PREDATION
GENERAL ECOLOGY LABORATORY

Location: Winona State Aquatics Laboratory

Objective: To investigate prey choice/selection in an aquatic predator

Hypothesis: Slimy sculpin will not exhibit selective feeding on various types of prey, rather consuming prey at random based on encounter rates.

Agenda:

1) Collect slimy sculpin from Garvin Brook and acclimate them to lab conditions (12 h light/12 h dark, 54°F).

2) Collect a variety of invertebrate prey (e.g., amphipods, isopods, caddisflies).

3) Present individual sculpin with equal numbers of different prey types, recording the number of each and the total number of prey offered.

4) Determine the number and types of prey remaining after 24 hours, and by deduction, the prey consumed.

Analysis:

1) Combine consumption data for all sculpin within each "feeding trial" (Tuesday-big, Tuesday-little, Thursday-big, Thursday-little).  Keep data from each trial separate for prey selection analyses.

2) In a figure, display the average numbers of each prey type offered and consumed by the sculpin in each trial.

3) Use a Chi-square test to determine whether sculpin in a trial consumed prey types in the same proportions as they were offered (equal numbers of each prey type as expected values), or whether they exhibited some type of prey choice/selection.  Perform a separate Chi-square test for each trial. Display the results in a table.

4) Use three separate t tests to compare big and little sculpin with respect to total length, wet weight, and numbers of prey consumed. Place these summarized (Mean ± SD) lengths, weights, and prey consumption values and the results of the t tests in a simple table.

Equipment:

Dip nets, Waders, Buckets, Electrofishing equipment, Aquaria, Feeding chambers