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Aquatic Invertebrate Ecology During a Simulated
Botulism Epizootic in a Sacramento Valley Wetland

Results

No significant interaction of treatment and sampling day was found for the counts or weights for any of the six major taxa (Table 1). Although there was no consistent pattern, significant differences were found between the treatments and controls (i.e., plots with and without carcasses) for Daphnidae counts and Corisella weights (Table 2). No significant differences were found between the treatments and controls for counts or weights for Cyclopoida, Goeldichironomus, Chironomus, and Tanypus; Daphnidae weights; and Corisella counts (Table 2). There were significant differences among sampling days for the counts of all six major taxa and for the weights of Daphnidae, Chironomus, and Tanypus (Table 3).

Table 1. Treatment by sampling day interaction for counts and wet weights (4 and 406 df) for six major aquatic invertebrate taxa collected between 10 August and 3 November 1988 and between 8 August and 2 November 1989 from a seasonal wetland on Sacramento National Wildlife Refuge, California.
Taxon Counts Wet Weights
F P F P
Cyclopoida 0.33 0.8601 0.50 0.7361
Daphnidae 0.52 0.7211 0.58 0.6771
Goeldichironomus 0.80 0.5283 1.47 0.2102
Tanypus 0.31 0.8696 0.54 0.7040
Chironomus 0.86 0.4886 0.42 0.7912
Corisella 0.55 0.6963 0.83 0.5037

Table 2. Treatment effect for counts and wet weights (1.51 df) for six major aquatic invertebrate taxa collected between 10 August and 2 November 1988 and between 8 August and 3 November 1989 from a seasonal wetland on Sacramento National Wildlife Refuge, California.
Taxon Counts Wet Weights
F P F P
Cyclopoida 1.30 0.2598 2.20 0.1445
Daphnidae 5.09 0.0284* 2.36 0.1306
Goeldichironomus 2.73 0.1044 0.95 0.3341
Tanypus 0.01 0.9163 0.04 0.8361
Chironomus 0.13 0.7168 1.03 0.3143
Corisella 1.03 0.3142 6.58 0.0133*
* Significant difference (P < 0.05).

Table 3. Day effect for counts and wet weights (4 and 406 df) for six major aquatic invertebrate taxa collected between 10 August and 3 November 1988 and between 8 August and 2 November 1989 from a seasonal wetland on Sacramento National Wildlife Refuge, California.
Taxon Counts Wet Weights
F P F P
Cyclopoida 11.28 0.0001* 2.28

0.0597
Daphnidae 10.52 0.0001* 3.09 0.0160*
Goeldichironomus 6.05 0.0001* 0.99 0.4144
Tanypus 16.02 0.0001* 12.13 0.0001*
Chironomus 5.08 0.0005* 9.32 0.0001*
Corisella 6.56 0.0001* 0.88 0.4750
* Significant difference (P < 0.05).

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