Estimating the Effect of Beach Nourishment on <i>Caretta caretta</i> (Loggerhead Sea Turtle) Nesting

TLDR

The study monitored daily loggerhead nesting at a nourished beach and two natural beaches over three pre‑nourishment and two post‑nourishment seasons, using BACIPS models to quantify the nourishment effect. Nourishment caused a 4.4–5.4 nests km⁻¹ day⁻¹ decline and a 5.0–5.6 false‑crawl increase in the first post‑nourishment season, with smaller reductions (0.5–1.6 nests km⁻¹ day⁻¹) and increases (0.7–0.9 false‑crawls km⁻¹ day⁻¹) in the second season, indicating a pronounced but diminishing impact.

Abstract

Abstract Caretta caretta (loggerhead sea turtle) nesting activity was recorded daily during three seasons prior to and two seasons immediately following a beach nourishment (replenishment) project in Palm Beach County, Florida. Surveys were done at the nourished beach (Jupiter/Carlin) and at two natural beaches (Juno and Tequesta). The size of the nourishment effect on nesting activity was estimated using Before‐After‐Control‐Impact Paired Series (BACIPS) models. Nesting declined by 4.4 to 5.4 nests km − 1 day − 1 on the nourished beach compared to the two natural beaches in the first season after nourishment. At the same time, false crawls (FC, non‐nesting crawls) increased by 5.0 to 5.6 FC km − 1 day − 1 on the nourished beach. In the second season following nourishment, nesting was reduced by 0.5 to 1.6 nests km − 1 day − 1 on the nourished beach compared to the two natural beaches. The increase in false crawl frequency in the second season following nourishment was 0.7 to 0.9 FC km − 1 day − 1 .These results suggest that beach nourishment significantly decreased loggerhead sea turtle nesting during the first season following the project. However, the size of the effect, in terms of nesting frequency and false crawl frequency, was much reduced by the second season following nourishment.