中国淡水双壳类特有种的地理分布

通过查阅有关文献整理得出,中国淡水双壳类特有种计有58种,隶属于双壳纲(Bivalvia)2科17属,其中主要是蚌科(Unionidae)的种类(16属57种)。我国淡水双壳类特有种的组成和区系成分,以东洋界华中区的种类占绝对优势,仅有少数种类渗透到古北界;特有种在我国16个省有分布,但主要集中分布于江西、湖南、安徽、浙江、江苏五省。双壳类特有种的形成和保存可能与我国古地理环境及其生活的水域环境有关。     

Zoobenthic communities of the Dagestan Region of the Caspian Sea

The results of bottom community studies of the Dagestan Region of the Caspian Sea were presented; key factors affecting their formation were distinguished. Special attention was paid to restoration of the amphipod Pontogammarus maeoticus, which was characteristic in the coastal zone community until it was destroyed after a rise in the sea-level. It was established that biomass of the benthos was much higher in the period of the rise in the sea level than in the years of a low sea level.Original Russian Text Copyright © 2005 by Biologiya Morya, Guseinov.     

Native Parasites Adopt Introduced Bivalves of the North Sea

Introduced species may have a competitive advantage over native species due to a lack of predators or pathogens. In the North Sea region, it has been assumed that no metazoan parasites are to be found in marine introduced species. In an attempt to test this assumption, we found native parasites in the introduced bivalves Crassostrea gigas and Ensis americanus with a prevalence of 35% and 80%, respectively, dominated by the trematode Renicola roscovita. When comparing these introduced species with native bivalves from the same localities, Mytilus edulis and Cerastoderma edule, trematode intensity was always lower in the introduced species. These findings have three major implications: (1) introduced bivalves are not free of detrimental parasites which raises the question whether introduced species have an advantage over native species after invasion, (2) introduced bivalves may divert parasite burdens providing a relief for native species and (3) they may affect parasite populations by influencing the fate of infectious stages, ending either in dead end hosts, not being consumed by potential final hosts or by adding new hosts. Future studies should consider these implications to arrive at a better understanding of the interplay between native parasites and introduced hosts.     

Phytoplankton distribution in the Caspian Sea during March 2001

Phytoplankton abundance, biomass and species composition of the Caspian Sea were evaluated by using samples collected from the Iranian (southern Caspian Sea) and southern Kazakhstan (eastern Caspian Sea) surface waters in March 2001. A total of 45 taxa were found in the samples (20 diatoms, 17 dinoflagellates and 8 others). Abundance and biomass of diatoms were high at the eastern stations, while dinoflagellates were dominant in terms of both biomass and abundance in the southern region. Average abundance and biomass were 40 000 ± 35 000 cell l⁻¹ and 580 ± 690 μg l⁻¹. The mean biomass value found here for the Middle and southern Caspian Sea in March are difficult to compare with the past due to limited information, but seems higher than previously registered values. Higher chlorophyll values were also apparent from the SeaWIFS images in 2001 compared to those in 1998. This is suggested to be due to decreased grazing of phytoplankton by zooplankton which is voraciously preyed by the recent invasive ctenophore Mnemiopsis leidyi.     

Oligo-Miocene fluvial-dominated deltas on the shelf of the South Caspian Sea (Paratethys)

The Oligo-Miocene Zivah Formation forms the principal reservoir unit in the Moghan area of northwest Iran. Characterization of the constituent facies of the formation and their spatial distribution represent a major aspect of this investigation. The combination of results from the field and laboratory studies lead to the determination of 18 lithofacies and 13 petrofacies (petrographic lithofacies). Three major types of sedimentary cycles (small-, medium-, and large-scale cycles) of variable thickness (few meters, few tens of meters, few hundreds of meters, respectively) are recognized on the basis of facies association properties. Depositional environments representing each facies and facies association are defined and interpreted on the basis of their sedimentological characteristics. The major depositional systems of the Zivah Formation are interpreted as fluvial-dominated deltas on the shelf of the South Caspian Sea (or Paratethys). The principal controls on sedimentation are discussed in terms of lithofacies/petrofacies characteristics and the nature of sedimentary cycles. Development of large-scale cycles is related to world-wide sea-level change (eustasy), medium-scale cycles to tectonism along the basin margin, and small-scale cycles to the rate of sediment supply and local environmental conditions. Active tectonism seems to be the main cause for high sediment supply to the Zivah Basin.     

Effect of extremely low frequency electromagnetic field on brain histopathology of Caspian Sea Cyprinus carpio

There is limited research on the effect of electromagnetic field on aquatic organisms, especially freshwater fish species. This study was conducted to evaluate the effect of extremely low frequency electromagnetic field (ELF-EMF) (50 Hz) exposure on brain histopathology of Cyprinus carpio, one of the important species of Caspian Sea with significant economic value. A total of 200 healthy fish were used in this study. They were classified randomly in two groups: sham-exposed group and experimental group, which were exposed to five different magnetic field intensities (0.1, 1, 3, 5, and 7 mT) at two different exposure times (0.5 and 1 h). Histologic results indicate that exposure of C. carpio to artificial ELF-EMF caused severe histopathological changes in the brain at field intensities ≥3 mT leading to brain necrosis. Field intensity and duration of exposure were key parameters in induction of lesion in the brain. Further studies are needed to elucidate exact mechanism of EMF exposure on the brain.     

Distribution and contamination pattern of heavy metals from surface sediments in the southern part of Caspian Sea,Iran

This study concentrates on the speciation and distribution patterns of some heavy metals (Pb, Ni, Cd, Zn, and Cu) in surface sediments in the southern part of the Caspian Sea, the biggest lake in the world, to obtain an overall classification for the origins of metals in the area using a sequential extraction technique. At all sampling stations, Pb, Ni, Zn, and Cu were mostly (>50%) accumulated in the resistant fraction, which indicated that there were no significant anthropogenic inputs of Pb, Ni, Zn, and Cu into the surface sediments of the south Caspian Sea. Guilan province on the west coast of Caspian Sea accumulated higher percentages of non-resistant fractions of Pb and Zn, while Mazandaran and Golestan provinces in the middle and western parts of the Caspian Sea, in the Iranian zone, accumulated higher percentages of non-resistant fractions of Ni and Cu. The present study revealed that the coastal area of the south Caspian Sea is still not seriously contaminated. Cadmium in Guilan and Golestan provinces were dominated by non-resistant fractions (55–69%), which indicated more anthropogenic inputs of Cd on the south coast of the Caspian Sea in comparison with other metals.     

Using multiple indicators to assess the environmental status in impacted and non-impacted bathing waters in the Iranian Caspian Sea

Human activities have increased in the Caspian Sea in last decades, impacting the coastal zone ecosystems. One of the increasing activities is recreation, including bathing areas in the south of the Caspian Sea, which have been scarcely studied and assessed. Investigating the interactions between human activities and the resulting environmental status in bathing areas, by using adequate indicators and assessment methods, is necessary to undertake management measures for ecosystem restoration. In this study, for the first time, we use the Nested Environmental status Assessment Tool (NEAT) outside the European waters to assess environmental status in bathing waters, to differentiate areas impacted and non-impacted by bathing activities. We have assessed the status in winter and summer seasons, by combining multiple indicators from different ecosystem components (8 physico-chemical, 4 bacteria, 2 plankton, and 1 benthos indicators). Despite the interactions between season and human affection, NEAT determined that the Caspian Seas is not in good status, differentiating, in summer, between impacted and non-impacted bathing areas, with a significant correlation with the number of beach users. Accordingly, management measures should be taken in the southern Caspian Sea to improve the environmental status in general and that of bathing areas in particular.     

Spatial distribution and diversity of commercial demersal fish species in the shelf waters of the Caspian Sea

The Caspian Sea (CS) is a unique ecosystem known for its several fish species, especially sturgeons. To exhaustively manage the fish stocks of this ecosystem, detailed knowledge of species composition, abundance, distribution, and the habitat traits of the living organisms is necessary. This study analyzed the diversity, spatial, and seasonal distribution of commercial demersal fish species, and examined the relationships between community structure and environmental variability in Iranian shelf waters of the CS. For this purpose, seasonally fish sampling took place between 2009 and 2011 with a bottom trawl. Among 11 fish species captured, Chelon spp., Rutilus kutum, and Vimba vimba showed the highest abundances (i.e. 88.49%, 10.67%, and 0.69%, respectively). Univariate and multivariate analyses showed differences in commercial fish assemblages (abundance and species richness) according to seasons and regions. Distance-based Linear Model (DisTLM) showed that eight environmental variables display significant linear relationships with the fauna resemblance matrix (p < .05). Based on AIC criteria, the combination of silt&clay, TOM, longitude, depth, bottom, and surface temperature used to build the parsimonious DisTLM model explain 67.03% of the total variability. The results revealed a biogeographical and temporal gradient from the west to the east and summer to winter, in terms of commercial demersal fish assemblages and species diversity, as a consequence of different geomorphological, bottom substratum conditions and benthic communities.     

Ion composition and osmolarity of Caspian Sea ctenophore, Mnemiopsis leidyi, in different salinities

The aim was to study osmotic and ionic regulation in alien ctenophore, Mnemiopsis leidyi (total length of 1.5-3 cm), acclimated gradually to artificial sea water of different salinities (8, 13, 18 and 23 ppt) in laboratory conditions (24 ± 2 °C) with the salt composition and proportion of the Caspian Sea. Results showed that this species is hyper-osmoconformer (maintaining internal osmolarity 2-22 mOsmol l^{− 1} above external) in non-lethal salinities ranging from 8 to 23 ppt. The results of ionic regulatory investigations revealed that this species can regulate Ca²⁺ and SO₄²⁻ so that the concentration of Ca²⁺ in the internal fluid and SO₄²⁻ in the external fluid were significantly more in 8 and 13 ppt, respectively. No regulation was observed about other ions such as Cl⁻, Mg²⁺ and K⁺ in the mentioned salinities.     

New Phase of Succession of the Bivalve Abra ovata Community in Sulaksii Bay, the Caspian Sea

The study of the Abra ovata community existing on the flooded area of Sulakskii Bay in the Caspian Sea since the mid-1980s was continued. It was found that the pioneer species A. ovata and Cerastoderma glaucum still dominate in the community structure and define the course of succession despite a reduction in their population density and frequency of occurrence. The species composition and structure of the modern A. ovata community and the processes occurring in it are similar to the climax stage of the A. ovata community in the Middle Caspian Sea. Both mollusk species exhibit seasonal variations in number, which are due to predation by sturgeon and natural mortality. A steady annual decrease in the sea level, retreat of the water's edge by 80–100 m, and mass burial of the shells of bivalve mollusks in the drying-out innermost part of the bay were observed.     

Endemic and Indo-Pacific plankton in the Mediterranean Sea: a study based on dinoflagellate records

Aim To investigate biogeographical patterns based on published dinoflagellate records from the Mediterranean and Black Seas, and to provide a tentative list of endemic and Indo‐Pacific dinoflagellates in the Mediterranean Sea. Location Mediterranean Sea, Black Sea. Methods Checklists of dinoflagellates of the Mediterranean and Black Seas were compared with worldwide literature records. Only species reported in the Indo‐Pacific Ocean or exclusively known in the Mediterranean Sea were selected for biogeographical analysis. Results Dinoflagellates in the Mediterranean Sea comprised c. 43% of the world marine species and c. 88% of the dinoflagellate genera. Species richness among the Mediterranean sub‐basins showed marked differences due to the less reliable records of unarmoured (athecate) and rare dinoflagellates. These differences disappeared when only the more easily identifiable taxa were considered. Of the 673 dinoflagellates cited in the Mediterranean, 87% were also reported in the Atlantic Ocean. Only 40 taxa (6% of the total) were considered to be potential Indo‐Pacific species. Most were reported from the Ligurian Sea (21), and only two species from the Levantine basin. The other 48 taxa (7% of total) were known exclusively from the Mediterranean Sea, mainly from the Ligurian Sea. Half of these taxa were reported by a single author. Main conclusions Substantial dinoflagellates species richness can be attributed, in part, to the historical tradition of taxonomic studies in the Mediterranean Sea. The list of species of both Indo‐Pacific and exclusively Mediterranean species included taxa of dubious taxonomic validity or that were insufficiently known. The exclusion of these questionable taxa revealed the near absence of endemic dinoflagellates in the Mediterranean Sea compared with macroscopic organisms. This could be related to: (1) continuous replenishment of the plankton populations by the inflow of Atlantic water through the Strait of Gibraltar, (2) the possibility that species introduced during the Pliocenic flooding after the Messinian salinity crisis have not had enough time to diverge from their Atlantic ancestors, and/or (3) the reliance on traditional taxonomy based on morphological characters, which precludes the detection of cryptic speciation.     

Bivalves with 'concrete overcoats': Granicorium and Samarangia

Two veneroidean bivalves Granicorium indutum from Australia and Samarangia quadrangularis from the tropical Indo-Pacific region, cement a thick, hard layer of sand over most of their shells. In Granicorium this layer forms low commarginal ribs while in Samarangia it forms more prominent radial features. Sand grains are cemented to the shell and to each other with growths of a crystalline aragonitic cement similar in morphology to inorganic marine cements. Both species secrete mucus layers at the growing shell margin which initially hold the sediment grains together and form a substrate for the nucleation and growth of calcium carbonate crystals. The ribs of Samarangia are formed by the accretion of successive sheets of spherulitic growths. In G. indutum , the middle and outermost of two inner mantle folds are large, glandular and capable of considerable extension beyond the shell margin. Mucus secreted by the folds contains abundant bacteria and small calcium carbonate crystals. It is proposed that initial nucleation of the calcium carbonate cement takes place within this biofilm possibly mediated by the bacteria. The function of the sand layers is unknown but predation resistance and protection of the shells from endobionts are the most likely possibilities.     

Population ecological parameters and stock assessment of Russian sturgeon Acipenser gueldenstaedti Brandt & Ratzeburg, 1833 in the Southern Caspian Sea

Russian sturgeon (Acipenser gueldenstaedti Brandt & Ratzeburg, 1833) is one of the major commercial sturgeon species, but there is no adequate information and previous‐published about population dynamics and stock assessment of this species in the southern Caspian Sea. This paper examines the age structure, growth parameters, maturity, age at first capture, optimum length, natural and fishing mortality and amount of biomass in the southern Caspian Sea (Iranian waters), during a two decades time series period from 1990–1991 to 2008–2009. For a pooled data, the growth parameters were estimated as L_∞ = 214.0 cm, K = 0.054, t₀ = ?4.5 year. Size at fifty percent sexual maturity was at FL = 118 cm for females and 113 cm for males. The age at first capture (t_c) estimated to be 12.1 years. In the catch composition, bulk of the catch (75%) belonged to 13–17 years old. The instantaneous coefficient of natural mortality (M) was estimated as 0.120 year^?1 and the instantaneous coefficient of fishing mortality (F) varied during the 19‐year period between 0.130 to 0.505 year^?1. The biomass showed a descending trend from 1,941.2 mt in 1990–1991 collapsed to about 55 mt in 2004–2005, and then decreased to the lowest level and represented 18.5 mt in 2008–2009. The result revealed that, the stock of Russian sturgeon is being over‐fished. We concluded that to manage the sturgeons stocks, a coordinated regional and international effort are needed to provide immediate implementation of stock enhancement and management in the Caspian Sea.     

Comparative morphology of the sagittal otolith in three species of south Caspian gobies

Sagittal otolith shapes were investigated in order to identify three sympatric species of south Caspian gobies (Caspian goby Neogobius caspius, deepwater goby Ponticola bathybius and bighead goby Ponticola gorlap). The sagittal otoliths in P. bathybius have a rectangular shape and are thick, whereas in N. caspius they are relatively round and thin. In P. gorlap, otoliths have an elongated shape and are relatively thick. The noticeable difference among the otoliths of the three species is the presence of one anterior and one posterior projection in the otoliths of N. caspius and P. gorlap. Among shape indices, form factor (irregularity of surface area), circularity, aspect ratio and rectangularity are the foremost that indicate interspecific variability. The canonical discriminant analysis correctly classifies 94·7% of the original group cases. The overall analyses show the relevance of applying otolith shape for interspecific distinction of the three species of Caspian gobies.     

Impact of Polluted Bottom Deposits on the Species Structure and Abundance of Bivalves in Peter the Great Bay,Sea of Japan

Data from long-term (1979–1988) studies of bivalve fauna and of the content of priority pollutants in the bottom deposits of Peter the Great Bay have been analyzed. It was established that the biomass, population density, number of species, and the species diversity indexes of Shannon-Weiner and of the Pielou evenness of bivalves negatively correlated with the total pollution factor, TPF, of bottom sediments. Changes in the ecological parameters of bivalves with an increase in pollution occurred in spurts within the 3.4–3.6 interval of TPF values. The area of such values covered not only the coastal zone of Vladivostok, but also a considerable part of Amursky Bay.     

Range expansion of quagga mussels Dreissena rostriformis bugensis in the Volga River and Caspian Sea basin

In 1992, we discovered populations of the nonindigenous quagga mussel Dreissena rostriformis bugensis in the middle reaches of the Volga River. The same species was found in samples collected between 1994 and 1997 in the Volga delta and in shallow areas of the Northern Caspian Sea. D. r. bugensis always co-occurred with its more widespread congener, the zebra mussel D. polymorpha (Pallas 1771). The quagga mussel's contribution to total Dreissena abundance increased over time in the middle Volga reservoirs and Volga River delta. D. r. bugensis was common in the Volga portion of Rybinsk Reservoir during 1997 and, by 2000, it was in Uglich, Rybinsk and Gorky Reservoirs on the Upper Volga River. D. r. bugensis was neither found in Ivankov Reservoir, nor in terminal sections of the Volga-Baltic corridor including the eastern Gulf of Finland. Presently, all but the northern-most regions of the Volga River have been colonized by D. r. bugensis. We hypothesize that its introduction into the Volga River and Caspian basin occurred no later than the late 1980s via commercial shipping that utilized the Volga-Don waterway to navigate between the source Black-Azov Sea region and recipient areas on the Volga River. Larval drift likely contributed to establishment of populations at downstream sites, while human-mediated vectors may be responsible for introductions to upstream locations on the Volga River. We anticipate continued northward dispersal in conjunction with shipping activities.     

Quantifying the cooling effect of rain events on outdoor thermal comfort in the southern coastal stations of the Caspian Sea

Pleasant outdoor thermal conditions depend on a wide range of climatic elements. The impact of rainfall events, as important climatic elements, on providing thermal comfort, has been less explored in the available literature. The work presented herein investigates the impact of Rainy Days as well as a Day Prior to (D_prior) and a Day Post rain (D_post) events on thermal conditions in the southern coastal region of the Caspian Sea. In this study, rainfall events during 1961–2017 observational period were categorized based on their intensity. Then, human thermal comfort during non-rainy (sunny) and rainy days was estimated and compared by using the radiation-driven Physiological Equivalent Temperature (PET) index, Universal Thermal Climate Index (UTCI) and Perceived Temperature (PT) index. Furthermore, difference between the average of thermal conditions in rainy days compared to a day prior and a day post rain events was calculated separately for comfort, cold and heat stress thresholds of each bioclimatic index. Finally, the correlation between the average of indices for rainy days and the frequency of rainfall events of each specific year was computed. Results suggested that overall average of studied indices for all rainy days is lower than the average for days prior and post the rain events. PET index has shown to be most impacted and reduced as a result of rain events and therefore more indicative of a cool ing effect. The observed difference in total average of PET in rainy days compared to non-rainy days were 8.30 °C, 5.86 °C and 8.85 °C for Babolsar, Rahst and Gorgan stations, respectively. Generally, the cooling effect of rain events on the temperature for a day prior rain events is higher than a day post rainfall. Finally, the trend analysis on rainy days in the studied period revealed that the average of bioclimatic indices in western stations (Babolsar and Rasht) are increasing whereas a decreasing trend was observed for Gorgan as more of an eastern station.     

Hematological parameters of Caspian salmon Salmo trutta caspius associated with age and season

Measurement of hematological parameters for Caspian salmon Salmo trutta caspius in two experimental trials was the main purpose of this work. There were no significant differences in RBC and large-lymphocyte counts between all seasons (p > 0.05). The proportions of monocyte, neutrophile and eosinophile were higher in winter than in other seasons (p < 0.05). The amount of Hb, RBC, MCHC, monocyte, neutrophile and eosinophile was higher in adult fishes in comparison with other ages (p < 0.05). However, the amount of HCT, WBC, MCV, MCH, lymphocyte and large-lymphocyte was greater in smolt fishes than the others (p < 0.05).     

海南岛两栖动物调查及珍稀和特有种的测量数据

1995年至2005年对海南岛进行了多次两栖动物调查,海南师范大学生物系每年进行本科生动物学野外实习,也采集了大量的两栖动物标本。所有标本均保存在生物系标本室内,经整理编号,统计共有955号,分类鉴定得35种,分别隶属16属7科2目。本文报道整理结果,并将其中海南特有物种及国内分布区狭窄的个别物种的测量数据加以报道,以供参考。