Effect of dietary genistein on growth performance,digestive enzyme activity,and body composition of Nile tilapia <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>

An 8-week feeding experiment was performed to evaluate the effect of dietary genistein on growth performance, body composition, and digestive enzymes activity of juvenile Nile tilapia (Oreochromis niloticus). Four isonitrogenous and isoenergetic diets were formulated containing four graded supplements of genistein: 0, 30, 300, and 3 000 μg/g. Each diet was randomly assigned in triplicate to tanks stocked with 15 juvenile tilapia (10.47±1.24 g). The results show that 30 and 300 μg/g dietary genistein had no significant effect on growth performance of Nile tilapia, but the higher level of genistein (3 000 μg/g) significantly depressed the final body weight and specific growth rate. There was no significant difference in survival rate, feed intake, feed efficiency ratio or whole body composition among all dietary treatments. An assay of digestive enzymes showed that the diet containing 3 000 μg/ggenistein decreased stomach and hepatopancreas protease activity, and amylase activity in the liver and intestine, while a dietary level of 300 μg/g genistein depressed stomach protease and intestine amylase activities. However, no significant difference in stomach amylase activity was found among dietary treatments. Overall, the results of the present study indicate that a high level of dietary genistein (3 000 μg/g, or above) would significantly reduce the growth of Nile tilapia, partly because of its inhibitory effect on the activity of major digestive enzymes. Accordingly, the detrimental effects of genistein, as found in soybean products, should not be ignored when applied as an alternative ingredient source in aquaculture.     

Immunogenicity and protective role of antigenic regions from five outer membrane proteins of <Emphasis Type="Italic">Flavobacterium columnare</Emphasis> in grass carp <Emphasis Type="Italic">Ctenopharyngodon idella</Emphasis>

Flavobacterium columnare causes columnaris disease in freshwater fish. In the present study, the antigenic regions of five outer membrane proteins (OMPs), including zinc metalloprotease, prolyl oligopeptidase, thermolysin, collagenase and chondroitin AC lyase, were bioinformatically analyzed, fused together, and then expressed as a recombinant fusion protein in Escherichia coli. The expressed protein of 95.6 kDa, as estimated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was consistent with the molecular weight deduced from the amino acid sequence. The purified recombinant protein was used to vaccinate the grass carp, Ctenopharyngodon idella. Following vaccination of the fish their IgM antibody levels were examined, as was the expression of IgM, IgD and IgZ immunoglobulin genes and other genes such as MHC Iα and MHC IIβ, which are also involved in adaptive immunity. Interleukin genes (IL), including IL-1β, IL-8 and IL-10, and type I and type II interferon (IFN) genes were also examined. At 3 and 4 weeks post-vaccination (wpv), significant increases in IgM antibody levels were observed in the fish vaccinated with the recombinant fusion protein, and an increase in the expression levels of IgM, IgD and IgZ genes was also detected following the vaccinations, thus indicating that an adaptive immune response was induced by the vaccinations. Early increases in the expression levels of IL and IFN genes were also observed in the vaccinated fish. At four wpv, the fish were challenged with F. columnare, and the vaccinated fish showed a good level of protection against this pathogen, with 39% relative percent survival (RPS) compared with the control group. It can be concluded, therefore, that the five OMPs, in the form of a recombinant fusion protein vaccine, induced an immune response in fish and protection against F. columnare.     

Screening and isolation of the algicidal compounds from marine green alga <Emphasis Type="Italic">Ulva intestinalis</Emphasis>

Twenty species of seaweed were collected from the coast of Zhejiang, China, extracted with ethanol, and screened for algicidal activity against red tide microalgae Heterosigma akashiwo and Prorocentrum micans. Inhibitory effects of fresh and dried tißsues of green alga Ulva intestinalis were assessed and the main algicidal compounds were isolated, purified, and identified. Five seaweed species, U. intestinalis, U. fasciata, Grateloupia romosissima, Chondria crassicaulis, and Gracilariopsis lemaneiformis, were investigated for their algicidal activities. Fresh tissues of 8.0 and 16.0 mg/mL of U. intestinalis dissolved in media significantly inhibited growth of H. akashiwo and P. micans, respectively. Dried tissue and ethyl acetate (EtOAc) extracts of U. intestinalis at greater than 1.2 and 0.04 mg/mL, respectively, were fatal to H. akashiwo, while its water and EtOAc extracts in excess of 0.96 and 0.32 mg/mL, respectively, were lethal to P. micans. Three algicidal compounds in the EtOAc extracts were identified as 15-ethoxy-(6z,9z,12z)-hexadecatrienoic acid (I), (6E,9E,12E)-(2-acetoxy-β-D-glucose)-octadecatrienoic acid ester (II) and hexadecanoic acid (III). Of these, compound II displayed the most potent algicidal activity with IC₅₀ values of 4.9 and 14.1 µg/mL for H. akashiwo and P. micans, respectively. Compound I showed moderate algicidal activity with IC₅₀ values of 13.4 and 24.7 µg/mL for H. akashiwo and P. micans, respectively. These findings suggested that certain macroalgae or products therefrom could be used as effective biological control agents against red tide algae.     

Diel variation in metabolism and ammonia excretion of <Emphasis Type="Italic">Marphysa sanguinea</Emphasis> (Polychaeta: Eunicidae)

Polychaetes provide an excellent food resource for fish and represent the dominant zoobenthos in marine ecosystems. Diel variation in the rates of metabolism and ammonia-N excretion of Marphysa sanguinea were studied. The worms were grouped according to their wet body weight into small (S; 1.24±0.06 g), medium (M; 4.00±0.30 g), and large (L; 8.54±1.08 g) categories. Their weight-specific metabolic rates, based on aerobic respiration (R), were measured at 16°C (±0.2°C) and classed as either routine (R _R) or standard (R _S) rates. Both respiration types decreased with increasing body weight. Respiration was described by R = a W ^b, where b was -0.400 9 and -0.532 0 for R _R and R _S, respectively. Diurnal changes in R _S for each group was relatively flat, with a slightly increasing trend with time, but was relatively stable as a whole. R _R of the diurnal variation of worms was higher than R S, but both had similar overall trends. The peak values of specific dynamic action (SDA) (R _SDA) in the S, M, and L groups were 2.704, 1.149, and 0.682 mg/(g?h), respectively. The durations of SDA were 13, 6, and 6 h, respectively and the energy expenditures of SDA were 377.98, 117.34, and 74.94 J/g, respectively. These data indicate that the metabolic rates were higher in smaller individuals, which is advantageous for their rapid growth.     

Inbreeding depression on growth and survival of full-sib family of Manila clam (<Emphasis Type="Italic">Ruditapes philippinarum</Emphasis>)

In present study, the inbreeding depression (ID) of growth and survival of Manila clam (Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families (A ₂, B ₂, C ₂, D ₂, E ₂, F ₂, G ₂, H ₂ and I ₂) were established by mating within nine full-sib families with expected inbreeding coefficient of 0.25. Inbred families showed significant differences in shell length and hatching rate of D-larvae (straight-hinged larvae). The larvae of the nine inbred families grew slower than those of control group (CG), and their ID value ranged from 0.81% ± 6.09% to 16.10% ± 1.49%. The ID value of larval survival rate varied between 27.47% ± 9.36% and 70.50% ± 13.66%. The ID was also detected for juvenile growth in A ₂, B ₂, C ₂, and D ₂, which ranged from 4.60 ± 2.21 to 17.71 ± 7.73. The A ₂ family maintained the highest juvenile survival rate, whereas the other inbred families exhibited ID values varying between 62.79% ± 4.54% and 96.14% ± 0.87%. The linear relationship of estimated ID between growth and survival was negatively correlated (R = ?0.434, P < 0.05). The results of this study suggested that the ID of growth was common at the larval stage but was less prevalent at juvenile stage. In contrast, the ID of survival increased from larval to juvenile stage. A better understanding of the effect of inbreeding may aid to selective breeding of Manila clam.     

Effects of nitrogen and phosphorus on the growth of <Emphasis Type="Italic">Levanderina fissa</Emphasis>: How it blooms in Pearl River Estuary

Effects of nitrogen (N) and phosphorus (P) from different sources and at different concentrations on the growth of Levanderina fissa (= Gyrodinium instriatum) were studied in laboratory conditions. The findings might explain the recurrent blooms of this species in Pearl River Estuary, China. Results showed that nutrient limitation significantly inhibited the growth of L. fissa. The values of specific growth rate (μ _max) and half-saturation nutrient concentration (K _S) were 0.37 divisions/d and 8.49 μmol L^?1 for N, and 0.39 divisions/d and 1.99 μmol L^?1 for P, respectively. Based on K _S values, dissolved inorganic N level in PRE was sufficient to support the high proliferation of L. fissa, while dissolved inorganic P concentration was far lower than the minimum requirement for its effective growth. L. fissa was not able to utilize dissolved organic N (DON) compounds such as urea, amino acids, and uric acid. However, it grew well by using a wide variety of dissolved organic P (DOP) sources like nucleotides, glycerophosphate, and 4-nitrophenylphosphate. The results from this study suggested that the ability in DOP utilization of L. fissa offers this species a competitive advantage in phytoplankton communities. The high level and continuous supply of DIN, enrichment of DOP, together with warm climate and low salinity in the Pearl River Estuary provided a suitable nutrient niche for the growth of L. fissa, and resulted in the recurrent blooms in the estuary.     

Compensatory growth of juvenile brown flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> following low temperature treatment for different periods

We investigated the effects of low temperature (8.5°C) on the growth and feeding rates and feed conversion efficiency of juvenile P. olivaceus with an average initial weight of 3.87 ± 0.06 g (mean ± SE). Fish were exposed to 8.5°C for 0 (control), 1, 2, 3 and 4 weeks, and then to 20°C for 10, 9, 8, 7 and 6 weeks, respectively. Low temperature clearly led to growth depression. The weight of fish exposed to low temperature for 1 week was restored to that of control, while that of fish exposed to low temperature longer was significantly decreased (P < 0.05). During the entire low-temperature period, specific growth rate, feeding rate and feed conversion efficiency of the fish were significantly lower (P < 0.05) than those of control, while in the whole recovery period, specific growth and average feeding rate were markedly higher (P < 0.05) than those of control. At the end of experiment, only the feeding rate of the fish exposed to low temperature for 1 week was not significantly different from that of control (P > 0.05). Feeding rate and feed conversion efficiency were reduced at low temperature in juvenile P. olivaceus. The compensatory growth of juvenile P. olivaceus may therefore be attributed to the improvement of feeding rate. Our results suggested that growth depression occurs when juvenile P. olivaceus are exposed to low temperature for more than one week.     

Effects of different phosphorus concentrations and N/P ratios on the growth and photosynthetic characteristics of <Emphasis Type="Italic">Skeletonema costatum</Emphasis> and <Emphasis Type="Italic">Prorocentrum donghaiense</Emphasis>

The effects of different phosphorus (P) concentrations (0.36, 3.6, and 36 μmol/L corresponding to low-, middle-, and high-P concentration groups, respectively) and nitrogen (N)/P ratios on the growth and photosynthetic characteristics of Skeletonema costatum and Prorocentrum donghaiense were studied. For both species, the high-P (HP) concentration group showed the greatest algal density and highest specific growth rate. Changes in the maximum efficiency of photosystem II (F _v /F _m ) were monitored under the various P and N/P conditions. The largest decrease in F _v /F _m was in the low-P (LP) group in S. costatum and in the HP group in P. donghaiense. There were high rapid light curves and photochemical quantum yields (Φ _PSII) for S. costatum in the HP group, while the actual photosynthetic capacity was higher in P. donghaiense than in S. costatum in the MP group. Under eutrophic but relatively P-restricted conditions, P. donghaiense had higher photosynthetic activity and potential, which could cause this dinoflagellate to increasingly dominate the phytoplankton community in these conditions. Under the same P concentration and N/P ratio, P. donghaiense had a larger relative maximum rate of electron transport and higher Φ _{PS II} values than those of S. costatum. These differences between P. donghaiense and S. costatum may explain the interaction and succession patterns of these two species in the Changjiang (Yangtze) River estuary from a photosynthesis perspective.     

Significance of different microalgal species for growth of moon jellyfish ephyrae, <Emphasis Type="Italic">Aurelia</Emphasis> sp.1

The scyphozoan Aurelia aurita (Linnaeus) sp. l., is a cosmopolitan species-complex which blooms seasonally in a variety of coastal and shelf sea environments around the world. The effects of different microalgal species on the growth of newly-released Aurelia sp.1 ephyrae were studied under laboratory conditions. We fed ephyrae with four different microalgal species (diatom, autotrophic dinoflagellate, heterotrophic dinoflagellate, and chlorophyta) plus Artemia nauplii for 12-24 d at 18°C. Results showed that the growth rate diverged significantly for Artemia nauplii compared to other food types. In addition, there was no significant variation between the growth rates for Skeletonema costatum and Prorocentrum donghaiense, and no significant variation was found in the growth rates for N. scintillans and P. subcordiformis. Artemia nauplii could support the energy requirement for the newly-released ephyrae to develop to meduase, and the ephyrae with Artemia nauplii showed a significant average growth rate of 25.85% d^?1. Newly-released ephyrae could grow slightly with some species of microalgae in the earliest development stage. Chain diatom Skeletonema costatum and autotrophic dinoflagellate Prorocentrum donghaiense, could not support the growth of the ephyrae, while heterotrophic dinoflagellate Noctiluca scintillans and chlorophyta Platymonas subcordiformis could support the growth of the ephyrae. However, none of the ephyrae fed with the tested phytoplankton could mature to medusae.     

Effects of a Potential Autochthonous Probiotic <Emphasis Type="Italic">Bacillus subtilis</Emphasis> 2-1 on the Growth and Intestinal Microbiota of Juvenile Sea Cucumber, <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> Selenka

The effects of Bacillus subtilis 2-1 from the intestine of healthy sea cucumber on the growth, digestive enzyme activities and intestinal microbiota of juvenile sea cucumber (Apostichopus japonicus) were determined in the present study. Sea cucumber was fed with Sargassum thunbergii powder supplemented with B. subtilis 2-1 at different concentrations varying among 0 (control), 10⁵, 10⁷, and 10⁹ CFU g^?1 for 8 weeks. Results showed that the growth performance and intestinal amylase and trypsin activities were significantly increased by dietary B. subtilis 2-1 at 10⁹ CFU g^?1 (P < 0.05). However, dietary B. subtilis 2-1 had no significant influence on the lipase activity in sea cucumber (P > 0.05). The polymerase chain reaction denaturing gradient gel electrophoresis and 16S rRNA gene sequencing analysis indicated that dietary B. subtilis 2-1 at 10⁵ and 10⁷ CFU g^?1 inhibited most of the Proteobacteria including those in genus Vibrio. Dietary B. subtilis 2-1 at 10⁹ CFU g^?1 not only decreased the abundance and species of genus Vibrio, but also increased the intensity of genera Psychrobacter and Bacillus. A specific dosage of dietary B. subtilis 2-1 could increase the growth and modulate the intestinal microbiota of sea cucumber; thus it might be a novel probiotic for keeping the health of sea cucumber.     

The characteristics of <Emphasis Type="Italic">vasa</Emphasis> gene from Japanese sea bass (<Emphasis Type="Italic">Lateolabrax japoni</Emphasis>cas) and its response to the external hormones

The RNA helicase Vasa is an important regulator of primordial germ cell development. Its function in mature fish, especially the hormone-related differences in maturing male fish has seldom been documented. In this study, a full length cDNA sequence of the vasa gene was cloned from Japanese sea bass, Lateolabrax japonicas, and it was named jsb-vasa. Homology analysis showed that jsb-vasa was closely related to its teleost homologs. The spatial distribution of jsb-vasa indicated that it was only highly expressed in testis, showing its germ cell-specific expression pattern. During the testicular development cycle, jsb-vasa was highly expressed during early period of spermatogenesis, and reduced when spermatogenesis advanced. In addition, the jsb-vasa gene expression was significantly inhibited at 6 h, 12 h and 24 h after injecting hCG (human chorionic gonadotropin) and GnRHa (Gonadotropin-releasing hormone analogue), indicating that jsb-vasa gene may play an important role in spermatogenesis of Japanese sea bass, and be under the regulation of external sex hormones.     

Antialgal and antilarval activities of bioactive compounds extracted from the marine dinoflagellate <Emphasis Type="Italic">Amphidinium carterae</Emphasis>

With the global ban on the application of organotin-based marine coatings by the International Maritime Organization, the development of environmentally friendly, low-toxic and nontoxic antifouling compounds for marine industries has become an urgent need. Marine microorganisms have been considered as a potential source of natural antifoulants. In this study, the antifouling potential of marine dinoflagellate Amphidinium carterae, the toxic and red-tide microalgae, was investigated. We performed a series of operations to extract the bioactive substances from Amphidinium carterae and tested their antialgal and antilarval activities. The crude extract of Amphidinium carterae showed significant antialgal activity and the EC₅₀ value against Skeletonema costatum was 55.4 μg mL^?1. After purification, the isolated bioactive substances (the organic extract C) exhibited much higher antialgal and antilarval activities with EC₅₀ of 12.9 μg mL^?1 against Skeletonema costatum and LC₅₀ of 15.1 μg mL^?1 against Amphibalanus amphitrite larvae. Subsequently, IR, Q-TOFMS, and GC-MS were utilized for the structural elucidation of the bioactive compounds, and a series of unsaturated and saturated 16- to 22-carbon fatty acids were detected. The data suggested the bioactive compounds isolated from Amphidinium carterae exhibited a significant inhibiting effect against the diatom Skeletonema costatum and Amphibalanus amphitrite larvae, and could be substitutes for persistent, toxic antifouling compounds.     

Interspecific competition and allelopathic interaction between <Emphasis Type="Italic">Karenia mikimotoi</Emphasis> and <Emphasis Type="Italic">Dunaliella salina</Emphasis> in laboratory culture

Algal allelopathy is a manifold ecological/physiological phenomenon that is focused on chemical interactions and autotoxicity. We investigated the allelopathic interactions between Karenia mikimotoi and Dunaliella salina in laboratory cultures based on diff erent temperature (15°C, 20°C, and 25°C) and lighting (40, 80, and 160 μmol/(m²·s)) conditions. The growth of D. salina in bi-algae culture (1:1 size/density) was significantly restrained. The results of cell-free filtrate culture indicate that direct cell-tocell contact was not necessary in interspecific competition. Further experimental results demonstrated that allelochemicals released from K. mikimotoi were markedly influenced by both temperature (P =0.013) and irradiance (P =0.003), resulting in diff erent growth characteristics of D. salina in filtrate mediums. Compared with the plateau period, K. mikimotoi exudates in the exponential phase had a stronger short-term inhibition effect on D. salina in normal conditions. A clear concentration-dependent relationship was observed in the effect of allelochemicals released from K. mikimotoi with low-promoting and high-repressing effects on D. Salina in a short time-scale. In addition, allelopathic substances remain stable and effective under high temperature and pressure stress. Many flocculent sediments adhering with D. salina cells were observed in all filtrate mediums, while the quantity and color depended on the original culture conditions.     

Genetic transformation of <Emphasis Type="Italic">Nannochloropsis oculata</Emphasis> with a bacterial phleomycin resistance gene as dominant selective marker

The gene ble from Streptoalloteichus hindustanus is widely used as a selective antibiotic marker. It can control the phleomycin resistance, and significantly increase the tolerance of hosts to zeocin. The unicellular marine microalga Nannochloropsis oculata is extremely sensitive to zeocin. We selected ble as the selective marker for the genetic transformation of N. oculata. After the algal cells at a density of 2×10⁷ cells mL^?1 was digested with 4% hemicellulase and 2% driselase for 1 h, the protoplasts accounted for 90% of the total. The ble was placed at the downstream of promoter HSP70A-RUBS2 isolated from Chlamydomonas reinhardtii, yielding a recombinant expression construct pMS188. The construct was transferred into the protoplasts through electroporation (1 kV, 15 μS). The transformed protoplasts were cultured in fresh f/2 liquid medium, and selected on solid f/2 medium supplemented with 500 ng mL^?1 zeocin. The PCR result proved that ble existed in the transformants. Three transformants had been cultured for at least 5 generations without losing ble. Southern blotting analysis showed that the ble has been integrated into the genome of N. oculata. The ble will serve as a new dominant selective marker in genetic engineering N. oculata.     

Biodeposition,respiration, and excretion rates of an introduced clam <Emphasis Type="Italic">Mercenaria mercenaria</Emphasis> in ponds with implications for potential competition with the native clam <Emphasis Type="Italic">Meretrix meretrix</Emphasis> in Shuangtaizi estuary,China

This study aimed to evaluate the potential impacts of an introduced clam Mercenaria mercenaria on estuarine ecosystem, and implications for the niche competition with a native clam Meretrix meretrix. The biodeposition, respiration, and excretion rates of M. mercenaria were determined seasonally using a sediment trap and a closed respirator in field. The biodeposition rates of M. mercenaria were 0.06–0.37 g/ (ind.·d), and the respiration rates were 0.31–14.66 mg/(ind.·d). The ammonia and phosphate excretion rates were 0.18–36.70 and 1.44–14.87 μg/(ind.·d), respectively. The hard clam M. mercenaria may discharge dry deposits up to 2.1×10⁵ t, contribute 18.3 t ammonia and 9.0 t phosphate to culture ponds, and consume 7.9×10³ t O₂ from ponds annually. It suggested that the hard clam M. mercenaria might play an important role in pelagic-benthic coupling in pond ecosystem through biodeposition and excretion. A comparison of the key physiological parameters of the introduced clam M. mercenaria and the native clam Meretrix meretrix suggested that M. mercenaria had a niche similar to that of Meretrix meretrix in Shuangtaizi estuary and might have a potential competition with Meretrix meretrix for habitat and food if M. mercenaria species escaped from the culture pond or artificially released in estuarine ecosystem.     

Assessment and comparison of <Emphasis Type="Italic">in vitro</Emphasis> immunoregulatory activity of three astaxanthin stereoisomers

In recent years, the immune-modulatory role of all-trans astaxanthin from different pigment sources has been studied. It was reported that all-trans astaxanthin might exist as three stereoisomers, and the composition of all-trans stereoisomers in natural materials differs from that of synthetic products. However, the different biological effects of various all-trans stereoisomers still remain unclear. In the present study, we evaluated the bioactivity of three astaxanthin stereoisomers, (3S,3’S)-trans-, (3R,3’R)-trans-and meso-trans-astaxanthin, in regulating cell-mediated immune response using mice lymphocytes and peritoneal exudates cells (PECs) systems. After the treatment with three astaxanthin stereoisomers (20 μmol L^?1), the lymphocyte proliferation capacity, neutral red phagocytosis of PECs and natural killer (NK) cell cytotoxic activity were comparatively assessed. The results showed that all three astaxanthin stereoisomers significantly promoted lymphocyte proliferation, phagocytic capacity of PECs, and cytotoxic activity of NK cells. Moreover, the (3S,3’S)-trans-astaxanthin exhibited a much higher response than others.     

A review of interaction between neon flying squid (<Emphasis Type="Italic">Ommastrephes bartramii</Emphasis>) and oceanographic variability in the North Pacific Ocean

The neon flying squid (Ommastrephes bartramii) is a short-lived opportunistic species widely distributed in subtropical and temperate waters in the North Pacific Ocean. The life cycle of O. bartramii from planktonic eggs to nektonic adults is closely linked to oceanographic conditions. The fluctuations in O. bartramii abundance and distribution tend to increase and widen continuously due to the heavy influences of ocean-climate events on various spatio-temporal scales. In this study, we reviewed the interaction between O. bartramii and oceanography variability in the North Pacific with respect to large-scale climatic-oceanic phenomena including El Niño, La Niña, Kuroshio, Oyashio and Pacific Decadal Oscillation (PDO), as well as regional environmental variables such as sea surface temperature (SST), sea surface height (SSH), sea surface salinity (SSS), chlorophyll-a (Chl-a) concentration, and plankton density. The population dynamics of O. bartramii is mediated mainly by meso- and large-scale climatic-oceanic events (e.g., Kuroshio and Oyashio Currents) rather than other local environmental conditions (e.g., SST and Chl-a concentration), because all of the oceanographic influences are imposed on the context of large-scale climate changes (e.g., PDO). An unstructured-grid finite-volume coastal ocean model coupled with an individual-based model is proposed to simulate relevant physical-biological oceanographic processes for identifying ocean-climate influence and predicting O. bartramii distribution and abundance in the North Pacific. Future research needs to be focused on improving the knowledge about early life history of O. bartramii and evaluating the relationship between marine physical environment and two separate passive drifting life stages of O. bartramii including free-floating eggs and planktonic paralarvae.     

Seasonal variation in species composition and abundance of demersal fish and invertebrates in a Seagrass Natural Reserve on the eastern coast of the Shandong Peninsula,China

Seagrass habitats are structurally complex ecosystems, which support high productivity and biodiversity. In temperate systems the density of seagrass may change seasonally, and this may influence the associated fish and invertebrate community. Little is known about the role of seagrass beds as possible nursery areas for fish and invertebrates in China. To study the functioning of a seagrass habitat in northern China, demersal fish and invertebrates were collected monthly using traps, from February 2009 to January 2010. The density, leaf length and biomass of the dominant seagrass Zostera marina and water temperature were also measured. The study was conducted in a Seagrass Natural Reserve(SNR) on the eastern coast of the Shandong Peninsula, China. A total of 22 fish species and five invertebrate species were recorded over the year. The dominant fish species were Synechogobius ommaturus, Sebastes schlegelii, Pholis fangi, Pagrus major and Hexagrammos otakii and these species accounted for 87% of the total number of fish. The dominant invertebrate species were Charybdis japonica and Octopus variabilis and these accounted for 98% of the total abundance of invertebrates. There was high temporal variation in species composition and abundance. The peak number of fish species occurred in August–October 2009, while the number of individual fish and biomass was highest during November 2009. Invertebrate numbers and biomass was highest in March, April, July and September 2009. Temporal changes in species abundance of fishes and invertebrates corresponded with changes in the shoot density and leaf length of the seagrass, Zostera marina.     

Temporal and spatial variations of abundance of phycocyanin- and phycoerythrin-rich <Emphasis Type="Italic">Synechococcus</Emphasis> in Pearl River Estuary and adjacent coastal area

Three surveys were carried out in Pearl River Estuary and adjacent coastal area in May, August, and November, 2013, to investigate the temporal and spatial variations of abundance of phycoerythrin-rich Synechococcus (PE-rich SYN) and phycocyanin-rich Synechococcus (PC-rich SYN). The effects of environmental factors on the alternation of the different Synechococcus groups were also elucidated. PE-rich SYN was detected in three surveys, whereas PC-rich SYN was detected in May and August, but not in November. The highest abundances of PE-rich SYN and PC-rich SYN were recorded in August and May, with mean values of 74.17×10³ and 189.92×10³ cells mL^?1, respectively. From May to November, the relative abundance of PE-rich SYN increased, whereas that of PC-rich SYN declined. PE-rich and PC-rich SYN presented similar horizontal distributions with high abundance in the southern estuary in May, and in the western estuary in August. The abundances of PE-rich and PC-rich SYN were high at 27–32°C and salinity of 10–20. PC-rich SYN was not detected at < 24°C, and PC:PE-rich SYN decreased in abundance with salinity increase. When less than 20 mg L^?1, suspended particulate matter (SPM) was helpful for Synechococcus growth. PE-rich SYN decreased in abundance when the concentration of dissolved inorganic nitrogen increased in May and November, and the concentration of phosphate increased in November. However, PC-rich SYN abundance and nutrients showed no correlation. Principal component analysis and regression analysis indicated that PE-rich SYN significantly correlated with the principal components that were affected by environmental factors.     

Status of two <Emphasis Type="Italic">Coreius</Emphasis> species in the Three Gorges Reservoir,China

Dam construction alters natural flow regimes which, in turn, cause significant changes in fish communities during and after impoundment. The construction of the Three Gorges Reservoir, from impoundment of the Changjiang (Yangtze) River, China, may have affected native fish species. Thus, the status of two lotic freshwater fish species, Coreius heterodon and C. guichenoti, were monitored in the Three Gorges Reservoir, including fish abundance, individual composition, growth, condition, and mortality. Data on both species were gathered from upstream, midstream and downstream areas of the reservoir and, where available, from studies published before and after dam construction. Lower abundance, slower growth, a less diversified age structure, poorer fish condition (indicated by hepatosomatic index) and higher mortalities were recorded in sites nearest the dam compared with upstream areas. Furthermore, after final impoundment, individual Coreius species inhabiting the area changed, with young individuals becoming more abundant, while upstream of the reservoir the two Coreius species became smaller at a given age. The results show that the status of the two Coreius species was subject to dramatic changes after impoundment.