TNJFU - Tamil Nadu Dr. J. Jayalalithaa Fisheries University

FISHERIES ENVIRONMENT

Total number of phytoplankton species recorded from the three stations viz. Tuticorin, Mandapam and Mullimunai were 33, 35 and 19 species, respectively. In Mandapam, Climacosphenia elongata was dominant in the seaweed culture site and normal waters. Leptocylindrus was dominant in Tuticorin. In Mullimunai coast, Coscinodiscus eccentericus was dominant.
A total of 35 zooplankton species were recorded and copepod nauplius was found dominant in all the stations. The overall density of zooplankton was relatively higher in seaweed culture site when compared to normal site. Among the benthos, macrobenthic polychaetes and meiobenthic nematodes were dominant both in the seaweed culture site and control site of all stations.
Distribution of bacteria examined in the three stations showed that 10 species were recorded in Tuticorin, 12 species in Mandapam and 6 species in Mullimunai coasts. Maximum density of bacteria was found in the sediments.
Ecosystem health near seaweed culture site was evaluated based on the underwater survey. Wild seaweeds were found unaffected. No Kapaphycus invasion was noticed in the coral reef ecosystem. Seagrass beds were also found healthy. Seaweed culture rafts were harboured by many crusteaceans, fishes and other benthic animals. All the water quality parameters were found in normal range at all stations.

Different seafood processing wastes such as fish waste, shrimp waste, crab waste and cephalopod waste were analyzed for their physico–chemical characteristics. Among various fish solid wastes, cephalopod wastes contained high concentrations of total nitrogen (13%) and other seafood wastes showed variations between 6.34 and 7.5%. The concentration of total phosphorous was very lower (0.56 %) than that of other fish solid wastes.
Laboratory scale biogas production unit consisting of gas container (20 L capacity) and collection unit (2 L capacity) was set up and tested for the efficiency of gas production using fish wastes and cowdung slurry. Gas production was observed but in limited volume due to low temperature inside the biogas unit and absence of separate duct for the removal of slurry.

A small outdoor biogas model unit was constructed with tank size of 7m x 1.3m x 1.15m and a biogas bag of premium quality tarpaulin with provision for raw material input, slurry discharge and gas collection. This outdoor unit warmed up during the day, which helped in the growth of thermophilic microbes that ensured the digestion of organic matter and enhanced gas production. Cowdung, 500 kg and fish waste, 100kg were introduced inside the biogas bag and allowed for gas production.

Hardness removal efficiency of four different plants, Azolla , Lemna sp., Ceratophyllum sp. and Hydrilla sp. were tested in two different borewell waters with the initial hardness value of 1560 and 685 mg/l, respectively.
At the end of experiment the final water hardness reduction percentage observed were 3.20 and 8.78%, 12.82 and 26.28%, 5.13 and 4.38%, 8.33 and 10.21%, 3.21% and 14.60% in the experiments conducted with Azolla , Lemna sp., Ceratophyllum sp., Hydrilla sp. respectively. All the plants showed ability to reduce water hardness. Among the four plants, Azolla pinnata had the highest ability to reduce hardness.
The gold fishes were introduced in the bore well water, which was treated with plants like Azolla pinnata, Lemna minor, Ceratophyllum and Hydrilla sp. The initial length and weight of the goldfish in Azolla pinnata, Lemna minor, Ceratophyllum sp., Hydrilla sp. and control were 7.2 cm, 7.5 cm, 7.4 cm, 7.2 cm, 7.8cm and 8.63 g, 7.18 g, 7.47 g 8.59, 8.77 g, respectively. On 30th day length and weight of the gold fish observed were as follows, 7.25 cm and 8.70 g, 7.5 cm and 7.35 g, 7.7 cm and 7.35 g, 7.5 cm and 7.55 g, 7.4 cm and 8.70 g, 8 cm and 8.90 g in experiment conducted with Azolla sp., Lemna sp., Ceratophyllum sp., Hydrilla sp.