Benthic macroinvertebrates assemblages were collected from 29 sites in the upper reaches of the Taihu Lake watershed,i.e.the Nanhe,Yunnan,Yunbei and Taoge water systems,in Changzhou area of China in 2003.A total of 113 species were found including 18 species in Gastropoda,10 speices in Lamellibranchia,8 species in Oligochaeta,4 species in Hirudinea,6 species in Crustacean and 67 species in Insecta,with Limnodrilus hoffmeisteri and Bellamya purificata being the dominant species.The average density of the communities was 658 m-2 with L.hoffmeisteri being the highest,i.e. 400 m-2.Among the 29 sampling sites,Guanshanqiao was the highest in benthic macroinvertebrate diversity and its species richness,Shannon-Wiener diversity,evenness and ecological dominant index was 54,4.36,0.76 and 0.08,respectively.In terms of benthic macroinvertebrate diversity,the 4 water systems were in the order of NanheTaogeYunnanYunbei.CCA analysis of the 24 species that were more than 15% in occurrence frequency and 6 environmental factors showed that total nitrogen,total phosphorus and dissolved oxygen were the major factors influencing distribution of benthic macroinvertebrates in the research area.
Kandelia obovata (S., L.) Druce and Sonneratia caseolaris (L.) Engl. are two dominant mangrove species in the subtropical coastlines of the Pearl River Estuary, China. The main aim of this study was to investigate the specific causes of K. obovata mortality versus S. caseolaris vitality on the west coast of Bao’an, Shenzhen, China and to propose sustainable management strategies for mangrove protection and future ecological planting restoration. Results showed that although both mangroves possessed simple and unstable community structures, S. caseolaris had a more tenacious vitality than the native species K. obovata, indicating that the former possesses stronger adaptability under adversity conditions. Moreover, the salinity of the seawater collection point 5 from the K. obovata plot was found to be lower than that of seawater collection point 1–3 from the S. caseolaris sample plots, indicating that no hydrologic connectivity existed in the K. obovata plots. In addition, the location of the drain outlet (seawater collection point 8) might be another potential risk factor for the dead of near K. obovata forests, implying that they were badly affected by poor oxygen and serious inorganic pollution, such as ammonium nitrogen, total phosphorus, and other inorganic substances. Depending on local circumstances, we should consider strengthening infrastructure construction to activate hydrological connectivity, reinforcing the stability of man-made mangrove communities, and controlling the pollution sources for sustainable mangrove protection and management on the western coast of Bao’an, Shenzhen, China.
The length, fresh weight and dry weight of stomach, small intestine, caecum and large intestine of striped field mice (Apodemus agrarius) in farmland, in forest and in the interlaced region between forest and farmland in different seasons were measured. The results showed that fresh weight and dry weight of the digestive tracts of the animals varied significantly in different seasons. All the fresh weight and dry weight of digestive organs were significantly greater in winter and in spring when the food supply was relatively short. These were presumably related to the increase of energy needs, deficient food and the food with low quality. However, the changes of the digestive tracts (weight or length) in different habitats were not significant in same season. The authors considered that it may be because of the similar food supplies in the three habitats. In addition, the differences of the length of the digestive tracts of striped field mice in different habitats or different seasons were not significant except the fresh weight of large intestine in farmland. The results of our research indicated that the morphological modification of the digestive tracts of striped field mice could adapt their living environments.
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