Background
Objectives
Significance
Anticipated benefits
Beneficiaries
Methods
Deliverables
Schedule

Background

Past PD/A CRSP research has predominantly emphasized fertilization practices, although some studies on supplementary feeding, stocking and polyculture practices have been conducted. Fertilization experiments have focused on estimating nutrient requirements for phytoplankton, under the assumption that the stocked fish, usually Oreochromis niloticus, preferentially feed on such resources. The use of manures in many of these experiments is believed to enhance food availability to fish via the detrital food chain. However, quantification of natural food resources in ponds remains an elusive goal, despite being critical both to predict fish growth and to better manage fertilizer, feed and stocking/harvest practices. Systems modeling of the pond environment provides opportunity to examine the dynamics of heterotrophic production, and interactions of fish with their food resources. Such models can also be used to conduct numerical experiments that can supplement and guide field research activities.

Objectives

1) To develop simplified models for heterotrophic (detrital) resources,

2) To refine and parameterize existing models that describe natural food resource consumption by fish species under monoculture and polyculture conditions,

3) To link the above models to existing fish bioenergetic and decision support algorithms in POND^©, and

4) To simulate natural food profiles, fish growth and production potential under polyculture conditions.

Significance

Quantification of natural food resources for pond fish will lead to an enhanced understanding of the interactions among pond fish, and their response to various intensities of pond management. Thus, the proposed study will aid improving our understanding of pond dynamics.

Anticipated benefits

Improved tools for the refinement of fertilization, feeding and stocking/harvesting practices, and the development of guidelines for polyculture.

Beneficiaries

Aquaculture managers, extension agents, planners, educators and researchers.

Methods

Simplified mass balance models that describe changes in pond detrital production as a function of resource (substrate) availability, temperature and other environmental conditions will be developed. The resource substitution approach of Tilman et al. (1982) which has proven to be a useful heuristic tool to examine fish consumption of phytoplankton and zooplankton in the current version of POND^© (Bolte et al., 1994) will be extended to include detrital resources as well. The fish energetics model in POND^© will be parameterized for various species that may be used in polyculture (e.g., different carp species) using literature data. Interactions among these species will be examined via their preferential consumption of different food resources in ponds as indicated by the resource substitution model. Simulations will be conducted to demonstrate production potential and species interactions under various management practices.

Deliverables

Models for heterotrophic dynamics and polyculture interactions implemented in the POND^© framework.

Schedule

8/1/96 to 10/1/97 (see also Table 1).

Report Submittal: 10/1/97