Exposure of Marine Turtle Nesting Grounds to Named Storms Along the Continental USA

Abstract

Named storms can cause substantial impacts on the habitat and reproductive output of threatened species, such as marine turtles. To determine the impacts of named storms on marine turtles and inform management, it is necessary to determine the exposure of marine turtle nesting grounds to recent storm activities. To address this, remote sensing information of named storm tracks coupled with nesting ground data were used to investigate the temporal and spatial overlap between nesting grounds for four species of marine turtles in the continental United States of America. All species of marine turtles were exposed to named storms, with variation in exposure driven by the spatial distribution of each population's nesting ground, the temporal overlap between the storms and reproductive events, and nest placement on the beach. Loggerhead turtles were the most exposed species to named storms, with the northern management unit having significantly higher exposure levels than all other loggerhead management units. Kemp's ridley turtles, in contrast, were found to be the least exposed species to named storms. This study establishes a valuable current baseline against which to measure and compare future impacts that result as climate change progresses and storms become more frequent and intense. Importantly, cumulative and synergetic effects from other climatic processes and anthropogenic stressors should be considered in future analysis.

Exposure of Loggerhead Sea Turtle Nests to Waves in the Florida Panhandle

“…The proportion of nests within the wave exposure polygon created in Section 2.3 were compared to the total nests laid per nesting beach to calculate the proportion of at-risk nesting locations. Each nesting beach was then ranked by their mean number of nests per year (i.e., nesting frequency) as well as the modeled proportion of exposed nests, similar to [26]. Nest frequencies per beach were categorized by quartiles with beaches in the highest quartile denoted as "very high nesting" and progressing to "high nesting", "medium nesting", and "low nesting" with subsequent quartiles.…”

“…Nesting females will also lay several nests throughout the nesting season in order to minimize the risk of complete reproductive failure [19][20][21]. Despite these environmental cues, wave exposure is a common occurrence, particularly during the hurricane season [22][23][24][25][26]. This exposure may become more frequent over the next several decades as sea level rises and hurricanes became more intense and frequent, threatening hatchling production [9,[26][27][28][29][30][31].…”

“…Despite these environmental cues, wave exposure is a common occurrence, particularly during the hurricane season [22][23][24][25][26]. This exposure may become more frequent over the next several decades as sea level rises and hurricanes became more intense and frequent, threatening hatchling production [9,[26][27][28][29][30][31]. Synergistically with implications from climate change, coastal modifications such as back-beach construction and armoring can exacerbate the risk of wave exposure by ultimately reducing the extent of available nesting beach [32][33][34][35][36].…”

“…While the exact number of nests laid across the recovery unit [41] and the proportion affected by wave exposure vary from year to year [45], mitigating losses at sites with high nesting density and high exposure to waves could lead to significant gains in hatchling production [39,45]. Similarly, preserving nesting beaches with high nesting density and low wave exposure could ensure sustained hatchling production in the face of climatic changes and stressors from coastal development [26,37,43,46]. In either case, nesting sites with high relative nesting density and either high or low relative wave exposure are priority candidates for future conservation initiatives (e.g., preservation of nesting habitat) and research to examine the pros and cons of intervention (such as nest relocation) prior to promoting it as a management strategy.…”

“…The identification of nesting beaches that will benefit most from conservation efforts can be aided by geographic information systems coupled with remote sensing data (e.g., LiDAR, aerial imagery, nighttime lighting). This approach has increasingly been used to identify threats to sea turtle nesting beaches and prioritize locations for conservation [26,27,43,[47][48][49][50][51][52]. For example, using historical data on wave height and wave period coupled with beach slope and sea turtle nest distribution, a wave runup model can be used to map wave exposure at the nesting beach in an effort to better inform sea turtle nest management [52][53][54][55].…”