Spatial-Temporal Distribution of Fish Larvae in the Pearl River Estuary Based on Habitat Suitability Index Model.

The spawning grounds are important areas for the survival and reproduction of aquatic organisms and play an important role in the replenishment of fishery resources. The density of fish larvae in the Pearl River Estuary (PRE) was analyzed to establish Habitat Suitability Index (HSI) based on marine environmental factors. Survey data and satellite remote sensing data, including sea surface temperature, sea surface salinity and chlorophyll a concentration, from 2014 to 2017 during April-September were analyzed. Results showed that the accuracy of the HSI model based on the larval density and environmental factors was more than 60%, and the distribution trend of HSI was consistent with the distribution trend of larval density. The HSI models constructed based on Arithmetic Mean Model (AMM), Geometric Mean Model (GMM) and Minimum Model (MINM) methods can better predict the spatial-temporal distribution of larvae in the PRE. Among them, the accuracy of the HSI model constructed by the AMM and GMM methods was the highest in April (71%) and September (93%); the accuracy of the HSI model constructed by the MINM method was the highest in June (70%), July (84%) and August (64%). In general, the areas with high HSI values are mainly distributed in the offshore waters of the PRE. The spatial-temporal distribution of larvae in the PRE was influenced by monsoon, Pearl River runoff, Guangdong coastal currents and the invasion of high-salinity seawater from the outer sea.

Characterization and phylogenetic analysis of the complete mitochondrial genome of Terapon theraps (Perciformes: Terapontidae).

We assembled the complete mitochondrial genome of Terapon theraps based on high-throughput Illumina sequencing. The mitochondrial genome of T. theraps is 16,587 bp in length, containing 13 protein-coding genes (PCGs), 22 tRNAs, two rRNAs, and one putative control region (CR), and its overall nucleotides base composition is 27.4% A, 25.7% T, 16.9% G, and 29.9% C. Bayesian Inference revealed that all species of Terapontidae formed into one group, while the other nine species within Perciformes clustered into the other group. Rhynchopelates oxyrhynchus and T. theraps were the closest relatives. These results should help to better understand the phylogenetic interrelationships of Terapontidae.

Ecological implications of purple sea urchin (Heliocidaris crassispina, Agassiz, 1864) enhancement on the coastal benthic food web: evidence from stable isotope analysis.

A responsible approach to marine stock enhancement is an effective approach to restore fishery resources. While the release strategy of target species has been well investigated, the impacts on local ecological equilibrium and habitat qualities have only been poorly considered. In the present study, we evaluated how the macro-benthic food web in Daya Bay was affected by purple sea urchin (Heliocidaris crassispina (Agassiz, 1864) stock enhancement using stable isotope analyses (δ13C and δ15N). Our results indicated that the distribution of local species and trophic diversity were influenced to a certain degree by release of purple sea urchins and changes in the feeding habit of the urchins were observed in line with food abundance, which seasonally varied. When food is abundant, the main food source of sea urchins was microphytobenthos and no significant differences were observed among sites; significant differences in the diet of purple sea urchins were detected when food is less abundant. These results suggested that optimization of the release strategy should include information on seasonal productivity of local recipient sites, food web structure and feeding habits of released species. Such information is essential for building a responsible release approach to maximize production enhancement.

Changes in the heavy metals and petroleum hydrocarbon contents in seawater and surface sediment in the year following artificial reef construction in the Pearl River Estuary, China.

Marine pollution is an important driver of ocean biodiversity loss, which can be mitigated by the construction of artificial reefs (ARs). Many studies have explored how ARs affect marine organisms, but our understanding of the changes in heavy metals and petroleum hydrocarbons after AR construction is limited. In the current study, we assessed the heavy metal and petroleum hydrocarbon contents of the seawater (surface and bottom seawater) and surface sediment before and after AR construction in AR habitat and in nearby non-reef control habitat in the Pearl River Estuary, China. AR construction tended to decrease the contents of Cu, Pb, Cd, and Hg but tended to increase Zn content in seawater and in surface sediment. Petroleum hydrocarbon content changed irregularly in seawater and surface sediment. Effects of AR construction were similar in the nearby non-reef habitat vs. the AR habitat. Seawater heavy metal and petroleum hydrocarbon contents were correlated with the seawater physicochemical properties (mainly temperature, inorganic nitrogen, chemical oxygen demand, available phosphate, and suspended particulate organic matter), and sediment heavy metal content was correlated with sediment organic matter content. Additional studies over longer time periods and at larger spatial scales are needed to clarify how AR construction affects heavy metal and petroleum hydrocarbon contents in marine environments.

Response of Sthenoteuthis oualaniensis to marine environmental changes in the north-central South China Sea based on satellite and in situ observations.

In the South China Sea (SCS), Sthenoteuthis oualaniensis (S. oualaniensis) generally has the highest stock density in spring and occupies an important position in fisheries. The responses of S. oualaniensis to marine environments in the north-central SCS in spring (March to May) from 2006 to 2010 were analyzed using satellite and in situ observations, with generalized additive models (GAMs). A high proportion variation in catch per unit effort (CPUE) was explained by environmental variables, including sea surface temperature (SST; explaining 13.8%) and the interaction between SST and chlorophyll a (Chl-a) concentration (explaining 16.9%). SSTs within the range of 24-28°C and Chl-a concentrations within 0.10-0.35 mg/m3 had positive effects on S. oualaniensis CPUE, and SST within 28-29.5°Cand Chl-a concentrations within 0.05-0.20 mg/m3 had negative effects. In addition, the response time of the maximum standardized catch per unit effort (SCPUE) in May to the maximum Chl-a in March was approximately six ten-day time step. The higher Chl-a and smaller stock size of S. oualaniensis in early March 2008 were partly associated with climatic anomalies caused by La Niña in spring and the limitation of S. oualaniensisby low temperature in 2008. The findings in this study can help better protect and manage S. oualaniensis resources in the SCS.

[Evaluation of ecosystem service and emergy of Wanshan Waters in Zhuhai, Guangdong Province, China].

The method for monetary value and emergy value analysis of ecosystem service was used in this paper to analyze the change in value of marine ecosystem service of Wanshan District, Zhuhai from 2007 to 2012. The result showed that the monetary value and emergy value of marine ecosystem service of Wanshan District, Zhuhai rose to 11512840000 yuan and 1.97 x 10(22) sej from 7721630000 yuan and 1.04 x 10(22) sej, respectively. Both monetary value and emergy value could forecast the change in the value of marine ecosystem service, but they reflected different value structures and ecological energy, which could be used to more objectively evaluate the ecosystem service. Ecological civilization development, as an inherent driving force to impel the development of marine ecosystem service structure, was important for rational exploitation of marine resources and optimization of marine ecosystem service.

[Annual changes of phytoplankton's ecological features in Qinzhou Bay of South China].

Four cruise surveys were conducted on the phytoplankton in Qinzhou Bay of South China in different seasons in 2008-2009. A total of 131 phytoplankton species were identified, among which, diatom (101 species) accounted for 30.0% of the total, followed by pyrrophyta (23 species), and other groups (7 species). Most of the phytoplankton was of eurytherm or warm-water species. The total species number and the diatom abundance were the smallest in spring, and increased successively in summer, autumn, and winter, being the highest in winter. The phytoplankton density varied from 232.28 x 10(4) cell x m(-3) to 977.0 x 10(4) cell x m(-3), with an average of about 558.57 x 10(4) cell x m(-3). Temporally, the phytoplankton density was the highest in summer, followed by in spring, and the lowest in winter and autumn. Spatially, the phytoplankton density was increased from the inner bay to the open bay, and decreased from the open bay to outside the bay. In summer, the highest density area switched from the open bay to the bay' s entrance. The average Shannon diversity index was 3.18, and the average evenness index was 0.63, suggesting a high diversity of the phytoplankton community. The correlations of the phytoplankton density with the water temperature, salinity, dissolved inorganic phosphorus, and dissolved inorganic phosphorus varied with seasons.