Digital Commons Network^™

The Response Of The Zooplankton Community In The Western Gulf Of Maine To A Shift In Oceanographic Conditions: 2005-2017, Emma Cecile Dullaert

Electronic Theses and Dissertations

The Gulf of Maine (GoM) harbors a productive ecosystem that supports a wide variety of marine life, providing services upon which local communities rely. The GoM ecosystem supports many important commercially harvested species, including the American lobster (Homerus americanus) which is the most valuable fishery in the US, Atlantic herring (Clupea harengus) and a variety of groundfish. The GoM is also home to the critically endangered North Atlantic right whale (Eubalaena glacialis), which has historically been known to feed in the eastern GoM and Bay of Fundy during the summer and fall months. In …

Multispectral Classification Of Gulf Of Maine Surface Waters: Seasonal And Interannual Variability, Brianna M. King

Electronic Theses and Dissertations

Bio-optically, surface waters of the northeastern US continental shelf are strongly heterogeneous, exhibiting highly variable distributions in both time and space of suspended sediment, colored dissolved organic matter (CDOM), and phytoplankton concentration and community structure. These render the standard global NASA satellite chlorophyll algorithm suspect. However, spectral signatures of the water are well quantified by the actual satellite-based multispectral reflectance (Rrs) measurements. Here, we use 6 bands of Rrs measurements from 19 years (1998-2016) of monthly composite SeaWiFS and MODIS data to identify the spectral signatures of dominant water types present over the northeast shelf. A merged multivariate clustering approach …

Spatio-Temporal Dynamics Of Atlantic Cod Bycatch In The Maine Lobster Fishery And Its Impacts On Stock Assessment, Robert E. Boenish

Electronic Theses and Dissertations

Of the most iconic fish species in the world, the Atlantic cod (Gadus morhua, hereafter, cod) has been a mainstay in the North Atlantic for centuries. While many global fish stocks have received increased pressure with the advent of new, more efficient fishing technology in the mid-20^th century, exceptional pressure has been placed on this prized gadoid. Bycatch, or the unintended catch of organisms, is one of the biggest global fisheries issues. Directly resulting from the failed recovery of cod in the GoM, attention has been placed as to possible sources of unaccounted catch. Among the most …

Polyp To Population: A Tale Of Two Corals, Christopher T. Fountain

Electronic Theses and Dissertations

Deep-sea corals are of conservation concern in the North Atlantic due to prolonged disturbances associated with the exploitation of natural resources and a changing environment. As a result, the recovery rates of deep-sea coral communities are of heightened interest. These recovery rates are suggested to be on the order of decades to millennia, based on slow growth rates and longevity, of various deep-sea coral species. In 2014 and 2017 two research cruises in the Gulf of Maine, collected samples of two locally dominant species, Primnoa resedaeformis and Paramuricea placomus. These specimen collections were coupled with video surveys, conducted by …

Reconstructing Late Holocene Hydrographic Variability Of The Gulf Of Maine, Nina Millicent Whitney

Electronic Theses and Dissertations

I present an annually resolved reconstruction of seawater temperatures in the

western North Atlantic from 1695-1915. This paleoclimate record was constructed

using oxygen isotopes measured in precisely dated Arctica islandica shells collected

off of Seguin Island in the western Gulf of Maine. The temperature reconstruction

was derived from this oxygen isotope time series using a modern d¹⁸O_w-salinity

mixing line developed for coastal waters in the Gulf of Maine from water samples

collected over the last decade. The d¹⁸O_w and salinity composition of these water

samples indicate that coastal surface waters consist of a …

Complex-Systems Approach To Simulating The Sea Urchin Ecology, Graham Andrew Morehead

Electronic Theses and Dissertations

Stocks of the native sea urchin (Strongylocentrotus droebachiensis) dropped dramatically during the peak of the urchin fishery in the early 1990’s and have not recovered. The current regulatory regime is based on analytic population models and two monolithic zones. Analytic models are insufficiently complex to capture many features that cause demise or survival of an urchin population. Scale, or granularity size, is too coarse. In contrast, a complex-systems-based model is able to capture these features. Presented here is a fine-scale simulation of a sea urchin fishery in the Gulf of Maine which behaves like a complex system, i.e. exhibits patchiness …

Assessing Allelopathic Effects Of Alexandrium Fundyense On Thalassiosira Sp., Emily R. Lyczkowski

Electronic Theses and Dissertations

Production of allelopathic chemicals by the toxic dinoflagellate Alexandrium fundyense is one suggested mechanism by which this relatively slow grower outcompetes other phytoplankton, particularly diatoms. Despite well documented allelopathic potential of Alexandrium spp., the potency is variable. To further characterize allelopathic effects of A. fundyense on diatoms in the Gulf of Maine, I studied growth and nutrient acquisition by the chain-forming diatom Thalassiosira sp. in the presence and absence of allelochemicals. Thalassiosira cells, upon exposure to filtrate of A. fundyense cultures exhibited “bleaching” and both growth and nutrient utilization ceased for up to 4 days compared to controls. Results from …

Salinity And Stratification In The Gulf Of Maine: 2001-2008, Heather E. Deese-Riordan

Electronic Theses and Dissertations

The salinity and vertical density structure (stratification) of the Gulf of Maine strongly influence the physical and biological character of the region including: circulation and transport, vertical mixing, and primary productivity. Variability in salinity and stratification also provides insights into the character and timing of the oceanic waters entering the region, a key to predicting regional climate change. This thesis addresses outstanding questions related to variability in salinity and the relative role of salinity and temperature in creating stratification. Hourly observations from Ocean Observing System buoys throughout the Gulf provide the primary data source for this investigation. Analysis of estimated …

The Role Of Larval Thermal Tolerance In The Distribution Of Blue Mussel Species Within The Gulf Of Maine, Susan J. Limbeck

Electronic Theses and Dissertations

Two species of blue mussel, Myrilus edulis and Myrilus trossulus, are sympatric throughout much of the Canadian Maritime Provinces and into the Gulf of Maine. While the distribution of M edulis extends south to the Mid-Atlantic, that of M. trossulus ends abruptly in the Gulf of Maine. I have hypothesized that these differences in adult distribution are the result of species-specific variation in larval thermal tolerances. Previously, it has been shown that when reared at 20 OC, from 36 hour post-fertilization through settlement, M. trossulus had significantly higher mortality rates than M. edulis. This study examined whether species-specific differences in …

An Investigation Of The Cumulative Impacts Of Shrimp Trawling On Mud Bottom Fishing Grounds In The Gulf Of Maine: Effects On Habitat And Macrofaunal Community Structure, Anne W. Simpson

Electronic Theses and Dissertations

Despite the widespread occurrence of trawl fisheries on mud-bottoms, there is limited knowledge concerning the effects of trawling induced disturbance on these habitats and their resident macrofaunal communities. I investigated the cumulative impacts of seasonal commercial shrimp trawling on infaunal habitat and macrofaunal community structure on two mud-bottom fishing grounds in the Gulf of Maine from June 2000 - December 2001. One fishing ground located near the Outer Pumpkin Ledges (Pumpkin) experienced trawling activity during the 2000-2001 fishing season. In contrast, the other fishing ground near Monhegan Island was not trawled during the same period because shrimp abundances were low. …

Modeling The Role Of No-Take Marine Reserves In Fisheries Management, Deidre F. Gilbert

Electronic Theses and Dissertations

In recent years there has been increasing interest in the potential of no-take marine reserves to benefit fisheries management. Scientific reviews have shown that reserves often lead to substantial increases in the density, biomass, size and diversity of marine fishes inside their boundaries. However, little empirical work has been done to determine the effect of reserves on the fisheries outside their boundaries, such as potential changes in yield, size of fleet, or variability in catch. In order to explore the interaction between the biological growth and dispersion processes of the harvested stock and the changing economic incentives of harvesters created …

Numerical Wave Simulations On Different Oceanic Scales, Khalid M. Zubier

Electronic Theses and Dissertations

In practical applications, numerical wave models are used as reliable tools to provide near future wave predictions and wave climatology for specific region. Obviously models first should go through extensive validation/verification procedures. Once validated, models can be used in scientific applications to investigate methods for improving performance and to develop better understanding of wave associated physical mechanisms and their interactions in specific field experiments. Two wave transformation models, SWAN and CGWAVE, are used to simulate wave conditions at the Field Research Facility, Duck (North Carolina). The motivation is to examine how well these models reproduce observations and to determine the …

Marine Protected Areas In The Gulf Of Maine: Policy For A Common Resource, Carolyn F. Skinder

Electronic Theses and Dissertations

In the wake of 25 years of unsuccessful single-fisheries management in the Gulf of Maine, there has been growing support for reform. Ecosystem management has been proposed as one alternative, but the information needed to manage whole ecosystems is greatly lacking. Implementing fully-protected marine protected areas (MPAs) is one way to preserve habitat while at the same time acquiring data for future ecosystem management. Under the current institutional arrangement in the Gulf, engineering agreement for MPAs is difficult due to the differing goals of varied user groups. The situation is reflective of a common property resource problem in that there …