A Comparison of Two Methods for Enhancing the Recovery of Seagrasses into Propellor Scars: Mechanical Injection of a Nutrient and Growth Hormone Solution vs. Defecation by Roosting Seabirds: Final Report.

Based on the recovery rates for Thalassia testudinum measured in this study for scars of these excavation depths and assuming a linear recovery horizon, we estimate that it would take ~ 6.9 years (95% CI. = 5.4 to 9.6 years) for T. testudinum to return to the same density as recorded for the adjacent undisturbed population. The application of water soluble fertilizers and plant growth hormones by mechanical injection into the sediments adjacent to ten propellor scars at Lignumvitae State Botanical Site did not significantly increase the recovery rate of Thalassia testudinum or Halodule wrightii. An alternative method of fertilization and restoration of propellor scars was also tested by a using a method of “compressed succession” where Halodule wrightii is substituted for T. testudinum in the initial stages of restoration. Bird roosting stakes were placed among H.wrightii bare root plantings in prop scars to facilitate the defecation of nitrogen and phosphorus enriched feces. In contrast to the fertilizer injection method, the bird stakes produced extremely high recovery rates of transplanted H. wrightii. We conclude that use of a fertilizer/hormone injection machine in the manner described here is not a feasible means of enhancing T. testudinum recovery in propellor scars on soft bottom carbonate sediments. Existing techniques such as the bird stake approach provide a reliable, and inexpensive alternative method that should be considered for application to restoration of seagrasses in these environments. Document contains 40 pages)

The effects of environmental stress on the physiology of growth in rainbow trout, Salmo gairderi Richardson

There is little doubt that both mammalian and teleost growth hormones can accelerate growth and increase food conversion efficiency in all commonly-reared species of salmonid fish. In those vertebrates that have been closely studied (predominantly mammals), the pituitary hormone somatotropin (GH or growth hormone) is a prime determinant of somatic growth. The hormone stimulates protein biosynthesis and tissue growth, enhances lipid utilization and lipid release from the adipose tissues (a protein-sparing effect) and suppresses the peripheral utilization of glucose. The present study is a prerequisite for future work on growth hormone physiology in salmonids and should contribute to our understanding of the mechanisms of growth suppression in stressed fish. Plasma growth hormone (GH) levels were measured in rainbow trout using a radioimmunoassay developed against chinook salmon growth hormone.

Effects of dietary supplementation of commercial human probiotic and antibiotic on the growth rate and content of intestinal microflora in ornamental fishes

The effects of dietary supplementation of commercial human probiotic, Lactobacil and antibiotic, oxytetracycline on the growth, survival, disease resistance and content of intestinal microflora in two ornamental fishes, viz., goldfish, Carassius auratus and swordtail, Xiphophorus helleri were studied. The total wet weight gain, food conversion ratio and specific growth rate of C. auratus did not vary significantly (p>0.05) among treatments. While in X. helleri, significant differences existed in the total wet weight gain, survival, food conversion ratio and specific growth rate among treatment groups (p<0.05). The counts of antibiotic resistant bacteria in fish gut increased with days of culture in all the treatments and the increase was more in antibiotic fed fishes. A reduction in the development of antibiotic resistance among the bacterial flora of fish gut was noticed in probiotic fed groups of C auratus and X. helleri. The results of the present study revealed that the effects of human probiotic on the growth, survival and disease resistance of ornamental fishes are variable and difficult to reproduce the similar effect on different species.