Species Diversity And Distribution Of Benthic Diatom In Zeng River And In Huizhou Section Of Dongjiang River

Diatom has been widely used for river biomonitoring, but there are only a few data from rivers in China, especially in southern China. In the present thesis, we investigated rives in Pearl river system. The benthic diatom and the environmental variables were studied in three sampling periods with distinct rainfalls over 21 sample points in Zeng River and 5 in Huizhou section of Dongjiang River.WT, DO, SD, pH, SC were measured in situ. TN, TP and other index were measured in the lab after sampling. The aboundance, relative aboundance and dominant species of diatom were analyzed quantitativly. The relationship between the benthic diatom and the environments variables were analyzed by Canoco:Correspondence Analysis and correlation analysis.Totally,260 benthic diatom species (including subspecies and varieties) were identified, belonging to 2 Classes,6 Orders,45 Families and species were identified. The dominant species were varying with sampling sites. Nitzschia genus was firstly the dominant genus, Navicula, Gomphonema and Achnanthidium was secondly. Navicula minima had the highest abundance in Navicula genus, Nitzschia clausii and Nitzschia palea was the most abundant in Nitzschia, Gomphonema parvulum and Gomphonema rhombicum had the most abundant in Gomphonema, Achnanthidium minutissimum and Achnanthidium rivulare had the most abundant in Achnanthidium. All the abundant species were dominant in many of the sampling sites.Nitzschia clausii, Nitzschia palea and Luticola goeppertiana often appeared in polluted water. Nitzschia genus seems a good indicator in moderate and heavy polluted water. The relative richness of Nitzschia has positive correlation with conductivity (R=0.7477, P<0.01) and TP (R=0.5498, P<0.05). Achnanthidium minutissmum has positive correlation with DO (R=0.476, P<0.05), and negative correlation with WT (R=-0.685, P<0.01), SC(R=-0.479, P<0.05) and TP (R=-0.450, P<0.05), and also this species has a strong relationship with flow velocity.The water quality was evaulated by the community of the benthic diatom and indices of GI, Shannon-Weaver and Lloyd-Ghelardi. The overall assessment showed that sampling sites in third and fourth class in Zeng river were polluted seriously because of human activies.Sampling sites in first and second class were less polluted except several sites. The assessment confirmed that diatom diversity and spatial distribution provided useful information for evalution. The water quality in HuiZhou sections of Dongjiang was evaulated by the community of the benthic diatom and indices of GI, Shannon-Weaver and Lloyd-Ghelardi. Among the 5 sampling sites, S2 and S3 were polluted heavily because of human activies. S4 and S5 were less polluted and S1 was moderate polluted.