REFINING CULTURE METHODS FOR THE CYCLOPOID COPEPOD Oithona colcarva

Marine fin fish can be challenging to culture with many species  heavily reliant  on small, nutritious live p rey  for their first feed.  Newly hatched copepod nauplii are an exemplary live feed due to their small  size  (~45 m) , high nutritional value, and quick escape responses thought to elicit predatory feeding behaviors in larval fishes.  The cyclopoid copepod Oithona colcarva is a candidate for aquaculture due to its small size and tolerance to fluctuating c ulture conditions. Experiments were conducted to evaluate initial culture protocols used for O. colcarva production. Culture parameters including diet, stocking density, and photoperiod were  assessed  to quantify effects on naupliar production.

Initial diet experiments compared  different combinations of  live micro algae using the species Tisochrysis lutea , Chaetoceros muelleri , and Tetraselmis chuii fed at 400,000 cells/mL. N aupliar production  was the highest  when adult copepods were fed a 1:1 carbon equivalence ratio of T. lutea and T. chuii . This diet became the control in  the following  diet experiment examining how algal concentrate blends effect naupliar production .  The  live microalgae  control diet outperformed the algal concentrate diets but further investigations are necessary before  ruling  out algae concentrat es as  potential feeds for O. colcarva.

In the stocking density experiments,  adults were stocked at 8, 12, 16, and 24/mL and t here was no significant difference in nauplii production among treatments. Photo period experiments  yielded comparable nauplii production  between 6-hr light : 18-hr dark and 12-hr light : 12-hr dark .  Nauplii production under the 18-hr light : 6-hr dark photoperiod was significantly lower than both other treatments (Figure 1 ).  Therefore,  natural  diurnal cycles should suffice for culture conditions . Results from these experiments  were translated to commercial sc ale production in a greenhouse.  Commercial scale (200L) production tanks produced an average of 2.56 million nauplii/day for 10 consecutive days.  Results from these experiments have contributed to commercial production protocols for O. colcarva, a  promising live feed for aquaculture.