Seasonal fluctuations and compositions of two populations of small demersal fishes on the west coast of Scotland

The soft sediment fish communities below 20 m depth were studied at two sites on the west coast of Scotland (Irvine Bay, Firth of Clyde and the Lynn of Lorne) using small meshed beam trawls. In both cases the emphasis was on the small demersal fish (<15 cm) within these communities. The Irvine Bay community was studied between May 1978 and December 1979 and the Lynn of Lorne community between February 1975 and October 1976.Twenty-seven fish species were recorded in Irvine Bay and 32 in the Lynn of Lorne. In both communities four species constituted more than 78% of the total annual abundance, two gobies (Lesueurigobius friesii and Pomatoschistus norvegicus) were high in the dominance ranking for both sites. The species abundance lists were similar for both sites (0·62 level of similarity) but the species lists for each site were different (0·36 level of similarity). The overall mean density of small demersal fish was similar for both sites (Irvine Bay = 0·045 individuals m^?2 and the Lynn of Lorne = 0·047 individuals m^?2). There were two periods of high abundance for both communities (late autumn to winter and late spring). There was, however, a low repeatability between successive years. The species richness (D) was relatively high (Irvine Bay = 1·5-3·08, Lynn of Lorne = 1·4-3·34) as was the species diversity (H′) (Irvine Bay = 1·17-1·97, Lynn of Lorne = 1·23-1·95). The proportional representation ($\text{J′}$) of each species within the community was greater in Irvine Bay ($\text{J′}$ = 0·57-0·77) than in the Lynn of Lorne ($\text{J′}$ = 0·50-0·72). Therefore these two communities of small demersal fish appeared to be similar at the community level but the way in which this was achieved was different.     

Reef fish structure assemblages in oceanic islands of the eastern tropical Pacific: Revillagigedo Archipelago and Clipperton atoll

Revillagigedo Archipelago and Clipperton atoll are oceanic islands located in the eastern tropical Pacific. The composition and trophic structure of their fish assemblages have never been characterized in detail, and the aim of this study was therefore to analyse the community structure and assess the similarity of fish assemblages between these two areas. Underwater visual fish censuses were conducted using band transects at two depth levels in three islands of the Revillagigedo Archipelago (Socorro, San Benedicto, and Roca Partida) and at Clipperton atoll. We calculated ecological indices (density, richness, Shannon diversity, Pielou evenness, and taxonomic distinctiveness) for each transect. These were compared in order to determine quantitative differences among the islands and bathymetric levels. Qualitative analyses (ANOSIM, nMDS, and SIMPER) were also performed. Finally, we analysed the trophic structure of the assemblages and the functional diversity of the four studied sites. The results showed significant differences for all indices, except diversity (H′). Roca Partida was the site with greatest abundance and richness due to the presence of pelagic species in large numbers. No significant differences were found in functional diversity, suggesting a high degree of ecological redundancy. Lower‐level carnivores with mean trophic level values of between 3.3 and 3.8 dominated both areas. The ordination analysis did not show a clear difference in fish composition among the islands, although Clipperton atoll has a particular fauna characterized by endemic species (Thalassoma robertsoni and Stegastes baldwini). In conclusion, the fish communities of the studied areas seem quite similar, but their assemblage structure differs. In particular, Clipperton is differentiated by the influence of endemic species.     

Structural aspects of the surf-zone fish assemblage at King's Beach,Algoa Bay,South Africa: Long-term fluctuations

Regular collections of fish were obtained from the surf-zone at King's Beach, Algoa Bay. A total of 3970 fish, representing 50 species was caught with a coarse net and 16 857 fish, representing 37 species, were caught with a fine net. Predominant species were the blacktail, Diplodus sargus; the sand steenbras, Lithognathus mormyrus; the mullet, Liza richardsoni; the gorrie, Pomadasys olivaceum; the white stumpnose, Rhabdosargus globiceps; the sandshark, Rhinobatos annulatus; and the streepie, Sarpa salpa. No seasonal trends were discernible in the overall abundance or species diversity. The species composition of the dominant component of the fish assemblage varied considerably. This indicated instability in the community structure and cast doubts on the applicability of a classic community concept and the use of diversity indices. Neither classification nor correspondence analysis were of any use in identifying a characteristic species component. Multiple regression analysis indicated that short-term variations in wind conditions might be a primary determinant of fluctuations in abundance. The lack of seasonality in the community parameters may reflect the fact that short-term variability masks seasonal perturbations.     

Structure of a mudflat diatom community in the Avon‐Heathcote Estuary,New Zealand

Parameters of community structure (species composition and relative abundance, number of taxa, diversity, evenness, and cell density) were measured for a mudflat diatom community in the Avon‐Heathcote estuary, New Zealand. Fifty three diatom species were identified: 25 taxa (species and varieties) are new New Zealand records. The Shannon‐Wiener information index (H') was 3.46, indicating high diversity. Evenness (J') ranged from 0.57–0.67. The association between the biomass of the pulmonate gastropod, Amphibola crenata, and benthic diatom community structure was studied using large open enclosures (4.0 m²) to manipulate snail biomass. Community structure was compared at 0, 5 (natural biomass), and 10 g A. crenata dry weight per m. A similarity index (SIMI=0.88–0.95), as well as H’ and J’ indicated close similarity between the diatom assemblages within all enclosures, but number of taxa increased from 33 to 49 with increasing snail biomass. Cell densities were significantly lower at high snail biomass (6088 valves per mm²) compared to enclosures with no snails (10 110 valves per mm ). A. crenata had a higher ratio of diatom fragments to whole diatom valves in its faeces (2.42) than in its crop (0.55), indicating that it is capable of fragmenting diatoms.     

Patterns of variability in ichthyoplankton occurrence and abundance in Biscayne Bay,Florida

Within-day variability in ichthyoplankton and microzooplankton abundances was examined at a single station in Biscayne Bay using replicate tows of 61-cm bongo nets and Niskin bottles to determine if patchiness occurred on the 10–1000 m scale and on the minutes to hours time scale. Fish eggs and larvae often were patchy but copepod nauplii, the predominant food of larvae, usually were randomly distributed at the scales examined and over the 3.15 m-depth water column. Mean patchiness index values were of similar magnitude for fish eggs and larvae but fish eggs were patchy more often than were larvae. Individual taxa of larvae had extremely high patchiness index values on some dates. Variability in fish egg catches often reflected increasing or decreasing abundance trends during the 2.5h sampling period while fish larvae catches often appeared to be clumped within the repetitive series of tows. There was no tendency for patchiness to be correlated among taxa on collection dates nor was it correlated with abundances or wind speeds. Patchiness indices of bay anchovy Anchoa mitchilli eggs and larvae were not significantly correlated, indicating little concordance in tendency to be aggregated, suggesting that distributions were influenced by biological processes related to spawning of adults and behaviour of larvae, in addition to physical processes. Although ichthyoplankton patchiness often did exist at the 10–1000 m scale, on many days ichthyoplankton was uniformly or randomly distributed. Copepod nauplii were abundant ($\text{x}\text{=90.41}{}^{\mathrm{?1}}$), randomly distributed on most dates, and apparently readily available as fish larvae food in Biscayne Bay.     

渤海湾排污区底栖动物调查初步报告

近年来,由于海河,蓟运河以及永定新河将天津、北京两市的工业废水和生活污水排入渤海湾,加之沿海和海上油田的开发,还投入了含油污水等,所以,渤海湾的环境质量已受到有关部门的重视。中国科学院海洋研究所自1978年至1980年对渤海湾的环境质量进行了水文、化学、地质、生物等方面的调查。现将底     

防城河口湾鱼类群落结构及其与环境因子关系研究

文章根据2016年5月、8月、11月和2017年2月在防城河口湾海域进行的渔业资源和环境调查数据, 研究了河口湾鱼类群落结构及其空间和季节变化, 分析了鱼类群落结构与主要环境因子的关系。结果表明: 全年调查共渔获鱼类95种, 隶属于2纲12目37科69属, 适温性以暖水性鱼类为主, 生态类型以底层和近底层鱼类为主。其中, 春季60种, 夏季59种, 秋季54种, 冬季46种, 夏—秋季间种类相似性指数最高。全年优势种为褐菖鲉Sebastiscus marmoratus和长鳍篮子鱼Siganus canaliculatus, 主要种有黄鳍棘鲷Acanthopagrus latus、条马鲾Equulites rivulatus、李氏?Callionymus richardsoni和真赤鲷Pagrus major等10种; 夏、秋季的最大优势种均为长鳍篮子鱼, 春、冬季的最大优势种分别为褐菖鲉和条马鲾。全湾鱼类年均资源密度为45836尾·km ^-2和 435.21kg·km ^-2, 资源密度具有明显的空间差异和季节变化。全年各站位种数变化范围在2~21种, 多样性指数H′在0.468~4.031, 丰富度指数d在0.120~1.926, 均匀度指数J在0.181~0.969。聚类分析、单因子相似性分析(ANOSIM)及相似性百分比(SIMPER) 分析表明该海域鱼类群落存在一定程度的时空异质性。相关性分析表明影响防城河口湾鱼类群落结构的主要环境因子为水温、盐度和硝酸盐。     

多样性指数在海洋浮游植物研究中的应用

对海洋浮游植物群落分析中常用的多样性指数进行了比较研究.对物种丰富度依赖型、丰度依赖型和实测浮游植物群落中物种丰富度、Shannon指数(以2或e为底)、Pielou均匀度指数、Simpson指数(1-D或1/D形式)、Margalef指数、Berger-Parker指数、McIntosh指数、McIntosh均匀度指数、Brillouin指数、Brillouin均匀度指数、Fisher α指数和Q统计指数等不同多样性指数计算结果进行了比较,发现不同多样性指数对浮游植物群落多样性的分析存在明显差异.对于一般情况下浮游植物群落多样性的研究,物种丰富度、Margalef指数、Fisher α指数、Shannon指数、Simpson相遇指数和Pielou指数的综合使用是较合适的,但对Margalef指数和Fisherα指数的结果要谨慎解释.并在综合应用各指数的基础上提出了浮游植物群落多样性分析的一般步骤.     

2009 年春季辽东湾网采浮游植物群落结构

分析了2009 年春季(5 月)渤海辽东湾网采浮游植物物种组成, 丰度分布, 生物多样性指数及群落相似性。春季共鉴定出浮游植物3 门23 属32 种, 主要隶属硅藻门和甲藻门, 生态类型多为温带近岸型和广布型种类, 少部分为暖海性物种或大洋性物种。优势种有夜光藻(Noctiluca scientillans)、翼鼻状藻(Proboscia alata)、旋链角毛藻(Chaetoceros curvisetus)、巨圆筛藻(Coscinodiscus gigas)和尖刺伪菱形藻(Pseudo-nitzschia pungens)等。浮游植物在各站位的细胞丰度分布不均匀, 其平面分布呈现由沿岸海域向海湾中部海域递减的趋势。Shannon-Wiener 指数、Pielou 指数较低, 群落结构简单, 稳定性较差。聚类分析结果表明群落之间的相似性较高。     

Trophic relationships in the demersal fish community off Namibia

The benthic fish community off Namibia (between the Cunene River and Walvis Bay) in 50–650 m of water was studied during three bottom trawl surveys. The community was investigated on the basis of distribution, abundance and diet of 51 species, constituting 95 per cent of the demersal fish biomass. Dietary studies revealed the existence of three major trophic groups, one containing species that prey on pelagic and nektonic organisms, a second dominated by predators that feed on benthic polychaetes and copepods and a third group containing predators of benthic crabs, demersal shrimps and fish. Well differentiated from these groups are a few species that prey mainly on jellyfish and ophiuroids. Because for most of the species, their trophic level changes with growth, they were divided into size classes which are analysed independently. To describe interactions between the size classes, a similarity index combining diet affinity with spatial coincidence was applied. Cluster analysis showed that, for Merluccius capensis, Raja straeleni, R. clavata and Trachurus trachurus, there is a large difference in both geographic distribution and dietary preference between the size classes. For species such as Hoplostethus atlanticus, Austroglossus microlepis and Coelorinchus flabellispinis, the different size classes seem to share the same ecological niche. Variation in the number of species and the parameters mean abundance and niche width are described to enhance knowledge of the general structure of the community.     

Tracing flocculent industrial and domestic sewage transport on San Pedro Shelf,Southern California,by nitrogen and sulphur isotope ratios

Domestic and industrial sewage is discharged at a depth of 60 m near Whites Point on the San Pedro Shelf, Southern California borderland. A density-stratified thermocline, above the outfall at a depth of 20 to 30 m, is thought to prevent most effluent particles from reaching shallower depths and recreational facilities. In this investigation, measurement of the natural abundance of nitrogen isotopes (${}^{15}\text{N}{}^{14}\text{N}$) is used to determine the level of sewage contribution to flocculent suspended material persisting at water depths of 7, 13 and 20 m. Organic nitrogen at 20 m depth was shown to be predominantly of sewage-origin and at 7 m, predominantly of marine origin. Organic nitrogen at 13 m depth and within 3 km of the outfall pipes is predominantly sewage in origin.Stable isotope composition of sulphur (${}^{32}\text{S}{}^{34}\text{S}$) in the flocculent material indicates that the effluent particles contain metabolic sulphur, incorporated from dissolved seawater, as well as bacterially produced mineral sulphide.     

2010-2011年长江河口及邻近水域春夏季仔稚鱼群落结构及其多样性的研究

根据2010—2011年春夏季对长江河口及邻近水域进行了仔稚鱼生态调查,应用单元和多元统计方法分析了春夏季长江河口及邻近水域仔稚鱼群落结构。4个航次调查共获得27个种类的仔稚鱼,隶属5目14科。优势种类主要包括鳀Engraulis japonicus、凤鲚Coilia mystus、康氏小公鱼Stolephorus commersonii、鮻Liza haematocheila、黄姑鱼Nibea albiflora、黄鳍刺虎鱼Acanthogobius flavimanus和寡鳞飘鱼Pseudolaubuca engraulis等。Shannon-Weaver指数(H′)在调查周期内的波动幅度较大,且2011年明显低于2010年。仔稚鱼群落结构和多样性指数春季年间较夏季年间差异性显著。调查区夏季群落结构年间相似性不高,春季群落结构格局年际变化则较明显。聚类分析表明,春夏季长江河口近岸水域仔稚鱼群落可划分为2个站位组,分别对应于长江河口淡水水域和长江口咸水水域。淡水水域组群落和咸水水域组群落总丰度与盐度相关性较高。表明盐度可能是造成长江河口仔稚鱼群落结构时空差异性的主要原因。     

南沙海域虫戎群落特征与季风、管水母关系分析

根据2013年3-4月、6-7月、9月和11-12月4个航次的调查资料;分析南沙海域浮游虫戎亚目的种类组成、优势种、栖息密度和群落结构特征;并探讨季风转换对其影响及其与管水母的关系。研究海域内共鉴定浮游虫戎亚目12科26属63种。生态类群结构属于热带大洋性。优势种较少;共出现7种;其中;孟加拉蛮虫戎（Lestrigonus bengalensis）为唯一的年度优势种;优势地位显著。物种组成存在季节性变化;分为春季、夏季与秋-冬季3个群落。虫戎年均栖息密度为18.30×10-2 ind/m3;高数量区主要分布于近岸水域;数量季节变化不明显;但平面分布季节差异明显。虫戎年均丰富度、多样性、均匀度指数和多样性阈值各是1.23、1.28、0.33、0.48。虫戎物种组成随季风转换左右近岸低盐水影响程度而变化;群落结构、生物多样性和栖息密度平面分布随季风转换所驱动的表层环流结构改变而变化。虫戎群落分布与管水母间的相关性证实研究海域两类群物种间的寄宿关系。这种关系促使孟加拉蛮虫戎在沿岸低盐水影响下更易形成高优势度;而表现出类似近岸海域优势种优势地位显著的特点。     

辽东湾中部海域春季大型底栖生物的群落结构及影响因子

2013年5月对辽东湾中部的大型底栖生物进行了调查,分析了该海域底栖生物的种类组成、丰度、生物量、群落结构及其与环境因子的关系。调查海域共发现大型底栖生物70种,包括多毛类24种,甲壳类18种,软体动物20种,棘皮动物7种,纽虫1种。相对重要性指数大于100的种类有14种,排名前3位的分别是日本游泳水虱、毛蚶、日本长尾虫。底栖动物丰度平均值为244.2个/m~2,生物量为52.52 g/m~2,棘皮动物是生物量的重要贡献者。多样性指数平均值为3.24,丰度生物量比较曲线分析结果认为调查海域大型底栖动物群落未受到干扰,底栖生物群落的结构相似性较低,在20%的相似程度上可分为5个组。底层水中溶解氧含量是影响底栖生物的主要因素,不同底质条件是影响底栖生物生物量和群落结构的重要因素。     

山东荣成临洛北湾夏季大型底栖动物群落生态学初步研究

利用2010年7月在山东荣成临洛北湾所获得大型底栖动物定量分析资料,研究了夏季该海域海带养殖区和邻近水域大型底栖动物在物种组成、生物量、丰度、优势种以及物种多样性等方面的特征和空间差异,并采用MDS和CLUSTER分析了大型底栖动物的群落结构,以期为该地区以后的科学研究提供基础数据.结果表明,本次调查通过采泥和拖网共采集到大型底栖动物88种,其中采泥得到大型底栖动物51种,拖网采得大型底栖动物45种,各站位的物种多样性差异明显,物种数量从2种到21种.与环境因子的相关性分析显示,各站的物种数和丰度与DO存在明显的负相关.在所有大型底栖动物中,甲壳动物26种,多毛类环节动物24种,软体动物23种,棘皮动物8种,其他类群动物6种(鱼类5种,尾索动物1种).该海域的优势种为多丝独毛虫和短叶索沙蚕.将CLUSTER结果以43%的群落结构相似性来划分,组内的相似性为50%~60%.该海域大型底栖动物的平均丰度为854个/m2,平均生物量为134.73 g/m2,与研究海域附近的历史研究结果相比较,该海域的平均丰度和生物量仍处于较高的水平.     

中街山列岛岩礁海域鱼类群落多样性研究

加快包括岛礁海域鱼类资源在内的渔业资源调查研究,可以进一步完善该区域鱼类群落生态学内容,探究岩礁海域生境生态学功能,为该海域鱼类资源的养护修复、可持续利用和有效管理提供科学依据。本文基于2013年11月—2014年10月的中街山列岛岩礁海域鱼类资源调查数据,对研究区域鱼类组成及群落多样性分析,结果如下:全年渔获鱼类49种隶属9目28科42属,暖水种和暖温种分别为25和24种,底层、近底层和中上层鱼类各为12、26和11种,定居种、季节性洄游种和偶见种各为28、19和2种;褐菖鲉为全年的绝对优势种,黄姑鱼年IRI值最大,为37.23;迁移指数分析显示群落7月份稳定性最高;ABC曲线分析显示6月受到的干扰最小,2月受到的干扰最大;流刺网年渔获率和CPUE分别为44.03尾/km、13.43 kg/km,延绳钓作业分别为4.91尾/100钓、1.67kg/100钓;群落多样性指数分析结果显示,Margalef种类丰富度指数2月最低,为2.35,7月最大,为4.93;Shannon-Wiener多样性指数7—8月均值最大,为2.80左右;均匀度指数最大和最小值分别是0.97、0.74;三种多样性指数均呈现随气温升高而增大的趋势,但均匀度指数变化没有前2个指数明显,12月和5月3种指数均有波动现象发生。     

Spatio-temporal variability in faunal assemblages surrounding the discharge of secondary treated sewage

Macrofaunal assemblages inhabiting the intertidal zone surrounding an input of secondary treated effluent were sampled in order to determine how the pollution impact varied temporally and spatially. Assemblages varied along the pollution gradient formed by the Bolivar Wastewater Treatment Plant outfall in Gulf St Vincent, South Australia. While the abundance of some species did not vary, the abundance of juvenile western king prawns (Melicertus latisulcatus) and blue crabs (Portunus pelagicus) progressively decreased with proximity to the outfall. Species richness and diversity also decreased towards the outfall. An increase in nutrient content in the water adjacent to the outfall is likely to explain these changes. At distances of 4 and 5 km away, species diversity increased and the abundance of M. latisulcatus decreased, possibly due to a change in habitat from sand to seagrass. The occurrence of a storm prior to sampling on one occasion masked the effects of pollution and habitat changes. The results of this study suggest that the disposal of treated effluent into Gulf St Vincent is having a localised effect on the faunal assemblages surrounding the discharge point.     

Mangrove habitat use by fishes in Southeastern Brazil: are there temporal changes in the structure of the community?

We compared fish community structure in Guaratiba Mangrove, SE Brazil, among three seasons of the hydrological cycle [(i) spring, increasing temperature and rainfall, decreasing salinity; (ii) summer/early fall, high temperature and rainfall, intermediate salinity; (iii) late fall/winter, low temperature and rainfall, high salinity] and between the years 2002–2003 and 2008–2009. The aim was to test the hypothesis that the fish community structure changes seasonally, associated with seasonal changes in environmental conditions, and that changes occurred between the two yearly periods because of increased anthropogenic activities. The sampling protocol for the two surveys was identical. A total of 63 species was recorded, with 38 species occurring in 2002–2003, and 53 species in 2008–2009. The main changes in the mangrove's fish assemblage between 2002–2003 and 2008–2009 were (i) an increase in species richness, fish density and total biomass; and (ii) an increase in the zoobenthivorous species of gerreids Eucinostomus argenteus, Diapterus rhombeus and Ulaema lefroyi, and a decrease in the planktivorous clupeid Harengula clupeola. Other abundant species, such as the opportunistic atherinopsid. Atherinella brasiliensis, the detritivorous mullet Mugil liza and the zoobenthivorous pufferfish Sphoeroides testudineus did not differ in abundance between the two yearly periods. Ten species occurred only in 2002–2003, and 23 species only in 2008–2009, indicating significant changes in community structure over the 6‐year period. Seasonal changes in community structure were more conspicuous in 2008–2009, when species abundance and richness were greatest. The highest fish abundance was recorded in spring and in summer/early fall, and the lowest in late fall/winter. The increased abundance and richness over time may be at least partially attributable to protection policies because of the effective implementation of a biological reserve in the area.     

Long-term trends in the structure of eastern Adriatic littoral fish assemblages: Consequences for fisheries management

Long-term interannual changes in abundance, biomass, diversity and structure of littoral fish assemblages were examined between 1993 and 2009 by experimental trammel net fishing up to six times per year, within the warm period - May to September, at multiple areas along the eastern Adriatic coast with the aim of testing for the consistency of patterns of change across a large spatial scale (∼600 km). The results revealed spatially consistent increasing trends of total fish abundance and biomass growing at an average rate of 15 and 14% per year, respectively. Of the diversity indices analysed, the same pattern of variability was observed for Shannon diversity, while Pielou evenness and average taxonomic distinctness measures Δ^∗ and Δ⁺ showed spatial variability with no obvious temporal trends. Multivariate fish assemblage structure underwent a directional change displaying a similar pattern through time for all the areas. The structural change in fish assemblages generally involved most of the species present in trammel net catches. A large pool of fish species responsible for producing the temporal pattern of assemblage change was relatively different in each of the areas reflecting a large geographic range covered by the study. An analysis of 4 fish species (Symphodus tinca, Pagellus erythrinus, Mullus surmuletus, Scorpaena porcus) common to each of the study areas as the ones driving the temporal change indicated that there were clear increasing trends of their mean catches across the years at all the study areas. A common pattern among time trajectories across the spatial scale studied implies that the factor affecting the littoral fish assemblages is not localised but regional in nature. As an underlying factor having the potential to induce such widespread and consistent improvements in littoral fish assemblages, a more restrictive artisanal fishery management that has progressively been put in place during the study period, is suggested and discussed.