Date of Award

2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Oceanography

Specialization

Biological Oceanography

Department

Oceanography

First Advisor

John W. King

Abstract

This dissertation is comprised of three chapters focused on benthic habitat mapping of coastal waters within northeast region of the United States to support science-based regulatory and management strategies. The first chapter is entitled: Shallow water benthic habitat mapping utilizing the Coastal and Marine Ecological Classification Standard (CMECS) to establish baseline conditions post-Hurricane Sandy at Fire Island National Seashore, New York. In response to Hurricane Sandy, a benthic habitat mapping study was conducted at Fire Island National Seashore (FIIS), New York, representing one of the first comprehensive mapping efforts undertaken by the National Park Service. FIIS was of particular interest because of the tidal inlet formed by Sandy, leading to an influx of ocean water into and consequently altering Great South Bay. Data acquired include sidescan, bathymetry, sediment profile imagery, and sediment and macrofauna samples. The Coastal and Marine Ecological Classification Standard (CMECS) played a key role in developing map units, interpreting habitats (biotopes), and examining statistically significant relationships between macrofaunal communities and their environment.

The resulting biotopes are primarily defined by sand waves, dunes, flats, and basins and dominated by polychaete worms, small bivalves, and amphipods. The data also reveal the variable distribution of seagrass. While this study’s findings cannot be directly compared to pre-Sandy conditions, evidence suggests the influence of the new inlet is positive. For example, seagrass has increased in close proximity to the inlet, while it has declined further away. Additionally, dense concentrations of blue mussels were recovered near the inlet, although they were largely absent elsewhere.

This study demonstrates the value of benthic habitat mapping and CMECS in providing ecologically meaningful information applicable to scientists and agencies, and argues the need for the establishment of a monitoring program. A multidisciplinary understanding of an ecosystem’s resources, structure, function and temporal variability will guide science-based management strategies that maintain a balance between the protection and use of submerged lands.

The second chapter is entitled: Benthic monitoring to assess near-field changes at the Block Island offshore wind farm. The Block Island Wind Farm, located in the northeast Atlantic Ocean, is the first offshore facility in the United States. The primary objectives for this two-year study were to investigate near-field alterations in benthic macrofaunal communities, sediment composition, and organic enrichment among turbine and control areas, as a function of distance from the turbine foundations. At three turbines, grab sample and imagery data were collected within the footprint of the jacket foundations and 30m – 90m from the center point under the foundations. No appreciable differences were detected in either abiotic or biotic variables, with the exception of substantial changes exhibited within the footprint of one turbine. The variable spatial and temporal pattern over which changes are occurring poses challenges for predicting future conditions and highlights the complexity of attempting to do so. Monitoring efforts should continue to be focused on documenting alterations from offshore development and understanding the complex abiotic-biotic interactions that cause such alterations.

The third chapter is entitled: Conclusions: Benthic habitat mapping and its application to coastal resource management. This chapter provides an overview of the two manuscripts and discusses how benthic habitat mapping and associated techniques are broadly applicable and can be used to accomplish various study objectives. As examples, the value of using multivariate statistics and the Coastal and Marine Ecological Classification Standard (CMECS) is examined. Additionally, the relevance of these studies from a management and regulatory perspective is provided.

Available for download on Friday, November 29, 2019

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