Analysis of estrogens as endocrine disrupting chemicals released from horse stables in Acadia National Park into the Stanley Brook watershed: possible effect on sea-run brook trout, methodology for screening and management implications

Lobozzo, Nicholas

Following from abstract: 'This thesis provides background and a literature review for a possible research project on Stanley Brook watershed in Acadia National Park (ANP). It proposes to identify, measure, and investigate the probability that EDCs from nearby horse stables are negatively affecting the native sea-run brook trout population. The EDCs excreted from horse urine, and feces to some extent, come in the form of three types of estrogens: estrone (E1), 17B-estradiol (E2), and estriol (E3), all of which, to different extents, build up in soils after excretion, enter waterways through runoff, and negatively affect wildlife (Bushee 1998). Although there are more complicated and expensive methodologies for measuring estrogens in surface water, it was found that th emost appropriate for ANP at this time is the relatively simple ELISA test kit. The kits vary in price from $280-$750, depending on their sensitivity. Given their physiochemical properties, which denotes their fate and transport within a system, estrogens will be at their highest concentrations in surface waters, and samples should be taken directly from the water column as opposed to in soil/silt/sludge (Mes 2005). Samples should be taken during periods of high flow because increased runoff results in the highest concentrations of estrogens. It was found that periods of high flow in Maine often correspond with periods of susceptibility in the life of a brook trout as increased levels of estrogens could lead to biological impairment during spawning periods in the fall and during the early spring when eggs hatch. Samples should be taken above and below each stable site on both branches of the stream, below where the two branches meet, and near the beach where effluent from the waste treatment plant might have an impact on estrogen concentrations. Future management plans might limit the use of the stables by pregnant females, include the planting of grass filter strips to minimize the amount of estrogens that ultimately appear in the stream, and dispose of the manure/bedding matrix found in the stalls (Nichols 1998). This thesis attempted to lay out the risk factors that are associated with the location of the horse stables, and they might be such that ANP decides to go ahead with the study. However, given the recent expansion in interest for dip-stick technology to measure estrogens, combined with the fact that experts suggest population-wide decreases of fishes due to increased concentrations of natural estrogens are uncommon, waiting a few years for the technology to catch up with the demand for easy-to-use measuring devices might be worthwhile.'