Nature Environment and Pollution Technology

Xinlong An ¹, Xuemei Li ¹, Zhixia Li ¹, Yanling Zhang ¹

Affiliations
1 Ocean College, Agricultural University of Hebei, Qinhuangdao 066003, Hebei, CN

Abstract

This study was aimed to investigate the growth characteristics of living diet Platymonas subcordiformis for aquaculture animals and its harmful organism Oxyrrhis marina in co-culture systems to provide experimental evidences for discussing their succession processes. The colour changes of culture media of P. subcordiformis and growth characteristics of O. marina and P. subcordiformis in co-culture were analysed by the combined methods of macro-observation, microscopic examination and microscopic counting. The results showed that with the decrease of the initial density of O. marina cell (0.65×10⁴ cells mL^-1, 0.37×10⁴ cells mL^-1 and 0.11×10⁴ cells mL^-1 in P. subcordiformis culture media), the time that the population of O. marina reached the stationary phase required longer, were 4d, 5d and 7d after inoculated by O. marina, respectively, and the death time of all cells of P. subcordiformis became longer, were 9d, 10d and 12d after inoculated by O. marina, respectively. After inoculation 9d, pale pink appeared in upper layer of culture media of P. subcordiformis in flasks and the density of O. marina was 2.10×10⁵ cells mL^-1. The results also indicated that the variation tendency of cell densities of O. marina and P. subcordiformis cultured in aquariums were consistent with that in flasks basically, pink flocs appeared in upper layer of culture media of P. subcordiformis after inoculation 12d and the density of O. marina was 2.10×10⁶ cells mL^-1. The experimental results showed that the feeding of O. marina on P. subcordiformis was affected by the initial concentration of O. marina, and P. subcordiformis populations were evolved to O. marina populations during the 15 days culture period, the colour of culture media appeared pale pink to pink depends on density of O. marina was confirmed, too. Also, the colour changes of P. subcordiformis culture media are indications of pollution by O. marina, which will be important for culture process of sP. subcordiformis.

Keywords

Oxyrrhis marina, Platymonas subcordiformis, Color Change, Growth Characteristics, Co-Culture System.

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Xinlong An ¹, Xuemei Li ¹, Zhixia Li ¹

Affiliations
1 Ocean College, Agricultural University of Hebei, Qinhuangdao 066003, Hebei, CN

Abstract

This study was aimed to investigate the growth characteristics of Oxyrrhis marina and Chattonella marina in co-culture to provide experimental evidences for discussing successions of harmful algal blooms (HABs) and coastal biological communities. The colour changes of culture media of C. marina and growth characteristics of O. marina and C. marina in co-culture were analysed by the combined methods of macroobservation, microscopic examination and counting. In co-culture, the colours of culture media of C. marina had changed and their transparencies had increased with increasing elapsed incubation time after inoculated by O. marina under different initial cell densities. With the increase of the initial density of O. marina (0.17×10⁴ cells/mL, 0.50×10⁴ cells/mL and 0.64×10⁴ cells/mL in C. marina culture media), the time required, that the populations of O. marina reached the stationary phases, was shorter i.e. 6d, 5d and 3d after inoculated by O. marina, respectively, and the death time of all cells of C. marina became shorter, i.e. 7d, 6d and 4d after inoculated by O. marina, respectively. During the 15 days culture period, all C. marina populations were evolved to O. marina populations. Residues of C. marina adhering to precipitates and chromatophores scattering in the culture media could strengthen the colour of culture media, C. marina populations were evolved to O. marina populations respectively within the concentrations designed in co-culture in this experiment. Disturbance feeding was one of the reasons for successions, and the results provide experimental evidences for discussing successions of red tides and coastal biological communities.

Keywords

Oxyrrhis marina, Chattonella marina, Growth Characteristics, Co-Culture.

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Xinlong An ¹, Xuemei Li ¹, Zhixia Li ¹

Affiliations
1 Ocean College, Agricultural University of Hebei, Qinhuangdao, 066 003, Hebei, CN

Abstract

In order to explore possible development process of red tides caused by Prorocentrum donghaiense, effects of concentrations of P. donghaiense and Oxyrrhis marina on the feeding behaviour of Oithona brevicornis were investigated. The results showed that within the concentration range of P. donghaiense, 1.0~5.0×10⁴ cells·mL^-1, ingestion rates (IRs) and faecal pellet production rates (FPPRs) of O. brevicornis on P. donghaiense increased with increasing concentrations of P. donghaiense, the maximum IR and FPPR were 620 cells·ind^-1·h^-1 and 31.67 pellet·copepod^-1·d^-1, respectively. When the concentration of P. donghaiense was 10.0×10⁴ cells·mL^-1, the IR value decreased to 400 cells·ind^-1·h^-1 and the FPPR value decreased to 13.33 pellet·copepod^-1·d^-1, respectively. Within the concentration range of P. donghaiense, 1.0~10.0×10⁴ cells·mL^-1, filtration rates (FRs) of O. brevicornis decreased with increasing concentrations of P. donghaiense. The results also showed that O. brevicornis could ingest O. marina fed P. donghaiense, and within the concentration range of O. marina, IRs of O. brevicornis on O. marina increased with increasing concentrations of O. marina, while its FRs decreased, the maximum IR value and FR value were 300 cells·ind^-1·h^-1 and 0.23 ml·ind·h^-1, respectively. Within the concentration range of O. marina, FPPRs of O. brevicornis increased with increasing concentrations of O. marina, the maximum FPPR was 21.67 pellet·copepod^-1·d^-1, and FPPRs had a good linear relationship with IRs. In this study, "Copepodsred tide algae" and "Copepods-protozoa-red tide algae" food chain models can provide references for the development process and regulating method of red tides caused by P. donghaiense.

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