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1.
福建九龙江和东屿地区全新世微型硅藻的初步研究   总被引：3，自引：0，他引：3  
利用透射电镜研究了九龙江口现代潮间带表层沉积物、九龙江地区中全新世剖面和东屿中-晚全新世剖面的微型硅藻(细胞大小为2～20μm)的组成和丰度.共计硅藻12属26种(包括变种).对每个种的生态分布作了描述,并提供了相应的壳面电镜照片.Thalassionema nitzschioides是九龙江口现代潮间带表层沉积物中的优势种;九龙江中全新世地层的优势种为Navicula climacospheniae,Thalassionema nitzschioides;东屿中-晚全新世地层中,Cyclotella striata,Thalassionema nitzschioides是优势种.微型硅藻在各个样品中所占比例都相对较高,最高可达86.7%,表明微型硅藻在沉积硅藻中占有重要的地位.  相似文献   

2.
From the continental shelf of the East China Sea, we have collected and recorded 157 taxa of planktonic diatoms, of which 57 are tropical species, 20 temperate species, 73 widely distributed species and 7 remain to be further investigated for their habitats. Chaetoceros peruvianus f. robusta, Chaet. setoenis, Rhizosolenia alata f. curvirostris and Triceratium campeachlanum are four species recorded for the first time in China.The diatoms flora in the present region is mainly warm-water in nature and is very much similar to that in the South China Sea but differs greatly from that in the Huanghai Sea. Gossle-riella tropica (30°00′ - 32°00′ N, 127°20′ - 128°30′E) and other warm-water floras are present in the waters due to the effect of the Tsushima Warm Current.  相似文献   

3.
Harvest control measures for Namibia and Angola are defined using reference points for spawning biomass, which requires knowledge of spawning potential and dynamics of fishery stocks. The reproductive biology of two species of horse mackerel, Trachurus capensis and Trachurus trecae, in these waters was investigated for spawning distribution in time and space. Samples were collected during two scientific cruises conducted in February and July/August 2007 off the coast of Namibia and Angola. A total of 396 fish ovaries was examined to determine the spawning dynamics of the two species. The ovaries were histologically analysed and their oocyte distributions mapped. The length (TL)–weight relationships of the two species differed significantly. The observed development of oocyte recruitment and absence of a hiatus in the oocyte distribution indicated that these species are indeterminate spawners. Analyses of the data from the NatMIRC database (2001–2004) indicated annual changes in gonadosomatic index (GSI) for T. capensis at different latitudes, but these changes were small. GSI also fluctuated between years and areas, but there were no clear spatial or temporal trends, with averages ≤4.0% at all stations. The GSI of both species was not indicative of the histologically determined development of gonad maturity. Oocyte maturation for T. capensis indicated that smaller and younger fish spawn first. Batch fecundity (F) for T. trecae was best described by F = 4 986 TL (cm) – 99 645 (r 2 = 0.83). This study provided the first analyses of oocyte development in time and space for the two species in the region.  相似文献   

4.
The most extensive and thickestHalimeda bioherms reported from modern seas occur along both open and protected margins of Kalukalukuang Bank, eastern Java Sea (Indonesia). Seismic profiles suggest these features average 20 to 30 m thick (maximum 50 m) and developed over large areas by coalescence of individual mounds. Bioherm morphologies range from numerous small mounds ( 10–20 m diameter) through hay-stack features ( 100 m diameter) to broad swells. Some modern bank bioherms display surface forms that appear related to onbank flow from Makassar Strait. Upwelling of cold, nutritive water is likely responsible for unusualHalimeda productivity and large bioherm development.  相似文献   

5.
A 42-d flow-through experiment was conducted to evaluate the effects of the organo-phosphate pesticide, chlorpyrifos, and microcosm size (small: 144 cm2; large: 400 cm2) on benthic estuarine macroinvertebrate colonization. Nested central and perimeter (outside margin) cores were used to assess animal distribution within microcosms. Fine-grained, organically-rich (approximately 4.0% organic carbon and 20% dry wt) sediments were nominally fortified with chlorpyrifos controls, low (1.0) and high treatments (10.0 μg−1 wet sediment). Large microcosms contained a significantly (p < 0.05) higher average taxa richness (10.9) than small microcosms (8.6) but small microcosms contained a significantly greater average animal density (295.8; numerical abundance adjusted to unit area) than large microcosms (120.5). Density of the polychaete, Neanthes succinea, the amphipod, Corophium acherusicum, and the barnacle, Balanus sp., was significantly greater in small microcosms but density of Ensis minor was significantly greater in large microcosms. In small and large microcosms, respectively, densities averaged significantly greater numbers in perimeter cores (e.g. 203.1 and 75.1) vs central cores (71.9 and 45.4). Average density decreased significantly with increasing chlorpyrifos concentration from controls (326.8), to low (123.8) and high (78.8) treatments. The density decrease was significantly related only to C. acherusicum whose densities decreased from controls (285.8) to low (88.5) and high (43.9) dosed microcosms. Application of an equilibrium partitioning model indicated that density of C. acherusicum was sensitive to an estimated interstitial water concentration of approximately 0.48 μg liter−1. Non-metric multidimensional scaling ordination analyses provided important insights into response patterns not available through ANOVA procedures. A permutation procedure (ANOSIM) detected a significant size effect (p < 0.0001) and a significant effect between controls and low (p < 0.042) and high doses (p < 0.013) but not between low and high chlorpyrifos treatments (p < 0.465). A single species, C. ascherusicum, as in the ANOVA analyses, dominated contributions to community average percent dissimilarity in most combinations of microcosm size and chlorpyrifos treatment effects (range: 8.4–21.9%). Community structure differed significantly in several combinations of microcosm size, core position and chlorpyrifos treatment. Results confirm earlier work that intrinsic design factors influence benthic macroinvertebrate community structure and determine taxa available to pesticide exposure in microcosms.  相似文献   

6.
The larva of the primitive mayfly Oniscigaster wakefieldi, McLachlan 1873 (Ephemeroptera: Siphlonuridae) was studied in the Waitakere Stream, near Auckland, New Zealand, over a 17‐month period extending from July 1965— November 1966. A wide‐mouthed dragnet enabled monthly samples (average 46 specimens) to be collected for detailed studies of the larval growth pattern; this collecting method revealed that the species, previously thought to be rare, is numerous both in the study area and elsewhere in North Island, New Zealand.

O. wakefieldi has a univoltine life cycle with 20–25 larval instars. The larvae prefer different habitats according to their age and can be divided into three distinct groups: larvae 1–10 mm in length are found on finer sediments in quiet shallow water; 11–18 mm in length inhabit waters up to 50 cm deep where the substratum is mainly of pebbles (0.4–4.0 cm diameter) set in a silt matrix; and mature larvae 19–26 mm in length are found adjacent to dry emergent boulders, often at the base of riffles.

Three larval characters are described for the first time to separate the larvae of O. wakefieldi and O. distans. Sexual dimorphism is evident in O. wakefieldi populations by size difference; in the last larval instar, females average 4 mm longer than males. The known distribution of the species in North Island is illustrated.  相似文献   

7.
基于中国科学院海洋生物标本馆历年收藏的标本对明管虫属开展了分类学研究，共发现两种明管虫：Hyalinoecia tubicola （Müller，1776）（明管虫）和H.papillata Imajima，1999（乳突明管虫）。二者均采集于南海北部海域沙质基底，Hyalinoecia tubicola广泛分布于广东省沿岸海域向南至西沙群岛，H.papillata则首次报道于中国南海，其区别于H.tubicola在于第一疣足具伸长舌状、两侧边缘具有乳突的前刚叶（ vs.耳状前刚叶、边缘光滑）。本文详细提供了二者的形态学描述和绘图。  相似文献   

8.
The littoral paranthurid isopod crustacean Paranthura nigropunctata (Lucas, 1846) is recorded for the first time from the littoral of El Jadida located on the Atlantic northwest coast of Morocco. Specimens were obtained from the invasive brown seaweed Sargassum muticum and the natives Bifurcaria bifurcata and Cystoseira tamariscifolia in January 2015. This new record further confirms a significant southward distribution of P. nigropunctata and contributes to the knowledge of the biogeography of this isopod. Heretofore, the species was only known from the western and eastern Mediterranean and some Atlantic coasts. The present finding is the first of the species from Moroccan Atlantic shores, and suggests that the species may also be present in other coastal localities from Morocco and Africa. Some data on morphology, ecology and spatial distribution of the species are provided.  相似文献   

9.
棕囊藻属(Phaeocystis)分类学上位于定鞭藻门(Haptophyta)定鞭藻纲(Haptophyceae)棕囊藻目(Phaeocystales)棕囊藻科(Phaeocystaceae)。迄今在我国海域仅分离鉴定到一种棕囊藻属物种,即自1997年以来在我国海域频繁形成有害藻华的球形棕囊藻(Phaeocystis globosa)。作者从中国南海分离到一个单细胞鞭毛类株系CNS01077,结合形态特征观察及基于18S rDNA序列的系统发育分析,将其鉴定为冠状棕囊藻(Phaeocystis rex)。这是该棕囊藻物种在我国海域的首次报道。该研究构建了该物种的首个叶绿体基因组序列和首个线粒体基因组序列。与球形棕囊藻和南极棕囊藻的细胞器基因组比较分析发现冠状棕囊藻的细胞器基因组发生了显著的结构重排和序列变异。该物种在我国海域的发现及细胞器基因组的构建,将为棕囊藻的生物多样性组成和地理分布研究提供支撑。  相似文献   

10.
作者在整理中国科学院海洋生物标本馆馆藏蜑螺科Neritidae标本时，鉴定出产自海南三亚的一新记录属饰纹蜑螺属Vittina Baker，1924和一新记录种：裂蜑螺Vittina pennata（von Born，1778）。文中详细描述了本种的贝壳形态特征，查明了其生活习性和地理分布特点，并与相似种进行了比较和总结。  相似文献   

11.
The Cape commercial linefishery, established during the first half of the 19th century, currently consists of about 2 500 vessels (±20 000 crew), which land some 15 500 tons of fish each year. In spite of a long history, a lack of a long-term catch and effort data series has severely hindered the management of the fishery. This paper providcs commercial catch and effort data for three periods during the 20th century: 1897–1906, 1927–1931 and 1986–1998. Trends in catch per unit effort (cpue) were verified with additional data from the inshore trawl-fishery, from fishery-independent surveys and, where possible, stock assessment. According to a Linefish Management Protocol developed for the Linefishery, any stock demonstrating a historical reduction in cpue or catch contribution of more than 75% is to be regarded as overexploited. Evaluations based on present datasets support this arbitrarily determined reference point for cpue, but reveal that catch composition is a poor indicator of stock status and should be used with caution. In spite of technological advances such as the advent of combustion engines, nylon lines. echo-sounders, electronic navigational aids, onboard freezer facilities and larger vessels, declines in catch rate indicative of severe overexploitation (i.e. 75–99%) were observed for many important linefish species during the 20th century. Most of these were higher-trophic-Level species from the warm/temperate East Coast, several of which are also endemic. Life-history characteristics of the vulnerable species (i.e those demonstrating declines in cpue of >75%) include predictable location in time and space (either coastal migrant or resident), longevity (>15 years) and late maturity (relative to maximum age). Apart frorreduced productivity associated with stock depletion, other setbacks, such as ecosystem alteration, loss of genetic diversity and shor-term commercial extinction, are also anticipated. In order to rebuild depleted linefish stocks it is deemed essential to create additional marine reserves, dramatically improve enforcement, develop extensive public awareness programmes and substantially reduce commercial effort.  相似文献   

12.
The taxonomic richness and geographic distribution of sponges stranded along Sardinian shores were investigated in the long term by means of a revisited ancient sampling method in order to support a comprehensive species inventory. Almost all stranded species were Keratosa (n = 20), plus 6 species of other Demospongiae taxa. Dictyoceratida were dominant, with 6 genera and 19 species of the families Irciniidae, Spongiidae and Thorectidae: 9 Mediterranean endemics, 7 Atlanto‐Mediterranean and 3 widespread species. Regarding Dendroceratida, only the genus Spongionella was found. Some species (n = 8) were recorded for the first time in circum‐Sardinian seas. A high percentage (54.3%; 19 out of the 35 species) of the total Mediterranean Dictyoceratida fauna was recorded, including the most endangered Mediterranean species, that is of the genera Spongia and Hippospongia. Hippospongia communis, Ircinia variabilis, Spongia zimocca and Spongia officinalis were the most common species. Morphotraits of rare and/or poorly known species were investigated by scanning electron microscopy (SEM). Comparison among Sardinian sectors, and between Sardinian and adjacent seas, revealed a high similarity of stranded Dictyoceratida, despite the fact that the data from Tyrrhenian and Balearic–Catalan seas were collected mainly from SCUBA records. The cost‐effective sampling method used in the present study seems appropriate to the gross qualitative monitoring of coastal areas (e.g. large unexplored Northern African coasts), in order to assess the conservation status of Mediterranean Keratosa species. The wide distribution of all Mediterranean bath sponge species indicates their good conservation status in circum‐Sardinian seas, a datum that could usefully support the future management of this bioresource, particularly in protected areas.  相似文献   

13.
Infaunal bivalve molluscs on the flood tidal delta of Tauranga Harbour, north‐eastern New Zealand, were surveyed twice over a 6‐month period, with the aim of assessing shellfish resources, assessing the magnitudes of temporal and spatial variability in abundances, and identifying potentially important processes. The surveys identified a total of 31 bivalve taxa from 27 sites. Species richness per site ranged between 0 and 9, and varied greatly in space and time, as did two other measures of diversity. Extremely high densities of bivalves (>20 000 m‐2) were encountered at several sites. Densities of several abundant species varied greatly in time, as a result of recruitment pulses. The abundances of the three species that dominated the fauna (Paphies australis, Tawera spissa, and Ruditapes largillierti) had characteristic spatial scales on the order of 200 m. Comparisons of size frequency distributions for individual sites suggested that mortality or emigration in the first year of benthic life was high. Substantial populations of bivalves occur on Centre Bank, and the most abundant of these are greatly influenced by events early in their lives.  相似文献   

14.
Pseudocycnus appendiculatus Heller is described and recorded, for the first time from New Zealand, on Thunnus alalunga (Bonnaterre, 1788). Pseudocycnus spinosus Pearse, 1951 and P. thynnus Brandes, 1955 are thought to be synonyms of P. appendiculatus. Other species previously placed in the genus are discussed and the action of Yamaguti (1963) in removing them to other genera supported. It is suggested that the family Pseudocycnidae Yamaguti, 1963 cannot be differentiated from the family Dichelesthiidae Bassett‐Smith, 1898.  相似文献   

15.
采用分步降温法冷冻保存太平洋鳕(Gadus macrocephalus)精液,并用扫描电镜和透射电镜技术研究了精子的超微结构损伤。分析了添加剂(蛋黄)及五种抗冻剂(PG(丙二醇)、DMSO(二甲基亚砜)、EG(乙二醇)、GLY(甘油)、MeOH(甲醇))不同浓度(8%、10%、12%、14%、16%、18%)对太平洋鳕精子冷冻保存效果的影响。实验结果表明,蛋黄能够显著提高太平洋鳕冷冻保存效果(P0.05);12%PG中添加10%蛋黄保存的冻融精子运动率最高(85.87%±1.6%),显著高于其他冻存组(P0.05)。添加蛋黄的12%浓度的DMSO组解冻后精子运动速率较高,平均直线速度、平均曲线速度、平均路径速度分别达到了(120.39±20.78)μm/s、(120.39±20.78)μm/s、(155.64±12.02)μm/s,与其他各实验组差异显著(P0.05)。通过扫描电镜和透射电镜观察新鲜和冻融后的鳕鱼精子发现,鲜精中75.5%精子形态结构正常、24.5%精子形态结构异常;运动率最高的冻精中67%精子形态结构正常、33%精子形态结构异常。超低温保存对太平洋鳕精子结构产生了显著影响,细胞膜破裂、线粒体肿胀变形,鞭毛脱落、断裂。  相似文献   

16.
The aim of this study was to test whether silver nanoparticles (Ag-NPs) released into estuarine environments result in increased antibiotic resistance amongst the natural bacterial population in estuarine sediments. A 50-day microcosm exposure experiment was carried out to investigate the effects of Ag-NPs (50 nm average diameter) on the antibiotic resistance of bacteria in sediments from an estuary in southwest England. Experimental microcosms were constructed using 3.5 kg sediment cores with 20 l of overlaying seawater treated with (final) Ag-NPs concentrations of 0, 50 or 2000 μg l−1 (n = 3). Sediment samples were screened at the end of the exposure period for the presence of bacteria resistant to eight different antibiotics. Multivariate statistical analyses showed that there was no increase in antibiotic resistance amongst the bacterial population in the sediment due to the dosing of the microcosms with Ag-NPs. This study indicates that, under the tested conditions, Ag-NPs released into the coastal marine environment do not increase antibiotic resistance among naturally occurring bacteria in estuarine sediments. These results contrast previous findings where antimicrobial effects of Ag-NPs on key bacterial species in laboratory experiments have been demonstrated, and reasons for this are discussed. The negligible effects demonstrated on bacterial populations under the selected estuarine conditions, provide important information on no observed effect concentrations (NOECs) for environmental regulation.  相似文献   

17.
The first detailed elasmobranch fisheries data for the Kingdom of Bahrain are presented, based on surveys of fish markets in April 2012. At least 25 species were recorded, including undescribed taxa. The milk shark Rhizoprionodon acutus was the most frequently recorded species; together with the Arabian smoothhound Mustelus mosis and banded eagle ray Aetomylaeus nichofii, these species comprised 53% of individual abundance. Sharks were almost entirely small individuals <1 m total length (TL). Males of small shark species were largely mature, whereas nearly all individuals of larger sharks were immature. For several elasmobranch species, landings were significantly biased towards males, which were largely mature. The species assemblage showed some notable differences in composition to that of adjacent Qatar, sampled at the same time of year, highlighting the importance of local data collection.  相似文献   

18.
中国近海艾裂虫亚科(多毛纲:裂虫科)的初步研究   总被引：1，自引：0，他引：1  
孙瑞平  吴宝铃 《海洋学报》1981,3(4):617-628
多毛纲的裂虫科Syllidae和沙蚕科Nereidae、海女虫科Hesionidae、白毛虫科Pilargiidae等同属于沙蚕型多毛类动物.它们与叶须虫科Phyllodocidae又有极近的亲缘关系.艾裂虫亚科是裂虫科中疣足具背、腹须,两触角至少一半以上愈合,体长多在2-5毫米的底栖动物.它们多栖于潮间带岩石海岸的海藻根部、牡蛎空壳下或砾岩石表面沉积的泥沙中.据报导,在深海底亦有分布.艾裂虫亚科的生殖除裂配生殖schizogamy(或称婚前现象)外,还具抱卵生殖gestation.  相似文献   

19.
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20.
Seven Skeletonema species were identified at one station in the industrial harbor Dokai Bay, Japan, in October 2007 and then monthly from January 2008 to December 2009 by morphological scanning electron microscopy observations and molecular analyses of mainly the large subunit (LSU) rDNA. We refer to one species identified as S. dohrnii using LSU rDNA, but as S. marinoi using the small subunit (SSU) rDNA and consequently we use the term S. marinoi-dohrnii complex. This is the first time that S. ardens, S. costatum s.s., and S. pseudocostatum have been recorded in Japan and that S. menzelii and S. tropicum have been identified by molecular methods in Japan. The S. marinoi-dohrnii complex was isolated with high frequency all year-round, and S. japonicum was also isolated with high frequency but not so in summer. S. Tropicum was isolated from September to December, but S. ardens and S. costatum s.s. were isolated only when the water temperature exceeded 20°C. S. pseudocostatum bloomed just once, in summer, but S. menzelii was isolated in May and again in October. The continuous year-round occurrence of S. costatum s.l. in the bay is supported by the succession of these seven species. Six of the species, except S. menzelii, were important components of algal blooms in the bay. One to four species of Skeletonema were isolated every month. Monthly species diversity was higher when S. ardens, S. costatum s.s., and S. tropicum that are usually associated with tropical or subtropical waters, were isolated. In general, species diversity of the genus Skeletonema was very high in Dokai Bay.  相似文献   

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