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Identifying and Handling Contaminant-related Wildlife Mortality/Morbidity Steve Sheffield, Joe Sullivan, and Woody Hill Introduction ► Wildlife biologists can encounter mortality and/or morbidity incidents in the field ► Mortality – incidence of death ► Morbidity ► Wildlife – incidence of sickness/ill health mortality/morbidity incidents can be natural, accidental, or result from disease or exposure to environmental contaminants Environmental Contaminants ► Environmental contaminants include: pesticides metals/metalloids organic chemicals inorganic chemicals pharmaceutical drugs natural plant/animal toxins Contaminant Impacts ► Understanding contaminant impacts involves examination of many parameters: species (or higher taxa) involved trophic level of the species involved chemical(s) involved route(s) of exposure signs of intoxication fate and transport through the environment environmental compartment (media) involved environmental persistence Species Specific Hazards ► Not all contaminants pose the same hazard to all taxonomic groups of animals ► Factors involved include: evolutionary status (detoxifying enzyme systems more advanced in mammals) physical /chemical properties of the chemical (e.g., lipid solubility, volatility, etc.) differing toxicities of chemicals routes(s) of exposure trophic level of the animal Trophic Level Effects ► Possible effects of trophic level: Bioaccumulation – chemicals accumulate in an animals faster than they can be metabolized and excreted Biomagnification – results from bioaccumulation and biotransfer where tissue concentrations of a chemical moves up the food chain through two or more trophic levels Factors to Consider ► Three factors to consider with discovery of a field mortality/morbidity incident suspected to be caused by environmental contaminants: (1) Time is of the essence! Generally, there is little time to plan/conduct a research study of the incident (2) Time available for collecting evidence such as tissue samples and/or other environmental media (plants, soil, water, sediment, air) may be hours to a few days (3) Chemicals decompose, tissues decay/dessicate, and carcasses are readily scavenged, all of which greatly affect time available for sampling Chapter Objective ► Provide guidelines for wildlife biologists in the field to assess wildlife mortality/ morbidity incidents and sampling techniques useful in detection and documentation of environmental contaminants impacting wildlife Environmental Contaminants ► Human activities have resulted in the pervasive and dynamic nature of contaminants in the environment ► Many different industries contribute to this contaminant load, including chemical, agriculture, mining, energy, electronics, pharmaceutical, pest control, and others ► Greatest number of wildlife mortality/ morbidity incidents have been reported for 2 specific categories of contaminants: Anticholinesterase (anti-ChE) insecticides Anticoagulant rodenticides Routes of Exposure to Environmental Contaminants ► Oral Primary consumption of contaminant Secondary poisoning from consumption of poisoned prey item ► Dermal ► Inhalation ► Placental/Egg yolk Possible Effects of Environmental Contaminants ► Lethal effects – death of the animal effects – serve to debilitate an exposed animal; reduced survival, growth, and reproductive rates can occur from impacts on one or more bodily systems ► Sublethal Lethal Effects of Environmental Contaminants ► The full extent of wildlife mortality from contaminants is difficult to assess – wildlife species often are secretive, camouflaged, mobile, live in dense habitat ► Typical field studies often reveal low estimates of mortality because carcasses disappear rapidly Difficulties in Conducting Field Studies ► Most animal carcasses disappear within 24-48 hours; scavenging rate very high ► Exposed animals that become sick may move from area or otherwise disappear ► Exposed animals may not always demonstrate visible signs of morbidity ► Exposed animals may become more vulnerable to predation or other mortality factor as a result of exposure Classes of Contaminants ► Metals/Metalloids ► Organic Chemicals ► Inorganic Chemicals ► Pharmaceuticals ► Pesticides ► Natural Plant/Animal Toxins Metals ► Metals can be essential or non-essential; that is, they may or may not have biological function ► Non-essential metals are most hazardous to wildlife species; they can enter body and replace those which are essential ► Non-essential metals Cd, Cr+6 of most concern: Hg, Pb, Metalloids ► Metalloids are transitory between metals and non-metals ► Metalloids can be essential or non-essential; that is, they may or may not have biological function ► Non-essential metalloids are most hazardous to wildlife species; they can enter body and replace those which are essential ► Non-essential metalloids Se of most concern: As, Organic Chemicals ► Organic chemicals are based on C-H pairs ranging from single carbon chains to multiple aromatic rings ► Organic chemicals of most concern are: organic solvents, ethylene glycol, petroleum products (PAHs), and polyhalogenated compounds (PCBs, PBDEs, PCDDs, PCDFs, PFOSs) Inorganic Chemicals ► Inorganic chemicals are a diverse group that do not have carbon as their principal elements ► Includes 4 general groups: alkalis and chlorine, industrial gases, inorganic pigments, and industrial inorganic chemicals ► Two inorganic chemicals pose a particular hazard to wildlife species: cyanide and white phosphorus Pharmaceuticals ► There is a wide diversity of pharmaceutical drugs, hormones, and related organic wastewater contaminants that pose a potential hazard to wildlife species ► Most of these prescription drugs have not been tested for effects on wildlife ► Two pharmaceutical drugs that have caused numerous mortality/morbidity incidents are sodium pentobarbital and diclofenac Pesticides – any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest ► Pesticide contaminant category – intentionally released into environment ► Unique ► Specific classes of pesticides of major concern to wildlife include insecticides, herbicides, fungicides, fumigants, rodenticides, avicides Pesticides (Insecticides) are neurotoxicants – target insect nervous system ► Most ► Four distinct groups of insecticides include: chlorinated hydrocarbons (e.g., DDT) anti-cholinesterases (organophosphorus and carbamate compounds) synthetic pyrethroids other botanicals (e.g, nicotine, rotenone) Pesticides (Herbicides) ► Herbicides are chemical compounds capable of either killing or severely injuring plants ► There are at least 65 different broad classes and >22 different chemical groups of herbicides, including: (germination inhibitors, photosynthesis inhibitors, meristem inhibitors, contact action, auxin growth regulators, and foliar grass inhibitors Pesticides (Fungicides) ► Fungicides derived from a wide variety of chemicals whose focus is to kill fungi ► There are at least 36 different chemical groups of fungicides – a direct result of the great diversity of fungi ► There are 3 general types of fungicides: foliar, soil, and dressings Pesticides (Fumigants) ► Fumigants are used to kill insects, nematodes, weed seeds, and fungi in soil as well as in stored grains, fruit, vegetables, clothes, and other products ► They usually are used in enclosed spaces due to the high volatility of the chemicals ► They generally are nonselective, highly reactive, and cytotoxic Pesticides (Rodenticides) ► Rodenticides were developed to control pest small mammals (particularly rodents) ► They cam be categorized into several groups: inorganic (metal-based) compounds (e.g., thallium sulfate) insecticides (e.g., DDT) natural plant toxins (e.g., strychnine) anti-coagulants (warfarin, brodifacoum, etc.) Pesticides (Avicides) ► Avicides were developed to control avian pests, particularly flocking species such as European starlings, blackbirds, and pigeons ► Several different insecticides and other pesticides with avicidal properties have been used for this purpose Natural Plant/Animal Toxins ► Natural plant and animal toxins are toxic chemicals of biological origin ► Produced by living organisms such as bacteria, blue-green algae, fungi, marine invertebrates and fishes, vascular plants, and poisonous aquatic and terrestrial animal species Natural Plant Toxins plant toxins – secondary plant compounds, some of which are used as the basis for pesticides (e.g., nicotine, pyrethrum, rotenone, etc.) ► Natural ► Chemical groups which can be highly toxic include alkaloids, tannins, phenols, lectins, glycosides, and terpenes, among others Natural Animals Toxins ► Three groups of microbial organisms (bacteria, algae, fungi) are capable of producing some of the most deadly toxins known ► Examples of this include: botulinum (bacteria), harmful algal blooms (blue-green algae in fresh and brackish waters, phytoplankton in marine waters, mycotoxins (fungi) Contaminant Diagnostics - Safety ► Personal safety is a primary concern in a wildlife mortality/morbidity incident ► Field investigators should not handle carcasses, collect environmental samples, or enter the area of the incident until adequate safety precautions have been taken ► If contaminant is known, information can be found regarding its toxicity; if contaminant is unknown, only trained personnel should attempt to enter site for samples Contaminant Diagnostics – Safety 2 ► Once contaminant(s) identified, proper protective clothing (including on feet and hands) for the contaminant(s) should be worn ► When retrieving carcasses or debilitated animals from water, impermeable gloves and rubber boots should be worn ► Depending upon the contaminant(s) involved, respirators and/or TYVEK suits may be required Contaminant Diagnostics – Safety 3 ► In hot/humid weather, heavy protective wear can be dangerous, so work periods should be shortened to prevent heat stress ►A clean, shaded area should be provided where workers can remove protective wear, cool off, and get rehydrated ► If disease is suspected, the list of precautions not as extensive as for contaminants because diseases generally are more species-specific than contaminants Contaminant Diagnosis – Initial Site Reconnaissance ► Three rules govern initiation of any wildlife mortality/morbidity investigation: Protect yourself and other involved (2) Obtain the best case history possible (3) Collect the best specimens possible (1) ► Handling and collection of specimens in the field will affect what the laboratory can (and cannot) do with them Contaminant Diagnosis – Initial Site Reconnaissance 2 ► When possible, notify a wildlife veterinarian (or other trained personnel) and wait for their arrival prior to initiating the investigation ► It is critical to presume that there will be legal implications of the investigation and the cause may be a highly toxic or contagious agent ► Field notes and documentation that begin with initial stages of investigation are important Contaminant Diagnosis – Initial Site Reconnaissance 3 ► Initial ID of chemical(s) causing the incident should be attempted if it can be done safely Early ID of the contaminant can: dictate safety precautions needed direct types of samples that should be collected How samples should be handled ► If source and cause of incident are not obvious, field investigator should err on side of safety, collecting samples inclusively Contaminant Diagnosis – Initial Site Reconnaissance 4 ► As a starting point to decide whether the cause is disease or contaminant-related, consider the species affected ► If a single species (or group of related species) is affected, disease more than likely involved; if many different taxa affected, contaminants more than likely involved ► Upon initial discovery of the wildlife mortality/morbidity site, the nearest wildlife contaminant expert should be contacted Contaminant Diagnosis – Initial Site Reconnaissance 5 incidents – personal safety of utmost importance because if a contaminant is present in concentrations high enough to kill or debilitate wildlife, it may pose a health hazard to the field biologist ► Mortality ► In many cases, locating carcasses can be difficult and exposure to contaminants is obvious Contaminant Diagnosis – Initial Site Reconnaissance 6 ► Once carcasses found, immediate goals are: to prevent further deaths identify the cause and source of contaminant involved ► The risk of contaminants to wildlife is dependent on: toxicity concentration route of exposure Contaminant Diagnosis – Initial Site Reconnaissance 7 – discovery of sick (morbid) animals requires fast action to be taken ► Morbidity ► Morbid animals may be able to fully recover if treated in time ► Prior to collecting morbid animals, destination must be identified and appropriate transport containers obtained ► Transportation and treatment of wildlife species usually require specific permits Contaminant Diagnostics – The Wildlife Contamination Investigation ► Investigations of wildlife mortality/morbidity incidents suspected to be caused by contaminants should proceed as though the cause was unknown ► All factors must be checked or eliminated unless there is solid evidence to support specific conclusions ► Initial decision as to whether or not an incident is contaminant-related is a process of elimination Contaminant Diagnostics – The Wildlife Contamination Investigation ► Document the incident with detailed field notes and photographs ► The investigator’s interpretation of the wildlife mortality/morbidity incident scene will affect the type, number, and location of samples taken and the analyses performed ► Wildlife mortality/morbidity incidents may be a result of illegal activities, thus has the potential to become a legal case Contaminant Diagnostics – The Wildlife Contamination Investigation ► Important factors in interpretation of the incident scene include: location time and date of incident species involved # of dead and/or sick animals rate of deaths chance of continuing mortality/morbidity clinical signs observed climatic conditions Field Procedures – Sample Documentation and Transport ► It is critical that samples collected in the field be handled properly to ensure that useable information can be obtained ► All samples should be properly bagged and labeled ► Label should include what type of specimen, location it was collected, sample date/time, name of person collecting the sample Field Procedures – Sample Documentation and Transport ► Samples should be placed on ice in the field as some contaminants degrade quickly and tissues/carcasses can degrade quickly at warm temperatures ► Once samples are taken from the field, they should be hard frozen ► Samples for contaminant analysis should be transported frozen or on dry ice Field Procedures – Sample Documentation and Transport – techniques for handling field-collected samples can vary by contaminant type ► Handling samples ► When animal tissues are collected, great care should be taken to avoid cross-contamination ► Tissues can be placed into plastic bags or small, sterile glass jars; larger samples can be placed in zip-lock bags Field Procedures – Record Keeping ►A field log is useful to make entries regarding each sample collected for analysis ► Entries should include: sample ID number type of sample collected name of site where collection occurred date name or initials of person collecting the sample Field Procedures – Record Keeping ► Accurate record keeping is critical to documenting wildlife mortality/morbidity incidents ► The more detailed information provided on the field data sheet, the better the chances the investigator(s) of the incident will be able to understand what happened Field Procedures – Sample Collection ► In addition to wildlife tissue samples, other environmental samples also are critical ► Environmental samples should be collected from the immediate area of where dead or debilitated animals are found ► Those experienced with site and contaminant types can provide advice on number of samples required and how far samples should be collected from the original site Field Procedures – Sample Collection ► In addition to animal tissues, samples can be taken from other environmental media, such as: Plant tissues Soil Water/sediment Air Laboratory Procedures – Residue Analysis ► Conducting residue analysis requires consideration of many factors, such as: cost (generally expensive) detection limits QA/QC (quality assurance/quality control) how to read and interpret the chemical analysis report how to interpret the toxicological data Laboratory Procedures – Residue Analysis ► Interpretation of residue analysis data can be tricky ► Overall, we know very little about how body residue levels of contaminants correlate to corresponding effects seen in wildlife species ► Correlating contaminant levels in the body (exposure) with an effect provides the most powerful use of residue analysis data SUMMARY ►A wide variety and volume of chemical contaminants are found in the environment, and frequently have been shown to exert negative impacts (mortality, morbidity) on wildlife species ► As a result, wildlife mortality/morbidity incidents will occur ► There is a strong need for field biologists to be able to adequately identify and handle these incidents SUMMARY - 2 ► Few field biologists receive training in environmental or wildlife toxicology, thus it is important that field biologists have a source for SOPs for successfully handling wildlife mortality/morbidity incidents ► This chapter provides field biologists with guidance on understanding wildlife toxicology and procedures that should be followed when confronted with a wildlife mortality/morbidity incident “The dose makes the poison” Paracelsus THE END