Lipid biomarkers of deep-sea hydrothermal vent polychaetes—Alvinella pompejana, A. caudata, Paralvinella grasslei and Hesiolyra bergii

The lipid composition was determined for 5 species of polychaete annelids collected by the Deep Submergence Vehicle ALVIN from high temperature chimneys at the 2500 m depth hydrothermal vent field of the East Pacific Rise. These are the first lipid biomarker analyses reported for these hydrothermal vent polychaetes. Lipid content was low in all samples (1.6–35.9 mg g^–1 wet mass) and was dominated by polar lipid (78–90% of total lipid) with 8–19% sterol (ST), and very low storage lipid (triacylglycerol and wax ester). Total polyunsaturated fatty acids (PUFA) were moderately high (22–31% of total fatty acids (FA)) with extremely low or no docosahexaenoic acid (DHA, 22:6(n-3)). Eicosapentaenoic acid (EPA, 20:5(n-3)) levels were 5–6% in Alvinella pompejana and A. caudata and 10.3–13.7% in an errantiate polychaete (likely Hesionidae) and Hesiolyra bergii. There were greater PUFA and a greater EPA/AA (AA is arachidonic acid, 20:4(n-6)) ratio in the anterior versus the posterior half of A. pompejana, which may correlate to the strong temperature gradient reported in its tube. Total nonmethylene interrupted diunsaturated fatty acids (NMID) were 4–9% of total FA for most polychaete species and included several 20:2 and 22:2 components. The principal monounsaturated fatty acids (MUFA) included 18:1(n-7)c (14–19%), 16:1(n-7)c (2.6–10%) and 20:1(n-11)c (3–7% of total FA). These polychaete species may desaturate and elongate the bacterial-derived 18:1(n-7)c to obtain the essential FA EPA and AA. The major ST in the polychaetes is cholesterol (89–98% of total ST) with less cholesterol in the gut contents of A. pompejana. Other ST included 24-ethylcholesterol (1.5–5% of total ST) with lesser amounts of 24-methylenecholesterol, desmosterol, lathosterol, 24-methylcholesterol, 24-ethylcholesterol, and the stanols dehydrocholestanol and cholestanol. The high ST levels could play a role in thermal adaptation of membranes at the hydrothermal vent environment. Differences in the FA profiles separated the closely related species A. pompejana and A. caudata from Paralvinella grasslei, H. bergii, and the errantiate polychaete (likely Hesionidae).     

Food and feeding habits of juvenile flounder Platichthys flesus (L.), abd turbot Scophthalmus maximus L. in the åland archipelago, northern Baltic Sea

The food choice of juvenile flounder (Platichthys flesus) and turbot (Scophthalmus maximus) was studied in the northern Baltic Sea during the years 1988, 1989, 1994 and 1995. The diet included organisms from 30 species/taxa in flounder (n = 306) and 10 species/taxa in turbot (n = 41). Flounder 45 mm mainly consumed meiofauna (dominating taxon: Harpacticoida, Copepoda) and larger fish (46–101 mm) consumed macrofauna (dominating taxa: Oligochaeta, Amphipoda and Chironomidae). In terms of biomass, macrofauna dominated for all sizes of flounders, and meiofauna was important only for the smallest fish. A strong seasonal variation could be detected in the diet. In spring, macrofauna dominated for all size classes of fish (only fish > 30 mm were caught in spring), while in summer and autumn meiofauna dominated the diets for fish 45 mm in size. Juvenile turbot (22–88 mm) consumed macrofauna and small fish. Turbot 30 mm consumed mainly amphipods, while > 30 mm turbot consumed mysid shrimps, amphipods and fish.The ontogenetic shift from meio- to macrofauna-sized prey in flounders occurs at a larger fish size in the northern Baltic Sea than reported in other areas, possibly depending on the increased relative importance of meiofauna in the northern Baltic. The seasonal variation in the diet could be due to seasonally changing abundances in the zoobenthos, or for the small fish (1-group, spring), to switching from meio- to macrofauna in order to optimize their energy gain. The 0-group flounders consumed meiofauna for a long period, possibly due to a learning-process or simply due to easy availability of meiofauna. Turbot has a much larger mouth gap than flounders, thus allowing them to consume macrofauna from the beginning of their benthic life.     

Successful colonization of the calanoid copepod Acartia tonsa in the oligo-mesohaline area of the Gironde estuary (SW France) – Natural or anthropogenic forcing?

The copepod Acartia tonsa appeared in Europe in the first half of the 20th century and colonized progressively European seas and estuaries, possibly transferred from North Atlantic Coast of America. It had been reported in the polyhaline area of the Gironde estuary for a long time but was first recorded in the oligo-mesohaline area in 1983. Its abundance has been increasing significantly. High abundances of A. tonsa were reported since 1999, supplanting the abundances of its autochthonous congeneric species, Acartia bifilosa. This colonization was characterized by analyzing the mean seasonal variability: (1) for three 5-year periods corresponding to three different steps of A. tonsa appearance (1978–1982, A. tonsa was absent; 1988–1992, low abundances of the species; and 1999–2003, high abundances of A. tonsa) in the oligo-mesohaline area and (2) for three stations distributed along the salinity gradient during the recent period. The aim of this work was to define if this colonization was due to natural or anthropogenic forcing and to evaluate its possible impact on autochthonous zooplanktonic community.Both natural and anthropogenic forcings seem to explain the colonization of Acartia tonsa in the oligo-mesohaline area of the Gironde estuary. First records (1983–1988) could be due to marine water inputs caused by high values of the North Atlantic Oscillation index. The global warming which caused the increase of the summer warm period, the marinisation of the system and the local decrease of the turbidity should have been the key factors favoring the establishment of the species. Anthropogenic forcings as the establishment of the nuclear power plant which locally causes warmer conditions are also important factors explaining the differences of seasonal cycle observed between oligo-mesohaline area and other stations: the seasonal pattern of A. tonsa in the oligo-mesohaline area was indeed characterized by an autumnal peak of abundances which has been observed in other stations and in many North European estuaries, and by a second spring peak that had only been observed in Southern estuaries.The introduction of Acartia tonsa in the Gironde estuary significantly changed the seasonal pattern of autochthonous copepods, by limiting their seasonal abundances without affecting their long-term population stability. Finally, the successful colonization of A. tonsa had led to the spread of the seasonal zooplanktonic production which could have had an impact on fish and shrimp productions.     

Risk assessment of TBT in the Japanese short-neck clam (Ruditapes philippinarum) of Tokyo Bay using a chemical fate model

A risk assessment of Tributyltin (TBT) in Tokyo Bay was conducted using the Margin of Exposure (MOE) method at the species level using the Japanese short-neck clam, Ruditapes philippinarum. The assessment endpoint was defined to protect R. philippinarum in Tokyo Bay from TBT (growth effects). A No Observed Effect Concentration (NOEC) for this species with respect to growth reduction induced by TBT was estimated from experimental results published in the scientific literature. Sources of TBT in this study were assumed to be commercial vessels in harbors and navigation routes. Concentrations of TBT in Tokyo Bay were estimated using a three-dimensional hydrodynamic model, an ecosystem model and a chemical fate model. MOEs for this species were estimated for the years 1990, 2000, and 2007. Estimated MOEs for R. philippinarum for 1990, 2000, and 2007 were approximately 1–3, 10, and 100, respectively, indicating a declining temporal trend in the probability of adverse growth effects.A simplified software package called RAMTB was developed by incorporating the chemical fate model and the databases of seasonal flow fields and distributions of organic substances (phytoplankton and detritus) in Tokyo Bay, simulated by the hydrodynamic and ecological model, respectively.     

Uptake and metabolism of arsenate by anexic cultures of the microalgae Dunaliella tertiolecta and Phaeodactylum tricornutum

Axenic cultures of the microalgae species, Dunaliella tertiolecta and Phaeodactylum tricornutum were grown at arsenic (As) concentrations typically found in uncontaminated marine environments ( 2 µg L^− 1) under different phosphorus concentrations. D. tertiolecta accumulated higher arsenic concentrations (mean: 13.7 ± 0.7 µg g^− 1 dry mass) than P. tricornutum (mean: 1.9 ± 0.2 µg g−1 dry mass). Media phosphorus concentrations (0.6–3 mg/L) had little influence on microalgae growth rates or arsenic accumulation. Arsenic was present as lipid bound (29–38%; 4.2–9.5%), water-soluble (20–29%; 26–34%) and residue bound (41–45%; 57–69%) arsenic species in D. tertiolecta and P. tricornutum respectively. Hydrolysed lipids contained mostly glycerol arsenoribose (OH- ribose), dimethylarsinate (DMA) and inorganic arsenic (As(V)) moieties. Water-soluble species of microalgae were very different. D. tertiolecta contained inorganic arsenic (54–86%) with variable amounts of DMA (7.4–20%), arsenoriboses (5–25%) and traces of methylarsonate (MA) ( 1%). P. tricornutum contained mostly DMA (32–56%) and phosphate arsenoribose (PO₄-ribose, 23–49%) and small amounts of OH-ribose (3.8–6.5%) and As(V) (9–16%). Both microalgae contained an unknown cationic arsenic species. The residue fractions of both microalgae contained predominately inorganic arsenic (99–100%). These results show that at natural seawater arsenic concentrations, both algae take up substantial amounts of inorganic arsenic that is complexed with structural elements or sequestered in vacuoles as stable complexes. A significant portion is also incorporated into lipids. Arsenic is metabolised to simple methylated species and arsenoriboses.     

Population dynamics of Cyathura carinata (Isopoda) in a eutrophic temperate estuary

From January 1993 to September 1995, Cyathura carinata was a target species of a monitoring programme carried in the Mondego Estuary (Portugal). Being one of the key species of the intertidal mud flats, this isopod was found to be most abundant in a eutrophic area, where seasonal macroalgal blooms usually occur. Its density decreased towards downstream areas, where some Zostera noltii beds exist. At the Mondego Estuary, the present work stated that C. carinata: (a) had a 2-year life span, even though, 80–90% of the individuals died when 1 year old, revealing a strong post-reproduction mortality; (b) produced a single cohort per year; (c) showed continuous growth (with lower rates during winter); (d) evidenced protogynous hermaphroditism and (e) presented a high growth production and a low turnover ratio. A latitudinal gradient reflected in the life features of C. carinata was described. Except for the life span and the frequency of reproduction, which are generally valid for all populations, C. carinata from the Mondego Estuary fitted the characteristics of other populations from the south of Europe.The effects of macroalgal blooms were assessed. Cyathura carinata seemed to temporarily benefit from the presence of macroalgae, due to higher energy resources and more efficient protection against predators. In a long term, algal blooms had negative consequences. It was particularly evident on the recruitment success, which had repercussions in population abundance, and on the secondary production. Therefore, repeated events of algal blooms embracing the distribution areas of C. carinata represent a threat to this species in eutrophic estuaries.     

Effect of native and invasive cordgrass on Macoma petalum density, growth, and isotopic signatures

Ecosystem engineers can influence community and ecosystem dynamics by controlling resources, modifying the flow of energy or biomass, or changing physical characteristics of the habitat. Invasive hybrid cordgrass (Spartina alterniflora × Spartina foliosa) is an ecosystem engineer in salt marshes in San Francisco Bay, California, U.S.A. that raises intertidal elevations and may be either increasing C₄ plant carbon input into food webs or tying up carbon in a form that is not usable by consumers. A manipulative experiment compared abundance, growth, and stable isotope (δ¹³C and δ¹⁵N) composition of the clam Macoma petalum (=M. balthica) among native marsh, hybrid Spartina, and mudflats in central San Francisco Bay. We found higher densities (individuals m⁻²) of M. petalum on mudflats compared to either native or hybrid Spartina (p < 0.001). Macoma petalum shell growth was significantly greater in mudflats than in either vegetation type in 2002 (p = 0.005) but not 2003. Differences in shell growth between native and hybrid Spartina were not significant. Stable isotope results showed differences between habitats in δ¹³C but not δ¹⁵N. Carbon signatures of M. petalum placed in Spartina were much more depleted than the isotopic signature of Spartina. Neither native nor hybrid Spartina appears to be a significant carbon source for M. petalum in San Francisco Bay, and we found no evidence that hybrid Spartina contributes carbon to M. petalum beyond what is provided by S. foliosa, despite the hybrid's much greater biomass. Our results show that loss of mudflat habitat, rather than increased input of C₄ carbon, is the greatest effect of the invasion of hybrid Spartina on M. petalum.     

Observations of a mass occurrence of Macoma balthica larvae in midsummer

In 1995 the seasonal development of concentrations of both phytoplankton and larvae of the bivalve Macoma balthica was studied in the coastal zone behind the back-barrier island of Spiekeroog (German Wadden Sea). In July/August larvae reached maximum concentrations of about 1000 to 4200 ind. m⁻³ (depending on the sampling site and tidal period), probably in relation to a phytoplankton bloom in July. This observation of an unusually late maximum of Macoma larvae is discussed in detail in connection with the recent literature available about spawning of M. balthica in the Wadden Sea.     

短小拟五角蟹的分布新记录

2022年9月作者在浙江宁波象山港海域采集到短小拟五角蟹(Paranursia abbreviata),由此短小拟五角蟹的地理分布记录从中国的海南岛、广东、香港和福建扩展到东海北部,即浙江北部的象山港。本文对其形态特征进行了详细的描述,并讨论了其与历史记载的外形差异。由于象山港冬季水温较低,推测短小拟五角蟹在象山港的出现可能是台湾暖流携带幼体定居导致的偶然现象。     

Reproductive success of Calanus pacificus during diatom blooms in Dabob Bay, Washington

While numerous laboratory studies in the last decade have shown that diatoms can induce reproductive failure in copepods, field evidence for a negative diatom effect is equivocal. To unambiguously elucidate the effects diatoms have on copepod reproduction in situ, we undertook a study of the abundance, distribution, grazing rates, and reproductive success of Calanus pacificus in Dabob Bay, Washington, USA, during two spring bloom periods. We simultaneously measured the phytoplankton composition, abundance, and distribution. Here we present results for the reproductive success of C. pacificus using four measurements: egg production rate, clutch size, egg hatching success, and naupliar survival (to the first feeding stage). Egg production rate was positively correlated with chlorophyll a concentration, and egg hatching success and naupliar survival were usually greater than 80%. However, in February 2002 and 2003 – during blooms of diatoms of the genus Thalassiosira – either egg hatching success, naupliar survival, or both were significantly depressed compared to other times in spring and summer. These effects, combined with evidence that C. pacificus was grazing aldehyde-producing Thalassiosira at the time of their blooms, indicate that diatoms can negatively affect copepod reproduction in the field, albeit only under specific circumstances and for brief periods.     

Distribution, condition, and growth of newly settled southern flounder (Paralichthys lethostigma) in the Galveston Bay Estuary, TX

Several flatfish species, including southern flounder (Paralichthys lethostigma) recruit to estuaries during early life. Therefore, evaluation of estuarine sites and habitats that serve as nurseries is critical to conservation and management. The present study used density data in conjunction with biochemical condition and growth measurements to evaluate settlement sites used by southern flounder in the Galveston Bay Estuary (GBE). In 2005, beam-trawl collections were made in three major sections of the GBE (East Bay, Galveston Bay, West Bay). Three sites were sampled in each bay. Within each sampling site, replicate collections were taken from three habitats: 1) marsh edge (< 1 m depth), 2) intermediate zone (10–20 m from marsh interface;  1 m depth), and 3) bay zone (typically > 100 m from marsh interface; depth > 1 m). Average size of southern flounder collected was 12–19 mm standard length, and peak densities occurred in January and February. Catch data indicated that densities of southern flounder were significantly greater in East Bay (2.75 per 100 m²) than in Galveston Bay (0.91 per 100 m²) or in West Bay (0.45 per 100 m²). Densities were statistically similar among habitats. Otolith-based estimates of age indicated that the majority of southern flounder collected were 35–45 days old and derived from early December to early January hatch-dates. Growth rates were similar among bays and among habitats, with the average growth rate being 0.40 mm day^− 1 (range: 0.21–0.76 mm day^− 1). RNA:DNA was above the established baseline value for nutritional stress, indicating that newly settled southern flounder in the GBE were in relatively high condition. Habitat-specific differences in RNA:DNA ratios were not observed; however, ratios were significantly lower in West Bay (average 8.0) than in East Bay (average 9.5) or in Galveston Bay (average 9.8), suggesting the condition of new recruits may vary spatially within the GBE. Findings from the current study suggest density and condition of newly settled southern flounder vary at the bay scale, suggesting that parts of GBE do not function equally as nurseries.     

Seasonal variability of leaf litter removal by crabs in a Kandelia candel mangrove forest in Jiulongjiang Estuary, China

The seasonal variability of leaf litter removal by crabs was observed from May 2006 to April 2007 in a Kandelia candel mangrove forest in Jiulongjiang Estuary, China. Daily average quantities of leaf fall ranged 0.85–3.86 gDW m⁻² d⁻¹, with high values in May, August, October and November. The whole-year's leaf fall was 6.48 t ha⁻¹ yr⁻¹ (1.81 gDW m⁻² d⁻¹). The standing stock of leaf litter on the forest floor was 7.78 gDW m⁻² averaged from the whole year's data, with the lowest value in December (1.23 gDW m⁻²) and the highest in April (16.18 gDW m⁻²). Annually averaged removal (consumption on mangrove floor + burial in burrows) rate of leaf litter by crabs was 0.59 gDW m⁻² d⁻¹. High seasonal variability was observed in the removal rates of leaf litter by crabs. Removal rates in the winter months (December, January and February) were 0.07–0.09 gDW m⁻² d⁻¹, much lower than those in other months with values of 0.59–1.18 gDW m⁻² d⁻¹. Annually averaged percentage of leaf fall removed by crabs was 33%, with the highest values in September (reached 76%) and the lowest values in winter months. Of leaf litter removed by crabs, a large proportion was buried by crabs, and only 12% was consumed by crabs on the forest floor. Leaf litter removal rate, consumption rate on the forest floor, percentages of leaf fall and standing stock removed on the forest floor were significantly positively correlated with air temperature, indicating that leaf removal ability by crabs was higher in warm months than in cold months.     

Seasonal and spatial variation in abundance and egg production of Paracalanus parvus (Copepoda: Calanoida) in/out Jiaozhou Bay, China

The spatial distribution of stage-specific abundance and reproduction of the copepod Paracalanus parvus were studied from October 2005 to September 2006 in the Jiaozhou Bay. This copepod occurred continuously in this bay throughout the year. The species reached the lowest abundance in April and peaked in June. From October to December, distribution center mainly occurred in offshore water and at the mouth of the bay. In winter, early copepodites and adults gradually decreased and till February, most of the population was only comprised of CIV–CV stages. Overwintering copepodites matured in March and males tended to mature before female. From May to September, each stage occurred in the population and gradually reached high abundance. Temperature and chlorophyll a (Chl-a) concentration in the three stations can't clearly explain the seasonal variation in stage-specific abundance, so we surmised the important effect of the Yellow Sea. Egg production rate (EPR) reached its lowest in winter and peaked in June at 60.8 eggs female⁻¹ day⁻¹ in nearshore water. In the warming period, EPR in nearshore water was statistically higher and EPR > 10 eggs female⁻¹ day⁻¹ lasted longer than that in offshore water, showing the importance of nearshore water for recruitment of P. parvus. Our study showed that EPR was positively related to temperature and total chlorophyll a in offshore water and mouth of the bay. In nearshore water, the relationships between EPR and temperature and Chl-a in three size fractions were not the same as those in offshore water, suggesting complicated ecosystem in such a eutrophic area in warming period.     

Relative abundance, age, growth, and fecundity of grubby Myoxocephalus aenaeus in Niantic River and Niantic Bay, Long Island Sound

Grubby (Myoxocephalus aenaeus, Cottidae) is a common benthic fish of inshore waters and estuaries of eastern Long Island Sound; however, little information exists on their life history or population demographics. This study utilised a long-term data series (1976–2002) to assess grubby life history and population demographics and explores trends in the Niantic River and Niantic Bay populations. In addition, we examined the age, size, and fecundity of adult grubby in 2001–02 to determine the population characteristics in the region. Mean grubby catch per unit effort (CPUE) in Niantic Bay ranged from 0.4 per trawl in 1976 to 2.9 per trawl in 1984 while river CPUE ranged from 0.4 per trawl in 1977 to 7.6 per trawl in 1989. Catch of grubby in bottom trawls varied seasonally with highest CPUE occurring in winter. Highest entrainment of grubby larvae occurred in 2001 while the lowest entrainment observed was in 1991. Four age classes, 0+ through III+, were derived from otolith analysis (N = 51) although length frequency analysis suggested the possibility of older fish in the population. The total number of eggs in ovaries ranged from 286 to 16 451 for grubby (N = 64) between 52 mm and 155 mm TL. Results of this study indicated a decline in abundance of adult grubby over the 26-year period, possibly related to concurrent declines in eelgrass (Zostera marina) abundance and/or increased water temperature.     

西北太平洋气候和海洋环境变化对柔鱼空间分布的影响

Ommastrephes bartramii is an ecologically dependent species and has great commercial values among the AsiaPacific countries. This squid widely inhabits the North Pacific, one of the most dynamic marine environments in the world, subjecting to multi-scale climatic events such as the Pacific Decadal Oscillation(PDO). Commercial fishery data from the Chinese squid-jigging fleets during 1995–2011 are used to evaluate the influences of climatic and oceanic environmental variations on the spatial distribution of O. bartramii. Significant interannual and seasonal variability are observed in the longitudinal and latitudinal gravity centers(LONG and LATG) of fishing ground of O. bartramii. The LATG mainly occurred in the waters with the suitable ranges of environmental variables estimated by the generalized additive model. The apparent north-south spatial shift in the annual LATG appeares to be associated with the PDO phenomenon and is closely related to the sea surface temperature(SST)and sea surface height(SSH) on the fishing ground, whereas the mixed layer depth(MLD) might contribute limited impacts to the distribution pattern of O. bartramii. The warm PDO regimes tend to yield cold SST and low SSH, resulting in a southward shift of LATG, while the cold PDO phases provid warm SST and elevated SSH,resulting in a northward shift of LATG. A regression model is developed to help understand and predict the fishing ground distributions of O. bartramii and improve the fishery management.     

Comparison of β-dimethylsulfoniopropionate (DMSP) levels in two mediterranean ecosystems with different trophic levels

β-dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) concentrations were recorded from September 1999 to September 2000 in two geographically close ecosystems, differently affected by eutrophication: the Little Bay of Toulon and the Niel Bay (N.W. Mediterranean Sea, France). Little Bay had higher nutrient levels ([NO₃⁻]_max. = 30.3 μM; [PO₄³⁻]_max. = 0.46 μM) and higher chlorophyll a concentrations ([chl a]_mean = 2.4 μg/L) compared to Niel Bay ([NO₃⁻]_max. = 19.7 μM; [PO₄³⁻]_max. = 0.17 μM; [chl a]_mean = 0.4 μg/L). In the two sites, we measured dissolved (DMSP_d < 0.2 μm) and particulate DMSP (DMSP_p > 0.2 μm) concentrations. The DMSP_p was particularly analysed in the 0.2–5, 5–90 and > 90 μm fractions. In the eutrophicated Little Bay, DMSP_d concentrations showed a clear seasonality with high values from January to March (124–148 nM). The temporal profile of the DMSP_p concentrations was similar, peaking in February–March (38–59 nM). In the less eutrophic Niel Bay, DMSP_p concentrations were much lower (6–9 nM in March–April), whereas DMSP_d concentrations were relatively high (110–92 nM in February–March). DMS concentrations were elevated from the end of the winter to the spring in Little Bay, ranging from 3 nM in October to 134 nM in March. In the less eutrophic Niel Bay, lower DMS levels were observed, generally not exceeding 20 nM. Each particulate fraction (0.2–5; 5–90; > 90 μm) contained less DMSP in Niel Bay than in Little Bay. At both sites, the 5–90 μm fraction made up most of the DMSP_p. This 5–90 μm fraction consisted of microphytoplankton, principally Dinophyceae and Bacillariophyceae. The 5–90 μm biomass calculated from cell biovolumes, was more abundant in Little Bay where the bloom at the end of the winter (165 μg/L in March) occurred at the same time as the DMSP peaks. The estimated DMSP_p to biomass ratio for the 5–90 μm fraction was always higher in Little Bay than in Niel Bay. This suggests that the high DMSP levels recorded in Little Bay were not only due to a large Dinophyceae presence in this ecosystem. Indeed, the peak of DMSP_p to biomass ratio obtained from cell biovolumes (0.23 nmol/μg in March) was consistent with the proliferation of Alexandrium minutum. This Dinophyceae species may account for between 50% (2894 cells/L) and 63% (4914 cells/L) of the total phytoplankton abundance in the Little Bay of Toulon.     

河流弧菌对牙鲆表皮黏液黏附作用的研究

为了解河流弧菌对牙鲆表皮黏液的黏附特性,采用3H-TdR同位素示踪方法研究了细菌浓度、孵育时间、孵育温度、pH值、阳离子、碳水化合物等因子对河流弧菌黏附作用的影响。试验结果表明:河流弧菌能很好地黏附于牙鲆表皮黏液,黏附量随菌浓度升高而增大并符合饱和黏附动力学:y=417.89ln(x)+691.57(R2=0.986);在30℃下黏附量随着孵育时间的延长而增加,180min趋于饱和;孵育温度在4~30℃范围内黏附量随温度升高而增多,30℃时黏附量最大;pH值酸性较碱性黏附作用明显,pH为5时最强;NaCl浓度在0.5%~4.5%范围内,细菌黏附作用随着浓度升高而增强,较纯水存在显著性差异(P<0.05);Ca2+,Mg2+能显著加强河流弧菌的黏附作用,但Ca2+作用明显超过Mg2+;葡萄糖等8种碳水化合物能显著促进河流弧菌的黏附作用(P<0.05)。以上结果说明:河流弧菌对牙鲆表皮黏液的黏附量较大,这有利于进一步感染、致病;河流弧菌的黏附作用受温度、pH值、阳离子、碳水化合物等多种环境因子的影响,较高的水温有利于河流弧菌的黏附,有利于疾病的发生。     

海州湾前三岛海域底播刺参群体特征初探

海州湾前三岛海域是中国刺参(Apostichopus japonicus)自然分布的最南界,2013年3月至2014年4月,采用潜水样带法,调查了前三岛海域底播刺参群体的体质量结构及季节变动特征,结合水下观察和视频调查,比较了不同生境类型中的刺参密度。结果表明,前三岛海域刺参密度为0.4~1.33头/m2,生物量为42.69~103 g/m2,刺参群体相对稳定,群体的体质量呈现冬春季节增长、夏秋季节下降的特点。不同生境类型中的刺参密度不同,大型藻类分布的礁石区刺参密度明显大于没有藻类分布的礁石区和砂质区,上述结果为揭示岛屿海域的刺参群体特征和资源养护提供了基础数据。     

Accumulation of Cu and Zn in discarded antifouling paint particles by the marine gastropod, Littorina littorea

The short-term (5 day) accumulation of Cu and Zn in different tissues of the marine gastropod, Littorina littorea, has been studied in the presence of 10 mg l⁻¹ of antifouling paint particles and pre- or simultaneously contaminated algal food (Ulva lactuca). Accumulation of Cu was observed in the head–foot, digestive gland–gonad complex and gills to extents dependent on how and when food was contaminated and administered. However, retention of Zn was only observed in the gills and only when L. littorea and U. lactuca were simultaneously exposed to paint particles. Relative to the alga, faecal material was highly enriched in Zn, suggesting that the animal is able to rapidly eliminate this metal, most likely through the formation and egestion of insoluble phosphate granules. Thus, L. littorea is a useful biomonitor of marine contamination by antifouling applications in respect of Cu but not Zn.     

Seasonal Variations in Abundance and Size Composition of the Lobate Ctenophore Bolinopsis Mikado (Moser) in Tokyo Bay, Central Japan

Surveys of the abundance and size composition of the ctenophore Bolinopsis mikado were conducted in Tokyo Bay over a 5-year period from 1990 to 1994. B. mikado appeared throughout the year, and its mass occurrence was observed between August and November; annual maximum abundance ranged from 19 to 91 ind. m^–2. Water temperature seems to influence the seasonal variation of B. mikado abundance. Environmental conditions (e.g. rough waters due to a typhoon) and predation by the beroid ctenophore Beroe cucumis appear to affect annual variations of B. mikado abundance. Size frequency distributions of B. mikado indicated that its reproduction was most active in summer and fall but occurred throughout the year in Tokyo Bay. A sharp decline of the copepod population in August 1990 was probably due to predation by B. mikado which was very abundant at that time; its predatory impact was estimated to be 24 % day^–1.