游植物总细胞丰度的贡献较大。多样性指数方面, Y3海山区浮游植物群落香农-威纳指数H′(shannon-wiener index)介于3.95～4.69,平均值为4.30; M2海山区浮游植物群落香农-威纳指数介于3.23～4.46,平均值为3.83。两个海山区浮游植物群落多样性指数均处于较高水平,但站位间的变化不明显。目前,关于热带西太平洋海山区浮游植物群落结构的研究还非常缺乏,亟需后续研究的补充。 相似文献
7.
生态浮床原位修复对海水养殖池塘浮游动物群落结构的影响 总被引：2，自引：0，他引：2
利用海马齿生态浮床技术原位修复海水养殖池塘,通过周期性监测试验池塘浮游动物群落结构种类组成、密度和生物多样性变化趋势,分析了浮游动物群落结构变化和养殖池塘水质改善之间的响应关系。结果表明:(1)生态浮床对养殖池塘水质和沉积环境都表现出良好的改善功能,表现为试验区较对照区,水体透明度明显增加,而TN、NH_(4-)~+N、TP、COD和底泥有机碳等污染物浓度均降低,其中TN、COD和底泥有机碳呈现出显著性降低(P0.05);(2)试验区浮游动物的种类相比对照区的34种增加到40种,趋于丰富;各次采样中试验区浮游动物的密度均高于对照区,平均由13559ind./L增加到15933ind./L;试验区的Shannon-Wiener多样性指数(H￠)和Margalef种类丰富度指数(D)均高于对照区,分别由初始的0.94和1.05提高到1.01和1.57。 相似文献
8.
《African Journal of Marine Science》2013,35(4):585-591
Lichia amia is an important coastal recreational fishery species with a cosmopolitan distribution in the eastern Atlantic. In southern Africa, it is distributed from southern Angola to northern KwaZulu-Natal in South Africa. A recent biological survey revealed differences between Angolan and South African individuals suggesting that they may represent separate stocks. As fishery management decisions should be based on accurate knowledge of population structure, an initial survey of the genetic substructuring of L. amia was conducted on samples collected in southern Angola and South Africa. Assessment of genetic diversity and population structure was conducted using a fragment of the mitochondrial Control Region. Obtained genetic diversity levels were within the expected range for marine teleosts (h = 0.867, π = 0.007), and two deeply divergent (southern Angolan and South African) populations were identified (average φ ST = 0.78) across the Benguela Current system. These results suggest that Angolan and South African L. amia should be managed as two independent stocks. This work represents the first assessment of population genetic substructuring across the Benguela Current of a valuable coastal fishery resource, and has application for future fisheries management. 相似文献
9.
《African Journal of Marine Science》2013,35(1):169-179
Age and growth of West Coast steenbras Lithognathus aureti, sampled from two separate populations (northern and southern) along Namibia's coast, was determined using sectioned otoliths, and the results were validated using mark-recapture data. For both populations, the special three-parameter Von Bertalanffy growth model described growth adequately. Growth of the southern population was described by the equation Lt = 73.556(1?e?0.065(t+3.92)) cm and for the northern population by Lt = 84.601(1?e?0.088(t+2.756) cm. Environmental conditions, such as difference in sea surface temperature, density-dependent competition for food, or biochemical genetic variations between the two populations, are possible reasons for the geographic differences found in the growth rates and length-at-age. Slow growth and longevity are characteristics of West Coast steenbras that make it extremely susceptible to overfishing; careful management of the resource is therefore essential. 相似文献
10.
Erik E. Cordes Derk C. Bergquist Meredith L. Redding & Charles R. Fisher 《Marine Ecology》2007,28(1):160-168
Seepiophila jonesi is a vestimentiferan tubeworm (Siboglinidae: Polychaeta) inhabiting the cold seeps of the upper slope of the Gulf of Mexico. It commonly co‐occurs with Lamellibrachia luymesi, which is among the most long‐lived non‐clonal animals known. The growth pattern of S. jonesi is best described by a model including a size‐specific probability of growth and an average growth rate that does not vary with individual size. This model, based on growth data from in situ staining and collection approximately 1 year later, predicts that S. jonesi is very slow growing and may attain ages comparable with L. luymesi. The efficacy of this model in describing L. luymesi growth rate was assessed, but the previously employed model of declining growth rate with individual size provided the better fit to the empirical data. Comparisons of both S. jonesi and L. luymesi growth rates among sites and among aggregations within a site indicate that there is some degree of habitat variability contributing to differences in growth rates. However, position of the anterior end of the worm within an aggregation did not have a significant effect on growth rate in comparisons among groups of L. luymesi from different distances from the center of an aggregation. The evolution of longevity in these species of vestimentiferans was favored by the relative stability of the seep habitat and sulfide sources, in contrast to the hydrothermal vent environment inhabited by relatively short‐lived and fast‐growing vestimentiferan species. 相似文献
11.
凡纳滨对虾(Litopenaeusvannamei)是世界也是我国的主导对虾养殖品种,产业的发展离不开良种的支撑,分子育种被认为是加快良种选育的最有效途径,而目标性状相关分子标记的开发是发展分子育种的基础。研究主要目的是建立一种适用于凡纳滨对虾等水产经济物种的高通量候选基因关联分析方法,并在抗弧菌相关标记筛选中进行应用。首次将三代靶向测序技术用于对虾候选基因的基因分型,在抗弧菌性状候选基因LvPI3K的全长序列上发掘到91个SNP位点,通过关联分析鉴定到21个与抗弧菌性状显著相关的SNP标记(P0.05),利用Sanger测序证实了三代靶向测序技术分型结果准确可靠。所建立的基于三代测序的靶向分型方法为凡纳滨对虾等水产动物提供了一种高效、低成本的基因分型方法,所发掘的抗弧菌性状相关位点对开展凡纳滨对虾抗弧菌性状分子育种具有一定指导意义。 相似文献
12.
Andrew J. Davies Max Wisshak James C. Orr J. Murray Roberts 《Deep Sea Research Part I: Oceanographic Research Papers》2008,55(8):1048-1062
Ecological-niche factor analysis (ENFA) was applied to the reef framework-forming cold-water coral Lophelia pertusa. The environmental tolerances of this species were assessed using readily available oceanographic data, including physical, chemical, and biological variables. L. pertusa was found at mean depths of 468 and 480 m on the regional and global scales and occupied a niche that included higher than average current speed and productivity, supporting the theory that their limited food supply is locally enhanced by currents. Most records occurred in areas with a salinity of 35, mean temperatures of 6.2–6.7 °C and dissolved oxygen levels of 6.0–6.2 ml l−1. The majority of records were found in areas that were saturated with aragonite but had low concentration of nutrients (silicate, phosphate, and nitrate). Suitable habitat for L. pertusa was predicted using ENFA on a global and a regional scale that incorporated the north-east Atlantic Ocean. Regional prediction was reliable due to numerous presence points throughout the area, whereas global prediction was less reliable due to the paucity of presence data outside of the north-east Atlantic. However, the species niche was supported at each spatial scale. Predicted maps at the global scale reinforced the general consensus that the North Atlantic Ocean is a key region in the worldwide distribution of L. pertusa. Predictive modelling is an approach that can be applied to cold-water coral species to locate areas of suitable habitat for further study. It may also prove a useful tool to assist spatial planning of offshore marine protected areas. However, issues with eco-geographical datasets, including their coarse resolution and limited geographical coverage, currently restrict the scope of this approach. 相似文献
13.
光照周期对曼氏无针乌贼(Sepiella japonica)繁殖、性类固醇激素系统及生长性能的调控作用 总被引：2，自引：1，他引：1
养殖条件下的性早熟、个体小型化是影响曼氏无针乌贼(Sepiella japonica)的养殖效益的重要因素。为探讨养殖条件下曼氏无针乌贼性早熟的可能因素,本文探讨了3种不同光照周期(23D:1L;12D:12L;1D:23L)对其繁殖性能及个体生长的影响。结果表明:光照周期对曼氏无针乌贼的繁殖性能总体影响不大,除长光照周期(1D:23L)下,睾酮(T)、雌二醇(E2)等激素水平有较显著的降低外(P0.05),光照对乌贼繁殖时间、性腺重及性腺发育指数等指标均无明显影响。但光照周期对曼氏无针乌贼生长却有明显影响,在胴长、体重、瞬时生长率(IGR)及肥满度等生长指标上均呈现出短光照组中光照组长光照的趋势。短光照组雌乌贼在体重、瞬时生长率和肥满度,雄乌贼在胴长等指标上,均显著优于长光照组(P0.05)。该结果表明光照周期可作为影响曼氏无针乌贼生长性能的重要因素,在今后的养殖条件优化中应加以考虑。 相似文献
14.
Four indexes of species diversity (H''), species richness (d), species evenness (J) and species dominance (D2) are used in this paper to analyse the.characteristics of the benthic faunal community structure in the soft-bottom intertidal zone along the northern coast of the Hang-zhou Bay.The results show a rather simple benthic faunal community structure in the survey area, with the average values of the four indexes from the five transects, namly, H''=2.06, d=3.34, J=0.46 and D2=0.73.Different degrees of the seasonal and regional variations have been observed from each index per transect. 相似文献
15.
采用三因素不完全正交设计方法,通过对细胞密度、干重、叶绿素和可溶性蛋白质含量的测定.确定了N、P源与蛋白酶解物之间的最佳组合,研究碳酸氢铵作为N源、磷酸二氢钠作为P源与动物蛋白酶解物之间的组合对小球藻生长和生化指标的影响.结果表明:(1)动物蛋白酶解物与N、P源间存在互作效应--影响小球藻细胞密度、叶绿素的主要因素分别是P浓度、蛋白酶解物浓度;而N浓度及蛋白酶解物浓度同时对小球藻的蛋白质含量起主要作用;(2)同时添加N 50mg/L、P 4mg/L、蛋白酶解物12ml/L能显著提高小球藻生物量,促进叶绿素和藻体蛋白质的合成(P<0.05). 相似文献
16.
A long-term mark-recapture study was used to assess the movement patterns of surf-zone fishes in the St Lucia Marine Reserve, a marine protected area within the iSimangaliso Wetland Park, a World Heritage Site on the east coast of South Africa. Between 2001 and 2013, 6 613 fish from 71 species, caught by hook and line, were tagged at four sites within and adjacent to a no-take marine sanctuary area. A total of 1 004 (15.2%) recaptures were made from 17 species. The majority (82.4%) of these species displayed station-keeping behaviour, whereas only three were classified as wider-ranging species, and no species with discernible migratory behaviour was observed. Findings for five species with the highest recapture rates, namely Pomadasys furcatus, Epinephelus andersoni, E. marginatus, Dinoperca petersi and Lutjanus rivulatus, are presented in greater detail. Recapture rates ranged from 7% to 50% and time at liberty from 0 to 3 163 days. Individuals of all five species displayed station-keeping behaviour, with the 95th percentile of intra-study-site movements varying between 200 and 1 025 m (linear distance). However, four of the five species also displayed some ranging behaviour and made exploratory excursions ranging from 3.5 to 125 km, in both northerly and southerly directions. The dominance of station-keeping behaviour suggests that the St Lucia Marine Reserve sanctuary zone provides an important refuge for these species, with some export to adjacent areas. 相似文献
17.
Acoustic telemetry and standard tag-recapture were used to determine the home range and residency of juveniles and sub-adults of Diplodus sargus and Diplodus vulgaris in the Ria Formosa (Portugal) coastal lagoon. Maximum time between recaptures for the standard tag-recapture method was 128 days for D. sargus and 30 days for D. vulgaris. The majority of the fish were recaptured in the vicinity of the tagging location. Fish tagged with acoustic transmitters had a maximum period of time between first and last detections of 62 days for D. sargus and 260 days for D. vulgaris. Minimum convex polygons areas ranged between 148?024 m2 and 525?930 m2 for D. sargus and between 23?786 m2 and 42?134 m2 for D. vulgaris. Both species presented a high residency index between first and last detections. Two D. sargus tagged with acoustic tags were recaptured by fishermen outside the coastal lagoon at distances of 12 km and 90 km from the tagging position, providing evidence that this species leaves the Ria Formosa during the winter time for the adjacent coastal waters. The results of this study reinforce the importance of Ria Formosa as a nursery for D. sargus and D. vulgaris in the south coast of Portugal. 相似文献
18.
19.
《African Journal of Marine Science》2013,35(1):39-48
The life history of Plesionika edwardsi (Brandt, 1851) around the Canary Islands in the Eastern Central Atlantic was investigated, based on a total of 11 434 shrimps ranging in length between 8 and 40 mm carapace length (CL). The species carries out seasonal migrations; they concentrate in deep water during winter, move shallower in summer and return to deep water again in autumn. Ovigerous females occur throughout the year, but a spawning peak was determined between April and September. The size at maturity for females was approximately 26 mm CL. Shrimp size generally increased with increasing water depth. The growth parameters for males were L ∞ = 25.75 mm CL and K = 0.55 year?1, and L ∞ = 28.28 mm CL and K = 0.66·year?1 for females. The species displays the typical reproductive pattern of tropical pandalids and is dioecious. 相似文献
20.
2011年胶州湾网采浮游植物群落结构及其环境影响因子 总被引：2，自引：1，他引：1
本文于2011年1-12月对胶州湾海域浮游植物进行了周年调查,获得了同步的温盐和营养盐数据,分析了浮游植物丰度、优势种类、多样性指数和季节变化特征及其与环境影响因子的关系。结果表明：共检出浮游植物108种（包括变种和变型）,其中硅藻门34属93种,甲藻门6属14种,金藻门1属1种。浮游植物主要由硅藻和甲藻两大类组成,其中硅藻占绝对优势,全年甲藻/硅藻比均小于0.08。优势种共有35种,夏、冬季优势种交替明显,全年几乎均出现的种类为圆筛藻（Coscinodiscus spp.）,旋链角毛藻（Chaetoceros curvisetus）和中肋骨条藻（Skeletonema costatum）。生态类型主要以广布种、广温近岸种、温带近岸种为主,也出现了少数暖水种和外洋种。浮游植物丰度分别在2月、4月和7月份达到峰值,其中4月全年最高,为591×106cell/m3,2月是次高峰,数量为468×106cell/m3,7月为172×106cell/m3,秋季浮游植物丰度相对较低。本研究结果与胶州湾浮游植物典型双峰型变化不同。浮游植物群落多样性指数平均为2.4,秋、冬季节较高,春、夏季节偏低,水平分布上呈现湾外 > 湾口 > 湾内的趋势,均匀度平均值为0.26,分布趋势与多样性指数基本相同。由此可见,湾外浮游植物群落结构较湾口和湾内更为稳定,温度、硅酸盐、亚硝酸盐、硝酸盐、铵盐和磷酸盐对浮游植物丰度和群落结构存在明显影响。 相似文献