Ac. Schwarzschild et al., ZOSTERA-MARINA L GROWTH-RESPONSE TO ATRAZINE IN ROOT-RHIZOME AND WHOLE-PLANT EXPOSURE EXPERIMENTS, Journal of experimental marine biology and ecology, 183(1), 1994, pp. 77-89
Atrazine ro-4-[ethylamino]-6-[isopropylamino-]-s-triazine?? ), a triaz
ine herbicide, is one of the most widely used herbicides in the Chesap
eake Bay watershed. Increased use of atrazine in the 1970s coincided w
ith a decline in the abundance of Zostera marina L. (eelgrass). Ground
-water surveys have found atrazine in concentrations that may affect e
elgrass growth and survival. The effects of atrazine in groundwater di
scharges on the growth of eelgrass through root-rhizome exposure were
examined in laboratory systems. A long term, dynamic, groundwater simu
lation study was conducted with atrazine concentrations ranging from 0
.0 to 2.5 mg.1(-1). No significant effects on chlorophyll content, gro
wth or survival were detected. A static root-rhizome exposure experime
nt was conducted using split chamber exposure systems to verify these
results, atrazine concentrations were increased by an order of magnitu
de. Neither mortality nor significant effects on plant growth were det
ected (maximum atrazine concentration 7.6 mg.1(-1)). A static, whole p
lant exposure experiment was conducted, and mortality was observed at
atrazine concentrations of 1.9 mg.1(-1) and above. This work suggests
that eelgrass is not susceptible to atrazine through root-rhizome upta
ke, and that atrazine exposure via groundwater seepage did not cause t
he declines in eelgrass abundance and distribution.