scholarly journals Preliminary assessment of large‐scale co‐culture of sandfish ( Holothuria scabra ) with the Babylon snail ( Babylonia areolata ) in earthen ponds and in raceways

2020 ◽  
Author(s):  
Gregory T. Dobson ◽  
Nguyen Dinh Quang Duy ◽  
Paul C. Southgate
Keyword(s):  
Large Scale ◽  
Preliminary Assessment ◽  
Babylonia Areolata ◽  
Holothuria Scabra ◽  
Earthen Ponds

Predation behaviour of millimetre-sized hydrozoan polyps on early ivory shell juveniles

2020 ◽  
Vol 100 (6) ◽  
pp. 889-895
Author(s):  
Yulin Huang ◽  
Jingqiang Fu ◽  
Yutong Shi ◽  
Yunan Wang ◽  
Qi Cui ◽  
...  
Keyword(s):  
Large Scale ◽  
Management Practices ◽  
Molecular Data ◽  
Babylonia Areolata ◽  
Polyp Stage ◽  
Benthic Pelagic Coupling ◽  
Morphological And Molecular Data ◽  
Almost All ◽  
Coupling Processes ◽  
Colonial Hydroid

AbstractMarine hydroids, the polyp stage of hydrozoans, are assumed to be carnivores and play an important role in benthic-pelagic coupling processes by regulating zooplankton populations and transferring energy. The known hydroid diets mainly consist of zooplankton as well as some benthic diatoms and metazoans, almost all of which have smaller dimensions than the polyp. In the present study, a large-scale breeding failure of the early juveniles of the ivory shell Babylonia areolata (Mollusca: Gastropoda: Babyloniidae) was found in a local aquaculture farm in Fujian, China in July 2018. About 640,000 out of 800,000 early juveniles (80%) died due to predation by a millimetre-sized colonial hydroid species that was initially overlooked. The hydrozoan species was identified as Eirene sp. (Cnidaria: Hydrozoa: Eirenidae) via the integration of morphological and molecular data. A laboratory feeding experiment showed that the hydroid predation led to an overall mortality of ivory shell juveniles of up to 92.6% after 48 h. The predation process was observed in the laboratory and a video showing the entire process was prepared. This is the first report of hydroids preying on gastropod juveniles, revealing a previously unknown threat to mollusc aquaculture including ivory shells. Several management practices are suggested to mitigate this newly recognized threat.

Development of techniques for the large-scale rearing of the larvae of the Australian freshwater fish golden perch, Macquaria ambigua (Richardson, 1845)

1996 ◽  
Vol 47 (2) ◽  
pp. 233 ◽  
Author(s):  
SJ Rowland
Keyword(s):  
Large Scale ◽  
Poultry Manure ◽  
Stocking Density ◽  
Crustacean Zooplankton ◽  
Positive Linear Relationship ◽  
Zooplankton Density ◽  
Eastern Australia ◽  
Earthen Ponds ◽  
Breeding Seasons ◽  
Australian Freshwater

Experiments were conducted over four consecutive breeding seasons. Golden perch, Macquaria ambigua, larvae (total length, 5.0 mm) held at 23� to 25�C, commenced feeding on crustacean zooplankton (<350 pm in length) five days after hatching, at age D6 (D1 = day of hatch). Zooplankton density had a significant effect (P < 0.01) on the survival of larvae in 70-L aquaria. A delay of only two days to age D8 in initial feeding significantly reduced (P < 0.01) survival, and larvae not offered zooplankton until D10 did not commence feeding. There was a positive linear relationship (r2 = 0.98) between survival in earthen ponds (0-57.6%) and the volume of small zooplankton sampled from the ponds at stocking, but survival was not affected by larval stocking density (32-365 m-2) or length of the culture period (28-53 days). A mean survival of 44.6% in ponds that were left dry over winter and then stocked 10-14 days after filling, was significantly higher (P < 0.01) than survival in ponds stocked only 2-5 days after filling or in ponds inundated during winter. Survival, growth and production were not significantly different among ponds fertilized with inorganic fertilizer (NPK) alone or in combination with lucerne hay or poultry manure. Larvae grew at rates of 0.5-1.1 mm day-1, production rates were up to 153 kg ha-1 and a maximum number of 271 000 juveniles were reared in a 0.3 ha pond. Approximately 3 × 106 golden perch are produced annually at hatcheries in eastern Australia using techniques developed during this study.

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