Assessment of the ecological quality status of sediment at the organic shrimp farming ponds in Ca Mau province by applying the abundance/biomass comparison (ABC) method on nematode communities

Abstract

Nematode communities in the Tam Giang’s organic shrimp farming ponds, Nam Can district, Ca Mau province were investigated in three seasons (March - dry, July - transfer and November - rainy season). Results showed that the average abundance (inds/10 cm2) ranged from 221.67 ± 122.08 to 2539.33 ± 1403.33 in the dry season. The tranfers and rainy season also showed a high density, from 1020.00 ± 354.30 to 7254.67 ± 5454.39, 822.00 ± 1086.17 – 4608.33 ± 1302.02, respectively. Total dry biomass (µg/10 cm2) of nematode communities in Tam Giang’s organic shrimp farming ponds varied from 51.11 ± 28.64 to 450.87 ± 49.53 in the dry, from 412.93 ± 291.87 to 1607.25 ± 507.42 in the transfer and ranged 49.54 ± 39.36 to 1874.09 ± 3033.16 in the rainy season. The following results were also recorded that abundance/biomass comparison (ABC) method has been used successfully for detecting the ecological quality status of sediment (EcoQ) in Tam Giang’s organic shrimp farming ponds. The results indicated that unfavourable deflections (stress) in EcoQ of Tam Giang’s organic shrimp farming ponds throughout the dry - transfer - rainy season. More specifically, the EcoQ of Tam Giang’s organic shrimp farming ponds has been classified as lightly stressed in most seasons, excpet for the transfer season which has been recognized as the highest EcoQ depending on its ABC curves and W values. Although EcoQ in the Tam Giang’s organic shrimp farming ponds has always been clear, information on Received 05-01-2017, accepted 14-08- 2017, published 12- 9-2018 Author: Tran Thanh Thai, Nguyen Thi My Yen, Ngo Xuan Quang- Department of Environmental Management and Technology, Institute of Tropical Biology, Vietnam Academy of Science and Technology, Le Dieu Linh - Ton Duc Thang University - thanhthai.bentrect@gmail.com the main cause effected biomass between natural stress or pollution stress remains uncertain.