GCE Schoolyard 2010

Ecological Relationships Between Spanish Moss and Live Oaks

Throughout the southeastern United States, fast-growing pines are overgrowing slower-growing, but historically-dominant, oaks due to a combination of changes in fire regime and an increase in the density of browsers (predominantly deer). The consequences of this transition in species dominance for the assemblage of epiphytes that thrive on oak limbs, specifically resurrection ferns (Pleopeltis polypodioides) and Spanish moss (Tillandsia usneoides), remain poorly understood. Evaluating the degree to which pine succession is altering the abundance and distribution of these epiphytes is especially important to preserving biodiversity in the southeastern US as resurrection ferns and Spanish moss are known to support a rich fauna (i.e. insects, spiders, Anole lizards, etc) that persist within the intricate matrices of these epiphytes.

In the summer of 2010, Schoolyard teachers helped take the initial data an experiment designed to quantify the effect of pine succession on epiphyte assemblages. The experiment involved removing all of the pine trees beneath 4 large live oak canopies and comparing the distribution of epiphytes to those in unmanipulated oak canopies. The teachers helped take measurements of the tree trunk and crown diameters and well as count the total density and measure the diameter of all of pine trees growing beneath the 8 oak canopies under investigation. Another team of teachers helped take data on the distribution of resurrection ferns and Spanish moss along each of 40 limbs using transect tapes and 25 ft tall measuring poles. The intention is to collect the same data with the Schoolyard teachers over the coming summers to quantify the response of the epiphyte community to pine removal over time.

Mud Crab Effects on Saltmarsh Creek Channels and Dieback

This project examines the biotic aspects of tidal creek formation in response to climate change. As the sea level rises, the volume of water that inundates the marsh at high tide increases and this could lead to the loss of the salt marsh. Yet, in some areas the marsh has remained relatively the same. The mechanism behind this phenomenon is unclear but it is believed that the formation of tidal creeks in these marshes aid in draining the marsh at low tide. Past studies of tidal creek formation focused only on the abiotic (hydrology, sediment transport, etc.) factors and failed to examine the biological factors. This project examines the interactions between marsh crabs and Spartina alterniflora with focus on how the crabs affect Spartina productivity and aid in marsh erosion.

Survey for Petrolisthes armatus (Green porcelain crab) on oyster reefs

One project that has been repeatedly used to involve schoolyard participants in field research is a long-term monitoring effort to determine the relative abundance of native mud crabs and non-indigenous green porcelain crabs (Petrolisthes armatus) on oyster reefs around Sapelo Island, GA. The porcelain crabs first became noticed in the mid-1990s and quickly became the most abundant crab on Georgia oyster beds. Dr. Dale Bishop has, for several years, used the assistance of the teachers to help collect and process samples from local reefs. These oyster samples are processed to remove all crabs and the crabs are divided by species and sex. Other population data are collected for each species and these data are compared with densities of the crabs from previous years. By monitoring these populations, it may be possible to better understand invasion processes and subsequent effects of non-indigenous species on native species. For 2010, P. armatus densities were lower than in previous year..

Blue crab predation on Littoraria irrorata

This field project on Sapelo Island is quantifying the impacts of blue crab predation on the dominant consumer, the marsh periwinkle (Littoraria irrorata) and evaluating the potential for the blue crab to control snail populations. Coupled with drought conditions, the marsh periwinkle can aggregate and form grazer fronts that devastate marsh grass in just a few months. However, the predator Callinectes sapidus (blue crab) is a voracious eater of snails that swims into the marsh at high tides. In a predator inclusion experiment we have found that the presence of just one blue crab in a 2m² area of marsh can consume enough snails to stop grass die off in 3 months. The Schoolyard participants helped with the initial setup of one of the phases of this project. They helped prepare plots of marsh grass by removing snails, counting snails, and redistributing them into the proper caged plots.

Other Resources

A 2010 SchoolYard participant published a journal article where she describes her participation in the GCE LTER SchoolYard Program and discusses how this experience benefited her professionally and her students back in the classroom. To learn more about this article, please visit 'The NSTA Learning Center'.