INTEGRATED ASSESSMENT ON THE LEVEL OF THE FOOD ORGANISMS IN KAOZHOU BAY

Supported by Geographical Information System(GIS),the level of the food organisms in Kaozhou Bay in February(dry season) and August (wet season) of 1999 was analyzed and evaluated by using the method of integrative model.In dry season the distribution of food organisms in the whole bay was even,and the dense area occurred in the northwest of the bay,the mouth of the bay and the estuary of Jilong River with the level of grade 4,representing that the food organisms were rich in these waters. In the wet season the level of food organisms varied greatly,and the dense area occurred in the middle of the bay and the coastal waters along Wangjingzhou Bay with the richest level of grade 4-5,and followed by the mouth of the bay with the level of grade 4. The comparison between the 2 cruises of survey showed that the level of food organisms in the wet season was higher than that in the dry season.The variation of the main dominant species of the food organisms showed obvious seasonal succession. The main dominant species of phytoplankton and zooplankton changed greatly in different season,while the composition of the dominant species of benthos remained steady.During the survey,the diversity index and evenness of the food organisms varied greatly with the largest ranges of 0.01-4.49 and 0.01-0.96,respectively,which indicated that the food organisms in the bay were affected significantly by the environmental condition,and the composition structure of the organism population and the level of biodiversity was unstable. During the survey,the distribution of the diversity threshold of the food organisms in the whole bay showed the characteristic of higher in the west and northwest of the bay and lower in the other waters,but the variation trend and distribution scope changed slightly in different season. In the dry season the dense area of the diversity threshold occurred in part of the western waters of the bay with level of grade 3,indicating that the diversity was well.While in the other waters the level was in grade 2 or lower,indicating that the diversity was normal or poor. In the wet season,the distribution of the threshold was similar to that in dry season with the dense area occurring in the western and northwestern waters of the bay,which was wider than that in dry season,while the level was obviously lower with the level of grade 2 in the dense area and the level down to grade 1 in most of the other waters.