Alligator Tales: New Lessons about Environmental Contaminants from a Sentinel Species

Milnes, Matthew R.; Guillette, Louis J.

doi:10.1641/b581106

Cited by 88 publications

(54 citation statements)

References 53 publications

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“…In addition, gonadal steroidogenesis was unresponsive to exogenous luteinizing hormone, suggesting that the gonads of these alligators had been permanently modified in ovo, and that normal steroidogenesis was no longer possible. Similar observations of abnormal gonadal morphology and steroidogenesis in alligators from contaminated wetlands continue to the present [for review, see Milnes and Guillette 2008].…”

Section: Alligators and Contaminant Effects On Reproduction And Gonadsupporting

confidence: 62%

Birth Defects in Wildlife: The Role of Environmental Contaminants as Inducers of Reproductive and Developmental Dysfunction

Hamlin

Guillette

2010

Systems Biology in Reproductive Medicine

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Section: Alligators and Contaminant Effects On Reproduction And Gonadsupporting

confidence: 62%

Birth Defects in Wildlife: The Role of Environmental Contaminants as Inducers of Reproductive and Developmental Dysfunction

Hamlin

Guillette

2010

Systems Biology in Reproductive Medicine

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“…As long-lived vertebrates and apex predators, crocodilians (gharials, caimans, alligators and crocodiles) in particular are excellent study subjects for understanding environmental and ecosystem health (Campbell 2003;Milnes and Guillette 2008). Multiple studies (Twinning et al 1999;Jeffree et al 2001;Rainwater et al 2007) report background or elevated Pb concentrations in the flesh and osteoderms of several species in the wild, but information about the clinical symptoms and reproductive effects of Pb toxicosis is mainly limited to studies on captive crocodilians fed meat contaminated with Pb shot (Camus et al 1998;Hammerton et al 2003;Lance et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Blood lead concentrations in free-ranging Nile crocodiles (Crocodylus niloticus) from South Africa

et al. 2016

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Generally crocodilians have received little attention with regard to the effects of lead toxicity despite their trophic status as apex, generalist predators that utilize both aquatic and terrestrial habitats, thereby exposing them to a potentially wide range of environmental contaminants. During July-October 2010 we collected whole blood from 34 sub-adult and adult free-ranging Nile crocodiles (Crocodylus niloticus) from three separate populations in northeastern South Africa in order to analyze their blood lead concentrations (BPb). Concentrations ranged from below detectability (<3 μg/dL, n = 8) to 960 μg/dL for an adult male at the Lake St Lucia Estuary. Blood lead concentrations averaged 8.15 μg/dL (SD = 7.47) for females and 98.10 μg/dL (SD = 217.42) for males. Eighteen individuals (53 %) had elevated BPbs (≥10 μg/dL). We assessed 12 general linear models using Akaike's Information Criterion (AIC) and found no significant statistical effects among the parameters of sex, crocodile size and population sampled. On average, crocodiles had higher BPbs at Lake St Lucia than at Ndumo Game Reserve or Kosi Bay, which we attribute to lead sinker ingestion during normal gastrolith acquisition. No clinical effects of lead toxicosis were observed in these crocodiles, even though the highest concentration (960 μg/dL) we report represents the most elevated BPb recorded to date for a free-ranging vertebrate. Although we suggest adult Nile crocodiles are likely tolerant of elevated Pb body burdens, experimental studies on other crocodilian species suggest the BPb levels reported here may have harmful or fatal effects to egg development and hatchling health. In light of recent Nile crocodile nesting declines in South Africa we urge further BPb monitoring and ecotoxicology research on reproductive females and embryos.

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“…As an apex predator throughout the Southeastern United States, the American alligator is considered a sentinel species [3]. Alligator health and population stability is indicative of the health of the wetlands they inhabit [3].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Alligator health and population stability is indicative of the health of the wetlands they inhabit [3]. Alligators have been regarded as, "an excellent model for investigating the effects of chronic exposure to xenobiotic chemicals on reproductive success and embryonic development" [3] (p. 1029). Regionally specific to this study, the seasonal movements, reproductive timing, habitat preference and cultural significance of the species in Louisiana have been extensively studied as a function of Louisiana's management program [4].…”

Section: Introductionmentioning

confidence: 99%

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Heterophil/Lymphocyte Alterations as a Measure of Stress in American Alligators in Relation to Anthropogenic Disturbance in a Louisiana Intermediate Marsh

Murray

Rheubert

Easter

et al. 2015

JMSE

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Numerous anthropogenic factors represent environmental threats to Gulf Coast wetland ecosystems and associated fauna. American alligators (Alligator mississippiensis) have been subject to long-term management and used as ecological and physiological indicators of habitat quality in response to anthropogenic events and stochastic natural disasters. The present study monitored heterophil to lymphocyte ratios (an indicator of stress), in American alligators in a Louisiana intermediate marsh from 2009 to 2011, a time period that coincides with an oil inundation event that occurred in 2011. Sixteen alligators were observed and processed morphometrically (total length, snout-vent length and body mass). Heterophil to lymphocyte ratios were negatively correlated with size, suggesting larger American alligators were physiologically more resilient to the disturbance, more able to actively avoid these poor conditions, or are less affected by localized disturbance.

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Alligator Tales: New Lessons about Environmental Contaminants from a Sentinel Species

Cited by 88 publications

References 53 publications

Birth Defects in Wildlife: The Role of Environmental Contaminants as Inducers of Reproductive and Developmental Dysfunction

Birth Defects in Wildlife: The Role of Environmental Contaminants as Inducers of Reproductive and Developmental Dysfunction

Blood lead concentrations in free-ranging Nile crocodiles (Crocodylus niloticus) from South Africa

Heterophil/Lymphocyte Alterations as a Measure of Stress in American Alligators in Relation to Anthropogenic Disturbance in a Louisiana Intermediate Marsh

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