Research on the Typhoon Disaster's Fatalness Assessment in Zhanjiang Aquiculture Based on GIS

According to the historical typhoon disaster's data and the influence on the aquiculture,three risk factors were selected as the assessment indexes of typhoon disaster's fatalness.The corresponding risk assessment model was established.Meanwhile,combined with the GIS (Geographic Information System) space visualization technology,the disaster data's functions which included the statistics,analysis,searching,etc.were realized,and the special topic image of typhoon disaster's fatalness was drawn.

DISSOLVED AND PARTICULATE ORGANIC CARBON IN YANTAI SISHILI BAY AQUICULTURE WATERS

Investigation of dissolved organic carbon (DOC) and particulate organic carbon (POC) at 12 stations in Yantai Sishili Bay in May, August, and November of 1997 and March and May of 1998 showed that DOC concentrations varied from 1.14 mg/L to 5.35 mg/L; that the average values at all stations in each cruise varied from 1.52 mg/L to 2.12 mg/L; that POC concentrations varied from 0.049 mg/L to 1.411 mg/L; and averaged 0.159 mg/L to 0.631 mg/L in each cruise. Horizontal distribution of DOC was influenced by factors such as continental input, organism activity, temperature, aquiculture environment, etc. The higher POC concentration occurred along the coast. The vertical distribution of DOC and POC changed obviously in spring and summer, but not obviously in autumn and winter. DOC concentration was highest in summer and POC in spring; both were lowest in winter. The seasonal change of DOC was consistent with primary productivity seasonal variation, and that of POC was consistent with chlorophyll a seasonal variation. The seasonal change trend of the C/N ratio of dissolved organic matter was obvious, but the C/N ratio of particulate organic matter had no such trend.

Food intake rate and delivery strategy in aquaculture

In aquaculture,it is important to estimate in advance how much food cultured animals would take.The rate of food consumption by cultured animals to available food amount is defined as the food intake rate(FIR) in this paper.To some extents,FIR reflects the quality of food,the health of cultured animals and the delivery efficiency.In practice,it is difficult to estimate in advance the accurate quantity of food that cultured animal needs.Usually,food is provided more than the need by animals,causing excess food that may pollute water and environment.Our experiments in past years show that FIR at 80% is recommended.

The benthic diatom community of Xiangshan Bay

The samples collected from the surface sediments in Xiangshan Bay,Zhejiang province in May and November 2005 were analyzed under a light microscope.The species composition,abundance,community structure and diversity were investigated.A total of 179 taxa belonging to 46 genera of diatom were identified.The result showed that the ecotypes of diatom were mostly eurytopic species,followed by warm water species and temperate species.The most dominant species were Cyclotella stylorum and Coscinodiscus jonesianus.The seasonal variation of diatom abundance was remarkable.The cell abundance of diatoms was higher in spring(2.974×10^3 cells/g)than that in autumn(0.071×10^3 cells/g).The number of species varies with change of season,demonstrating the adaptability of diatoms to the temperature of water.The species diversity of benthic diatom was lower in autumn than that in spring.

Exploration on Suitable Stocking Period for Aquaculture

To determine suitable stocking period is extremely important for increasing yield, improving quality and especially increasing breeding efficiency. The purpose of this study was to provide a technical approach for determination of suitable stocking period in aquaculture. Agricultural mete- orology, mathematical statistics, methodology of economics, methodology of management, and other methods were used to explore suitability of stocking period in aquaculture, As learned from stocking of Penaeus orientalis in coastal area of Yancheng City of Jiangsu, we believed that to es- tablish model for benefit assessment was one of ideal ways to determine suitable stocking period. In order to determine stocking period more scien- tifically, stocking test must be performed for specific aquatic species. The effects of environmental conditions on growth and development of juvenile aquatic livestock should be studied to identify key restraining factors, e.g., water temperature, for growth and development. The study provides the basis for establishing model for determination of suitable stocking period.