There is no comprehensive study that details the abundance of crayfish in Big Cypress National Preserve (Duever, et al., 1986). However, there are studies that have looked at crayfish in other systems, which allow conclusions to be drawn about crayfish densities in cypress wetlands (Jordan, et al., 1996a, Jordan et al., 1996b).

The biomass estimates were determined based on data reported in Jordan, et al. (1996a), which illustrated the high variation in reported biomasses of crayfish in South Florida. Jordan offers a hypothesis that crayfish density increases as habitat complexity increases. An increase in complexity implies an increase in surface structures that impede movement (increases in emergent stems, debris, etc). This increase in complexity provides protection from predation for the crayfish, and leads to the higher density of crayfish (Jordan, et al., 1996a).

There is less complexity in cypress wetlands than in the surrounding graminoid habitats, but sufficently more than in unobstructed open waters. Based on this assumption, we have estimated crayfish biomasses to be 1.3059 g C / m² for the dry season and 1.4801 g C / m² for the wet season. These numbers reflect an average of the multiple biomasses presented in Jordan, et al. (1996). The wet season biomass is higher because studies indicate reproduction occurs during the summer months (Pennak, 1978).

Below are listed the numbers and equations used to determine Consumption, Respiration, Production and Egestion. For a complete description of the methodology, see the Aquatic Invertebrates compartment description.

2.653 grams wet mass (Kushlan, et al., 1986).



The following relationship was used to determine a general rate of respiration for crayfish in this model:

R = 19.24 W ^0.81 (Jørgensen et al., 1991).



kilocalories per crayfish: 1.2508 (Kushlan, et al., 1986).

log₁₀ (P/B) = -0.2 + (-0.4 (log₁₀ (1.2508))) (Banse and Mosher, 1980).



crayfish assimilation efficiency: 60% (Jørgensen et al., 1991).

Consumption = Production + Respiration / 0.6



Egestion was determined after the rates of consumption, production and respiration were estimated. Egestion is simply the remainder of consumption after production and respiration have been subtracted.

 

In many cases, there were no quantitative results indictating the diet of the species in the compartment. In these cases, input flow rates were estimated based on most likely prey compartments and on the relative biomasses of these prey compartments. The source material which we used to establish a link between compartments, and to estimate a flow rate, is listed below. Very little specific information exists about the diet of Procamarus alleni in this system; the rates of flow are all estimations based on qualitative data from the listed sources:


Living POC

Living Sediment

Phytoplankton

Periphyton

Macrophytes

Labile Detritus




Jordan et al., 1996a; Jordan et al., 1996b; Pennak, 1978; Rader, 1994.