Effects of anthropogenic disturbance and environmental factors on patterns of parasitism in Cross River gorillas (Gorilla gorilla diehli) Pubblico
Breen, Faith (Spring 2023)
Abstract
Deforestation, agricultural expansion, urbanization, expansion of infrastructure, and natural resource exploitation and other forms of anthropogenic disturbance are occurring globally and have devastating effects on the biodiversity of ecosystems. Changes in biodiversity affects many ecosystem processes, including zoonotic diseases. This study investigated the patterns of parasitism, particularly of enteric protozoan and helminthic parasites, in Cross River gorillas (Gorilla gorilla diehli). This study is the first assessment of enteric parasites in Cross River gorillas in Nigeria and examines which environmental or anthropogenic factors affect the prevalence and richness of these parasites. Cross River gorillas are a vulnerable subspecies, that lives in fragmented populations across one of the most densely population regions in Africa. Living in such small and potentially isolated subpopulations exacerbates the risk of potential disease outbreaks. Fecal samples from Cross River gorillas were collected between November 2016 and March of 2018 at three known gorilla localities in Nigeria. These sites are Afi Mountain Wildlife Sanctuary (n=89), Mbe Mountains Community Forest (n=96) and the Boshi Extension of Cross River National Park (n=11). These samples were analyzed using standardized parasitological techniques to identify which parasite taxon were present in each sample. The samples were also analyzed using fecal DNA extract and microsatellite genotyping to identify which individual gorilla contributed the sample. Thirty-four individual gorillas were represented, and nine parasite taxa were detected in the samples. Five taxa were commensal entodiniomorph ciliates and four were pathogenic nematodes. Prevalence of Strongyloides sp. was found to vary across sites, with prevalence as high as 75.28% at Afi Mountain Wildlife Sanctuary, or as low as 21.88% at Mbe Mountains Community Forest. Pathogenic richness was found to vary between the wet and dry season with higher richness in the wet season. Two of the pathogenic nematodes were also found in higher prevalence in the wet season. Strongyloides sp. had a positive relationship with disturbance intensity and Trichostrongylus sp. had a negative relationship. There is no clear relationship between anthropogenic disturbance and parasites richness, which reflects complex ecological mechanisms.
Table of Contents
Table of Contents
1. Introduction
1.1 Anthropogenic Disturbance and Fragmentation
1.2 Zoonotic Disease Risks
1.3 Disease in Great Apes
1.4 Cross River gorillas (Gorilla gorilla diehli)
2. Purpose and Hypotheses
3. Materials and Methods
3.1 Study Sites
3.2 Sample collection
3.3 Parasitology analysis
3.4 Human disturbance SMART Patrol Data
3.5 Spatial Analysis
3.6 Statistical Analysis
4. Results
4.1 Sample demographics
4.2 Parasite prevalence
4.3 Parasite richness
4.4 Disturbance
4.5 Model results
5. Discussion
6. References
7. Tables
Table 1
Table 2
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8. Figures
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About this Master's Thesis
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