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Abstract

Results and Discussion

Conclusion

References

Background

Methods

1. Of the 83 dissected river otter intestines 60 were infected with parasites and the remaining 23 were not infected.

2. Echinostoma spp., Acanthocephala spp., Nematode spp., and Cestode spp. are of the known parasites found in the different counties.

3. From the 60 infected intestines, 33 of these were males and 27 were female. The data shows that 76.7% (33/43) of males were infected and 67.5%(27/40) females. This suggests that the males have a higher infection percentage, based off this survey sample.

4. The data shows there is no evidence to suggest that there is a significant difference in the existence of all parasites between the four regions (NE, SE, NW, SW,) in Wisconsin with the exception of Echinostoma spp. which has a lower incidence in the SE region.

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River otters (Lontra canadensis) are a species of interest for the Wisconsin DNR due to fluctuations in population size. The Wisconsin DNR collects carcasses of legally harvested otters trapped throughout the season and then makes them available for research studies. On February 14th, 2013 our laboratory obtained 100 intestines to examine for parasites. The intestines were then dissected and the digested material was separated through sieves of different sizes. The digested material was then examined microscopically and any parasites that were collected were stored in 70% ethanol. Some parasites were stained for further identification. With additional data supplied by the Wisconsin DNR, conclusions were made about the prevalence and intensity of parasites and their impact on the river otter population. All 100 intestines have been examined, but data was analyzed based upon 83 intestines, which had complete records. It was found that 72.3% (60/83) of the intestines were infected with parasites, with an average intensity of 31(1-620, range) parasites.

The North American river otter (Lontra canadensis) is a mammal that preys predominantly on fish and crayfish, although other aquatic species also contribute to their diet. River otters can be found throughout the state of Wisconsin.

Acknowledgements We would like to thank the Wisconsin DNR, Erika Vail, Dr. Brant Deppa, and Dr. Kimberly Bates for their resources and contributions to our research. We would also like to thank the students who contributed to this research in years past.

Gastrointestinal Parasites of Wisconsin River Otters (Lontra canadensis) Ashley Wiederin, Johnna Miller, Kelsie Kovac, Lucas Seaberg, Nadia Nassif, Shaylee Larson, Kaitlyn Dreher, Samantha Christiansen, Girma Kenea, Chelsey Otto, and

Mohamed Warsame

Dr. Kimberly Bates and Kelsey HoffmannBiology Department. Winona State University, Winona, MN 55987

Otter intestines were cut open and digested material was rinsed out through four sieves ranging in pore size diameter. Digested material was examined for parasites under a dissecting microscope. Parasites found were removed, cleaned, and placed into labeled vials containing 70% EtOH for preservation.

Echinostoma are a genus of trematode whose first intermediate hosts are typically snails. Otters become the definitive host when they consume the second intermediate host which is typically mussels or fish. Acanthocephala are parasitic worms that attach to the digestive tract by an anterior, spiny, retractile proboscis. Otters become the definitive host when they consume an infected intermediate host which is typically crustaceans.

Prevalence represents the proportion of individual otters that are infected with a specific parasite type (table 2).

The mean intensity defines the number of each species of parasite found per infected otter (Table 3).

After examination of 100 river otter intestines, data was analyzed based upon 83 intestines, which had complete records. Of the 83 intestines, 60 were infected with parasites and 23 had no parasites present. Of the parasites collected and identified, several variables were used for comparison. Among these were region, gender, parasite prevalence, and parasite type. These variables were used for correlation of parasites and the river otter population. Positive identification could be made for four different types of parasitic infection.

Of the 83 river otter intestines analyzed, 60 were infected with parasites. Males accounted for 33 of those infected while females accounted for the remaining 27. Of the 23 non-infected river otter intestines,10 were from males and 13 were from females (Figure 8).

1.  Acanthocephaliasis: DPDx - Laboratory Identification of Parasitic Diseases of Public Health Concern. (2013, November 29). Retrieved March 17, 2015, from http://www.cdc.gov/dpdx/acanthocephaliasis/index.html

2. "Echinostoma." Center for Disease Control. Center for Disease Conrol, 28 11 2013. Web. 31 Mar 2014. <http://www.cdc.gov/dpdx/echinostomiasis/index.html>.

3. North American River Otter - National Wildlife Federation. (n.d.). Retrieved March 16, 2015, from http://www.nwf.org/wildlife/wildlife-library/mammals/north-american-river-otter.aspx

4. Ramel, G. (2001, January 1). The Phylum Acanthocephala. Retrieved March 17, 2015, from http://www.earthlife.net/inverts/acanthocephala.html

5. Shapiro, L. (2014, January 1). Descriptions and articles about Echinostoma. Retrieved March 17, 2015, from http://eol.org/pages/61251/details

6. Wisconsin Department of Natural Resources. (n.d.). Retrieved March 15, 2015, from http://dnr.wi.gov/topic/WildlifeHabitat/Furbearers.html

Figure 1: Counties within the state of Wisconsin

Table 1: Number of Otter Intestines Harvested by County Figure 6 : SEM photos of

Acanthocephala spp. (left) andEchinostoma spp. (right)

Female otters had a higher mean intensity for all parasites except for Tapeworm spp., which was higher in males, and Nematode spp., which had the same mean intensity for both males and females (figure 10).

Figure 7: Dissecting microscope images of (in order from left to right): Acanthocephala spp., Cestode spp., Echinostoma spp., and Nematode spp. found in WI River Otters

collected in 2012-2013

Figure 8: Number of River Otter Intestines of which were Infected versus Not Infected in Males and Female River Otters Harvested in WI, 2012-2013

Figure 10: Mean Parasitic Intensity of Echinostoma spp., Acanthocephala spp., Nematode spp., Tapeworm spp., and Unknown Parasites in Male and

Female River Otters Harvested in WI, 2012-2013

Table 2: Prevalence of Parasitic infection (by type) in River Otters collected from WI DNR in 2012-2013

Table 3: Mean Intensity of Parasitic infection (by type) in River Otters collected from WI DNA in 2012-2013

Average intensity of each type of parasitic infection was separated by the 4 regions of Wisconsin. Overall, there was a lesser number of otters collected from the northern regions of Wisconsin (figure 11), however, they still presented with a higher mean intensity of parasitic load than the otters collected from the southern regions. The error bars show that there is no evidence to suggest that there is a significant difference in the existence of parasites between the four regions with the exception of Echinostoma spp. which has a lower incidence in the SE region (figure 12).

Figure 3: Lifecycle of Acanthocephala.Figure 2: Lifecycle of Echinostoma.

Figure 4: Echinostoma found in Wisconsin River Otter Feces harvested in WI, 2012-2013

Some parasites were stained using various staining protocols to help with the identification process. Some parasites were gold sputtered then examined with a scanning electron microscope (SEM). Pictures were taken and will be used to help with further identification.

Figure 11: Number of River Otter Intestines of which were Infected versus Not Infected in the 4 Regions of WI (NW, SW, NE, SE) in 2012-2013

Nematode spp. and Cestode spp. were also found in the river otter intestines harvested from Wisconsin. These phyla of parasites commonly inhabit the digestive tract of vertebrates.

Figure 5: Echinostoma Ventral Sucker Stained with Borax-carmine and Aniline Blue

Figure 12: Average Parasitic Intensity of Acanthocephala spp., Echninostoma spp., Nematode spp., Tapeworms spp., and Unknown Parasites in River Otters

Separated by the 4 Regions of Wisconsin, (NW, SW, NE, SE) Harvested in 2012-2013

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Figure 9: Number of River Otters Infected with Acanthocephala spp., Echninostoma spp., Nematode spp.,Tapeworms spp., and Unknown Parasites

by sex of River Otters Harvested in WI, 2012-2013

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Male and female infected otters were further separated by type of parasitic infection. More male otters were infected with every parasite type except for the unknown species where the same number of males and females were infected.