Regional inhibition of cholinesterase in free‐ranging western pond turtles (Emys marmorata) occupying California mountain streams

Abstract

Abstract-The present study investigated the potential effects of cholinesterase (ChE)-inhibiting pesticides on western pond turtles (Emys marmorata) occupying streams in two regions of California, USA. The southern region was suspected of having increased exposure to atmospheric deposition of contaminants originating from Central Valley agriculture. The northern region represented reference ChE activities because this area was located outside of the prominent wind patterns that deposit pesticides into the southern region. Total ChE activity was measured in plasma from a total of 81 turtles from both regions. Cholinesterase activity of turtles was significantly depressed by 31% ( p ¼ 0.005) in the southern region after accounting for additional sources of variation in ChE activity. Male turtles had significantly increased ChE activity compared with females ( p ¼ 0.054). Cloaca temperature, length, mass, handling time, body condition, and lymph presence were not significant predictors of turtle ChE activity. In the southern region, 6.3% of the turtles were below the diagnostic threshold of two standard deviations less than the reference site mean ChE activity. Another diagnostic threshold determined that 75% of the turtles from the southern region had ChE activities depressed by 20% of the reference mean. The decrease in ChE activity in the southern region suggests sublethal effects of pesticide exposure, potentially altering neurotransmission, which can result in various deleterious behaviors. Environ. Toxicol. Chem. 2013;32:692-698. # 2012 SETAC

Organic contaminants in western pond turtles in remote habitat in California

“…Historical over-harvesting, habitat loss, and invasive species have been implicated as the primary factors threatening E. marmorata (Bury et al, 2008). However, negative biological effects from environmental contaminants have only recently received attention as a contributing factor, and the present study sheds further light on this possible cause of decline in a sensitive status species (Meyer et al, 2013(Meyer et al, , 2014. With these goals in mind, the presence of prominent environmental contaminants was examined at three California locations in three distinct sample types: 1) blood plasma of free ranging E. marmorata; 2) a composite sample of potential E. marmorata macroinvertebrate prey; and 3) stream sediments collected from E. marmorata habitat.…”

“…Turtles were captured by hand following methods previously described (Meyer et al, 2013). A total of 80 turtles were captured in relatively comparable abundances and sex ratios across sites (male:female:juvenile ratio: NFKR ¼ 14:11:2, CLCK ¼ 9:11:5, SFTR ¼ 11:12:5).…”

“…Thus, while it may be too late to study the accumulation of pesticides and their physiological effects in frogs that have been extirpated from the Sierra Nevada foothills, the western pond turtle (Emys marmorata), native to this region, still persists and may prove to be an appropriate biosentinel. In fact, a recent study of E. marmorata from the southern Sierra Nevada foothills found they had significantly reduced ChE activity compared to turtles from northern sites farther from agricultural areas (Meyer et al, 2013), offering support for the idea that heavy pesticide use in the San Joaquin Valley may be negatively affecting downwind ecosystems.…”

Atividade da colinesterase plasmática como biomarcador de impacto ambiental em tartarugas verdes (Chelonia mydas) no litoral do Arquipélago de Fernando de Noronha, Pernambuco

“…A primeira, é quantificar os indivíduos que apresentarem diminuição da atividade enzimática equivalente a duas vezes o desvio padrão da média obtida de todos os animais avaliados. A segunda forma, é identificar os animais que apresentarem diminuição da atividade equivalente a 20% da média obtida de todos os animais (Meyer et al 2013).…”

“…encontrou diminuição significativa da enzima em lagartos (Gallotia galloti palmae) que ocupavam um local de agricultura nas Ilhas Canárias. Meyer et al (2013) realizaram o primeiro estudo em tartarugas de água doce (Emys marmorata) e encontrou diminuição da atividade enzimática em animais influenciados por contaminação por pesticidas.…”