Fishes are important prey for most species of wading birds in the Everglades, and provide a critical link between water management and restoration of wading bird populations. The Across Trophic Level Systems Simulation (ATLSS) model of fish population dynamics was developed to evaluate the ecological effects of hydrological restoration alternatives on fish productivity. The model incorporates assumptions regarding predator-prey and population growth parameters, which are poorly understood because of the difficulty of studying them under field conditions. Controlled experiments in large outdoor tanks and field cages will provide improved estimates of some of these parameters, and will explore some important biological interactions that must be included in future model versions to improve credibility. These include predator-prey interactions involving the mosquitofish (Gambusia holbrooki), an abundant and highly predatory species throughout the Everglades. This is the "model" small fish on which the ATLSS fish model is based. It is known to prey upon the young of other fish, even driving some fish species to extinction where it has been introduced. They also feed on their own offspring when possible. Mosquitofish are also important predators on the eggs and larvae of nesting sunfishes. These interactions are being explored experimentally.

There are three research objectives for this study: (1) document the extent, patterns, and results of cannibalism and predation by mosquitofish on mosquitofish juveniles and those of other small fishes. Limitation of growth through intraguild actions is a potential feedback relations that must be included in the ATLSS and similar management models; (2) test the relations of water depth and small-fish predation with the survival of eggs and larvae of nesting sunfish, also a potentially important feedback in community regulation; (3) by the addition of nutrients to tanks, test the effects of variations in primary production through an experimental food web. Primary productivity varies naturally and along anthropogenic gradients in the Everglades, affecting both food availability and habitat structure.

---

(This abstract was taken from the Greater Everglades Ecosystem Restoration (GEER) Open File Report (PDF, 8.7 MB))

Note: PDF files require the Adobe Acrobat Reader to be read. Download the FREE Adobe Acrobat Reader ®.

Back to Project Homepage