Pesticides in blood from spectacled caiman (Caiman crocodilus) downstream of banana plantations in Costa Rica

Abstract

Spectacled caiman (Caiman crocodilus) are fish-eating crocodilians that inhabit freshwater habitat in tropical regions of the Americas. To assess the exposure of caiman to pesticides from banana plantations, the authors collected whole blood samples (30 mL) from 14 adult caiman that were captured in the North Atlantic region of Costa Rica. Blood samples were analyzed for 70 legacy- and current-use pesticides and breakdown products using newly developed ultra-trace, high-resolution mass spectrometry (HRMS). Caiman accumulated pesticides ranked by concentration as dieldrin > permethrin > mirex > 4,4'-DDE > alpha-endosulfan > heptachlor epoxide > oxychlordane > heptachlor > cypermethrin. Caiman within the high-intensity banana crop watershed of Rio Suerte had higher pesticide burdens relative to other more remote locations (F = 12.79; p = 0.00). Pesticide concentration decreased with distance from upstream banana plantations in this river system (F = 20.76; p = 0.00). Caiman body condition was negatively correlated with total pesticide concentrations (F = 6.23; p = 0.02) and with proximity to banana plantations (F = 5.05; p = 0.04). This suggests that either pesticides elicited toxic effects in caiman, resulting in diminished overall health, or that the quantity or quality of their prey was reduced by pesticides downstream of plantation waterways. The authors' results indicate that pesticide use in banana plantations is impacting a high trophic level species inhabiting one of the most important wilderness areas in Costa Rica (Tortuguero National Park).

Conservation of a Neotropical Herpetofauna: An Introduction to the Crisis of Amphibians and Reptiles in Central America and Beyond

“…Agricultural runoff in this watershed has resulted in the feminization of male alligators (Miller 2007). Very similar conditions have recently been published concerning spectacled caimans in Costa Rican waterways (Grant et al 2013). Central America and its sur-rounding areas are widely influenced by heavy spraying from pineapple and banana plantations (Thrupp 1991;de la Cruz et al 2002).…”

The authors' reply

“…For example, Mr. Laprade suggests that our 2 significant correlations ( Figure 4 of Grant et al [1]; total pesticides in caiman increased as a function of proximity to banana plantations, p ¼ 0.00; and caiman body condition decreased as a function of total pesticides in their blood, p ¼ 0.02) might be "incorrect" because of small sample size or inadvertent selection of contaminated individuals. For example, Mr. Laprade suggests that our 2 significant correlations ( Figure 4 of Grant et al [1]; total pesticides in caiman increased as a function of proximity to banana plantations, p ¼ 0.00; and caiman body condition decreased as a function of total pesticides in their blood, p ¼ 0.02) might be "incorrect" because of small sample size or inadvertent selection of contaminated individuals.…”

“…To protect this biodiversity, Costa Rica has nurtured an elaborate system of national parks, which cover 27% of its 51 100 km 2 area. A schematic representation that may explain the poor condition of spectacled caiman observed in the proximity of banana plantations and their higher blood concentrations of 9 legacy and current-use pesticides in the Rio Suerte system in the North Atlantic Zone of Costa Rica [1]. Given the rapid growth in organic fruit and vegetable sales in consumer nations, the 35% price premium on bananas grown without heavy inputs of pesticides [27] Figure 1.…”

To the editor

“…Grant et al [1] mention historical fish kills as plausible reasons for reduced populations of fish; however, they did not actually measure the populations of fish in their study, and the reasons for the reduced condition of caiman are purely speculative. Grant et al [1] mention historical fish kills as plausible reasons for reduced populations of fish; however, they did not actually measure the populations of fish in their study, and the reasons for the reduced condition of caiman are purely speculative.…”

“…In addition, we question why a scientific journal would accept comments that have no scientific basis, such as "Although these plantations are economically important to Costa Rica, the ready detection of a range of legacy and currently used pesticides in caiman in a national wilderness area raises important questions about the moral sustainability of banana agricultural production" [1]. In addition, we question why a scientific journal would accept comments that have no scientific basis, such as "Although these plantations are economically important to Costa Rica, the ready detection of a range of legacy and currently used pesticides in caiman in a national wilderness area raises important questions about the moral sustainability of banana agricultural production" [1].…”