Biomass In Ponds Research Articles

Effet des variables abiotiques sur la biomasse animale de sept mares temporaires d'eau douce du Qu�bec m�ridional

The aim of this study was to ascertain the influence of environmental variables on the seasonal variations of total animal biomass in temporary ponds. We thus collected weekly, in seven major types of mosquito-breeding habitats, a total of 163 samples and calculated the dry weight (µg/l) of 75 taxa, using the length-weight relationships described in the literature. The total biomass was found to be more stable than the proportions of individual taxa. Multiple regression analysis showed that most of the dispersion of total animal biomass could be explained by environmental variables, especially water temperature, volume of water body and season.

Biological Control of Excessive Phytoplankton Growth and the Enhancement of Aquacultural Production

A method is proposed to control phytoplankton biomass in aquacultural ponds, using both zooplankton and filter-feeding silver carp (Hypophthalmichthys molitrix). The technique maintains co-existence of zooplankton and filter-feeding fish by excluding the fish from part of the water column. Zooplankton, which feed on smaller algal species, and silver carp, which feed on large algae and zooplankton, together can consume all sizes of phytoplankton, thus controlling algal biomass. This technique was tested in 1000-L tanks, some containing channel catfish (Ictalurus punctatus) alone, some both catfish and silver carp, and others catfish and silver carp with a zooplankton refuge. The refuge permitted coexistence of high densities of large zooplankters with the filter-feeding fish. This combination of filter-feeders reduced algal biomass by as much as 99%, increased phytoplankton diversity, and showed a trend toward improved silver carp growth compared with treatments without a refuge. The proposed technique could be applied to both intensive and extensive aquacultural systems.

Discharge of Solids from Fish Ponds

Abstract Water samples were collected from effluents of fish ponds and analyzed for settleable, nonsettleable, and suspended solids. Fish biomass in ponds was not consistently associated with amounts of settleable or nonsettleable solids, but was correlated with amounts of suspended solids. The amount of solids discharged was relatively small, suggesting little or no pollution of receiving waters.

A POPULATION DYNAMICS MODEL FOR PRAWN AQUACULTURE

AbstractWe have used a stochastic population model to simulate the prawn size distribution in the grow‐out ponds as a function of time. The model allows for growth and mortality parameters which are dependent on size class and pond biomass. We have written a computer program based on this model in which the user inputs a stocking number, a stocking size distribution, a stocking schedule, the harvest size classes, and a harvest schedule. The computer then computes the number of prawns and the prawn size distribution in the pond at specified time increments and a quarterly production economics summary.We compare simulated growth and harvest data generated by the program to actual growth and harvest data from Hawaii and Florida. We also use the program to evaluate the effects of stocking number, stocking schedule and stocking size on annual yields from a prawn grow‐out pond.