Showing 301 - 310 of 583 Items
Using data from the LISST-100 to recreate phytoplankton size distribution and processes in Harpswell Sound, Maine
Date: 2014-08-01
Creator: Schuyler Nardelli
Access: Open access
- Phytoplankton are the simple single-celled photosynthesizers that live in the ocean and form the base of the food chain. Cell size is a basic proxy for physiological rates as well as ecosystem structure. Thus, cell size can be used in a model framework to track changing environmental conditions that could potentially lead to harmful algal blooms (HABs, aka “red tides”)—events that can be detrimental to human health, marine life, and fisheries. HABs occur when a single algae (phytoplankton) species either grows unconstrained to a concentration such that it becomes toxic or causes low oxygen concentration in the water. In typical estuaries, less dense freshwater flows towards the ocean, and denser salty seawater flows into the estuary in the subsurface. However, Harpswell Sound is a reverse estuary that receives its freshwater input at its mouth from the upstream Kennebec River. This yields upstream surface low salinity flow and downstream deep high salinity flow. This rare dynamic allows phytoplankton located in the surface of seawater to be retained in the sound in conditions conducive to high growth and HABs, and can be used as a warning for conditions throughout the Gulf of Maine. To study the temporal and spatial dynamics of phytoplankton in the sound, we used the LISST-100, which uses light scattering properties to collect continuous in-situ water column observations of particle concentrations and size distributions. Although the LISST-100 was built to measure sediment size with a spherical shape, studies have been conducted that show it can accurately describe a diverse range of phytoplankton shapes and sizes, provided the population has sufficient size differences and is fairly concentrated, conditions found in Harpswell Sound. Weekly profiles of the water column were collected at the Bowdoin Buoy from 5/21/14-6/18/14, as well as a 20-day continuous time series collected at Bowdoin’s Coastal Studies Center dock from 5/30/14-6/18/14 along with supplementary oceanographic data. We determined that semi-diurnal tidal fluctuations are sufficient to move water masses past the buoy and dock with each tide, thereby connecting them. Phytoplankton were found to be in the 3-50 micron size range, with a peak diameter of approximately 7 microns. Additionally, three independent phytoplankton blooms were observed over the course of the 20-day time series as different water masses flowed through the sound. They were sourced in the oceanic water masses found under the freshened surface layer. Over the five-week period the populations gradually surfaced with their water mass as the overlying freshwater dissipated in the absence of rainfall. The LISST-100 served as a useful tool for determining phytoplankton distribution and dynamics within Harpswell Sound, and with further research there is great potential to continue to increase proficiency with the instrument in order to better understand phytoplankton dynamics and harmful algal blooms. Final Report of research funded by the Rusack Coastal Studies Fellowship.
Vulnerability of eelgrass (Zostera marina) to green crab (Carcinus maenas) invasion
Date: 2014-08-01
Creator: Sabine Y Berzins
Access: Open access
- Eelgrass (Zostera marina) is a perennial seagrass that is widely distributed among the shallow subtidal and intertidal Atlantic coastline of the United States and Canada. A highly productive keystone species, eelgrass helps maintain healthy estuarine and ecosystem functions by stabilizing sediments, regulating water flow, absorbing nutrients, and providing critical habitat for animals including commercially important species like soft-shell clams, blue mussels, and migrating waterfowl. Loss of eelgrass beds can therefore result in degraded water quality, shoreline erosion, and reduced fish and wildlife populations. Historically, the Maine coast supported extensive eelgrass beds. However, between 2010 and 2013, eelgrass distribution in Casco Bay declined in area by over 55%. This decline in eelgrass distribution coincides with a regional population explosion of green crabs (Carcinus maenas), an invasive species that physically disturbs eelgrass while foraging for prey. This summer, I collaborated with several Casco Bay Eelgrass Partners including individuals from the Fish and Wildlife Service, Maine Department of Environmental Protection, and the Friends of Casco Bay. Led by U.S. Geological Survey biologist Dr. Hilary Neckles, this project identifies factors that make eelgrass more or less resilient to invasion by green crabs. In June, we established permanent eelgrass survey transects at five locations spanning eastern Casco Bay. Where possible, two transects were established in different types of sediment (fine or coarse/sandy). Most of the eelgrass loss observed over the past decade has been in fine sediments. The question remains; is eelgrass in coarse sediments prone to similar levels of damage? In addition to differences in substrate type, each site also exhibited varying degrees of eelgrass density, shoot height, green crab density and population structure, and other environmental stressors including light availability, temperature, nutrient availability, and natural physical disturbance. I made biweekly measurements of green crab densities at one site, Widgeon Cove in Harpswell. Crap trapping indicated few green crabs occurred near the Widgeon Cove transect, but traps at the other four Casco Bay sites collected as many as 300 crabs within a 24-hour period. Final measurements in the eelgrass transects will be taken in September and data collection will be completed in October. Data gathered this summer will provide information to help move forward with a plan to protect and potentially restore eelgrass in Casco Bay. Additionally, I identified patches of eelgrass in the Kennebec Estuary that might be viable sites for replanting next summer. I hope to continue working on this project next year, thinking about ways to restore eelgrass to the system while identifying ways to increase trapping pressure on green crabs such that their numbers might be reduced. Final Report of research funded by the Rusack Coastal Studies fellowship.
Torture under the Regime of Bashar al-Assad: Two Decades of Failed Human Rights Campaigns and Foreign Interference in Syria
Date: 2020-01-01
Creator: Olivia Giles
Access: Open access
- This honors thesis analyzes human rights campaigns to end the practice of state-sponsored torture in Syria during the presidency of Bashar al-Assad. It compares the 2000 Damascus Spring and the 2011 Arab Spring using the concept of the “contentious spiral model.” The model is based on the elements of the original “spiral model” introduced in The Power of Human Rights (1999) and the factors of contentious politics discussed in Dynamics of Contention (2001). It suggests that human rights movements that emerge from uprisings need effective mobilization by domestic and international actors. Sustained pressure from both sources should gradually force the state to make concessions until there is an absence of human rights violations. The study uses research on social movements and international politics in Syria, in addition to data on the practice of torture, to suggest that human rights campaigns to end state-sponsored torture in Syria have been unsuccessful because of the interference of Assad’s foreign alliances. These countries have helped the regime backlash against the opposition during uprisings, which has led to the fracturing of the movement. During the Damascus Spring, this interference took the form of shifting the world’s focus to other regional issues, and during the Arab Spring, Syria’s allies directly supported the Assad regime militarily, financially, and legally.
Nonprophets: a novel This record is embargoed.
- Embargo End Date: 2025-05-14
Date: 2020-01-01
Creator: Nathan Osiason Blum
Access: Embargoed
Adapting Greek Heroines: Penelope and Medea Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Ishani Agarwal
Access: Access restricted to the Bowdoin Community
Re-formando cuerpos: Las identidades femeninas en escritoras cubanas durante el Período Especial
Date: 2014-01-01
Creator: Amanda M Montenegro
Access: Open access
- Esta tesis explora cómo una variedad de autoras cubanas representan el cuerpo, las identidades femeninas y la relación entre las mujeres y la nación. Las autoras estudiadas incluyen Marilyn Bobes, Karla Suárez y Daína Chaviano. Sus narrativas ilustran y desarrollan una variedad de personajes –desde las mujeres blancas prerrevolucionarias hasta las “hijas de la revolución” afrocubanas—que representan diferentes maneras en que las mujeres construyen y reconstruyen sus identidades en la Cuba revolucionaria y hasta el comienzo del “Período especial”. Ilustran además cómo las mujeres vivieron fenómenos propios de ese período como la migración, la dolarización y el jineterismo. Así, revelan los fracasos en cuanto a la igualdad de género de la revolución, que no transformó la estructura patriarcal de la sociedad. Sin embargo, las autoras presentan una nación cubana polifacética compuesta de más que el Estado, donde las escritoras y las mujeres luchan por definirse a sí mismas. This paper explores how various female Cuban authors represent the body, female identities and the relationship between women and the nation. The authors studied include Marilyn Bobes, Karla Suárez and Daína Chaviano. Their narratives illustrate and develop a variety of characters—ranging from white prerevolutionary women to afro-Cuban “daughters of the Revolution”—which represent different ways in which women construct and reconstruct their identities during revolutionary Cuba and at the beginning of the “Special Period.” The characters also illustrate how women in particular experienced and dealt with the effects of the Special Period such as migration, dollarization and jineterismo. Thus, they reveal the failures of the Cuban Revolution regarding gender equality of the Revolution, which did not transform the patriarchal structure of society. However, the authors present a multifaceted Cuban nation comprised of more than just the State, where writers and women struggle to define themselves.
Investigating the Role of Heterochromatin Protein 1 (HP1) in the Formation of Chromosome Compartments Access to this record is restricted to members of the Bowdoin community. Log in here to view.
- Restriction End Date: 2025-06-01
Date: 2020-01-01
Creator: Diego Andres Villamarin
Access: Access restricted to the Bowdoin Community
Convexity Properties of the Diestel-Leader Group Γ_3(2)
Date: 2014-05-01
Creator: Peter J Davids
Access: Open access
- The Diestel-Leader groups are a family of groups first introduced in 2001 by Diestel and Leader in [7]. In this paper, we demonstrate that the Diestel-Leader group Γ3(2) is not almost convex with respect to a particular generating set S. Almost convexity is a geometric property that has been shown by Cannon [3] to guarantee a solvable word problem (that is, in any almost convex group there is a finite-step algorithm to determine if two strings of generators, or “words”, represent the same group element). Our proof relies on the word length formula given by Stein and Taback in [10], and we construct a family of group elements X that contradicts the almost convexity condition. We then go on to show that Γ3(2) is minimally almost convex with respect to S.
Egg Size, Breeding Phenology, and Parental Investment in Leach’s Storm Petrels Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: James L. O'Shea
Access: Access restricted to the Bowdoin Community
Accounting for Gender Differences in Cultural Industries: Evidence from Film and the Fine Arts Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Madeleine Rose Dupré
Access: Access restricted to the Bowdoin Community