INVESTIGADORES
STOKER Cora
congresos y reuniones científicas
Título:
Organochlorine compound egg burden and eggshell features in Caiman Latirostris
Autor/es:
ZAYAS MA; STOKER C; FERREIRA MA; DURANDO M; GALOPPO GH; RODRIGUEZ H; CALDINI EG; LUQUE E H; MUÑOZ-DE-TORO M
Lugar:
Santa Fe
Reunión:
Workshop; 2nd Latin American Pesticide Residue Workshop; 2009
Institución organizadora:
FIQ-UNL
Resumen:
Organochlorine
compounds (OCCs) present in the environment include agricultural and industrial
compounds. Due to their widespread use, lipid solubility, persistence in the
environment, biomagnification through the food net and endocrine disrupting
activity, OCCs are a serious concern for wildlife. Caiman latirostris is an oviparous species
with aquatic habits widely distributed in South America. Because of
their position in the upper trophic levels, prey preferences, nonmigratory
habits, and longevity, caimans have the potential to accumulate high
concentrations of OCCs. The eggshell
is formed during passage of the eggs through the oviduct. Since the oviduct is
a target of hormone actions, OCCs exposure could modify oviductal histofunctional
characteristics. In birds, reduced eggshell quality due to OCCs exposure has
been reported. A decrease in eggshell thickness and porosity could affect gas
and water exchange contributing to poor hatch rate. In this background, we
assessed the relationship between the burden of OCCs in C. latirostris eggs, eggshell thickness and porosity. Eleven
clutches were collected from wetlands on Parana River tributaries, in northeastern
Argentina. Eggs were collected shortly after oviposition, two eggs by clutch were
used to establish OCCs burden and eggshell thickness, while one egg by clutch
was used for eggshell porosity. A high frequency of OCCs was found in 95% of
egg samples. OCCs most frequently found were: p,p´-DDE; oxychlordane and PCBs. Eggshell thickness, measured from
photomicrographs by image analysis, was 397.4±5.24 mm and no association with
OCCs burden was found. Eggshell porosity was examined by scanning electron microscopy.
The number of pores in the outer surface was 29.5±7 pores/cm2. A
trend for an inverse correlation between porosity and OCCs burden was found. These
results support the use of caiman eggs for OCCs monitoring in wetlands.
Furthermore, a reduced eggshell quality due to OCCs pollution
suggests that caiman embryonic viability could be threatened. The
preservation of the caimans entails the preservation of whole wetland
ecosystems, which would otherwise be drained and converted to croplands
producing biodiversity loss and habitat fragmentation.