Description

Food webs and trophic dynamics are important biological topics that explain community interactions, ecosystem energetics, and other ecological phenomena. Interactions among organisms in different trophic levels are particularly important factors shaping the structure and function of communities and ecosystems. To investigate the interactions between producers and consumers, a simple ecosystem containing an algal producer and a crustacean herbivore will be constructed and observed over the course of a two-week period. In this experiment, students will use an experimental design developed by Hudon and Finnerty (2013), but in a “flipped” format. Students should first view the assigned videos that describe the fundamental features of the experimental procedure.  Notes should be taken about experimental design to investigate bottom-up or top-down effects in a simple ecosystem composed of a single producer and consumer species.

The producer is a unicellular, marine alga in the genus (Platymonas sp.). This species has a flagellum which allows it to swim through its aquatic environment. The consumer is Artemia salina (brine shrimp), a crustacean related to crabs and lobsters. They hatch from cysts and are easily grown in lab. The larva, called a naupilus, are active swimmers and develop into the mature adult form in a few days. The mature adults are grazers that feed on algae.

Hudon, D. and J.R. Finnerty. 2013. To build an ecosystem: an introductory lab for environmental science and biology students. The American Biology Teacher 75:186-192.

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