PW12 Pesticide II
Exhibit Hall
8:00 AM - Wednesday
(PW212) Pesticide exposure and reproductive effects in two species of native amphibians using agricultural habitat, South Okanagan, British Columbia.
Ashpole, S1, 2, Bishop, C2, Elliott, J2, Wilson, L2, 1 University of Guelph, Guelph, ON, Canada2 Canadian Wildlife Service, Delta, BC, Canada
ABSTRACT- The Okanagan valley in BC is an intensive agricultural area where 80% of the natural wetlands and riparian zones have been developed. Due to the presence of many rare species and the high potential for multiple exposure effects to pesticides and the lack of natural habitat, it is necessary to assess the risk of amphibian populations to the impact of pesticides. In 2003/2004 forty ponds, including 14 conventional and 9 organic agricultural ponds, were surveyed to determine breeding adult and larval productivity and relative population densities. Historic PCB and organochlorine contaminant levels were measured in sediment samples from eleven ponds. All samples had non-detectable PCB levels and with the exception of DDT and its metabolites, relatively low to non-detectable organochlorine pesticides. Sediment concentrations of DDT (0.24 - 47 ng/g d.w. (dry weight)), DDE (2.52−1938.9 ng/g d.w.), and DDD (5.26−1334.4 ng/g d.w.) had the highest levels detected. In 2004, early amphibian stages of development were investigated using two COSEWIC listed species; the Great Basin Spadefoot (Spea intermontana) and the Western Toad (Bufo boreas). Enclosures with eggs were placed in either conventional orchards (N=2) and exposed to realistic pesticide applications, or in organic orchards (N=3). Current use pesticides include azinphos-methyl, carbaryl, diazinon, endosulfan, and pirimicarb. Water samples for pesticides were conducted at standard times and after known spray events. Hatching success, tadpole survival to two days-post hatch, and developmental abnormalities were recorded. Substantial mortality was observed in both species at one of our conventional sites (92% and 100%) whereas, mortality was very low at one of our organic sites (3% and 4%). Mortality among our remaining sites ranged between 15% and 38%. A third year of inventories and reproductive studies examining amphibian development and a risk assessment of agricultural ponds will be conducted in 2005.−−
Key words: Amphibians, Pesticides, Mortality, Enclosure study