Community Ecology

Stacey Havard pulls up a survey plate from a marina in Tampa, Florida. Photo by Michele Repetto. 
Community ecology is the study how the various populations making up a community interact and the factors that influence biodiversity, community structure, and the distribution and abundance of species. The structure, dynamics, and function of communities result from the interaction of many different factors. Communities are constantly being shaped by human activities, activates that can affect hydrology, chemical inputs, species richness (number of species that make up the community), as well as habitat quantity and quality. To complicate matters, these changes are occurring with changes in the climate. Added to this is the introduction on nonnative species that can alter the recipient community in many ways including changing the physical habitat/landscape, altering existing predator-prey interactions, and reducing species richness.

Our research focuses on how biological invasions change the marine and estuarine communities they invade and how recipient communities protect themselves from invasion. The following highlights a few of our recent projects exploring community changes resulting from nonnative species introductions.

Community Structure and Composition: The Fouling Community Survey
One of our largest projects is the fouling community survey. This survey was started in 1994 and has been conducted in most of the major bays in the United States and Puerto Rico, as while as Australia, Canada, Belize, and Panama. Through this survey we’re gaining valuable information about the diversity of the fouling community, how it changes over time, and how new species change community structure, composition and abundance. We have also detected new invasions and documented the resulting changes in community structure. See the July 2012 Feature Story for more on this survey.

Biotic Resistance: The Tropics vs. the Temperate Zone
In early 2013 Dr. Amy Freestone (Temple University), Dr. Gregory Ruiz (Smithsonian Environmental Research Center), and Dr. Mark Torchin (Smithsonian Tropical Research Institute) published an article in Ecology, documenting the results of the first experimental test of the resistance of communities to invasion (the Biotic Resistance Hypothesis). Using predation as an indicator of resistance, they conducted experiments to test whether the more diverse communities of the tropics were better at preventing colonization from an invader than the less diverse communities of the temperate zone. They concluded that tropical communities were more difficult for nonnative species to invade compared to the communities at higher latitudes. For more on this research see the June 2013 Feature Story and their recent publication (Freestone et al. 2013).

Predator-Prey Interactions: The Nearshore Survey
The Nearshore Survey examines the interactions between native grass shrimp and their predators in the Rhode River (Chesapeake Bay). Each summer for the last 22 years the abundance of fish and crab predators in the nearshore zone where shrimp seek refuge has been measured, shrimp distribution and relative abundance has been monitored and direct observations of shrimp predation through the use of tethered shrimp have been made. The results of this long-term comprehensive dataset allow us to see how the populations of shrimp and their predators change over time and what factors may be influencing those changes. Find more detailed information on the survey here.

Updated July 2013