Geographical variation in Fucus vesiculosus morphology in the Baltic and North Seas

Effects of stress and disturbance on morphology, reproductive effort, size and sex ratio were studied for Fucus vesiculosus populations from the Baltic Sea at Askö and the North Sea on the west coast of Sweden at Tjäm[otilde]. High morphological variation was found between Fucus populations, with significant differences in length and weight of individuals, thallus breadth, number of branches and receptacles and receptacle weight, not only between Baltic and North Sea populations but also between populations within the same area, differing in wave exposure. With increasing disturbance, individuals in both studied populations were smaller and less branched. Differences were observed in plant size, with longer, broader and more branched plants being found in Askö compared with Tjärnö. Fucus populations at Tjämö allocated more biomass to reproduction and had longer, heavier receptacles than at Askö. Although the observed morphological changes may be partly explained by differences in wave exposure and salinity between the two sites, it is not possible to rule out genetic differences between the Baltic and North Sea populations. However, it is unlikely that the variations observed within the populations and between populations from the same area are genetically determined.     

Salinity gradient shapes distance decay of similarity among parasite communities in three marine fishes

Published data were used to compare the distance decay of similarity in parasite communities of three marine fish hosts: Atlantic cod Gadus morhua, the dab Limanda limanda and the flounder Platichthys flesus in two adjacent areas that differ with respect to the strength of a salinity gradient. In the Baltic Sea, which exhibits a strong salinity gradient from its connection with the North Sea in the west to its head in the north‐east, parasite communities in all three fish hosts showed a significant decline of similarity with increasing distance. In contrast, among host populations in the North Sea, which is a fully marine environment, there was no such decline or only a weak relationship. The results suggest that environmental gradients like salinity can be strong driving forces behind patterns of distance decay in parasite communities of fishes.     

Seasonal variations of microphytoplankton assemblages and environmental variables in the coastal zone of Bozcaada Island in the Aegean Sea (NE Mediterranean Sea)

Seasonal changes in the microphytoplankton assemblages were examined in the coastal zone of Bozcaada Island with regard to some major physical and chemical variables. Samples were collected from May 2000 to December 2001 at four stations. A total of 108 dinoflagellates, 102 diatoms, 1 chrysophycean, 3 dictyochophycean, and 1 prasinophycean species were identified and quantified during the study period. Diatoms and dinoflagellates were the most important in terms of species number and abundance. The maximum values of total microphytoplankton were observed at 0.5 m depth (46.2 × 10³ cells l⁻¹ at st. 3) in May as this was the month when the diatom Pseudo-nitzschia pungens bloomed. Chlorophyll (chl) a concentration ranged between 0.08 (August) and 0.78 μg l⁻¹ (February). May was another important month in which chlorophyll a increased (0.41–0.47 μg l⁻¹). Species diversity values (H′_log2) ranged from 1.66 bits (June, 20 m) to 4.11 bits (November, 0.5 m). The increase was attributed to a more balanced distribution of abundance among species. The amounts of nitrate + nitrite (0.6−3.7 μg-at N l⁻¹), phosphate (0.2−0.6 μg-at P l⁻¹) and silicate (0.7−2.5 μg-at Si l⁻¹) were recorded on each sampling occasion. Nutrient concentrations and chl a values of the research area were found to be poorer than those of the many other coastal areas in the northeastern Mediterranean. The mean atomic ratio of nitrogen to phosphorus varied from 1.3 (June) to 12.9 (February). This ratio was lower than the Redfield ratio of 16 for ocean phytoplankton, and phytoplankton was potentially limited by nitrogen for most of the months. The result of this study confirms and emphasizes the oligotrophic nature of the eastern Mediterranean.     

Phytoplankton biomass and species composition in a Mediterranean coastal lagoon

Phytoplankton populations were investigated weekly at a central station in the Fusaro lagoon (Mediterranean Sea) from 27 November 1989 to 18 June 1990 to assess species composition, temporal succession and standing stock of the different species. Chlorophyll concentrations varied from 1.2 to 73.2 µg 1^–1 in surface waters, and from 1.3 to 53.5 µg 1^–1 at the 4.5 m depth. Phytoplankton communities were dominated by Prorocentrum micans Ehrenberg in December and January, and by small-sized diatoms in the rest of the sampling period. In surface waters, a maximum biomass of 9.5 mg C 1^–1 was measured in January, in correspondence with high concentrations (8.1 × 10⁶ cells 1^–1) of P. micans, whereas an abundance peak of 159.9 × 10⁶ cells 1^–1 was registered on the last sampling date due to a massive bloom of a very small diatom, Minutocellus polymorphus (Hargraves & Guillard) Hasle, von Stosch & Syvertsen. On the whole, phytoplankton populations of the Fusaro lagoon showed distinct characters as compared to those of southern Tyrrhenian coastal waters and of other lagoons.     

依据大规模捕捞统计资料分析东黄渤海白姑鱼种群划分和洄游路线

根据我国10多个主要渔业公司1971-1982年间白姑鱼(Argyrosomus argentatus)捕捞统计资料,从产量分布,鱼群移动等方面,研究了东黄渤海白姑鱼的种群划分和洄游路线。结果显示,我国沿海白姑鱼可分为2个种群。其中,黄渤海种群越冬场主要在黄海中部34°00'N以北水域。每年3-4月份,鱼群陆续进入山东半岛的乳山沿海、渤海各海湾、黄海北部沿岸和海州湾产卵。栖息在渤海的白姑鱼9-11月份在渤海中部索饵,形成越冬群体,11月后绕过成山头向越冬场洄游,12月至1月份到达越冬场;东黄海种群越冬场主要是在东海外海和中南部近海。每年3-4月份东海外海白姑鱼向西进入舟山渔场。在舟山渔场,这部分鱼群与从东海中南部近海北上的产卵群体汇合,向西进入舟山群岛沿海水域产卵。到了5月份,在浙江北部近海形成索饵群体。6-8月份,索饵群体经过长江口北上黄海南部近海索饵,9月份,索饵群体前锋到达34°00'N禁渔线外侧。此后,索饵场的白姑鱼向南做越冬洄游,并在10月份回到长江口。从这里,一部分群体游向外海越冬场,一部分群体继续南下回到东海中南部近海的越冬场。另外,在东海中南部近海越冬群体,部分就近游向沿岸的海湾,河口产卵,产卵后在产卵场外侧索饵,冬季回到就近的越冬场。     

2009年冬季东海浮游植物群集

2009年12月23日—2010年1月5日在东海海域(24°00’—32°00’N,120°00’—128°00’E)68个站位进行了水文、化学和生物的综合调查,应用Utermhl方法对调查海域的浮游植物群集进行了研究。经284个浮游植物采水样品的分析,共发现浮游植物4门67属171种(含13个未定种)。浮游植物群集主要由硅藻和甲藻组成,还有少量的蓝藻和金藻,物种以沿岸广温型为主,优势种为:具槽帕拉藻(Paralia sulcata)、菱形海线藻(Thalassionema nitzschioides)、柔弱伪菱形藻(Pseudo-nitzschia delicatissima)、安哥拉海链藻(Thalassiosira angulata=并基海链藻Thalassiosira decipens)和细弱海链藻(Thalassiosira subtilis)等。调查浮游植物细胞丰度介于0.356×103—142.578×103个/L,平均值为14.137×103个/L;硅藻占浮游植物细胞丰度的比例最大,介于0.356×103—142.578×103个/L,平均值为13.023×103个/L;其次为甲藻,细胞丰度介于0.356×103—11.378×103个/L,平均值为1.177×103个/L。调查海域表层浮游植物细胞丰度的平面分布由硅藻刻画,高值区出现在调查区北部即长江口东北部海域,甲藻在调查区南部和东南部丰度较高。细胞丰度在水体中的垂直分布趋势为先上升后下降,最大值出现在10m层。从断面分布上看,细胞丰度在调查区近岸和远岸较高、中部较低。Pearson相关性分析表明,调查区浮游植物细胞丰度与磷酸盐和硅酸盐浓度呈显著正相关,与温度呈显著负相关,与硝酸盐相关性不明显。     

Effects of the severe winter 1995/96 on the benthic macrofauna of the Wadden Sea and the coastal North Sea near the island of Sylt

The development of benthic macrofauna in the Wadden Sea and in the coastal North Sea after the severe winter of 1995/96 is compared with the preceding years with mild to moderate winters. In the intertidal of the Wadden Sea, ice-drift and low temperature caused the expected changes in species composition by increasing winter mortality in sensitive species, and by exceptionally high recruitment of some species during the succeeding summer. In the shallow subtidal (10–20 m depth), similar winter effects were observed. However, recovery of many subtidal populations was still incomplete until the summer of 1997. It is suggested that this was due to hydrographic conditions that carried many larvae or drifting juveniles into more distant offshore areas. This may have limited larval supply and may have delayed recovery at the onshore sites. Since in the eastern North Sea severe winters are accompanied by frequent easterly winds, it is not clear whether decreasing winter abundances in some species were due to increased mortality, or to a seaward dislocation of organisms. Received in revised form: 7 May 2001 Electronic Publication     

Marine molluscs and fish as biomarkers of pollution stress in littoral regions of the Red Sea, Mediterranean Sea and North Sea

The intensive development of industry and urban structures along the seashores of the world, as well as the immense increase in marine transportation and other activities, has resulted in the deposition of thousands of new chemicals and organic compounds, endangering the existence of organisms and ecosystems. The conventional single biomarker methods used in ecological assessment studies cannot provide an adequate base for environmental health assessment, management and sustainability planning. The present study uses a set of novel biochemical, physiological, cytogenetic and morphological methods to characterize the state of health of selected molluscs and fish along the shores of the German North Sea, as well as the Israeli Mediterranean and Red Sea. The methods include measurement of activity of multixenobiotic resistance-mediated transporter (MXRtr) and the system of active transport of organic anions (SATOA) as indicators of antixenobiotic defence; glutathione S-transferase (GST) activity as an indicator of biotransformation of xenobiotics; DNA unwinding as a marker of genotoxicity; micronucleus test for clastogenicity; levels of phagocytosis for immunotoxicity; cholinesterase (ChE) activity and level of catecholamines as indicators of neurotoxicity; permeability of external epithelia to anionic hydrophilic probe, intralysosomal accumulation of cationic amphiphilic probe and activity of non-specific esterases as indicators of cell/tissue viability. Complete histopathological examination was used for diagnostics of environmental pathology. The obtained data show that the activity of the defensive pumps, MXRtr and SATOA in the studied organisms was significantly higher in the surface epithelia of molluscs from a polluted site than that of the same species from control, unpolluted stations, providing clear evidence of response to stress. Enhanced frequency of DNA lesions (alkaline and acidic DNA unwinding) and micronucleus-containing cells was significantly higher in samples from polluted sites in comparison to those from the clean sites that exhibited genotoxic and clastogenic activity of the pollutants. In all the studied molluscs a negative correlation was found between the MXRtr levels of activity and the frequency of micronucleus-containing hemocytes. The expression of this was in accordance with the level of pollution. The complete histopathological examination demonstrates significantly higher frequencies of pathological alterations in organs of animals from polluted sites. A strong negative correlation was found between the frequency of these alterations and MXRtr activity in the same specimens. In addition to these parameters, a decrease in the viability was noted in molluscs from the polluted sites, but ChE activities remained similar at most sites. The methods applied in our study unmasked numerous early cryptic responses and negative alterations of health in populations of marine biota sampled from the polluted sites. This demonstrates that genotoxic, clastogenic and pathogenic xenobiotics are present and act in the studied sites and this knowledge can provide a reliable base for consideration for sustainable development. Received: 2 March 1999 / Received in revised form: 2 August 1999 / Accepted: 3 August 1999     

Biogeography of the family Acartiidae (Calanoida) in the Ponto-Mediterranean Province

In the Ponto-Mediterranean Province, the geographical distribution of 19 species plus 1 variety belonging to the family Acartiidae has been studied. The study utilised cartographic techniques of terrestrial biogeography and the entire Province was subdivided in 1375 squares. The geographic distributions obtained derived from data published during the last 126 years. The first result was that about 3/4 of the area considered has never been sampled, and only about 8% of the entire area has been repeatedly sampled (at least seasonally). Long time-series of sampling are known only from very few sites. The species considered belong to three genera. Species distributions are discontinuous either in space or in time. Three species are endemic. The historical analysis suggests that four species arrived in the Province recently (two of them are Lessepsian migrants; the others have been introduced by human activities). Two species appear to have crossed the Suez Canal from the Mediterranean to the Red Sea (anti-Lessepsian migration). Two species are considered to be ante-Lessepsian (they were tropical species present in the Mediterranean before the Suez Canal opening). The doubtful presence of two species in the Mediterranean is discussed. At the present time, it seems that the distribution of many species is rapidly changing, probably as a consequence of the anthropogenic influence on communication between areas of the Province, and supported by the ability of Acartiidae to cross geographic barriers, mainly as resting stages.     

Life history strategies of four small-size fishes in the Suez Canal, Egypt

Of 35 species collected from the shores of the Suez Canal and its lakes, five were abundant year round. Sihouettea aegyptia and Aphanius dispar are of Red Sea (warm water) origin, whereas Pomatoschistus marmoratus, Aphanius fasciatus and Atherina boyeri are Mediterranean species. S. aegyptia and A. dispar are distributed throughout the Suez system whereas A. fasciatus is restricted to the northern canal. P. marmoratus and A. boyeri have not spread southward beyond the Bitter Lakes. Salinity is the main limiting factor for the distribution of Mediterranean species. S. aegyptia and A. dispar are dominant in the Bitter Lakes (salinity 44‰), whereas P. marmoratus and A. boyeri are abundant in Timsah Lake (salinity 7·8–41·6‰). There was considerable interannual and monthly variation in the relative abundance of each species. The populations were dominated by a single age group, and life spans were no more than 2 years. Rapid growth was evident during the first spring in P. marmoratus and A. boyeri and during the first summer, early autumn in S. aegyptia and A. dispar . The relative abundance of each food item in the diet varied with fish size and season. S. aegyptia, P. marmoratus and A. dispar fed mostly on harpacticoid copepods, polychaetes, demersal eggs, diatoms and blue-green algae whereas A. boyeri fed mostly on planktonic copepods. The warm water species are summer spawners, whereas the temperate species are autumn-winter spawners.     

2012年夏季挪威海和格陵兰海浮游植物群落结构的色素表征

对2012年中国第5次北极科学考察期间的挪威海和格陵兰海两个断面的光合色素进行了高效液相色谱（HPLC）分级分析,通过藻类色素化学分类分析软件（CHEMTAX）获得了不同浮游植物类群对叶绿素a的贡献,进而得到该海域表层和次表层（30 m）的浮游植物群落结构。结果表明：表层总叶绿素a的浓度为23.59 ng/L,低于次表层的30.38 ng/L,其中浮游植物根据粒径划分对总叶绿素a的贡献由高到低依次是微型浮游植物、小型浮游植物和微微型浮游植物。该海域同时存在葱绿叶绿素（Prasino）、墨角藻黄素（Fuco）、别藻黄素（Allo）、多甲藻素（Perid）、玉米黄素（Zea）、19-丁墨甲藻黄素（19’BF）和19-六已墨甲藻黄素（19’HF）等色素,其浓度和分布与温盐和营养盐等环境因子存在一定的相关性。不同粒径浮游植物色素组成显示,微微型浮游植物群落中以S型定鞭藻（28%）、N型定鞭藻（21%）、硅藻（18%）和青绿藻（12%）占优;微型浮游植物群落的优势类群为S型定鞭藻（53%）、N型定鞭藻（20%）和硅藻（12%）;而小型浮游植物群落主要为硅藻（63%）和甲藻（17%）。     

Overland movement and migration phenology in relation to breeding of Arctic Terns Sterna paradisaea

It is often implicitly assumed that seabirds migrate using marine environments, but this assumption is increasingly being challenged by electronic tracking data. The arrival and departure routes of Arctic Terns breeding on the North Sea coast of the United Kingdom (UK) are unknown but there has been speculation about the possibility of overland migration. Analysis of light-level geolocator data from birds breeding on the Farne Islands suggests that these birds arrived and left their North Sea colony overland via the Irish Sea, rather than taking coastal routes along the east coast of the UK and through the English Channel. In addition, some departing birds may enter the North Atlantic by crossing Ireland rather than through the Irish Sea. The direction of arrival in spring had a more southerly orientation than the direction of autumn departure. The geolocator data allow migration phenology in relation to breeding to be defined and indicated that the birds arrived around 15 days before the first eggs were laid in the colony. Departure timing may be determined by seasonal progression and not markedly influenced by breeding success. This study supports the idea that overland migration may be a more widespread and consistent strategy for seabirds than has been realized.     

A new species of Hormathia (Actiniaria, Hormathiidae) from the eastern Weddell Sea, Antarctica

A new species of sea anemone in the genus Hormathia, is described and illustrated based on forty-two specimens collected during the Polarstern cruises ANT XV/3 and ANT XVII/3 in the Weddell Sea. The main features of the new taxon are the crown of flattened and hooked tubercles at the distal end of the scapus, the regular arrangement of pointed tubercles along the column and the cnidom. The new species shares the pointed tubercles, at least in the upper part of the scapus, with two other species of Hormathia in the southern hemisphere: Hormathia spinosa Hertwig 1882 and H. pectinata Hertwig 1882 Received in revised form: 27 December 2000 Electronic Publication     

Changes of sea level, landscape and culture: A review of the south-western Baltic area between 8800 and 4000 BC

The global warming at the end of the last glacial period led to a sea level rise, which induced substantial long-term landscape changes in the southwestern Baltic Sea. During the Preboreal and Boreal periods, this region, bordering on the Ancylus Lake in the east, was dry land with numerous lakes and rivers. However, with the beginning of the Littorina Transgression around 6700 BC, during the Atlantic period, the area became connected to the ocean. People settling along the coast of the former Ancylus Lake, Mesolithic hunter–gatherers, continuously had to adapt to rapid changes.

The Littorina Transgression made a new source available to man: the young Baltic Sea. Important settlement sites were founded in the coastal regions, and were consumed one by one by the constantly rising sea level. At the time of the decline of the sea level rise and the beginning consolidation of the coast lines, a socially motivated turn towards a productive economy started. Hunting and fishery were widely replaced by agriculture and stock farming.

To understand the interplay between all of these developments, it is necessary that scientists from a variety of disciplines undertake collective investigations. This paper presents first culture-historical, palaeozoological, palaeobotanical, palaeoecological and palaeogeographical results yielded by from the multidisciplinary research group SINCOS (Sinking Coasts) and uses these to create a new comprehensive picture of the development of the south-western Baltic Sea region during the Ancylus Lake and Littorina Sea stages.     

Effect of caulerpenyne,a toxin extracted from Caulerpa taxifolia on mechanisms regulating intracellular pH in sea urchin eggs and sea bream hepatocytes

The proliferation of the green marine alga Caulerpa taxifolia in the Mediterranean led us to investigate the toxic effects on marine organisms of caulerpenyne (Cyn), the major secondary metabolite synthesized by the alga. This study was performed on sea urchin eggs (Paracentrotus lividus) and isolated hepatocytes from the sea bream (Sparus aurata), in which accumulation of the toxins by metabolic processes may be of significance. Cyn provoked an acidification of seawater containing both unfertilized and fertilized eggs, as revealed by a titrable efflux of protons. The pHi in unfertilized eggs continuously increased in the presence of Cyn, whereas there was a biphasic response in both fertilized eggs and isolated hepatocytes, with a decrease of the pHi followed by recovery to the initial value. Cyn inhibited the accumulation of ¹⁴C-methylamine in acidic granules present in the cortical zone of sea urchin eggs. Dicyclocarbodiimide (DCCD), a well-known H⁺-ATPase inhibitor, provoked a similar inhibition. Both molecules increased pH in the acidic compartments of isolated bream hepatocytes. These results suggest that Cyn inhibits intracellular sequestration of protons and thus liberates protons into the cell cytoplasm from which they leak toward the extracellular medium. © 1997 John Wiley & Sons, Inc.     

东海和黄海主要鱼类的食物竞争

以2000年和2001年在东、黄海两次大面调查所收集的、占总生物量90%的重要生物种类中的鱼类为研究对象,通过分析胃含物获得各饵料成分的重量百分比,用Pianka(1973)提出的公式计算的饵料重叠系数分析了东、黄海主要鱼类之间的食物竞争状况,以了解食物竞争与种群变动和优势种交替之间的相互关系。结果表明:黄海主要鱼类的食物竞争对象主要为太平洋磷虾、脊腹褐虾和,东海主要鱼类的食物竞争对象主要为太平洋磷虾、细条天竺鱼、发光鲷、、七星底灯鱼和带鱼。东、黄海鱼类通过摄食种类、摄食食物大小、摄食时间和栖息地的分化来减少食物竞争,从而维持群落结构的动态平衡。渔业资源群落结构的变化将导致食物竞争状况发生改变;鱼类食物竞争状况也会影响种群动态,但要确定食物竞争程度还需进一步深入研究     

M.M. Kamshilov and Plankton Investigations in the Murmansk Region

In this paper, the results of plankton investigations from 1952 to 2000 in the Barents and Kara seas by the Laboratory of Plankton of the Murmansk Marine Biological Institute (Kola Branch, Russian Academy of Sciences) are briefly outlined. The development of ideas on the seasonal and long-term succession of plankton communities in the Barents Sea, which were propounded by M.M. Kamshilov, the founder of the Plankton Laboratory, is shown.     

Broad-scale patterns of abundance of non-indigenous soft-bottom invertebrates in Denmark

Quantifying the broad-scale distribution and abundance of non-indigenous species (NIS) is necessary to provide accurate estimations on impacts of invasions, to prioritize research, and to guide national management. Sediment grab-sampling is a standardized method for monitoring marine benthos. In Denmark, ~45,000 grab-samples were collected from 1970 to 2005. Using these samples, we compared densities of NIS and native species among 27 broad spatio-temporal groupings. Eight known NIS and one ‘cryptogenic species’ (the polychaete Neanthes succinea) were found in the samples. Most were present in low abundance, but the bivalve Mya arenaria, likely introduced by the vikings from North America, was particularly abundant. M. arenaria was found in ca. 20% of all samples and was among the 10 most common species in all of Denmark. M. arenaria’s high abundance, high filtration capacity and importance in food-web interactions, suggest that this species has dramatically impacted shallow coastal ecosystems in Denmark. The polychaete Marenzelleria viridis, the gastropod Potamopyrgus antipodarum and N. succinea were also widespread and abundant, and they too are likely to have had broad-scale impacts. In conclusion, 28% of grab-samples collected in Denmark over 35 years were affected by some degree of NIS or cryptogenic species, suggesting that centuries of human-mediated transfer of organisms has had a profound impact on the ecology of soft-bottom systems in Denmark.     

Morphology and systematic significance of sclerolepidia in the weevils (Coleoptera: Curculionoidea)

The Russian sturgeon, Acipenser gueldenstaedtii, is closely related to three other sturgeon species (A persicus, A. naccarii and A baerii), with populations in the Caspian Sea containing a cryptic lineage with an A. baerii‐like mtDNA profile. Using morphological evidence (morphometrics, meristics) and additional genetic analysis (cytochrome b gene and control region sequencing), cryptic lineages within the Russian sturgeon and their relation to other closely related species of sturgeons are further examined. These data indicate that three genetic forms exist within what is presently known as A. gueldenstaedtii. These forms include the pure A. gueldenstaedtii and A. baerii‐like individuals plus a third rare genetic form whose mtDNA is similar to the mtDNA of the Adriatic sturgeon, A. naccarii. Morphological comparison of the three forms and the Yenisei River A baerii indicates that although the three forms of A. gueldenstaedtii are not different from one another, all three significantly differ from the Yenisei River A. baerii. Competing explanations, including translocation and centre of origin hypotheses are considered. The three geneticforms of A. gueldenstaedtii likely colonized different geographic areas during different geological periods, and subsequently evolved in these regions independently into the species currently recognized as A. gueldenstaedtii, A. naccarii and A. baerii.