For marine environment observation, especially for open-sea wave-measuring application, a low cost and small size Wave Drifter is introduced as a preferred wave observing instrument. The Wave Drifter is developed based on Global Positioning System (GPS) receivers and deployed in open sea. Based on a single low-cost GPS receiver, the Wave Drifter can provide the standard wave parameters. A Wave Drifter Prototype was launched in the West Pacific area. Wave conditions were recorded especially during Typhoon KROSA (201329). In order to verify the effective of GPS Wave Drifter, comparison between the derived wave parameters and wave model forecast data is carried out. The results show good agreement and discover the underlying applications such as data assimilation into wave forecast models, validation of wave forecast models, calibration of satellite wave sensors and investigation of ocean wave climate and variability.
To reveal spatial and seasonal pattern of planktonic ciliate communities and its relationship with environmental variables,we investigated the planktonic ciliate composition,abundance and response to environmental changes during four seasons of 2014 in Dapeng Cove,the South China Sea. A total of 31 species belonging to eight orders were identified,11 of which were dominant species. The average abundance of ciliate was 1 487 ind[middot]L~(-1)( 10 ~ 5 040 ind[middot]L~(-1)),and Tintinnida,Strombidium and Cyclotrichida were the most abundant in terms of number and abundance. Planktonic ciliate communities showed a distinct seasonal pattern of ciliate abundance and a clear seasonal shift of the taxonomic composition. The highest number of ciliate species occurred in summer,whereas the highest abundance peaked in spring,mainly due to the strombidium. Spatially,planktonic ciliate was more abundant and diverse in the cage fish culture area and oyster-algae mixed culture area,but the lowest abundance and species occurred in the estuary of Wangmu River. Multivariate analyses illustrate that ciliate abundance was significantly correlated with water temperature,nutrient leveland chlorophyll-a concentration. Moreover,the dominant abiotic environmental factors affecting the seasonal pattern of ciliate communities were different between seasons.
The effects of dietary protein level on nutrient digestibility and utilization of protein and energy of juvenile Chinese soft-shelled turtle, Pelodiscus sinensis, were investigated. Seven isoenergetic diets containing graded levels of protein (25, 27, 29, 31, 33, 35, and 43%) were fed to turtles initially averaging 4.8 +/- 0.7g for 8wk at 30 +/- 0.5C. The apparent digestibilities of dry matter, protein, and energy were generally increased with dietary protein level. Proportions of nitrogen intake (CN) allocated to excretory nitrogen (UN) were higher in 25 and 43% protein diets than the other diets. UN proportion was lowest in the 33% protein diet, whereas retained (growth) nitrogen (RN) followed an inverse pattern with UN. Percentages of gross energy intake (IE) used for excretory energy (UE) generally increased when dietary protein levels increased. Turtles fed 25-29% protein diets showed a markedly higher proportion of metabolizable energy (ME) than those fed 31-43% protein diets. Analysis by second-order polynomial regression using RN as the indicator indicated that the estimated optimal dietary protein level was 34.6%. The lowest and highest percentages of retained (growth) energy (RE) were observed in the 25 and 33% protein groups. Nitrogen and energy budget equations of turtles fed 33% protein diet were 100 CN=8.22 FN+37.48 UN+54.30 RN and 100 IE=10.88 FE+2.82 UE+65.60 ME+20.69 RE, respectively. Diets with excessive protein resulted in high proportions of protein and energy used for excretion.
Based on the data of the cruise that was carried out in Dapeng Cove, mainly including thermal discharge area from nuclear power plant, artificial reef area, aquaculture area and three main estuarine areas into Dapeng Cove, Nanyong River, Longqi River and Wangmu River in Aug., 2014( summer), we investigated the urea concentration( expressed by nitrogen, Urea-N) and urease activity of phytoplankton together with the other environmental parameters to discuss the bioavailability of urea for phytoplankton. Obvious difference between the bay and the estuary with average urea concentrations ranging from 0. 28 to 1. 21 [mu]mol[middot]L- 1and0. 38 to 3. 50 [mu]mol[middot]L- 1, respectively, and the urea concentration was 6. 30% ~ 24. 31% of DIN in the bay and 3. 13% ~ 6. 77%of DIN in the estuary, resulting in inorganic nitrogen source for phytoplankton in Dapeng Cove. Urea concentration reached the maximum at Longqi estuary and Wangmu estuary, followed by aquaculture area. The urease activity of phytoplankton in the bay and theestuary ranged from 0. 61 to 1. 03 [mu]mol[middot]( L[middot]h)- 1and 0. 82 to 1. 07 [mu]mol[middot]( L[middot]h)- 1, respectively. Urease activity was positively related with urea concentration, and was also affected by inorganic nutrient and phytoplankton biomass. In the artificial reef area, aquaculture area and Nanyong estuary without N and P limitation, high Chl-a concentration could promote urease activity; in the aquaculture area, urea was the main nitrogen source for phytoplankton, and Chl-a had very significant positive correlation with urease activity; in the thermal discharge area( Longqi estuary and Wangmu estuary), P limitation resulted in inhibitory regulation of urease activity.
Phytoplankton pigment concentrations in the surface sediments of a fish and oyster farm in D apeng C ove, S outh C hina S ea, were measured monthly to investigate the effects of mariculture on the environment from D ecember 2011 to D ecember 2012. The highest contents of the identified phytopigments, sulphides and total organic carbon in the surface sediments were all found at the fish farm, followed by the oyster farm; the lowest contents were detected at the control site. Fucoxanthin in the surface sediments was the most abundant carotenoid and was significantly correlated with chlorophyll a (Chl a ; r = 0.922, P < 0.01). This finding suggested that the deposited diatoms could be the main source of the Chl a concentration. Besides a differential sedimentation of phytoplankton (i.e. higher downflux at fish and oyster site than that at control site), we assume that the extent of pigment diminution from the fish site to control site was also controlled by the chemical conditions of the surface sediments. The fish farm provided the most optimum preservation conditions for the phytopigments and was a good sink for phytodetritus among the three sites because of its anoxic and reductive characteristics. Phytoplankton pigments could be useful biomarkers to evaluate the influence of mariculture on sediment environment.
Base on the 201 groups of data that accepted in the last ten years, a 3 layer (3,8,1) BP artificial neural network model on quickly predicting chlorophyll-a concentration in marine cage fish farming area was established. The model was established in software MATLAB7.1 (MATTrix LABoratory) using BP network. Three field accurate measurement parameters (water temperature, pH, dissolved oxygen) was as the input variable and chlorophyll-a was the output in our model. In most condition the forecast results was closely to the actual data when using this model. Its prediction accuracy was significantly higher than the linear regression equation. For the reason that the data used in building model which has some question and the complexity of predicting chlorophyll-a content, there existed some error between forecast value and actual value when using this model in several sets of data. This article put forward the methods to consummate the model in the next step.