Abstract:
Non-point source pollution is not generated from any single source, rather can
arise from a mixture of agricultural, residential, and industrial activities. As a result of
these activities millions of tons of chemicals enter into aquatic environments annually
with the potential to disrupt the fragile ecosystems existing within. Common
anthropogenic compounds most frequently seen in estuarine environments include
pesticides, antifoulants, polycyclic aromatic hydrocarbons (PAH), and industrial
solvents.
This dissertation examines the acute toxicity and sub-lethal effects of diuron,
CuPT, B(a)P, and styrene in the mud snail, Ilyanassa obsoleta, the American oyster,
Crassostrea virginica, the sea urchin, Lytechinus variegatus, and/or the barnacle,
Amphibalanus (= Balanus) amphitrite. In addition, the general effects of non-point source
pollution within the Rachel Carson Estuarine Research Reserve (RCERR) were examined
at six sites in order to gain a better understanding of the current health of this unique
habitat.
Of the four compounds tested, only the industrial solvent, styrene, resulted in an
LC50 (1341 µg L-1, I. obsoleta) that was within the range of currently reported
environmental levels. Diuron and CuPT did not elicit mortality at environmentally
relevant concentrations, but did significantly reduce fecundity in I. obsoleta and C.
virginica and fertilization success and larval development in L. variegatus. The only
notable sub-lethal effect elicited by the PAH, benzo(a)pyrene, was a significant decrease
in egg capsule production by I. obsoleta following exposure to concentrations as low as
50 µg L-1.
Within the RCERR, animals from Sites 4, 5, and 6 were observed to have
significant differences with respect to fecundity, condition index, and/or ECOD activity
when compared to conspecific organisms from control Site 1. This is most likely a
consequence of their proximity to anthropogenic sources. Large variation in mortality
(15-98.9%) was observed when families of A. amphitrite from a single population where
exposed to CuPT.
It is often difficult to extrapolate data from laboratory findings into natural
populations. Frequently the organisms used under laboratory conditions are genetically
very similar, while field population can vary with anthropogenic exposure. Caution
must be taken when developing protocols for risk assessment to ensure that actual
environmental conditions are being represented.
