Graduation Year

2021

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Biology (Integrative Biology)

Major Professor

Jeremiah Sean Doody, Ph.D.

Committee Member

Deby Cassill, Ph.D.

Committee Member

Laura Wright, M.Sc.

Keywords

light pollution, beachfront development, Caretta caretta, disorientation, local conservation

Abstract

Artificial light (i.e. unnatural light emitting from a human-made source) is one of the most extensively distributed, and least managed, type of anthropogenic pollution. Due to the disproportionally high rates of urbanization in critical coastal ecosystems, species, like marine turtles that use beach habitat for nesting activities, are especially vulnerable. Marine turtles employ the use of multiple visual cues (e.g. wavelength, intensity, background illumination, and dark silhouettes) to conduct sea-finding behavior and different variations in cue usage exist across species and geographic location. During nesting and emergence activities, orientation can be interrupted and manipulated by artificial lighting resulting in lower sea-finding success and implications for marine turtle population decline. Published literature regarding this topic ranges widely in study location, and within Florida, the Gulf Coast is substantially less studied compared to the east. The first part of this study reviews all published literature on marine turtle orientation and artificial light impact and analyzes the distribution of studies across location and species, finding that, out of 73 publications, the majority of studies are located in Florida’s East Coast (39.7%) and include loggerhead (Caretta caretta) turtles (46.6%). Secondly, lighting impact was analyzed in Pinellas County, Gulf Coast, Florida, using light survey information and disorientation report and mortality count for C. caretta from FWC Marine Turtle Disorientation Reports as proxies. A Wilcoxon-Kruskal-Wallis test was used to determine significance between property type (e.g. condo/hotel, undeveloped, single-family home/duplex, business) and year with lighting impact, and a quadratic regression was used to determine if proportions of property types per municipality could be a predictor for number of reports and mortality. While beach length (km) accounted for the majority of the variation between municipalities, these analyses demonstrated that a higher proportion of businesses (p < .0001), in combination with a nonhomogeneous variation in property types, indicates higher predictors of lighting impact for that beach section. Lastly, this study discusses a potential management tool that utilizes data from the same common reports to construct a heatmap using ArcGIS, displaying both disorientation reports and light infractions attached to the causal properties and indicating the most impactful properties and regions. This study sets up framework for future evaluations of light impact on a local level and offers new management suggestions for the conservation of local marine turtle populations.

Download

Included in

Biology Commons

Share

COinS