(full paper is archived in the Miller Library)
Title: Negative effects of the herbicide atrazine on planula
settlement in the scyphozoan medusa Aurelia labiata
Student Author(s): Nava, Raul
Faculty Advisor(s): Epel, David
Pages: 38
Location: Final Papers Biology 175H
Date: June 2004
Abstract: Anthropogenic pollution has widespread impacts on
development of marine organisms as myriad chemicals make their way
into coastal ecosystems. The present study examined effects of the
commonly used herbicide atrazine. Potential effects of atrazine were
observed using scyphozoans, model organisms useful as indicators of
unbalanced ecosystems, specifically testing effects on cultured
planula larvae of the medusa Aurelia labiata. Planula
settlement was observed over 14 days in seawater with 3 dilutions of
atrazine (l ppb, 10 ppb, and 30 ppb). Turnover time, when population
dominance shifted from free-swimming larvae to sessile polyps, was
longest in the highest atrazine dilution relative to the control
treatment (6.27 days versus 1.96 days, respectively), indicating a
significant treatment effect of atrazine (P=0.0015). Similarly,
cumulative mortality was higher with increased atrazine
concentration. These data suggest atrazine negatively effects
development of cnidarians. Scyphozoans are typically more tolerant
of poor ocean conditions, therefore these results raise concern for
effects on other marine organisms more sensitive to environmental
conditions.