Environmental Science

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Now showing 1 - 5 of 8
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    Assessing impacts of multiple parasites on Striped Bass (Morone saxatilis) across age classes, rivers and salinity in Chesapeake Bay.
    (Wheaton College. (Norton, Mass.), 2023-05-15) Brunelle, Hannah
    Striped Bass (Morone saxatilis) are ecologically and economically important anadromous species that live along the East Coast of the United States between Canada and Florida. Most of the fish are born in the tributaries of the Chesapeake Bay, which is where the samples for this study were collected, including fish from the age classes: Young-Of-Year (YOY) (<1year) (n=486), juveniles(n=68) and adults(n=20). In this study, I examined the potential linkage between the health of the Striped Bass with the intensity and richness of various parasite taxa, such as acanthocephalans, nematodes, trematodes (digenea and monogenea), copepods (argulidae, caligidae and ergasilidae) and isopods. I also examined variation in parasite intensity and richness across age classes, tributaries and salinity. The Fulton’s Condition Factor (K) was used as the metric of health. Pearson’s correlation test was used to determine if there was a statistically significant difference among each variable examined and the Fulton’s Condition Factor (K). None of the results were statistically significant (p > 0.05), indicating fish with and without parasites present are in similar conditions. However, there were more Striped Bass infected with parasites (n=419, 73%) compared to those without (n=155, 27%), and many of these infected fish were YOY (n=331, 79%). Second, there was a difference between the Striped Bass collected across nine tributaries. The furthest North tributaries (Upper Bay, Rhode and Choptank) had fish with the highest parasite intensity and richness (> 100 individuals per sample). Third, there was a difference between Striped Bass collected from the various salinity ranges (0.00-12.99 ppt). The higher salinity levels (7.00-12.99 ppt) had more fish infected with high parasite intensity but less parasite variability compared to the lower salinity levels (0.00-6.99 ppt). Overall, there may be a difference in the health condition of the Striped Bass compared to non parasitized fish, but more samples across all age classes need to be collected.
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    A comparison of mercury contamination in invertebrates associated with a stormwater catch basin and a vernal pool
    (Wheaton College. (Norton, Mass), 2022-05-16) Fischer, Kevin
    Mercury is an environmental contaminant that reaches aquatic environments through atmospheric deposition of inorganic mercury. A highly toxic form of mercury, methylmercury, occurs as a result of methylation by anaerobic bacteria. Methylmercury (MeHg) bioaccumulates through trophic levels in aquatic ecosystems, and it spreads to terrestrial food webs largely from insectivory. For this reason, it is highly important ecologically to look at the mercury and methylmercury contamination of aquatic insects. Deposition and methylation of mercury in an environment is related to several anthropogenic and natural factors. Agricultural land use, as well as gold mining, can aid in the process of transport of mercury through sediment into water bodies. The environmental factors that carry the strongest association with total and methyl mercury in aquatic food webs are low water pH, intermediate to high organic matter, low water retention time, and high rates of fluctuation in water level. These factors were considered when collecting samples and comparing data from insects and sediments at a stormwater catch basin and a vernal pool on the Wheaton College campus in southeastern Massachusetts, especially organic matter and residence time. Higher concentrations of total mercury were detected in sediment at the basin site (mean=128.3 ng/g s=67.9) compared to the vernal pool site (mean=61.4 ng/g, s=17.6); however, no significant difference in MeHg or %MeHg was observed between invertebrate samples at the two sites. Two sample collection methods, emergence traps and pitfall traps, were used to collect aquatic and terrestrial invertebrates, respectively. Significantly higher levels of MeHg were found in invertebrates from the emergence traps, regardless of site. This finding is consistent with MeHg production in aquatic sediments.
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    Monitoring vegetation health in the Great Marsh : 25 years of satellite observations and freshwater input data.
    (Wheaton College (MA), 2019) Schrank, Keaton
    Salt marshes are extremely valuable coastal ecosystems that carry out a wide range of ecosystem services; however, these ecosystems face serious threats from human- caused environmental changes, such as sea level rise and drought. This study aims to assess the relationship between freshwater input and the overall health of a salt marsh over a 25-year time period. The Great Marsh in northern Massachusetts was selected due to its susceptibility to variations in freshwater input into the marsh, and 13 Landsat scenes between 1993 and 2018 were acquired along with discharge data from two of the marsh’s rivers. Using LiDAR data, elevation masks were created for the low, high and fringe marsh zones, and the Normalized Difference Vegetation Index (NDVI) was used to assess marsh vegetation health in each of the zones. No relationship was discovered between the amount of freshwater input into the marsh and the health of each of the marsh zones; however, upstream regions of the marsh tended to be healthier than downstream regions. These results indicate that freshwater input may not play as important a role as other factors in determining salt marsh health.
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    American kestrel nest box occupancy and success in cranberry bogs in Southeastern Massachusetts.
    (Wheaton College (MA), 2019) Malachi, Anneliese
    American Kestrel (Falco spaverius) Northeastern populations have been declining over the past decades. European Starling (Sturnus vulgaris) competition for nest boxes with American Kestrels have also increased. This study examined local, landscape, and weather variables around kestrel nest boxes in cranberry (Vaccinium macrocarpon) bogs across southeast Massachusetts in order to determine how the kestrel nest box occupancy and fledging success and the starling occupancy changed over time and which variables encouraged kestrel nest occupancy and success and discouraged starling occupancy. We used data collected from an 18- year study, ArcGIS, and generalized linear mixed models in order to create models to determine these impacts. We found that kestrel nest box occupancy and success decreased over time, while kestrel nest box failure stayed consistent and starling kestrel nest box occupancy increased. Kestrel fledging success stayed relatively consistent throughout the study. We also found that cranberry and grassland area, as well as distance to nearest nest box and human habitation were significant variables in predicting kestrel nest box occupancy and fledging success, while only distance to nearest nest box and human habitation were significant to predicting starling occupancy.
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    Stability and resilience of plant-pollinator networks in an Andean montane community in Southern Ecuador.
    (Wheaton College, (Norton, Mass.), 2020-05-10) Crafford, Rachel Elizabeth
    Mutualistic interactions sustain biodiversity and influence community stability. If there are only a few interactions within a community, or multiple interactions that are weak, the community is more likely to collapse. This research investigated the stability of a plant-pollinator community in the Ecuadorian Andes to understand how vulnerable these interactions are to environmental stressors such as climate change and habitat degradation. To do this, we used two species interaction networks based on foraging fidelity (i.e., consistent returns to a particular plant species) and floral association data from both native and non-native pollinators. We used the network metrics connectance, specialization, and weighted network nestedness to determine the strength of these interactions, and therefore, the resiliency of this montane community. Based on these metrics, we found that our visitation network is relatively robust to ecosystem stressors, however, our larger-scale survey, which may be a more accurate depiction of the community due to sample size and increased diversity, showed a lack of resilience to stressors. Honey bees (Apis mellifera) were much more abundant than native bees in both networks, and may be providing many of the pollination services previously provided by native bees. Honey bees were generalists at the species level, but individuals were faithful to particular plant species. This research can help inform future conservation and non-native species management efforts, and can be used to further understand the nuanced relationships between plants and pollinators, which are essential to agricultural production and ecosystem maintenance on a global scale.