Ecology Rules

Mangrove islands, a common sight in the Bocas del Toro archipelago, are more than just a clump of trees. Within the island a complex set of interactions occurs between the animals, mostly arthropods such as insects and arachnids, and the plants, which provide the architecture for the ecosystem.  Ecologists call this set of interactions a food web. Food webs visually and mathematically show the feeding relations “who eats whom” between species in communities. In the mangrove food web shown here, the plants are at the bottom of the web along with algae, bacteria, and fungi. The next level up is the herbivores, animals that feed on plants. Next you get the omnivores, animals that feed on both plants and other animals. Finally near the top we see species that only feed on other animals, the predators, and a few species that nothing feeds on. We call these species top predators.

The structure of food webs can tell us a lot about how ecological communities function. For example, if you know the number of species in a community and how densely connected the species are through their feeding relationships, many aspects of the structure of community, such as the proportion of top predators, can be predicted with high accuracy. It is even possible to predict how resilient the community might be to disturbances such as nutrient enrichment, a major environmental problem in the Bocas del Toro region.

Food webs are a powerful way to look at nature, as the structure of the food webs, follows ecological rules.