Status of research during March 1, 2000 through May. 31, 2000, on the effect of PUFAs on the growth and development of the larval and juvenile tautog (Tautoga onitis).

Progress on Tautog Lipid Food Resources

I. Lipid protein ratios

Crude lipid/protein ratios were determined on Tautog aquaculture food resources by determining lipid and residual protein content gravimetricly after chloroform/MeOH lipid extraction.  The resultant data indicate that the alga strain T-iso has the greatest lipid content among the algae, Fig. 1.  Green crabs are the best lipid source among the adult food items tested, Fig. 2.  T-iso followed by Ply are the best soure of lipids for overnight enrichment of rotifers, Fig. 3.  In the time series of  rotifer enrichment it appears that 24 hours of enrichment achieves the highest lipid/protein ratios in the rotifers, approaching 0.7-0.8:1 by 24 hours after which the ratio declines, Fig 4.

II. Lipid content during tautog development in aquaculture

Tautog eggs (0 days), larvae (2 - 21days after hatching) and juveniles (33 and 37 days after hatching) sampled from the aquaculture facility at NMF, Milford and submitted to lipid analysis.  The larvae at 21 days has resumed lipid accumulation, presumably from eating rotifers.
 
 

Algal strains were harvested from growing cultures at NMF, Milford lab, and were analysed for their FA content and then the PUFAs were estimated as a percentage of total FA.

IV. PUFA content in adult food items

Adult food items were provided by NMF, Milford lab, and were analysed for their FA content and then the PUFAs were estimated as a percentage of total FA.
 
 

V. PUFA content in rotifers enriched with algal strains overnight

Rotifer cultures enriched with algae overnight were provided by NMF, Milford lab, and were analysed for their FA content and then the PUFAs were estimated as a percentage of total FA.  Two enrichment experiments were analyzed.  In the first rotifers were enriched overnight (18 hours) and concentrated using a seive plus centrifugation of the seive contents.  This was a one time point analysis which resulted in one estimate of lipid for each algal strain, Figs. 10 and 11.  A second experiment concentrated on T-iso and Ply in a time course of enrichment.  This time course was done in paralell wuith the two algal strains and the initial 8 hours of sampling was done at NMF, Milford Lab and the cultures transported to UMass Amherst and subsequent sampling continued there.  The two time courses are illustrated in Figs. 12-15.  The time courses suggest that maximal rotifer enrichment would be achieved at 20-24 hours based on lipid/protein ratios (Fig. 4) and C18-C22 enrichment (Fig. 12, 14) and n-3,4,6 content (Fig. 13, 15).  In general it seems that T-iso
 
 

VI. PUFA transfer to larvae and juveniles

The 21day larvae and 33 and 37 day juveniles of aquaculture reared tautogs (and perhaps 13 day larvae) demonstrate increased evidence of PUFA content of their FA fraction as a result of feeding by algal enriched rotifers, Fig. 16, 17.
 

VII. Conclusions

Since the tautogs were not on a specific diet regimen of one type of algal enriched rotifer, it is not possible to suggest which enriched rotifers would have resulted in better growth of the tautogs.  However it was clear from analysis of the algae and the algal enriched rotifers that there were clear differences in the PUFA content of different algal strains and rotifers enriched by them, and that the appropriate timing  of enrichment could produce rotifers of substantially higher PUFA content.

VIII. Active Personnel during this reporting period.

  1. Joe Kunkel, PI.  Morphometric analysis and protein purification and analysis.
  2. Joe Zydlewski, Postdoctoral Associate.  Lipid analysis and immunologic assay.
  3. Ray Moniz, Undergraduate.  Senior undergraduate student assisting Joe Zydlewski in HPLC.
  4. Rahul Sharma, Undergraduate.  Graduate technician assisting Joe Kunkel in immunology.
  5. Jeff Xu. Graduate student working on image analysis.
 

Respectfully submitted,
Joseph G. Kunkel
7/7/2000