Biological and Abiotic Factors Influencing Cetacean Mass Strandings in the Northeastern United States
M.S. Marine Biology
Bernhard Riegl, Ph.D.
David Kerstetter, Ph.D.
Marine mammal strandings are frequent occurrences along many coastal areas around the world. The significance of stranded cetaceans has been of interest since around 300 B.C. when philosophers, like Aristotle, pondered why marine mammals, including whales, dolphins and porpoise beach themselves; and famous authors, like Henry David Thoreau, whose fascination in mammal strandings lead him to write a book about these mass occurrences off the coast of Cape Cod. Numerous hypothetical theories have been developed to explain these mass stranding phenomena. Though the causes of mass strandings remain unresolved, recent investigations suggest contributing factors could include environmental elements. Less emphasis has been placed on the importance of biological factors while increasing research has been conducted on how seasonal fluctuation and geographical location influences the number of mass strandings. Major studies have focused on mass stranding events along the southeast region of the United States (North Carolina to Florida) with less focus on the northeastern regions (Virginia to Maine). Stranding data from 1988-2006 in the Northeastern United States, collected by the National Marine Fisheries Service (NMFS) and the Cape Cod Stranding Network (CCSN), show a peak in mass stranding frequency along the coast of Massachusetts during the winter and spring seasons. With mass stranding events continuing along the eastern coast of the United States, data suggests that multiple factors coexist for a stranding (single or mass) to occur. Throughout this report, scientific theories are reviewed correlating seasonal changes, wind circulation patterns, geographical location, and parasitic infections as potential causes of mass stranding events. Seasonal variations have been proven to influence wind direction and speed, creating frontal convergences in the ocean environment. These changes when tracked by cetaceans may navigate them into shallow shoreline areas. Strandings in the northeast United States are more likely to occur on beaches with sloping typography, increased sand accumulation, and regions with elevated coastlines, allowing pockets of deep water to be located near the shore (Klinowska, 1985). In addition, biological samples obtained during necropsy procedures from deceased mammals throughout the eastern United States revealed high levels of parasitic infections within these animals’ cranial sinuses and brain cavities – areas which are known to directly affect marine mammal neurological and navigational capabilities. A combined literature review suggests that many of these biological and environmental factors need to be considered as potential contributors during the initial stages of cetacean stranding events.
Octavia Williams. 2018. Biological and Abiotic Factors Influencing Cetacean Mass Strandings in the Northeastern United States. Capstone. Nova Southeastern University. Retrieved from NSUWorks, . (336)
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