Abstract:
Pond-farming is the main form of fisheries production in the Pearl River Delta region. We monitored the water quality in intensive ponds of
Ctenopharyngodon idellus,
Oxyeleotris marmoratus,
Micropterus salmoides and
Channa argus in the Pearl River Delta region during May to December of 2012. Ten parameters including pH, dissolved oxygen(DO), non-ionic ammonia(NH
3), ammonia nitrogen(NH
4+-N), nitrate nitrogen(NO
3--N), nitrite nitrogen(NO
2--N), total nitrogen(TN), total phosphorus(TP), potassium permanganate index(COD
Mn) and transparency were assessed by single pollution index and duty ratio. The water quality was assessed by comprehensive pollution index. The results reveal that high nutrient loadings were the prominent problems, and NH
3, NO
3--N, NO
2--N, TN and TP were the main pollutants in intensive ponds. The main pollutants in
C.idellus pond were NH
3 and TN (pollution load: 37.58%). The main pollutants in
O.marmoratus pond were NH
3, TN and NO
3--N (pollution load: 59.37%). The main pollutants in
M.salmoides pond were NH
3, TN and NO
3--N and NO
2--N (pollution load: 66.80%). The main pollutants in
C.argus pond were TN, NO
3--N, TP and NH
3 (pollution load: 59.43%). The research on COD
Mn reveal that there was a large amount of reducible organic matters in these ponds. The pond water was heavily polluted, and the degree of contamination exceeded the alert level based on comprehensive pollution index.