Ecological Assessment of the Anemone Cave in Acadia National Park

Petraitis, Peter; Fegley, Steven; Beal, Brian

FIELD WORK: 1999 A map of sampling locations within the caves and on the open coast is provided. In Appendix A1 there are GPS coordinates for all of the pools sampled. Spcies lists of organisms found in the pools is available in the appendices as well, along with statistical outputs, graphs, and other relevent material. 'Analysis of the distributions and abundances of the species found in the Anemone Cave and outside of the Cave was undertaken to provide a benchmark for future assessments of changes within the Cave as well as a critical evaluation of the Cave's uniqueness. Intertidal pools inside the Anemone Cave, which is in Acadia National Park, contain large numbers of three species of sea anaemones: Tealia (=Urticina) felina, Bunodactis stella, and Metridium senile. The anemone speices are rarely found in intertidal pools outside of the Cave but are reported to be common in the subtidal waters surrounding the Park. The Anemone Cave is the only known cave of such size that contains a large number of anemones in Acadia National Park...Data were collected to address five specific goals, which were: 1) Provide a census of anemones in the Anemone Cave that would be directly comparable to earlier censuses. 2) Determine the depth of the freshwater lens on the pools in the Anemone Cave and whether mixing could lower the salinity levels in pools. 3) Provide data on visitation to the Cave which would supplement earlier reports on visitor use and provide the Park with information about the level of threat from visitor use. 4) Test whether the abundance of barnacles can be used as a bioindicator of visitation and can provide an assessment of visitor damage. 5) Investigate the uniqueness of the pools in the Anemone Cave by comparing them to pools with and without anemones outside of the Cave..... Six major conclusions were drawn from the analyses... 1) Anemones in the Anemone Cave show seasonal changes but numbers appear to be similar to counts done in 1991, Tealia and Bunodactis are common and Metridium is rare. Tealia has decreased and Bunodactis has increased. Anemones in the Cave are clearly more common than on the open coast. 2) There are freshwater lenses in the pools but there is no strong evidence for mixing and lowering of the pools' salinities by tourists dipping thier hands in the pools. The freshwater lens tends to be less than 10 cm. 3) Data support earlier observations that many people visit the Anemone Cave. People enter the cave and play in pools. While it is difficult to assess the levels of threat, tourists trample and may injure anemones and other speicies in the cave. 4) Barnacle densities are significantly less in areas with numbers of tourists and are a good seasonal indicator of shoreline visitiation. Barnacle densities could be used to assess damage not only in Anemone Cave but also in other areas of the Park. Barnacles are extraordinarily common and so tourist activities present little threat to barnacles themselves. 5) Survey of pools on the open coast showed no striking differences between pools with and wihtout anemones. There are no meaningful differences in physical characters or species compsoition. Chance appears to play a large role in determining which pools contain anemones. 6) Pools within caves are uniquely different from pools outside of caves. THe difference bwtween Stag Cave and Anemone Cave is greater then the difference between pools on the open coast with and without anemones. Each cave is unique. Data from the pools on open coast provide little guidance as to the species composition of the pools in Stag Cave and Anemone Cave. Seven recommendations are offered: (see continuation in Notes)