Uncertain future for global sea turtle populations in face of sea level rise

Sea level rise has accelerated during recent decades, exceeding rates recorded during the previous two millennia, and as a result many coastal habitats and species around the globe are being impacted. This situation is expected to worsen due to anthropogenically induced climate change. However, the magnitude and relevance of expected increase in sea level rise (SLR) is uncertain for marine and terrestrial species that are reliant on coastal habitat for foraging, resting or breeding. To address this, we showcase the use of a low-cost approach to assess the impacts of SLR on sea turtles under various Intergovernmental Panel on Climate Change (IPCC) SLR scenarios on different sea turtle nesting rookeries worldwide. The study considers seven sea turtle rookeries with five nesting species, categorized from vulnerable to critically endangered including leatherback turtles (Dermochelys coriacea), loggerhead turtles (Caretta caretta), hawksbill turtles (Eretmochelys imbricata), olive ridley turtles (Lepidochelys olivacea) and green turtles (Chelonia mydas). Our approach combines freely available digital elevation models for continental and remote island beaches across different ocean basins with projections of field data and SLR. Our case study focuses on five of the seven living sea turtle species. Under moderate climate change scenarios, by 2050 it is predicted that at some sea turtle nesting habitats 100% will be flooded, and under an extreme scenario many sea turtle rookeries could vanish. Overall, nesting beaches with low slope and those species nesting at open beaches such as leatherback and loggerheads sea turtles might be the most vulnerable by future SLR scenarios

Individual variation in home‐range across an ocean basin and links to habitat quality and management

Overgrazing may lead to management intervention (e.g. culling, animal relocation) to try and prevent habitat destruction. Overgrazing leading to seagrass meadow collapse has been recorded for green turtles (Chelonia mydas) at several sites around the world, although the generality of this phenomenon and the need for intervention to prevent widespread seagrass destruction is unknown.Where turtles have degraded seagrass meadows, home-ranges are expected to be large and turtles will relocate as meadows are destroyed. We used high resolution Fastloc GPS tracking (n = 32 individuals, mean = 171 days per individual, SD = 99) to record the home-range of adult green turtles at foraging sites spanning 4523 km of longitude across the Western Indian Ocean. Contrary to predictions if overgrazing was occurring, we recorded small home-ranges and turtles rarely relocated their daytime foraging areas.Based on all locations received, the mean 50% and 95% utilisation distributions (UD50 and UD95) were 2.4 km2 (SD = 2.7) and 15.4 km2 (SD = 17.7). Space use was often particularly small at night, when turtles rest, averaging 11% of the overall space use with the mean night-time UD50 and UD95 being 0.15 km2 (SD = 0.1) and 1.1 km2 (SD = 0.8), respectively. Variation in home-range across individuals was not influenced by the data volume (number of locations per day, duration of tracking) or animal size (carapace length) but increased significantly as the distance between the centre of day and night areas increased, that is individuals that had a larger daily commute had the larger home-ranges.Synthesis and applications. Comparisons with home-range estimates from 16 previous studies, showed that those we recorded are among the smallest for adult green turtles globally. These results suggest that despite population size increases at several major nesting sites in the Western Indian Ocean, green turtles are generally not destroying the seagrass meadows on which they forage and so management intervention to prevent overgrazing is not needed. In this way, our work illustrates how movement data may inform management decisions for green turtles. Further targeted work on the seagrass ecosystem health could help confirm this suggestion

Remote submerged banks and mesophotic ecosystems can provide key habitat for endangered marine megafauna

The importance of some ecosystems remains poorly understood. We showed that mesophotic ecosystems (30 to 150 m) are a key habitat for a critically endangered species, with strong evidence that a globally important population of adult hawksbill turtles (Eretmochelys imbricata) almost exclusively foraged at these depths on remote submerged banks. This discovery highlights the need for such areas to be included in conservation planning, for example, as part of the United Nations High Seas Treaty. We equipped nesting turtles with Fastloc-GPS (Global Positioning System) satellite tags at an Indian Ocean breeding area and they all traveled to deep foraging sites (6765 days of tracking data across 22 individuals including 183,921 dive-depth measurements) rather than shallow coral reef sites. Both chart depths and depth data relayed from the tags indicated that turtles foraged at mesophotic depths, the modal dive depths being between 35 and 40 m. We calculate that 55,554 km2 of the western Indian Ocean alone consists of submerged banks between 30 and 60 m

Predation of sea turtle eggs by rats and crabs

Egg predation by invasive and native species may have severe impacts on endangered species and negatively affect species recovery. We assessed the levels of egg predation within green turtle (Chelonia mydas) clutches on the island of Diego Garcia (7.42°S, 72.45°E), Chagos Archipelago (Indian Ocean). Native coconut crabs (Birgus latro) and ghost crabs (Ocypode spp.), as well as introduced black rats (Rattus rattus), were predators of eggs, with these species entering nests via tunnels dug obliquely in the sand. Often whole eggs were removed from clutches. For example, the mean clutch size at oviposition (mean 127.8 eggs, n = 23, range = 74–176) was significantly larger than at the end of incubation (mean 110.9 hatched and unhatched eggs, n = 16, range = 9–147). In other cases, egg predation was recorded where the egg had been opened and contents were eaten in the nest. Overall, hatching success (the percentage of eggs laid leading to a hatchling emerging from the egg) was 64.9%, while 3.1% of eggs were predated within nests, 18.1% died during incubation without predation and 13.9% were removed. We reviewed evidence from 34 sites around the world identifying 36 predators that were either native (e.g., crabs, and goannas, n = 30) or invasive (e.g., rats, and pigs, n = 8). Depending on location, a predator could be identified as both native and invasive (e.g., dogs). We discuss how either nest protection and/or invasive predator eradication may be used to increase egg survival and when these approaches might be used

Extraction and quantification of luteolin and apigenin from artichoke (Cynara cardunculus var. scolymus (L.) cv. Madrigal) by-products

Stems, outer bracts, and leaves represent a huge concern for industries as by-products from the processing of artichokes, accumulating in tonnes per week and thus exerting considerable impact on the environment. The present study investigated the use of these industrial by-products from Cynara cardunculus var. scolymus (L.) cv. Madrigal as a source of flavones that might be used as neutraceuticals. These flavones were extracted according four different protocols that included (A) dried and ground material extracted with ethanol, (B) Ultrasound-Assisted Extraction (UAE) of dried and ground material extracted with ethanol, (C) dried material homogenized with ethanol, and (D) fresh material homogenized with ethanol. An HPLC isocratic separation with UV-detection was used to quantify the amounts of flavones obtained with each extraction protocol. It was found that the cultivar Madrigal yielded more apigenin than luteolin. For the former, the best extraction protocols were A (37 mg/kg dry weight) and B (61 mg/kg dry weight); for the latter, the best extraction protocol, that using UAE, yielded just 9 μg/kg dry weight.Los tallos, brácteas exteriores, y hojas al ser subproductos del procesamiento de las alcachofas representan una gran preocupación para las industrias, debido a que se acumulan en toneladas semanales y por lo tanto ejercen un impacto considerable en el medio ambiente. El presente estudio investiga el uso de estos subproductos industriales provenientes de Cynara cardunculus var. scolymus (L.) cv. Madrigal como una fuente de flavonas que pueden ser usadas como nutracéuticos. Estas flavonas fueron extraídas siguiendo cuatro protocolos diferentes que incluyeron: (A) material seco y molido extraído con etanol, (B) una Extracción Asistida por Ultrasonido (EAU) de material seco y molido macerado con etanol, (C) material seco homogenizado con etanol, y (D) material fresco homogenizado con etanol. Se utilizó un equipo HPLC y se llevó a cabo una separación isocrática con detección UV para cuantificar la cantidad de flavonas obtenidas mediante cada protocolo de extracción. Se encontró que el cultivar Madrigal rindió más apigenina que luteolina. En cuanto a la flavona apigenina, los mejores métodos de extracción fueron A (37 mg/kg peso seco) y B (61 mg/kg peso seco); el mejor método de extracción de luteolina fue el que usó EAU, el cual mostró un rendimiento de sólo 9 μg/kg en peso seco