Chronic exposure to glyphosate in Florida manatee.

Florida manatees were found to be chronically exposed to glyphosate and AMPA present in freshwater water bodies. This exposure was greater before and during the sugarcane harvest, when glyphosate is sprayed as a sugarcane ripener, but it is also used to control aquatic weeds, or to prepare farms before planting. AMPA's concentration is directly associated with the presence of glyphosate in the environment, suggesting a constant input of glyphosate. Glyphosate can breakdown into AMPA during the warmer months of the year due to bacterial degradation. Florida manatees depend on freshwater resources all year round, but more intensively during the cold weather (December to January). Water sampling periods are shown in black. [Display omitted] • Florida manatees exposed to glyphosate have increasing body burdens since 2009. • Glyphosate and AMPA were ubiquitous in Florida water bodies. • Concentrations of glyphosate and AMPA were higher, before and during sugarcane harvest. • Florida manatees were continuously exposed to both compounds in 2019–2020. Florida manatees depend on freshwater environments as a source of drinking water and as warm-water refuges. These freshwater environments are in direct contact with human activities where glyphosate-based herbicides are being used. Glyphosate is the most used herbicide worldwide and it is intensively used in Florida as a sugarcane ripener and to control invasive aquatic plants. The objective of the present study was to determine the concentration of glyphosate and its breakdown product, aminomethylphosphonic acid (AMPA), in Florida manatee plasma and assess their exposure to manatees seeking a warm-water refuge in Crystal River (west central Florida), and in South Florida. We analyzed glyphosate's and AMPA's concentrations in Florida manatee plasma (n = 105) collected during 2009–2019 using HPLC-MS/MS. We sampled eight Florida water bodies between 2019 and 2020, three times a year: before, during and after the sugarcane harvest using grab samples and molecular imprinted passive Polar Organic Chemical Integrative Samplers (MIP-POCIS). Glyphosate was present in 55.8% of the sampled Florida manatees' plasma. The concentration of glyphosate has significantly increased in Florida manatee samples from 2009 until 2019. Glyphosate and AMPA were ubiquitous in water bodies. The concentration of glyphosate and AMPA was higher in South Florida than in Crystal River, particularly before and during the sugarcane harvest when Florida manatees depend on warm water refuges. Based on our results, Florida manatees were chronically exposed to glyphosate and AMPA, during and beyond the glyphosate applications to sugarcane, possibly associated with multiple uses of glyphosate-based herbicides for other crops or to control aquatic weeds. This chronic exposure in Florida water bodies may have consequences for Florida manatees' immune and renal systems which may further be compounded by other environmental exposures such as red tide or cold stress. [ABSTRACT FROM AUTHOR]