Life Sciences Commons^™

Host-Pathogen Interactions In A Changing World: Microbes, Mucosal Defenses, And Multiple Hosts, Brandon C. Labumbard

Graduate Doctoral Dissertations

As fungal diseases continue to emerge, research increasingly focuses on host-microbiome interactions and links to disease. Certain skin-associated microbes may benefit hosts by protecting them from invading pathogens. Seasonal changes in the host environment can also result in shifts in the microbial community and pathogen virulence – potentially influencing disease dynamics. I investigated how cutaneous microbial communities differ across hosts, seasons, and Batrachochytrium dendrobatidis (Bd) infection status by sequencing the microbial communities of 1,100 leopard frogs at five locations across the US. Percent anti-Bd function varied seasonally and with Bd infection status. Bacterial communities also varied across locations and time. …

Characterizing The Relationship Between Species Richness And The Seasonal Phenomenon Of Tropical Fish Dispersal In New England Waters, Michael E. O'Neill

Graduate Masters Theses

The Gulf Stream exerts tremendous influence over oceanographic conditions in the Northwest Atlantic as it transports tropical water to higher latitudes. As the Gulf Stream’s path traverses the east coast of North America, there are implications for the biogeography of marine ecosystems within this range and beyond. While the meandering eddies and warm core rings generated by the Gulf Stream persist year-round, the seasonal warming of New England’s coastal waters afford many tropical species transported by the current temporary residence through the summer and fall. Many aspects that shape this phenomenon and its impact on coastal ecosystems remain a mystery. …

Promoting The Sustainability Of The Gulf Of Maine Recreational Groundfish Fishery Through Discard Mortality Estimation, Mitigation, And Outreach, Connor W. Capizzano

Graduate Doctoral Dissertations

Recreational fishing (i.e., angling), a popular leisure activity that provides socio-economic benefits to human societies around the world, can represent a significant source of fishing mortality and impact fish populations and marine ecosystems. Although fish are often released by recreational anglers to reduce fishing mortality rates, the efficacy of discarding fish is often criticized given that fish can die from the factors experienced during the capture, handling, and release process (i.e., discard mortality). Despite this recognition, the rate at which fish suffer discard mortality in specific commercial and recreational fisheries is often unknown and difficult to obtain due to logistical …

Impact Of Disturbance Regimes On Community And Landscape Biodiversity In Atlantic Coastal Pine Barren Ecoregion Streams, Sean T. Mccanty

Graduate Doctoral Dissertations

Streams are dynamic systems shaped by geographic location, hydrology, riparian vegetation, and in-stream habitat. Furthermore, ecosystem disturbance plays a major role in structuring stream communities and ecosystem processes. Disturbances include natural occurrences, such as flooding, drought, and fire events and anthropogenic disturbances such as land use changes, damming, and pollution. Agricultural use acts as a press disturbance regime, homogenizing the surrounding landscape and simplifying in-stream habitat, leaving legacy effects after farming ceases. Active restoration is intended to ameliorate these effects by reintroducing variation, with the goal of shifting the ecosystem into a more diverse and natural state. The act of …

Characterization Of Microbial Communities Across Disease States And Environmental Conditions In Kemp’S Ridley (Lepidochelys Kempii) And Green Sea Turtles (Chelonia Mydas), Kerry L. Mcnally

Graduate Doctoral Dissertations

All species of sea turtles are threatened or endangered, with various diseases and conditions affecting populations around the world. Understanding healthy populations as well as populations beset by disease conditions, such as fibropapillomatosis and cold-stunning, could lead to helpful tools in the conservation management and medical treatment needed to protect these species. Microbial communities, or the microbiome, at different body sites of sea turtles likely play important roles in the health of these animals, from aiding in digestion to immune system regulation. Disruption of these communities, either through disease and/or environmental factors, may play a role in disease processes and …

Characterizing The Impacts Of The Invasive Hemlock Woolly Adelgid On The Forest Structure Of New England, Peter Brehm Boucher

Graduate Doctoral Dissertations

Climate change is raising winter temperatures in the Northeastern United States, both expanding the range of an invasive pest, the hemlock woolly adelgid (HWA; Adelges tsugae), and threatening the survival of its host species, eastern hemlock (Tsuga canadensis). As a foundation species, hemlock trees underlie a distinct network of ecological, biogeochemical, and structural systems that will likely disappear as the HWA infestation spreads northward. Remote sensing can offer new perspectives on this regional transition, recording the progressive loss of an ecological foundation species and the transition of evergreen hemlock forest to mixed deciduous forest over the course of the infestation. …

An Acoustic Monitoring Method For Assessing River Dolphin Presence And Changes In The Context Of Anthropogenic Development, Charles A. Muirhead

Graduate Masters Theses

Populations of river dolphins throughout Asia are in decline as a direct result of intensified anthropogenic activity along river systems. Water development projects, land use change, contamination, and intensified fishing practices are known factors contributing to the probable extinction of the Yangtze river dolphin (Lipotes vexillifer) and declining populations of the South Asian river dolphin (Platanista gangetica spp.), Irrawady dolphin (Orcaella brevirostris), and finless porpoise (Neophocaena a. asiaeorientalis). Although not yet as extensive, river system development in South America is following a similar path as that of Asia, with impacts on dolphin species likely to follow. Currently, the Amazon river …

Evolution In The Deep Sea: Scales And Mechanisms Of Population Divergence, Amanda E. Glazier

Graduate Doctoral Dissertations

The deep sea is the Earth’s largest ecosystem and harbors a unique and largely endemic fauna. Although most research has focused on the ecological mechanisms that allow coexistence, recent studies have begun to investigate how this remarkable fauna evolved.. My work quantifies geographic patterns of genetic variation and investigates potential mechanisms that shape evolution in the deep ocean.

Bathymetric genetic divergence is common in the deep sea with population structure typically decreasing with depth. The evolutionary mechanisms that underlie these patterns are poorly understood. Geographic patterns of genetic variation indicated that the protobranch bivalve Neilonella salicensis was composed of two …

Identification And Use Of Indicator Data To Develop Models For Marine-Sourced Risks In Massachusetts Bay, Marin M. Kress

Graduate Doctoral Dissertations

The coastal watersheds around Massachusetts Bay are home to millions of people, many of whom recreate in coastal waters and consume locally harvested shellfish. Epidemiological data on food-borne illness and illnesses associated with recreational water exposure are known to be incomplete. Of major food categories, seafood has the highest recorded rate of associated foodborne illness. In total, the health impacts from these marine-sourced risks are estimated to cost millions of dollars each year in medical expenses or lost productivity. When recorded epidemiological data is incomplete it may be possible to estimate abundance or prevalence of specific pathogens or toxins in …

Examining The Toxicity, Exposure, And Regulatory Approach To Potential Human Health Risks Of The Algal Toxin Domoic Acid, Thomas H. Angus

Graduate Doctoral Dissertations

Domoic acid is a neurotoxin produced by the marine diatom genus Pseudo-nitzschia and causes cell death primarily in the area of the brain responsible for long-term memory. The resulting severe illness has been termed amnesic shellfish poisoning. Domoic acid accumulates in shellfish and planktivorous fish that consume Pseudo-nitzschia, resulting in exposure to humans through consumption of planktivorous seafood. A regulatory standard in seafood was developed shortly after its discovery in 1987 to protect against acute effects. This regulatory standard has not been revised despite significant recent data in the scientific literature.

This dissertation is divided into four sections: (1) …

The Conservation And Habitat Ecology Of Antillean Manatees (Trichechus Manatus Manatus) In The Drowned Cayes Area Of Belize, Central America, Katherine Spencer Lacommare

Graduate Doctoral Dissertations

The Drowned Cayes area of Belize, Central America is regionally important for the conservation of Antillean manatees in the Caribbean (Lefebvre et al. 2001; Quintana-Rizzo & Reynolds 2008). These islands are increasingly threatened by human activities such as tourism, development and population growth. The objective of this dissertation is to evaluate manatee habitat use and status in this area. The 5 specific objectives are to examine manatee (1) distribution in the Drowned Cayes, (2) use of seagrass beds and forage selection, (3) resting habitat use and selection (4) response to disturbance, and (5) trends in abundance and to suggest a …