Showing 1 - 10 of 14 Items
Gracefully Navigating Industry Exit: Modeling Regional Climate Change-Driven Decline in Maine’s Lobster Fishery and the Urgent Need for Statewide Comprehensive Cost Data Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2025-01-01
Creator: Luisa Isabelle Louchheim
Access: Access restricted to the Bowdoin Community
Eelgrass meadow structure drives epifaunal community composition more than temperature during a Marine Heat Wave in the Gulf of Maine This record is embargoed.
- Embargo End Date: 2029-05-16
Date: 2024-01-01
Creator: Nicholas Takaki Tienhui Yoong
Access: Embargoed
Clam shells and sea temperature: Evaluation of the oxygen isotopic climate proxy in Arctica islandica and development of a shell-derived sea temperature reconstruction from Isle au Haut, Maine Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2024-01-01
Creator: Brielle Martin
Access: Access restricted to the Bowdoin Community
Freezing temperatures drive functional trait clustering more than habitat structure in eelgrass communities in the Gulf of Maine This record is embargoed.
- Embargo End Date: 2026-05-18
Date: 2023-01-01
Creator: Bridget Marjorie Patterson
Access: Embargoed
Working Hands and Shifting Identities among Lobstermen in the Gulf of Maine’s Waterscape Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2023-01-01
Creator: Meghan Gonzalez
Access: Access restricted to the Bowdoin Community
Diatom blooms in Harpswell Sound: seasonality, succession, and origin
Date: 2023-01-01
Creator: Charlie Francis O'Brien
Access: Open access
- Harpswell Sound (HS) is an inlet in northeastern Casco Bay that exerts control on Gulf of Maine ecosystem health, yet its complex phytoplankton community dynamics have not been characterized with sufficiently detailed analyses. In this research, high-resolution automated microscopy and current velocity observations were used to test the seasonality, ecological succession, bloom origin location, and potential toxicity of populations in HS between 2020 and 2022. Winter months could exhibit slow accumulation of diatom biovolume. Cold, salty surface water has net outflow in winter as nutrients from depth are replenished during net upwelling conditions, and populations could be exported from the inlet at the surface. Extreme current velocity variability in spring due to the Kennebec River plume in HS destabilizes spatially uniform populations. Warm, low-salinity surface water with net inflow in summer (net downwelling which retains populations at the head of the sound) corresponds with temporally separate dinoflagellate and diatom blooms. Large, multi-peaked spring and fall diatom blooms are recurrent, contrasting small, short-lived blooms in summer. A successional pattern from diatoms to dinoflagellates is confirmed for summer but refuted for other seasons. The hypothesis that diatom succession during all blooms in HS is characterized by large centric cells preceding small cells or pennate cells was explored but no clear pattern in decreasing cell size was observed. Observed tidal effects on biovolume concentration could mask that blooms develop at coherent times but spatially separated. A diverse community of toxic phytoplankton, including dinoflagellates and Pseudonitzschia, are observed throughout the year.
Evaluating Dam Relicensing and River Herring Habitat Restoration from a Broad, Multi-Ecosystem Perspective
Date: 2022-01-01
Creator: Matthew L. Thomas
Access: Open access
- This study investigates the potential benefits of using a broad, multi-ecosystem analysis in the licensing and relicensing of hydropower facilities. Specifically, it considers the impact of river herring restoration on coastal food webs and cod and other groundfish populations in the Gulf of Maine. The past two decades of research on fisheries management, ecosystem connectivity, and the connection between river herring and groundfish in the Gulf of Maine have resulted in a better understanding of the ways in which human activities, such as dam building, influence ecological processes. The paper analyzes two case studies of six Maine dams currently engaged in the Federal Energy Regulatory Commission’s (FERC) hydroelectric dam relicensing process. The analysis illustrates the shortcomings of the Federal Power Act’s provisions that address the balancing of ecological and power generation concerns. Following the case studies, a series of policy recommendations are presented to encourage a more transparent and predictable relicensing process that adequately values both ecological and power generation goals. Changes are suggested for both the FERC process itself and the process by which state and federal resource agencies may provide comments regarding how a proposed dam licensing or relicensing affects natural resources under their jurisdiction. The proposed policy recommendations will increase the resilience of natural systems as they adapt to climate impacts.
Mutual benefits of inducible defenses to crab predators in the blue mussel Mytilus edulis in a multi-predator environment
Date: 2021-01-01
Creator: Sophia Walton
Access: Open access
- The blue mussel Mytilus edulis alters its phenotype in species-specific ways in response to either green crab (Carcinus maenus) or sea star (Asterias sp.) predation. Previous studies have shown that only sea stars induce changes in abductor muscle morphology, while green crabs generally alter the shape and thickness of shells. In the Western Gulf of Maine, Blue mussels collected from wave protected sites with abundant green crab predators were shown to have significantly thicker shells and larger adductor muscles than mussels collected from wave exposed sites with few green crab predators. The phenotypes of mussels originating from wave-protected and high green crab abundance sites increased the handling time by A. forbesi compared to sites with low wave exposure and high green crab abundance. These results contradict the paradigm that shell thickness trades off with abductor morphology, and I propose that a likely candidate for increased energy allocation to these traits is a decrease in reproductive allocation. My results further suggest that the escalating “arms race” between invasive green crabs and blue mussels in the Western Gulf of Maine is leading to changes in the phenotypic response of mussel populations in ways that are likely impacting sea star foraging dynamics.
The impact of temperature on the sea star oscillatory gait This record is embargoed.
- Embargo End Date: 2025-05-14
Date: 2020-01-01
Creator: Emma Victoria Bertke
Access: Embargoed
Living Upstream: Kennebec River Influence on Nutrient Regimes and Phytoplankton Communities in Harpswell Sound
Date: 2020-01-01
Creator: Siena Brook Ballance
Access: Open access
- Phytoplankton underpin marine trophic systems and biogeochemical cycles. Estuarine and coastal phytoplankton account for 40-50% of global ocean primary productivity and carbon flux making it critical to identify sources of variability. This project focuses on the Kennebec River and Harpswell Sound, a downstream, but hydrologically connected coastal estuary, as a case study of temperate river influence on estuarine nutrient regimes and phytoplankton communities. Phytoplankton pigments and nutrients were analyzed from water samples collected monthly at 8 main-stem rivers stations (2011-2013) and weekly in Harpswell Sound (2008-2017) during ice-free months. Spatial bedrock and land use impacts on river nutrients were investigated at sub-watershed scales using GIS. Spatial analysis reveals a 10-fold increase in measured phytoplankton biomass across the Kennebec River’s saltwater boundary, which demonstrates ocean-driven phytoplankton variability in the lower river. The biomass pattern is accompanied by a transition in phytoplankton community structure with respect to which groups co-occur (diatoms, chlorophytes, and cryptophytes) and which are unique (dinoflagellates in Harpswell). Upstream, the timing of each community depends on land-use proximity and seasonal discharge. In Harpswell Sound, the nutrient regime and phytoplankton community structure vary systematically: first diatoms strip silicate, then dinoflagellates utilize nitrate, followed by chlorophytes and cryptophytes that utilize available phosphate. These findings reveal, for the first time, patterns in phytoplankton communities and nutrient dynamics across the fresh to salt water interface. Ultimately the Kennebec River phytoplankton communities and nutrient regimes are distinct, and the river is only a source of silicate to Harpswell Sound.