Keywords

sea turtle, remote sensing, seascape ecology, Sargassum, fragmentation, conservation

Abstract

Floating marine structures, like the brown macroalgae Sargassum, provide essential habitat and support several life history stages for many marine organisms; habitat fragmentation and persistence of these floating habitats are poorly understood. Extending landscape ecology principles to the seascape realm requires new methodologies to understand dynamics of patch mosaics and functional utility of the moving seascape system. I examine Sargassum in a seascape ecology context, exploring 1) structural descriptions of the Sargassum patch seascape and whether 2) historical Sargassum patch distribution is represented by delineated proposed and finalized Sargassum-as-a-critical-habitat designations under the US Endangered Species Act (ESA). I utilize historical Sargassum data at two spatial scales: a coarse scale (1.6km) and a medium scale (328m) to determine whether habitat fragmentation processes are occurring at either spatial scale across seven marine regions in the Northern Atlantic Ocean. In the Gulf of Mexico specifically, the size of Sargassum patches is increasing, while the Caribbean Sea Sargassum patch density has increased by an order of magnitude during the study period suggesting habitat gain. In the Northern Brazil Shelf and the Sargasso Sea, there is evidence of habitat fragmentation occurring due to rapid changes in patch density, proportion of seascape, and distance between patches. In addition, all regions within the study area exhibit cyclic patterns, which suggests Sargassum habitat characteristics may occur alternating between high and low years, which can impact critical habitat strategies for Sargassum. Lastly, Sargassum patches were found to exhibit a notable increase in occurrence within the ESA's proposed green turtle critical habitat designation of Sargassum when compared with the ESA's loggerhead critical habitat Sargassum designation Sargassum. These data provide valuable insight into Sargassum as an important and highly dynamic seascape that may provide critical habitat for dispersal-stage juvenile sea turtles during their oceanic ‘lost years.'

Completion Date

2024

Semester

Spring

Committee Chair

Mansfield, Kate

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Biology

Degree Program

Integrative and Conservation Biology

Format

application/pdf

Identifier

DP0028329

URL

https://purls.library.ucf.edu/go/DP0028329

Language

English

Rights

In copyright

Release Date

May 2025

Length of Campus-only Access

1 year

Access Status

Doctoral Dissertation (Campus-only Access)

Campus Location

Orlando (Main) Campus

Accessibility Status

Meets minimum standards for ETDs/HUTs

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Restricted to the UCF community until May 2025; it will then be open access.

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