Article

Young sea turtles of the pelagic Sargassum-dominated drift community: Habitat use, population density, and threats

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

In the western Atlantic young sea turtles in their surface-pelagic juvenile stage, a stage often described as the lost year(s), have been hypothesized to occupy habitat dominated by pelagic Sargassum macroalgae. But despite substantial indirect evidence, there has been no direct study of sea turtles within this community. To determine the importance of Sargassum to young sea turtles, we transected surface-pelagic habitat, measured relative abundance of sea turtles, recorded their behavior and association with surface features, and assessed their diet. On vessel transects in the eastern Gulf of Mexico and Atlantic Ocean off Florida (USA), we recorded 1884 turtles of 4 species-loggerhead sea turtle Caretta caretta, green turtle Chelonia mydas, hawksbill Eretmochelys imbricata, and Kemp's ridley Lepidochelys kempii. Most (89%) were initially observed within 1 m of floating Sargassum. Turtles included both post-hatchlings (39 to 78 mm straight carapace length, SCL) and juveniles (130 to 280 mm SCL). Dive-profile data from overnight logs (18.5 to 23.1 h duration) of 3 juvenile Kemp's ridleys showed that they spent an average of 97% (day) or 87% (night) of their time within 1 m of the surface. Juvenile turtles from which esophageal lavage and fecal samples were obtained showed a diet composed principally of Sargassum-community associates, primarily marine animals. Other items included marine plants (predominantly pelagic Sargassum), synthetic material (e. g. plastics), terrestrial plants (mostly wood), and terrestrial animals (flying insects). Plastics in diet samples averaged 13% of dry mass. Data support a description of pelagic Sargassum as a transient hot spot for young sea turtles and a focal point for threats, including debris ingestion and petroleum.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Our current understanding of sea turtle diet, in any of the seven species, is primarily based on visual identification of diet items from esophageal lavage samples (e.g., Carrion-Cortez et al. 2010, Witherington et al. 2012, Holloway-Adkins and Hanisak 2017, fecal samples (e.g., Witherington et al. 2012, Seney 2016, Martinez-Estevez et al. 2022, and gut contents from necropsied individuals (e.g., Seney and Musick 2007, Williams et al. 2014, Santos et al. 2011, Donaton et al. 2019, Howell and Shaver 2021, Molter et al. 2022, or from stable isotope analyses (e.g., Arthur et al. 2008, McClellan et al. 2010, Ramirez et al. 2020). However, methodological constraints associated with these methods reduce detection sensitivity and classification specificity for many diet items. ...
... Our current understanding of sea turtle diet, in any of the seven species, is primarily based on visual identification of diet items from esophageal lavage samples (e.g., Carrion-Cortez et al. 2010, Witherington et al. 2012, Holloway-Adkins and Hanisak 2017, fecal samples (e.g., Witherington et al. 2012, Seney 2016, Martinez-Estevez et al. 2022, and gut contents from necropsied individuals (e.g., Seney and Musick 2007, Williams et al. 2014, Santos et al. 2011, Donaton et al. 2019, Howell and Shaver 2021, Molter et al. 2022, or from stable isotope analyses (e.g., Arthur et al. 2008, McClellan et al. 2010, Ramirez et al. 2020). However, methodological constraints associated with these methods reduce detection sensitivity and classification specificity for many diet items. ...
... These taxa may have been consumed intentionally by turtles or they may have been present around turtle carcasses when collected or necropsied (e.g., scavengers). Terrestrial insects are known to be consumed by smaller green turtles in the surface-pelagic zone (Witherington et al. 2012) and in early neritic stages (Howell and Shaver 2021), as well as by juveniles of other sea turtle species (Frick et al. 2009, Witherington et al. 2012, Jones and Seminoff 2013. Therefore, taxa in the insect/arachnid category could potentially include diet items, but no insects or arachnids were found during visual identification of other gut content subsamples from the same turtles (Seney, unpublished data). ...
Article
Synopsis The green turtle (Chelonia mydas) is a circumglobal species with a wide dietary breadth that varies among regions and life history stages. Comprehensive understanding of foraging ecology over space and time is critical to inform conservation and management of this species and its habitats. Here, we used DNA metabarcoding to test candidate primer sets with 39 gut content homogenates from stranded green turtles (FL, USA) to identify primer sets that maximize detection of food items and specificity of taxonomic classifications. We tested six existing universal primer sets to detect plants, animals, and eukaryotes more broadly (CO1, 18SV1-V3, 18SV4, rbcL, UPA, ITS). The CO1 and 18SV4 primer sets produced the greatest number of dietary amplicon sequence variants (ASVs) and unique taxonomic classifications, and they were the only primer sets to amplify taxa from all three kingdoms relevant to green turtle diet (Animalia, Chromista, and Plantae). Even though the majority of CO1-derived reads were of host origin (>90%), this primer set still produced the largest number of dietary ASVs classified to species among the six primer sets. However, because the CO1 primer set failed to detect both vascular plants and green algae, we do not recommend the use of this primer set on its own to characterize green turtle diet. Instead, our findings support previous research highlighting the utility of using multiple primer sets, specifically targeting CO1 and the V4 region of the 18S gene, as doing so will provide the most comprehensive understanding of green turtle diet. More generally, our results highlight the importance of primer and loci selection and the need to validate primer sets against the study system of interest. The addition of DNA metabarcoding with optimized primer sets to the sea turtle researcher's toolbox will both increase our understanding of foraging ecology and better inform science-based conservation and ecosystem management.
... To conduct this comparison, we compared strandings of green turtles less than or equal to 30 cm SCL in Texas over the previous decade with hatchling production from beaches in Campeche, Mexico, including Isla Aguada, Sabancuy, Isla del Carmen, and Cayo Acras (Guzmán 2020). This size class was selected to represent turtles that most recently recruited into their neritic phase (Witherington et al. 2012, Howell et al. 2016). The Campeche nesting data was used as a relative measure of annual nesting beach productivity in the region and is based on a combination of direct counts from nests in corrals and polystyrene foam boxes, and estimates from in situ nests using average clutch sizes and hatching success values. ...
... (Figure 3-21). Turtles in this category fell between the expected sizes for the surface-pelagic (20.6 ± 2.2 cm, Witherington et al. 2012) and neritic (36.6 ± 8.9 cm, Shaver 2000, Howell et al. 2016) life history stages of green turtles reported for the Gulf of Mexico. ...
... With regard to life history, these turtles were a smaller cohort relative to other strandings in Texas. Their size range overlapped with both the higher end of surface-pelagic phase and lower end of neritic phase green turtles (Shaver 2000, Foley et al. 2007, Witherington et al. 2012) and is consistent with the size at which green turtles recruit to neritic habitat associated with armored inlets (Howell et al. 2016). Some individuals in this group had evidence of recent pelagic feeding (ingestion of Sargassum sp.) offering further support that these green turtles recently recruited from the surface-pelagic phase. ...
Technical Report
Full-text available
This report presents information, analyses, and conclusions related to the investigation of sea turtle strandings in Texas during 2019. During this year, sea turtle strandings were more than two times above average based on statewide stranding numbers for the previous 5 and 10 years. We identified multiple causes based on analysis of stranding data, postmortem examinations, diagnostic testing, and study of environmental factors. Based on these results, four major features characterized sea turtle strandings in Texas in 2019, each with specific temporospatial distributions and different attributed causes: 1. Numerous strandings of small juvenile green turtles (Chelonia mydas) during spring and summer. Most of these occurred in NMFS zone 20 concurrent with strong onshore winds. These strandings were a substantial contributor to total statewide stranding numbers. Many were found alive and entrapped within inlet jetty rocks or stranded within the intertidal zone. Findings suggest that a combination of factors most likely contributed to these strandings including seasonal or ontogenetic (developmental) transition into nearshore waters, recent increases in green turtle nesting within the western Gulf of Mexico, use of man-made structures for foraging habitat, and environmental conditions. 2. Stranded Kemp’s ridley (Lepidochelys kempii) and loggerhead turtles (Caretta caretta) with findings suggestive of drowning by forced submergence. Most of these turtles were found on the Upper Texas Coast during April and May. Observations are similar to reports from previous years that have implicated bycatch in shrimp trawls based on necropsy findings and reduction of these strandings following the annual closure of Texas state waters to commercial shrimping. 3. Stranded loggerheads in poor nutritional condition. Most of these strandings occurred in NMFS zone 20 and had comorbidities including ulcerative gastrointestinal disease and impaction by ingested sea pens (order Pennatulacea). Similar presentations have been observed sporadically in loggerheads found stranded in Texas during previous years and throughout other areas of the southeastern U.S. The cause(s) of this condition is not known at this time. 4. Green turtle mass mortality event linked to illegal gillnetting. These strandings occurred near the U.S.-Mexico border in November and December and are attributed to drowning in gillnets based on a concurrent discovery of illegal gillnets containing captured green turtles in adjacent coastal waters and exclusion of other causes. These characteristics and events comprised a majority of strandings observed in Texas during 2019. In addition, many other well-known causes of sea turtle strandings were also identified during this period, including vessel strikes, entanglement and entrapment in fishing-related material, and wounds inflicted by predators.
... IntroductIon Floating mats of Sargassum (hereon referred to simply as 'pelagic Sargassum') typically comprise several morphotypes of 2 holopelagic species (Sargassum natans and S. fluitans) and provide essential habitat, refuge, nursery ground and foraging habitat for a wide variety of associated and endemic species (Butler et al. 1983, Witherington et al. 2012, Moser and Lee 2012, Martin 2016, Martin et al. 2021. Much of this knowledge comes from assessments in the Sargasso Sea where pelagic Sargassum has existed for centuries (Parr 1939, Fine 1970, Butler et al. 1983, Lapointe et al. 2014, and significant steps have been taken to protect it (Laffoley et al. 2011). ...
... Despite these concerns, the potential impacts of in-water collection of pelagic Sargassum on the associated biodiversity have not been adequately examined to provide appropriate guidance for this management intervention. Sargassum is well known to support diverse taxa (Coston-Clements et al. 1991, Casazza and Ross 2008, Laffoley et al. 2011, Moser and Lee 2012, Witherington et al. 2012, thus the impact of in-water harvesting could be significant. To date, the lack of consistency in biodiversity assessment studies in the tropical Atlantic and Caribbean limits the understanding to the patterns of diversity and thus the ability to understand the potential impact of large-scale removal. ...
Article
Over the past decade unprecedented blooming of pelagic Sargassum has occurred across the Equatorial Atlantic from West Africa to the Caribbean. Although pelagic Sargassum mats are considered beneficial in the open ocean, providing valuable habitat for a diverse array of endemic and associated species, they also inundate coastal areas and cause a plethora of management challenges for fisheries, tourism, nearshore coastal ecosystems, public health and the socioeconomic welfare of coastal communities. In—water harvesting has been suggested as a desirable management solution to prevent shoreline inundation, but destruction of the associated biodiversity is a concern with this approach and has not been adequately examined. Furthermore, in—water harvesting methods within the Tropical Atlantic and Caribbean have been ad hoc and highly variable with no established sampling protocol. Here we review 30 published studies detailing methods to collect information on the biodiversity associated with pelagic Sargassum. Nets, hook and line, video recordings, bare—hands and plastic bags have all been used to collect epiphytic, clinging and free—swimming fauna associated with Sargassum. Net sampling was the predominant method; however, in the absence of a standardized approach a wide range of net types and sizes were used. Similarly, separation, identification and preservation methods were all unstandardized. This review highlights the need for standardization and provides the first set of guidelines for the collection and assessment of Sargassum—associated biodiversity. Nevertheless, these approaches are labor intensive and require extensive replication in time and space to produce a reasonable assessment of the biodiversity associated with the Sargassum community.
... Further, published observations and samples of dispersal-stage juveniles to date are mostly in the Atlantic basin (Bolten et al., 1998;Putman & Mansfield, 2015;Shamblin, Witherington, et al., 2018;Witherington, 2002;Witherington et al., 2012). ...
... Within the Atlantic, there is high potential for multiple species and stocks to mix in the Gulf of Mexico, as ocean currents pass in close proximity to major rookeries throughout the basin and oceanic habitats within the Gulf occur relatively close to shore. These conditions present a unique opportunity to sample turtles in this elusive life stage (Putman & Mansfield, 2015;Shamblin, Witherington, et al., 2018;Witherington et al., 2012). Five of the seven sea turtle species are commonly found in the Gulf of Mexico at various life stages, including the Atlantic-only Kemp's ridley (Valverde & Holzwart, 2017). ...
Article
Full-text available
Regional genetic differentiation of mitochondrial lineages occurs in migratory species with natal philopatry such as sea turtles. However, early juvenile dispersal represents a key opportunity for gene flow and colonization of new regions through founder events, making it an important yet under-studied life stage. To assess connectivity among sea turtle life stages and ocean basins, we sequenced mitochondrial DNA (mtDNA) fragments from 35 juveniles sampled in the Gulf of Mexico from the rarely observed dispersal stage across three species: green turtles (Chelonia mydas; n = 30), hawksbills (Eretmochelys imbricata; n = 3), and loggerheads (Caretta caretta; n = 2). We estimated green turtle rookery contributions using a many-to-many Bayesian mixed stock analysis that incorporated dispersal probabilities based on rookery size and transport via ocean currents. We assembled a gene tree including 709 distinct mtDNA control region haplotypes from the literature for all seven extant sea turtle species to assess gaps in life-stage data across ocean basins, as well as contextualize the lineages we sampled from dispersing juveniles. Our results indicate a high likelihood that green turtles sampled in the Gulf of Mexico originated from rookeries along the coast of Mexico, with smaller contributions from Costa Rica and Suriname. The gene tree analysis yielded species-level relationships consistent with those presented previously, while intra-species relationships between lineages and ocean basins differed, particularly within loggerhead and green turtle clades. Our results highlight the lack of genetic data from juvenile sea turtles, especially the early dispersal stage, and the potential for these data to answer broader questions of connectivity and diversification across species and lineages.
... Evidence from regionally relevant riverine inputs show polyethylene, polypropylene and nylon fishing gear can contribute to ALDFG in the environment (Nelms et al., 2021).This ghost gear has the capacity to breakdown into bioavailable pieces following long-term degradation (Cole et al., 2011;Jâms et al., 2020). Juvenile turtles are known to seek refuge under rafts of sargassum and other floating debris (Witherington et al., 2012) which may increase their chances of consuming rope fibres if foraged food is attached to drifting ALDFG. Results from Pacific Ocean are in concordance with those from other studies, with the recorded debris dominated by hard plastic fragments, being predominately clear and white in colour (Ryan et al., 2016;Clukey et al., 2017a;Pham et al., 2017;White et al., 2018;Eastman et al., 2020). ...
... Floating material on the surface of these areas now contains potentially harmful levels of plastic pollution (Carr, 1987;Wolanski, 2017). This makes this life stage particularly susceptible to floating plastic ingestion because they feed at or near the ocean surface in ocean currents in search of planktonic prey (Witherington, 2002;Witherington et al., 2012;Ryan et al., 2016). In addition ingestion probability is higher due to feeding largely in a non-selective manner (Schuyler et al., 2014;Nelms et al., 2016;Eastman et al., 2020). ...
Article
Full-text available
The ingestion of plastic by marine turtles is now reported for all species. Small juvenile turtles (including post-hatchling and oceanic juveniles) are thought to be most at risk, due to feeding preferences and overlap with areas of high plastic abundance. Their remote and dispersed life stage, however, results in limited access and assessments. Here, stranded and bycaught specimens from Queensland Australia, Pacific Ocean (PO; n = 65; 1993-2019) and Western Australia, Indian Ocean (IO; n = 56; 2015-2019) provide a unique opportunity to assess the extent of plastic (> 1mm) ingestion in five species [green (Chelonia mydas), loggerhead (Caretta caretta), hawksbill (Eretmochelys imbricata), olive ridley (Lepidochelys olivacea), and flatback turtles (Natator depressus)]. In the Pacific Ocean, high incidence of ingestion occurred in green (83%; n = 36), loggerhead (86%; n = 7), flatback (80%; n = 10) and olive ridley turtles (29%; n = 7). There was an overall lower incidence in IO; highest being in the flatback (28%; n = 18), the loggerhead (21%; n = 14) and green (9%; n = 22). No macroplastic debris ingestion was documented for hawksbill turtles in either site although sample sizes were smaller for this species (PO n = 5; IO n = 2). In the Pacific Ocean, the majority of ingested debris was made up of hard fragments (mean of all species 52%; species averages 46-97%), whereas for the Indian Ocean these were filamentous plastics (52%; 43-77%). The most abundant colour for both sites across all species was clear (PO: 36%; IO: 39%), followed by white for PO (36%) then green and blue for IO (16%; 16%). The polymers most commonly ingested by turtles in both oceans were polyethylene (PE; PO-58%; IO-39%) and polypropylene (PP; PO-20.2%; IO-23.5%). We frame the high occurrence of ingested plastic present in this marine turtle life stage as a potential evolutionary trap as they undertake their development in what are now some of the most polluted areas of the global oceans.
... The hypothesis linking early juvenile-stage sea turtles to convergence zones and pelagic Sargassum was reviewed by Carr (1987) who reported anecdotal observations of stranded turtles which had commonly washed ashore along with mats of Sargassum or were recorded to have Sargassum associates or other neustonic organisms in their gut. Witherington et al. (2012) recently highlighted the importance of Sargassum as a transient hotspot for four different species of sea turtle: loggerheads (Caretta caretta), greens (Chelonia mydas), hawksbills (Eretmochelys imbricata) and Kemp's ridleys (Lepidochelys kempii). The Sargassum community is also used for foraging by some pelagic seabirds (Haney, 1986;Moser and Lee, 2012;De Boer et al., 2014;De Boer and Saulino, 2017). ...
... Our observations of two juvenile green sea-turtles basking in Sargassum in May 2015 ( Fig. 4f-g) are therefore unique as they occurred at the farthest (global) offshore distances (420 km and 273 km). A study by Witherington et al. (2012) discovered young sea turtles within a Sargassum dominated drift community off Florida between 45 and 110 km from the coast. Whereas offshore, Sargassum offers an important habitat for young sea turtles, the morphology of the mats can become too dense and this may cause young turtles to drown as they struggle to reach the surface to breathe. ...
Article
Full-text available
Recent atypical blooming events of the macroalgae Sargassum have affected humans and animals within the wider Caribbean region. Little is known how Sargassum affects marine megafauna offshore in Suriname. Data from dedicated marine megafauna surveys were pooled (2012 and 2015; May-September). A significant higher presence of Sargassum was found in May and July and particularly over the Demerara plateau. Sargassum constituted localised 'hot-mats' for biodiversity: 77 sightings comprising 25 species associated with Sargassum mats. Young green turtles (Chelonia mydas) basked in Sargassum at a farthest reported (global) distance from the coast. Cetaceans were significantly more abundant in waters with Sargassum. Dolphins (Stenella longirostris and S. attenuata) showed higher abundance indices in presence of Sargassum, while deep diving cetaceans showed higher indices without Sargassum. All three species of booby (Sula sp.) foraged on flying fish in Sargassum. Terns (Onychoprion fuscatus) and shearwaters (Calonectris diomedea, Puffinus gravis, P. lherminieri) foraged amongst Sargassum. Manx shearwater (P. puffinus) and red-billed tropicbird (Phaethon aethereus) were flying low over Sargassum. Using bird transect-data we found that in 2012, Sargassum attracted significantly larger groups of foraging seabirds compared to 2015. These differences may have been affected by mat-morphology (2012: 'loose' vs 2015: 'dense'). It is unknown how mat-morphology may affect marine megafauna during future blooming-events. It has been reported that Sargassum natans VIII provides less suitable feeding-mats than other forms, but more research is needed. Nevertheless, Sargassum offers opportunities to a diverse marine megafauna community in what are otherwise relative nutrient-poor tropical offshore waters.
... En mar abierto, la estructura tridimensional del sargazo proporciona un hábitat para organismos sésiles y fauna nectónica (Thiel & Gutow, 2005). En los conglomerados de sargazo se encuentran decenas de especies de peces en fases larvaria y adulta, además de juveniles de tortugas marinas (Stoner y Greening, 1984;Witherington et al., 2012), invertebrados, crustáceos y algas (Wells y Rooker, 2004;Huffard et al., 2014). Varias de estas especies utilizan el sargazo en alguna etapa de su desarrollo (Laffoley et al., 2011), lo que manifiesta la importancia del sargazo como zona de crianza y desarrollo de especies de interés ecológico y comercial (Luckhurst, 2015;Witherington et al., 2012). ...
... En los conglomerados de sargazo se encuentran decenas de especies de peces en fases larvaria y adulta, además de juveniles de tortugas marinas (Stoner y Greening, 1984;Witherington et al., 2012), invertebrados, crustáceos y algas (Wells y Rooker, 2004;Huffard et al., 2014). Varias de estas especies utilizan el sargazo en alguna etapa de su desarrollo (Laffoley et al., 2011), lo que manifiesta la importancia del sargazo como zona de crianza y desarrollo de especies de interés ecológico y comercial (Luckhurst, 2015;Witherington et al., 2012). También sirven como vectores de conectividad y transporte de biodiversidad entre áreas alejadas a miles de kilómetros, permitiendo el intercambio genético de especies y el transporte de nutrientes entre las costas del Atlántico (Thiel & Fraser, 2016). ...
Article
Full-text available
Article La retirada de restos vegetales de Sargassum spp. depositados sobre la playa emergida constituyen una parte de la limpieza de playas en el Caribe. Estas gestiones realizadas a lo largo de las últimas décadas han dado lugar a la pérdida de superficies y volúmenes de playa y dunas. El estudio analiza los volúmenes de sedimento retirados mediante la limpieza de Sargassum spp. en 12 playas de México y República Dominicana, cuantificando el volumen total en 18.987,3 m 3 , con un 61,23 % de sedimento intercalado, equivalente a 9.872,36 T de arena. Este tipo de ges-tión supone un impacto geomorfológico continuo con una importante pérdida de sedimento anual que afecta a la estabilidad del balance sedimentario del sistema playa. Palabras clave: Caribe, Sargassum spp., limpieza de playas, erosión. Loss of sediment associated with the removal of deposits of Sargassum spp. on the beaches of the Caribbean Part of the cleaning of beaches in the Caribbean islands involves the removal of Sargassum spp. that remains deposited on the emerged beach and dunes. The study analyses the volumes of sediment removed with the Sar-gassum spp. at 12 beaches in México and the Dominican Republic, quantifying the volume of material removed at 18,987.3 m 3 , of which an estimated 61.23 % (or 9,872.36 T) was sand. This kind of management involves a continuous geomorphological impact with an important loss of sediment that affects the stability of the sedimentary balance of the beach system. El turismo de sol y playa es la modalidad que mayores flujos genera a escala internacional y supone una importante aportación al producto interior bruto (PIB) en países denominados turísticos. En el Caribe, México y República Dominicana son unos de los principales destinos turísticos de este tipo con una aportación al PIB de 8,7 y 8,4 % respectivamente, y modelos turísticos basados en el producto turístico litoral. Para mantener una playa a largo plazo, el balance debe ser positivo, o al menos equilibrado, ya que los balances negativos en última instancia causan su erosión (Komar, 1999). La presión derivada de la industria turística ha hecho que muchos ambientes sedimentarios litorales se hayan visto gravemente afectados a lo largo de la costa. Los ambientes litorales de México y República Dominicana (Fig. 1) están some-tidos desde hace décadas a una problemática geoam-biental asociada a su uso y explotación (Peynador & Méndez-Sánchez, 2010; Roig-Munar et al., 2018; Guima-rais et al., 2021), pero en la última década presentan la llegada y varado masivo de sargazo, la gestión de su retirada generando impactos geoambientales con pérdida de superficie y volumen de playa. Una de las preocupaciones fundamentales nace inicialmente desde el sector turístico en la región del Caribe por la afectación que implican las grandes masas de sargazo Pérdida de sedimento asociada a la retirada de depósitos de Sargassum spp. en las playas del Caribe
... Pelagic Sargassum is a floating macroalgae with the majority of drifts occurring within the western North Atlantic, Caribbean Sea, and Gulf of Mexico between latitudes of 20 and 40⁰ N. Sargassum habitats are well known highly productive patches (Dooley 1972;Butler et al. 1983). Witherington et al. (2012) examined Sargassum habitat to determine how important this habitat is to juvenile sea turtles. From 1992 to 2004, they observed 1,884 turtles of four species in the Atlantic Ocean and Gulf of Mexico. ...
... From 1992 to 2004, they observed 1,884 turtles of four species in the Atlantic Ocean and Gulf of Mexico. Overnight data from observing three juvenile Kemp's ridleys showed that they spend 97% of the day and 87% of the night within 1 m of the surface (Witherington et al. 2012). Adults spend less time at surface and more time diving deep into open water habitats. ...
... Pelagic Sargassum is an important component of aquatic ecosystems in tropical and subtropical areas. It freely floats in seas and oceans, forming a natural habitat that benefits a great diversity of species [20,21]. Sargassum biomass can be beneficial to the environment at moderate densities, as it provides food and shelter for various species, and may help fighting erosion and provides nutrients [22]. ...
... The number of beaches and coasts plagued by algae has dramatically increased in recent years with the so-called "golden tides" [19]. Among the large number of macroalgae species, two genders are responsible for the majority of coastal and beach invasive incidents: Ulva, a green macroalgae [23][24][25] and pelagic Sargassum, a brown algae causing golden tides [20,21,[26][27][28][29]. Although researchers have reported the presence in the Caribbean of different Sargassum species [19,28], others have identified two species that annually arrive to coasts in high proportion: Sargassum natans and Sargassum fluitans [30][31][32][33]. ...
Article
Full-text available
The use of algal biomass as a renewable source of energy is potentially promising. The literature on biofuels derived from Sargassum is limited compared to other macroalgae. The unusual seaweed bloom of Sargassum from 2011 to date can be caused by the following factors: eutrophication of the sea, climate change, and other oceanographic patterns. The atypical invasion has had great ecological and economic effects in the affected regions. Traditionally, Sargassum has been recovered from coasts and beaches for use as fertilizer, but new markets need to be found to exploit the large volumes produced by the seaweed influx and mitigate its impact. The biochemical composition of Sargassum biomass defines it as a potential feedstock for biofuel production. However, the high moisture and ash content constitute the limitations for the development of some energy extraction methods. On the other hand, the costs associated with the removal of high volumes of accumulated Sargassum from coasts and beaches, transportation, cleaning, and storage are relatively high. Therefore, the production of biofuels from Sargassum seaweed is still a technical, economic, and energy challenge. This review proposes a multifactorial approach to the potential use of Sargassum biomass as feedstock for energy production, especially by thermochemical conversion (combustion, gasification, pyrolysis, and hydrothermal liquefaction). The survey analyses the chemical composition, biomass productivity and coastal impact, energy output, thermochemical conversion processes, techno-economic challenges, and future perspectives. In addition, a Sargassum biomass biorefinery approach with a circular bioeconomy approach is proposed.
... Across most marine turtle species, juveniles and posthatchlings spend their early years foraging in nutrient-rich oceanic convergence zones which also concentrate floating plastic (Barstow, 1983;Carr, 1987 et al., 2012). In the GoM, pelagic green turtles inhabiting these zones forage among large floating mats of Sargassum, and GoM diet studies confirm greater debris ingestion in turtles primarily feeding on Sargassum (Howell et al., 2016;Witherington et al., 2012). Further, pelagic-stage turtles feed more generally than larger turtles, ingesting diverse food items with little selectivity (Nelms et al., 2016). ...
... Along much of the Texas coast, debris primarily washes ashore from the ocean, while a much smaller proportion originates from freshwater influx as is more common in the northern GoM (Wessel et al., 2019). Juvenile green turtles in the GoM occupy different geographic areas seasonally (Witherington et al., 2012), so high springtime ingestion rates could also be related to spatial variation of plastic in the environment. There was also a positive relationship between latitude and ingestion likelihood in this study (though mass was inversely related to latitude), but surveys of barrier island beaches showed little latitudinal variation in the amount of debris along the Texas coast (Wessel et al., 2019). ...
Article
Full-text available
Despite exponential growth of anthropogenic marine debris in recent decades, plastic ingestion by marine turtles in the Gulf of Mexico is not well understood. Gastrointestinal tracts were examined from 464 green turtles that stranded in Texas between 1987 and 2019, and 226 turtles ingested plastic (48.7%). This number doubled from 32.5% in 1987–1999 to 65.5% in 2019, but mass of ingested items was lowest in 2019. No turtles showed evidence of death directly related to plastic ingestion. Compared to other regions, plastic ingestion was low. Small turtles (<25 cm straight carapace length) ingested plastic more frequently and in greater amounts than larger turtles. Small turtles also ingested more hard plastic while larger turtles ingested more sheet-like and thread-like plastics, which may correspond to size-based habitat shifts. This is among the largest marine turtle ingestion studies to date and demonstrates an increasing prevalence of plastic ingestion.
... Pelagic Sargassum is a floating macroalgal community with the majority of drifts occurring within the western North Atlantic, Caribbean Sea, and Gulf of Mexico between latitudes of 20 and 40⁰ N. Sargassum habitats are known to be highly productive patches and associated with thousands of animals (Dooley 1972;Butler et al. 1983). Witherington et al. (2012) examined Sargassum habitat to determine how important this habitat is to juvenile sea turtles. From 1992 to 2004, they observed 1,884 turtles of four species in the Atlantic Ocean and Gulf of Mexico. ...
... From 1992 to 2004, they observed 1,884 turtles of four species in the Atlantic Ocean and Gulf of Mexico. Data from observing three juvenile Kemp's ridleys showed that they spend 97% of the day and 87% of the night within 1 m of the surface (Witherington et al. 2012). Adults spend less time at the surface and more time diving deep into open-water habitats. ...
... After identification of a general H recruitment trajectory best aligned with CTS and TTS NSE, potential association with climate was explored. Given the importance of Sargassum sp. as a developmental habitat for oceanic sea turtle species (Witherington et al. 2012 Stepwise regression (Minitab 20 , entry α = 0.05) computed a best fit equation between monthly climate values and temporal decline in proportionate H recruitment C eq. A second stepwise regression equation (entry α = 0.5, P eq.) reproduced particle emigration rates (2003 to 2010) predicted by Putman et al. (2013). ...
... AMO and AMM). This association is ecologically plausible given increased occurrence of Sargassum, a floating macroalgae recognized as critical habitat for oceanic sea turtles (Witherington et al. 2012), in the western GOM during the warm phase of the Atlantic Multidecadal Oscillation (AMO) (Sanchez-Rubio et al. 2018). ...
Article
Full-text available
Abundance of Kemp’s ridley sea turtle Lepidochelys kempii Garman, 1880 in the Northwest Atlantic Ocean (NWA) is far less than in the Gulf of Mexico (GOM), but encounters of this species in the NWA have increased in recent decades. Consequently, improved opportunity exists to evaluate population structure, which is of particular interest given suggestions of renewed decline in annual survival rates in the GOM. Here we use size structure for Kemp’s ridley sea turtles captured (n = 617) by research trawling in the South Atlantic Bight (SAB) to assess survival since 1990 following age assignment using recently published size-at-age keys. With limited exception, the ratio of older (≥age 10) to younger (ages 1 to 9) sea turtles captured randomly was overwhelmingly stable and best aligned with high (≥0.9) annual neritic survival in theoretical models with fixed annual hatchling (H) recruitment. When annual H recruitment reflected exponential increase in H production since 1985, following low and generally stable production between 1966 and 1984, reduced H emigration proportion from the GOM to NWA and further increase in annual neritic survival were required to achieve the size/age structure reported for in-water data. Stepwise regression using monthly values for 5 climate indices simulated (adj. r ² = 0.77) proportionate annual H decline, which better explained observed survey size/age structure than climate-based prediction (adj. r ² = 1.00) of published particle emigration rates. Temporal decline in proportionate H recruitment to the NWA should increase retention of juveniles in the GOM to further enhance multi-generational population rebuilding.
... Recently, van der Zee et al. 22 suggested that changes in contributions observed in a juvenile mixed stock in Bonaire could be associated with a variation in the size of the source nesting populations. Third, green turtles leave nesting beaches as hatchlings and swim away from the coast to offshore habitats where they reside for a number of years 30 . Even though oceanic-stage green turtles are not complete passive drifters and may actively swim and orient 31 , there is substantial evidence suggesting marine turtle juvenile dispersal is also influenced by oceanographic currents, especially during the first few years of their life cycle [32][33][34] (but see 35 ). ...
Article
Full-text available
The distribution of marine organisms is shaped by geographic distance and oceanographic features like currents. Among migratory species, individuals from multiple populations may share feeding habitats seasonally or across life stages. Here, we introduce a modification for many-to-many mixed stock models to include distance between breeding and foraging sites as an ecological covariate and evaluate how the composition of green turtle, Chelonia mydas , juvenile mixed stock aggregations changed in response to population growth over time. Our modified many-to-many model is more informative and generally tightens credible intervals over models that do not incorporate distance. Moreover, we identified a decrease in genetic diversity in a Florida nesting site and two juvenile aggregations. Mixed stock aggregations in central Florida have changed from multiple sources to fewer dominant source populations over the past ~ 20 years. We demonstrate that shifts in contributions from source populations to mixed stock aggregations are likely associated with nesting population growth. Furthermore, our results highlight the importance of long-term monitoring and the need for periodical reassessment of reproductive populations and juvenile aggregations. Understanding how mixed stock aggregations change over time and how different life stages are connected is fundamental for the development of successful conservation plans for imperiled species.
... 37% in LUa). Ochrophyta appeared poorly attractive to green turtles (but see Awabdi et al., 2013 for a counter-example), probably due to indigestibility (Witherington et al., 2012) or low protein content (Fiset et al., 2019). Low diet richness and diversity in the HUa contrast with the pattern of relatively higher numbers of diet items reported in foraging areas relatively less degraded (Sazima and Sazima, 1983;Seminoff et al., 2002;López-Mendilaharsu et al., 2005;Makowski et al., 2006;Arthur and Balazs, 2008;Awabdi et al., 2013;Santos et al., 2015), and may have an impact on turtles' ...
Article
Full-text available
This study evaluated the influence of environmental degradation on the nutritional value of the main marine macrophytes consumed by green sea turtles (Chelonia mydas) in areas with different degrees of urbanization. Macrophyte assemblages in the highly urbanized area (HUa) showed lower richness compared to the lightly urbanized area (LUa) (Mann-Whitney U test: 10.0 ± 3.6 SD genera and 11.9 ± 4.2 taxa per transect vs. 20.1 ± 7.0 genera and 23.5 ± 9.2 taxa per transect) respectively. Also, diet was poorer with 4.0 ± 1.6 genera per turtle (vs. 8.5 ± 4.0 in HUa) and less diverse with Shannon index of diversity = 0.45 ± 0.29 (vs. 0.64 ± 0.46 in LUa). Body condition was similar in both areas. About half of individuals were classified as having normal body condition, 14–15% as underweight and 23–34% as being emaciated. Fibropapillomatosis prevalence (χ² = 8.720; n = 222; df = 1; p = 0.003) was higher in the HUa but, in affected animals, severity was marginally non-significant (χ² = 5.721; n = 82; df = 2; p = 0.057). Significant differences in energy content (kcal) were detected between areas in both summer (S) and winter (W). All ANOVAs on total lipids (F = 22.15 [S] and 30.39 [W]), total water-soluble proteins (F = 327.65 [S] and 64.42 [W]) and total carbohydrates (F = 70.90 [S] and 27.62 [W]) showed high significance (p < 0.001). Carotenoids concentration yielded significant results for Halodule in summer and Hypnea in winter (ANOVAs, F = 39.42 and 13.07, respectively). For both, tests revealed that concentration was higher in LUa than HUa. High levels of phycobiliproteins and proteins in this area probably reflect nitrogen accumulation. Frequency and severity of fibropapillomatosis suggest that urbanization-caused alterations in species diversity and in chemical composition of marine plants affect green turtles' health. Light abstract The use of coastal areas by humanity is widespread and increasing. The impacts caused to the coastal environment, be it terrestrial, estuarine or marine, are important and affect numerous species. Our study evaluated the influence of environmental degradation on the nutritional value of the main algae eaten by the green turtle, one of the very few marine megaherbivores (those herbivores with body mass above 10 kg). Diet in the highly urbanized area was richer in proteins, lipids and carbohydrates (sugars) and lower in carotenoids (photosynthetic and photoprotectant pigments in algae and plants; precursors of vitamin A involved in oxygen transport in animals—animals do not synthetize such molecules). High levels in phycobiliproteins (photosynthetic pigments present in some algae) and proteins in the highly urbanized area probably result from organic pollution and nitrogen accumulation in coastal waters. Nitrogen compounds dissolved in water are a threat to vertebrates due to its toxicity and negative effects on the immune system. Our results suggest that algae chemical composition and severity of fibropapillomatosis (tumors caused by a herpesvirus in green sea turtles) are directly related through environmental alterations caused by urbanization.
... The switching in habitat and trophic niche during life history has been suggested to influence the exposure risks to litter according to individuals' size (Casale et al., 2008). Small individuals, transported relatively passively in upwellings and gyres (Witherington et al., 2012), and pelagic juveniles could be more exposed to litter than large individuals in these Table 3 For each hypothesis and each predictive variable (occurrence (%), dry mass (g), abundance (number of pieces)), determination coefficient (R 2 ) and p-value of the models selected. For Hypothesis 1, both country/area (Atlantic and Mediterranean -dark grey) and sub-region (Mediterranean -light grey) were tested. ...
Article
Full-text available
Sea turtles are considered as bio-indicators for monitoring the efficiency of restoration measures to reduce marine litter impacts on health. However, the lack of extended and standardised empirical data has prevented the accurate analysis of the factors influencing litter ingestion and the relationships with individual health. Historic data collected from 1988 and standard data collected from 2016 were harmonised to enable such analyses on necropsied loggerhead turtles (Caretta caretta) in eight Mediterranean and North-East Atlantic countries. Litter was found in 69.24 % of the 1121 individuals, mostly single-use and fishing-related plastics. Spatial location, sex and life history stage explained a minor part of litter ingestion. While no relationships with health could be detected, indicating that all individuals can be integrated as bio-indicators, the mechanistic models published in literature suggest that the high proportion of plastics in the digestive contents (38.77 % per individual) could have long-term repercussions on population dynamics.
... Pelagic Sargassum in the Atlantic Ocean constitutes a floating ecosystem serving as a habitat for marine species like sea turtles, seabirds, fish or invertebrates. Additionally, a number of micro-and macro-epiphytes have been described (Parr, 1939;Weis, 1968;Fine, 1970;Casazza and Ross, 1972;Ryland, 1974;Haney, 1986;Jobe and Brooks, 2009;Ballard and Rakocinski, 2012;Witherington et al., 2012;Jacobucci and Leite, 2014;Susilowati et al., 2015;Monroy-Velazquez et al., 2019), and a few of them are endemic species. Endophytic and epiphytic communities of small eukaryotes are likely to be involved in the growth of Sargassum, and might contribute to nutrient uptake, macroalgae spore release and germination, the defense against bactericidal pathogens and other competing organisms, reproduction and settlement (Egan et al., 2013;Florez et al., 2017;Van Der Loos et al., 2019). ...
Article
Full-text available
Rafts of drifting pelagic Sargassum that are circulating across the Atlantic Ocean are complex ecosystems composed of a large number of associated species. Upon massive stranding, they lead to various socio-environmental issues including the inflow of contaminants and human health concerns. In this study, we used metabarcoding approaches to examine the differences in both the eukaryotic- and prokaryotic-associated communities from Sargassum present in two islands of the Lesser Antilles, namely Guadeloupe and Martinique. We detected significant differences in microbial community structure and composition between landing Sargassum, the surrounding seawater, and Sargassum from inland storage sites. In total we identified 22,214 prokaryotic and 17,679 eukaryotic OTUs. Among them, functional prediction analyses revealed a number of prokaryotes that might contribute to organic matter decomposition, nitrogen cycling and gas production, including sulfate-reducing bacteria at coastal landing sites, and methanogenic archaea at inland storage sites. We also found that Metazoan was the most abundant group in Sargassum samples, with nematode clades that presented exclusive or specific richness and abundance patterns depending on their Sargassum substrate. Together, these molecular inventories of the micro- and meiofauna communities provide baseline information for further characterization of trophic interactions, algal organic matter decomposition and nutrient transfers at coastal and inland storage sites.
... The high frequency of occurrence of plastic ingestion (86%) further confirms that green turtles are highly susceptible to feeding on plastic litter (Schuyler et al., 2012), with oceanic-stages being at higher risk in environments where marine litter is ubiquitous (Witherington et al., 2012). For example, Choi et al. (2021) found plastic ingestion in green turtles to be two orders of magnitude higher in pelagic than in subadults. ...
Article
Survivorship of early life stages is key for the well-being of sea turtle populations, yet studies on animals that distribute around oceanic areas are very challenging. So far, the information on green turtles (Chelonia mydas) that use the open NE Atlantic as feeding grounds is scarce. Strandings occurring in oceanic archipelagos can provide relevant information about the biology, ecology and current anthropogenic pressures for megafauna inhabiting the open ocean. In this study, we analysed stranding events of green turtles found in the Azores archipelago to investigate interactions with marine litter. In addition, we quantified and characterized litter items stranded on beaches to provide a direct comparison between the ingested items with the debris found in the environment. A total of 21 juvenile green turtles were found stranded in the region between 2000 and 2020 (size range: 12–49 cm, CCL). Overall, 14% of the animals were entangled in marine litter and 86% of the turtles necropsied had ingested plastic. The mean abundance of items ingested was 27.86 ± 23.40 and 98% were white/transparent. Hard plastic fragments between 1 and 25 mm were the most common shape recovered in the turtles, similarly to what was found on the coastline. All of the litter items analysed with pyrolysis GC-MS revealed to be polyethylene (PE). This study provides the first baseline assessment of interactions of plastic litter with juvenile green turtles found at the east edge of the North Atlantic Subtropical Gyre. The combination of these results supports the hypothesis that migratory megafauna that use remote oceanic islands as a feeding ground are exposed to anthropogenic litter contamination dominated by plastics, even when these regions are located far away from big industrial centers or populated cities.
... With the increase in the amount of algae, it began to cover a region much wider than the previously described (Gower and King, 2011), especially from 2011, with a recurrent occurrence in the Tropical Atlantic. The new formation was named "Great Atlantic Sargassum Belt (GASB)", extending from West Africa to the Gulf of Mexico, passing through northern Brazil (Fidai et al., 2020;de Széchy et al., 2012;Milledge et al., 2020;Ferrero et al., 2013;Witherington et al., 2016;Smetacek and Zingone, 2013;Johns et al., 2020;Wang and Hu, 2017;Wang et al., 2019;Langin, 2018). In 2018, it was estimated that the GASB was about 8850 km long, with more than 20 million tons of Sargassum biomass (Davis et al., 2021a). ...
Article
Pelagic Sargassum, usually found at the Sargasso Sea and the Western portion of the North Atlantic and Gulf of Mexico, has been detected in many new locations through the tropical Atlantic. The huge biomass found from the African coast to the Caribbean was called the Great Atlantic Sargassum Belt and is responsible for the stranding of tons of algae on coastal regions. Despite the environmental, social, and economic impacts, sargassum is a valuable source for multiple uses at the industry, such as alginates, cosmetics, recycled paper and bioplastics, fertilizers, and as raw material for civil construction. This work presents a systematic literature review on the use of algae at the civil construction sector, with a focus on the valorization of the pelagic Sargassum spp. biomass, by identifying the potential applications related to the use of other algal species. The review considered other genera of marine algae and marine angiosperms, resulting in a total of 31 selected articles. The marine grass Posidonia oceanica was the most used species, found in eight published papers, followed by the red alga Kappaphycus alvarezii with four studies. Two articles were available on the use of pelagic Sargassum spp. (S. fluitans and S.natans) for construction materials (adobe and pavement), with potential good results. The literature presented results from the use of marine algae and sea grasses for particleboards, polymeric and cemented composites, adobe, pavement, facades, and roofs. This article provides a state-of-the-art review of algal application in the civil construction sector and points out the main directions for the potentialities on the insertion of the Sargassum spp. biomass into the production chain of the sector.
... cipalmente por macroalgas del género Sargassum sp. (Witherington et al., 2012, Mansfield et al., 2017. En este trabajo se utilizó la distribución del sargazo pelágico como indicador de la distribución espacial de las áreas susceptibles de ser utilizadas como hábitats de desarrollo por crías y juveniles tempranos de tortugas marinas en el área de estudio. ...
Chapter
Full-text available
os ecosistemas marinos y costeros son sostenidos por un conjunto de procesos estructurales que ocurren en distintos niveles de organización ecológica (poblaciones, especies, comunidades), y que han sido objeto de numerosos estudios alrededor del mundo (Moberg y Rönbäck, 2003; Guannel et al., 2016). Estos procesos brindan estabilidad a los sistemas y fortalecen su viabilidad, resistencia y resiliencia (Timpane-Padgham et al., 2017). Asimismo, facilitan su funcionamiento y permiten que aporten servicios ambientales a las comunidades humanas, por lo que el conocimiento de las condiciones de sus poblaciones y hábitats críticos que los conforman es crucial para su preservación (Bouchard y Bjorndal, 2000; Bjorndal y Jackson, 2003; Friedman et al., 2017; Hammerschlag et al., 2019).
... Sargassum spp. are home to a wide range of species (many of which are endemic), provide nurseries and cover habitat for species going from invertebrates to fishes (including commercially important fish species), and endangered turtles (Casazza and Ross 2008;Witherington et al. 2012). ...
Article
Full-text available
Over the last decade, increasing proliferations of Atlantic Sargassum populations have led to massive beaching with disastrous environmental consequences. This study is a preliminary assessment of open ocean Sargassum spp. element concentration to assess their potential contribution on coastal ecosystems. Sargassum spp. samples from seven sites, collected along a transect from the center of the Atlantic Ocean to near the coast of Martinique (French West Indies), were analyzed to determine their potential metal and metalloid enrichment. Mean element concentrations from the Sargassum spp. samples were ranked in the following descending order: As > Fe > Mn > Al > Zn > V > Ni > Cu > Cr > Cd > Hg. Element concentrations are relatively low compared to previous results of beached Sargassum spp. except for As that need to be carefully considered before reusing Sargassum spp.
... Ten species are considered endemic to pelagic Sargassum ( Fig. 1; Hemphill 2005), exhibiting specialized coloration and morphology to camouflage with their macroalgal habitat. Many larger, migratory species, including larval American and European eels (Kracht and Tesch 1981;Siuda 2011), mahi mahi and flying fish (Beardsley 1967;Bortone et al. 1977;Casazza and Ross 2008), juvenile sea turtles (Carr and Meylan 1980;Witherington et al. 2012), and seabirds (Haney 1986;Moser and Lee 2012) temporarily visit aggregated mats to feed on motile epifauna, find shelter, and spawn. Their presence confirms the trophic, ecological, and commercial value of the pelagic Sargassum ecosystem, which has been the focus of regional (NMFS 2003) and international conservation efforts (Laffoley 2011). ...
Article
Full-text available
Pelagic Sargassum macroalgal rafts in the North Atlantic support sessile and motile epifauna that attract ecologically and economically important migratory organisms. Three prevalent pelagic Sargassum morphotypes vary in their degree of branching and foliation, and thus have different structural complexities that can influence their respective value as motile epifauna habitat. Sargassum fluitans III and S. natans I have denser foliation, creating a complex habitat; in contrast, S. natans VIII is more open and architecturally simple. In 2015/2016, 373 dip net samples of algae were collected from the Tropical Atlantic, Greater Caribbean, Gulf of Mexico, Gulf Stream, and Sargasso Sea. 20,975 individual motile epifauna from 32 taxa were recorded. Sargassum fluitans III supported higher densities of individuals and greater numbers of taxa than S. natans VIII or S. natans I, a pattern attributed to its more complex architecture and consistent with communities on benthic and floating macroalgae. Most assemblages comprised a few dominant and many rare motile epifauna; when compared to historical studies , dominant motile epifauna had shifted. These findings suggest important differences in ecological value between pelagic Sargassum morphotypes with implications for coastal and pelagic conservation strategies, which warrant consideration given recent shifts in morphotype distribution and recurring pelagic Sargassum inundation events.
... Flatback hatchling are entirely neritic [28] and they are thought to forage in murky, turbid waters [29]. Thus, the reduction in flatback RMR may reflect their patchily distributed or hard to find prey placing greater constraints on their energy consumption, compared to other species that associate with sargassum mats and may have more predictable and consistent access to food [30]. ...
Article
Full-text available
Background Sea turtle hatchlings must avoid numerous predators during dispersal from their nesting beaches to foraging grounds. Hatchlings minimise time spent in predator-dense neritic waters by swimming almost continuously for approximately the first 24 h post-emergence, termed the ‘frenzy’. Post-frenzy, hatchling activity gradually declines as they swim in less predator-dense pelagic waters. It is well documented that hatchlings exhibit elevated metabolic rates during the frenzy to power their almost continuous swimming, but studies on post-frenzy MRs are sparse. Results We measured the frenzy and post-frenzy oxygen consumption of hatchlings of five species of sea turtle at different activity levels and ages to compare the ontogeny of mass-specific hatchling metabolic rates. Maximal metabolic rates were always higher than resting metabolic rates, but metabolic rates during routine swimming resembled resting metabolic rates in leatherback turtle hatchlings during the frenzy and post-frenzy, and in loggerhead hatchlings during the post-frenzy. Crawling metabolic rates did not differ among species, but green turtles had the highest metabolic rates during frenzy and post-frenzy swimming. Conclusions Differences in metabolic rate reflect the varying dispersal stratagems of each species and have important implications for dispersal ability, yolk consumption and survival. Our results provide the foundations for links between the physiology and ecology of dispersal of sea turtles.
... The hatchlings produced along these beaches enter the water and many will travel to the Sargasso Sea in the western North Atlantic . Here, they likely associate with large dense mats of Sargassum spp. in open oceanic habitats for the first years of their life (Reich et al. 2007;Witherington et al. 2012;Mansfield et al. 2021). When they reach a minimum size of 20-25 cm straight-line standard carapace length (nuchal notch-posterior tip) hereafter referred to as SSCL, green turtles undergo ontogenetic diet and habitat shifts (Price et al. 2017) and begin feeding primarily on drift macroalgae and seagrass species found in neritic waters (Holloway-Adkins 2001; Redfoot and Ehrhart 2013;Long et al. 2021). ...
Article
Full-text available
Assessing the distribution, density, and abundance of organisms is essential for conservation and management of imperiled species. Simple counts of sampled individuals are often inadequate to make such estimates. This is especially true for highly mobile marine animals like green sea turtles (Chelonia mydas). We used distance sampling and density surface model techniques to generate estimates of green turtle abundance on foraging grounds at the Eastern Quicksands, located west of Key West, Florida, USA. From 2006 to 2018, we conducted 18 surveys of six standardized transect lines from which we estimated abundances, plotted spatial distributions, and identified spatial segregation of life stages using density surface models and null model analysis. The Eastern Quicksands represent one of the densest foraging aggregations of green turtles worldwide. Spatial segregation of Large Juvenile and Adult turtles was evident, which we hypothesize may be due to benthic habitat preferences and differing predator detection and avoidance strategies among the sea turtle life stages. Given the high green turtle densities in this foraging area, and recent increases in Florida green turtle nesting, combined with anthropogenic stressors to seagrass pastures, we foresee management concerns for long-term sustainability of seagrass at the Eastern Quicksands and recommend that this area be given Critical Habitat designation.
... In the North Atlantic, those patches consist primarily of algae of the genus Sargassum (Bolten, 2003). In those brightly illuminated habitats, the turtles find both cover and food consisting of a wide assemblage of small organisms such as sessile epiphytes (hydrozoans, barnacles, bryozoans), as well as jellyfishes, pelagic snails, fish eggs and drift carrion such as insects that accumulate nearby (Witherington, 2002;Witherington et al., 2012). All of these items are small, and some are often camouflaged or transparent, so they require sufficient visual acuity to be distinguished from an algal or underwater background. ...
Article
Full-text available
After completing embryonic development, marine turtle hatchlings emerge from their subsurface nest, generally at night, and crawl to the ocean ('sea finding'). That response depends upon the ability of the turtles to discriminate between the brighter seaward versus a dimmer landward horizon, followed by a positive phototaxis. While the crawls of most marine turtle hatchlings are well oriented and straight, those of leatherback hatchlings are sometimes interrupted by bouts of circling. We conducted experiments comparing the orientation and crawling behaviour of leatherbacks to those of loggerhead hatchlings to determine why those differences occur. The two species did not differ in the light spectra attracting the hatchlings, but leatherback thresholds for detection and for intensity discrimination were significantly higher than those of loggerheads. At the nesting beach, loggerheads under full (bright) or new (darker) moon conditions crawled straight to the ocean; circling rarely occurred. Leatherback crawls under a full moon were indistinguishable from those of loggerheads, but during new moon trials, when horizon brightness differences approached leatherback intensity discrimination thresholds, circling increased significantly. We conclude that circling is probably used by leatherbacks to reinforce orientation decisions when horizon cues become more difficult to discern. Circling could be costly as it lengthens the crawl and increases exposure to terrestrial predators. We hypothesize that those costs persist because other visual adaptations affecting sensitivity enhance the ability of leatherbacks to detect prey, mates or favourable habitats in an open ocean environment.
... Pelagic Sargassum have begun blooming in the North Equatorial Recirculation Region (NERR), and due to the wind (driven Langmuir-circulation) (Rhyter,1956) and ocean currents (Loop current and Gulf Stream), those algae are transported throughout the North the Atlantic Ocean, to the Sargasso Sea, the Gulf of Mexico and the Caribbean Sea (Johnson et al., 2013;Wang et al., 2019). Sargassum rafts provide an essential ecosystem habitat and refuge for different marine organisms Witherington et al., 2012) and are notably for marine species of high economic importance (Hu et al., 2016;Lapointe et al., 2014). ...
Article
Since 2011, the Caribbean Islands have witnessed unprecedented massive stranding of a pelagic brown algal Sargassum spp. inducing damages for coastal ecosystems and economy. By accumulating heavy metals, Sargassum can play a role in contaminant transportation from offshore to the coast. In 2019, three genotypes of Sargassum (S. fluitans III, S. natans I, and VIII) were sampled in seven stations along a 3400 km transect in the Atlantic Ocean. Concentrations of 15 heavy metal(loid)s elements were analyzed by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Mean metal concentrations were ranked following descending order: As >Fe > Al > Mn > Cd > Zn > Ni > V > Cu > Cr > Hg. The metalloid As was the most abundant contaminant with a maximum value of 115 ppm, previously observed in the Caribbean area (80–150 ppm). At Atlantic Ocean Basin-scale, metallic element concentrations do not present spatial longitudinal gradients. Genotypes S. fluitans III and S. natans (I and VIII), present differents metal(loid)s contamination distinct patterns.
... Over the past decade, the Atlantic Ocean has seen a massive proliferation of brown algal mats composed of pelagic Sargassum, particularly S. natans and S. fluitans (Lapointe et al., 2021). Within their native habitat such as the Sargasso Sea, these floating macroalgae provide invaluable habitation for a diverse marine ecosystem (Coston-Clements et al., 1991;Witherington et al., 2012). However, since 2011, massive amounts of pelagic Sargassum algae have begun washing ashore on the coasts of the Caribbean, Gulf of Mexico, and West Africa in events known as golden tides (Amador-Castro, 2021;Wang and Hu, 2016). ...
Article
Since 2011, a massive influx of pelagic brown algae Sargassum has invaded coastlines causing environmental and economic disaster. Valorizing this plentiful macroalgae can present much needed economic relief to the areas affected. Here the production of biodiesel and a high-value alginate stream using Sargassum biomass collected from the coast of Quintana Roo, Mexico is reported. Biomass was pretreated via AEA (Alginate Extraction Autohydrolysis) and enzymatic saccharification via fungal Solid State Fermentation, releasing 7 g/L total sugars. The sugar mixture was fermented using engineered Yarrowia lipolytica resulting in 0.35 g/L total lipid titer at the lab tube scale. Additionally, the capability of extracting 0.3875 g/g DW of a high-value, purified alginate stream from this material is demonstrated. The findings presented here are promising and suggest an opportunity for the optimization and scale up of a biodiesel production biorefinery for utilization of Sargassum seaweeds during seasons of high invasion.
... We fit generalized additive models (GAMs) with remotely sensed covariates, including sea surface temperature (SST), bathymetry, and salinity, to examine species-specific and spatiotemporal variation in time-at-surface patterns. Furthermore, while a handful of studies on marine turtles and ocean fronts can be found for several regions in the Pacific Ocean (e.g., [34,35]), or the North Atlantic (e.g., [36]), similar studies for the Gulf of Mexico are rare [37] or nonexistent. Therefore, one aspect of our study explicitly examines the potential connection between turtle dive patterns and ocean fronts in the Gulf of Mexico. ...
Article
Full-text available
The aftermath of the 2010 Deepwater Horizon oil spill highlighted the lack of baseline spatial, behavioral, and abundance data for many species, including imperiled marine turtles, across the Gulf of Mexico. The ecology of marine turtles is closely tied to their vertical movements within the water column and is therefore critical knowledge for resource management in a changing ocean. A more comprehensive understanding of diving behavior, specifically surface intervals, can improve the accuracy of density and abundance estimates by mitigating availability bias. Here, we focus on the proportion of time marine turtles spend at the top 2 m of the water column to coincide with depths where turtles are assumed visible to observers during aerial surveys. To better understand what environmental and oceanographic conditions influence time at surface, we analyzed dive and spatial data from 136 satellite tags attached to three species of threatened or endangered marine turtles across 10 years. We fit generalized additive models with 11 remotely sensed covariates, including sea surface temperature (SST), bathymetry, and salinity, to examine dive patterns. Additionally, the developed model is the first to explicitly examine the potential connection between turtle dive patterns and ocean frontal zones in the Gulf of Mexico. Our results show species-specific associations of environmental covariates related to increased time at surface, particularly for depth, salinity, and frontal features. We define seasonal and spatial variation in time-at-surface patterns in an effort to contribute to marine turtle density and abundance estimates. These estimates could then be utilized to generate correction factors for turtle detection availability during aerial surveys.
... Over the past decade, the Atlantic Ocean has seen a massive proliferation of brown algal mats composed of pelagic Sargassum, particularly S. natans and S. fluitans (Lapointe et al., 2021). Within their native habitat such as the Sargasso Sea, these floating macroalgae provide invaluable habitation for a diverse marine ecosystem (Coston-Clements et al., 1991;Witherington et al., 2012). However, since 2011, massive amounts of pelagic Sargassum algae have begun washing ashore on the coasts of the Caribbean, Gulf of Mexico, and West Africa in events known as golden tides (Amador-Castro, 2021;Wang and Hu, 2016). ...
... Indeed, both marine turtle species consumed terrestrial insects, such as butterflies, flies, beetles and grasshoppers, but only in trace amounts. This has been demonstrated previously in low quantities but mostly in young oceanic-pelagic posthatchling marine turtles (Richardson and McGillivary 1991;Witherington 2002;Witherington et al. 2012;McDermid et al. 2018). Very few records exist of marine turtles that are not post-hatchlings consuming terrestrial insects (Godley et al. 1998), this study included. ...
Article
Full-text available
Dietary studies provide key insights into threats and changes within ecosystems and subsequent impacts on focal species. Diet is particularly challenging to study within marine environments and therefore is often poorly understood. Here, we examined the diet of stranded and bycaught loggerhead ( Caretta caretta ) and green turtles ( Chelonia mydas ) in North Cyprus (35.33° N, 33.47° E) between 2011 and 2019. A total of 129 taxa were recorded in the diet of loggerhead turtles ( n = 45), which were predominantly carnivorous (on average 72.1% of dietary biomass), foraging on a large variety of invertebrates, macroalgae, seagrasses and bony fish in low frequencies. Despite this opportunistic foraging strategy, one species was particularly dominant, the sponge Chondrosia reniformis (21.5%). Consumption of this sponge decreased with increasing turtle size. A greater degree of herbivory was found in green turtles ( n = 40) which predominantly consumed seagrasses and macroalgae (88.8%) with a total of 101 taxa recorded. The most dominant species was a Lessepsian invasive seagrass, Halophila stipulacea (31.1%). This is the highest percentage recorded for this species in green turtle diet in the Mediterranean thus far. With increasing turtle size, the percentage of seagrass consumed increased with a concomitant decrease in macroalgae. Seagrass was consumed year-round. Omnivory occurred in all green turtle size classes but reduced in larger turtles (> 75 cm CCL) suggesting a slow ontogenetic dietary shift. Macroplastic ingestion was more common in green (31.6% of individuals) than loggerhead turtles (5.7%). This study provides the most complete dietary list for marine turtles in the eastern Mediterranean.
... Indeed, while it has been demonstrated that Sargassum algae provide ecosystem services, habitats, and shelter for various organisms in a structurally sterile ocean ecosystem (Witherington et al., 2012;Bertola et al., 2020), the beachings over the past decade have induced health risks for the population and have had considerable socioeconomic impacts (Franks et al., 2012). For example, when looking at the French West Indies, the Guadeloupe archipelago, and Martinique, the findings are as follows. ...
Article
Full-text available
The massive Sargassum algae beachings observed over the past decade are a new natural hazard currently impacting the island states of the Caribbean region (human health, environmental damages, and economic losses). This study aims to improve the prediction of the surface current dynamic leading to beachings in the Lesser Antilles using clustering analysis methods. The input surface currents were derived from the Mercator model and the Hybrid Coordinate Ocean Model (HYCOM) outputs in which we integrated the windage effect. Past daily observations of Sargassum beaching on Guadeloupe coasts and satellite-based Sargassum offshore abundance were also integrated. Four representative current regimes were identified for both Mercator and HYCOM data. The analysis of the current sequences leading to beachings showed that the recurrence of two current regimes is related to the beaching peaks respectively observed in March and August. The performance score of the predictive model showed that the HYCOM data seem more suitable to assess coastal Sargassum hazard in the Lesser Antilles. For 1 year of tests (i.e., 2021), the decision tree accuracy respectively reached 70.1 % and 58.2 % for HYCOM and Mercator with a temporal uncertainty range ±3 d around the forecast date. The present clustering analysis predictive system, requiring lower computational resources compared to conventional forecast models, would help improve this risk management in the islands of the region.
... The beaches of SE Florida serve as a major nesting site for the western Atlantic population of loggerhead turtles (Caretta caretta; Carr, 1986;Casale and Tucker, 2017;Witherington et al., 2009). Posthatchling and juvenile loggerheads, originating from nests in this region, associate with offshore Sargassum mats (Mansfield et al., 2014;Witherington, Hirama, and Hardy, 2012). The increased density of both beached and nearshore Sargassum, however, may provide both adult and hatchling sea turtles with a unique set of obstacles that might make reaching the beach and nesting energetically more expensive (Maurer et al., 2021). ...
Article
Full-text available
Schiariti, J.P. and Salmon, M., 0000. Impact of sargassum accumulations on loggerhead (Caretta caretta) hatchling recruitment in SE Florida, United States. Journal of Coastal Research, 00(0), 000-000. Coconut Creek (Florida), ISSN 0749-0208. Hatchling loggerhead turtles emerge from subsurface nests on oceanic beaches at night, then crawl toward and enter the sea. Recently, increases in a floating algae (Sargassum) have been reported in the mid-Atlantic and Caribbean, resulting in large accumulation on Florida's beaches. The purpose of this study was to determine if, during the 2020 nesting season, these accumulations acted as a barrier that prevented the hatchlings from crawling to the sea. Seasonal changes in Sargassum density were recorded to determine when, and under what circumstances, hatchlings could cross the accumulated wrack. There was a significant overlap between when Sargassum accumulations peaked and when the turtles emerged, with the result that during the 2020 nesting season the number of hatchlings that entered the ocean was reduced by an estimated 22%. These results suggest that algal accumulations represent a significant threat that could potentially impede the recovery of loggerhead populations that currently are either threatened or endangered, worldwide.
... The green turtle has a complex life cycle that includes the use of different food resources and foraging strategies at different life stages. After hatching, green turtles enter an epipelagic or oceanic stage, during which there may be continuous travel and an omnivorous diet in pelagic drift habitats (e.g., rafts of Sargassum spp. in the Atlantic) at or near the ocean surface (Witherington et al. 2012;Hardy et al. 2018;Mansfield et al. 2021). At about 25 cm (SCL min ), most individuals in the West Atlantic settle on benthic foraging grounds (Meylan et al. 2011) at which seagrasses or marine algae are their primary food source (Bjorndal 1997). ...
Article
Full-text available
To understand the demographic responses of green turtles to seagrass decline, we examined a data set from study of a mixed-stock foraging aggregation of immature green turtles, Chelonia mydas, collected in Bermuda (32o18’N, − 64o46’W) over five decades. Average turtle size (SCLmin) and mass declined by 22.3% and 58.2%, respectively. Aggregation size structure shifted to smaller sizes and now consists of more small turtles and fewer large turtles. Density (turtles ha⁻¹) increased significantly but biomass (kg ha⁻¹) remained unchanged and low compared to C. mydas biomass observed elsewhere. Green turtles exhibited reduced site fidelity during two portions of the study period, suggesting increased foraging effort. Reduction in turtle body condition index and seagrass coverage occurred from offshore to inshore. Changes in aggregation composition and behavior were consistent with expectations given a documented decline in seagrass availability, combined with increased output from source rookeries. Apparent response to resource decline is traced back to 1976, well before seagrass loss was first documented. Green turtles and their primary food source (Thalassia testudinum) are at the northern limit of their range in Bermuda, where seagrasses would be expected to have a reduced tolerance for natural grazing pressure and increased susceptibility to synergistic stressors, especially temperature, bioturbation and phosphorus limitation. Our results suggest that synergistic stressors, and not green turtles alone, have produced the observed reduction in seagrasses on the Bermuda Platform. Given that seagrass declines have been reported worldwide, our findings may suggest how green turtles will respond elsewhere.
Chapter
Full-text available
This Region comprises 48 parties, amongst countries and territories (Anguilla, Antigua & Barbuda, Aruba, Bahamas, Barbados, Belize, Bermuda, Bonaire, British Virgin Islands, Canada, Cape Verde, Cayman Islands, Colombia, Costa Rica, Cuba, Curacao, Dominica, Dominican Republic, French Atlantic & Channel coasts, French Guiana, Grenada, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Martinique, Mexico, Monserrat, Nicaragua, Panama, Portugal, Puerto Rico, Saba (Dutch West Indies), Saint Barthélemy, Saint Vincent & The Grenadines, Saint Eustach, Saint Maarten, Saint Kitts & Nevis, Saint Lucia, Saint Pierre & Miquelon, Suriname, Trinidad & Tobago, United Kingdom [U.K.], the United States [U.S.], U.S. Virgin Islands, Venezuela). The present report includes a total of 19 parties (39.5%, Belize, Canada, Colombia, Cuba, Curacao, France Atlantic, French Guiana, Guadeloupe, Guatemala, Martinique, Mexico, St. Bartholome, St. Eustach, St. Lucia, St. Martin, St. Pierre et Miquelon, UK-Ireland, the U.S., and Venezuela). It demands a large and constant effort to bring together the detailed information from all the parties, and although there are still several parties to include in this document, as it stands it is intended to provide panorama of the complete information on the reproductive ecology and status for sea turtle populations in the North Atlantic.
Article
Full-text available
For species reaching maturity at a range of ages or sizes, factors that influence juvenile growth and size at maturity may have lasting impacts on overall fitness. Assessing when animals reach maturity is especially challenging for species which are difficult to follow through time as a result of highly migratory behavior, long life spans, or both. We examined nesting female size in a reproductive assemblage of green turtles (Chelonia mydas) and loggerheads (Caretta caretta) on the east coast of Florida, USA. We used a long‐term dataset from 1982 to 2019 to estimate a minimum size at maturity interval on the basis of two standard deviations below mean female size for each species. The minimum size intervals for green turtles (81.4–89.3 cm) and loggerheads (68.1–79.1 cm) were lower than most previous estimates in the literature, many of which were simply the smallest individual ever observed. There was a significant decrease in the upper bound of the minimum size interval over the study period for both green turtles (1.6 cm) and loggerheads (4.1 cm). These shifts in size at maturity may be the result of changes in population demographics, habitat quality, and behavioral reactions to these changes. The development and periodic reassessment of robust estimators of maturity are an important part of programs centered around the monitoring and conservation of vulnerable wildlife populations.
Article
Full-text available
Between 2011 and 2020, 6,790 visual observations of holopelagic Sargassum were recorded across the North Atlantic Ocean to describe regional distribution, presence, and aggregation state at hourly and 10 km scales. Influences of oceanographic region and wind/sea conditions as well as temporal trends were considered; marine megafauna associates documented the ecological value of aggregations. Holopelagic Sargassum was present in 64% of observations from the western North Atlantic. Dispersed holopelagic Sargassum fragments and clumps were found in 97% of positive observations whereas aggregated windrows (37%) and mats (1%) were less common. Most field observations noted holopelagic Sargassum in quantities below the AFAI algorithm detection limit for the MODIS sensor. Aggregation state patterns were similar across regions; windrow proportion increased with higher wind speeds. In 8 of 10 years in the Sargasso Sea holopelagic Sargassum was found in over 65% of observations. In contrast, the Tropical Atlantic and Caribbean Sea exhibited greater inter-annual variability (1–88% and 11–78% presence, respectively) that did not align with extremes in central Atlantic holopelagic Sargassum areal coverage determined from satellite observations. Megafauna association patterns varied by taxonomic group. While some study regions were impacted by holopelagic Sargassum dynamics in the equatorial Atlantic, the Sargasso Sea had consistently high presence and operated independently. Field observations capture important dynamics occurring at fine spatiotemporal scales, including transient aggregation processes and ecological value for megafauna associates, and therefore remain essential to future studies of holopelagic Sargassum .
Article
Full-text available
פסולת ימית נפוצה בכל חלקי הסביבה הימית, משפיעה רבות עליה ועל החיים בה, ומהווה מקור לדאגה עולמית. צבי ים, הנפוצים בכל העולם, משתמשים בבתי גידול מרובים במהלך מחזור חייהם, חשופים למגוון רחב של מפגעים וכמות גבוהה של פסולת. אוכלוסיית צבי הים בים התיכון נמצאת תחת איום, בפרט באגן הלבנט שבו אחוזי התמותה הגבוהים ביותר בים בתיכון. המפגש בין צבי הים לסוגי הפלסטיק השונים מתרחש בכל אזורי המחייה שלהם ולכן נבחרו כביו אינדיקטורים עבור ניטור השפעת הפסולת הימית על בע"ח. הפגיעה מפלסטיק מגוונת, ומתחלקת לשני סוגים עיקריים: הסתבכות ועיכול. הפסולת שגורמת להסתבכות מתחלקת לשתי קטגוריות עיקריות: ציוד דיג (אקטיבי ופסיבי) ופסולת ממקור יבשתי. הפגיעה מציוד דיג יכולה לנבוע מדיג אקטיבי ברשתות דיג ומכמורת, קרסים ומערכי חכות בעודן פעילות במרחב המחייה של הצבים. שחרור הצב שהסתבך ללא טיפול מתאים עלול להוביל בהדרגה גם להסתבכות פסיבית שגורמת לזיהומים, נמקים, לתזונה לקויה, לאבדן גפיים ולמוות. דו"ח זה מציג לראשונה מידע על השפעת פסולת הפלסטיק על צבי ים בישראל ממידע שנאסף במשך 22 שנים במרכז להצלת צבי הים וכן בפיילוט של שנה בניטור פסולת בקיבות צבי הים, שנעשה בשיתוף פעולה של המרכז עם החברה לחקר ימים ואגמים לישראל. ניתוח המידע מצביע על לא פחות ממצב חירום סביבתי. המרכז הארצי להצלת צבי ים אוסף נתונים בנוגע לפגיעות צבים החל משנת 1999 . בעבודה זו מוצגות הרשומו ת ממסד הנתונים בנוגע ל-1,473 צבים שנאספו בשנים 1999-2021 . הרשומות מחולקות על פי מין הצב, פיזיולוגיה )אורך, משקל, זוויג( וסוג הפגיעה. כשליש מהצבים (566 רשומות, חיים או מתים) תועדו כנפגעים ממפגעים הקשורים בפלסטיק. הפגיעותמפסולת פלסטיק מחולקות לשלושה סוגים: פגיעות פלסטיק שונות (n=115) המהוות 21% מסך הפגיעות, פגיעות דיג (n=255) מהוות 47% והפגיעות משקי פוליפרופילן (n=176) המהוות 32% . כחמישית מהצבים המטופלים ( 22% , n=123) לא שרדו . בשנים 2017-2021 נצפתה עליה חדה במספר הצבים הצעירים שנפצעו או מתו בחופי ישראל בגלל הסתבכות (צוואר וגפיים) בשקים ארוגים מפוליפרופילן. דבר זה עלול להשפיע באופן חמור על הגיוס לאוכלוסייה. לכן המרכז להצלת צבים זיהה את השקים כסכנת חיים מרכז ית עבור צבי הים הצעירים, בשלב החיים הפלאגי. שקים אלו משמשים במגוון תעשיות, אך הכתובות עליהם מציינות שייעודם במקור הוא לאריזת מזון של בעלי חיים בחקלאות ונמצאו מספר ספינות שיכולות להיות קשורות למקור השקים בים. ההסתבכויות בשקי פוליפרופילן שכיחות יותר ( 88% מצבי הים חומים, 48% מצבי הים הירוקים) במהלך חודשי הקיץ (יוני-ספטמבר) לאורך כל קו החוף של ישראל . נתיחות לאחר המוות לבדיקת נוכחות פסולת במערכות עיכול בוצעו ב- 2021 במרכז ההצלה ובחקר ימים ואגמים בשני מיני צבי ים: 6 צבי ים ירוקים ו- 15 צבי ים חומים (שנבחרו כמין המייצג באיחוד האירופי). בכל הפרטים נמצאה פסולת במערכת העיכול. בצבי הים הירוקים נמצאה כמות גבוהה בהרבה של פסולת בהשוואה לצבי הים החומים, אך ריכוז הפסולת במערכות העיכול היה גבוה יותר בצב הים החום. ריכוז הפסולת היה גבוה משמעותית בצבים הצעירים בהשוואה לבוגרים, זאת ככל הנראה כתוצאה מאזורי המחייה השונים. חוטי דיג הופיעו ב 8% מקיבות הצבים שנותחו, ייצוג גבוה משמעותית ביחס לתפוצתם בפסולת הצפה או השקופה שנוטרה באזורינו. ניטור הפסולת במערכות עיכול של צבים החל בשנת 2021 ולכן לא נאספו מספיק נתונים על מנת להבין לעומק את הקשר בין סיבת המוות לתכולת הפלסטיק במערכת העיכול. הנתונים המובאים בעבודה זו מייצגים את הנתונים שנאספו במרכז להצלת צבים בלבד וקשה להעריך את אחוז הצבים הפגועים המטופלים במרכז ההצלה מכלל האוכלוסייה. לכן ככל הנראה נתוני הדוח מספקים הערכה בחוסר של כמות הצבים הפגועים והמתים כתוצאה מפסולת ימית. ההשפעה החמורה של הפסולת הימית על צבי הים באזורינו, ובפרט הסתבכות הצבים בפסולת ימית , מחייבת המשך מעקב והבנת התנהגות הצבים והפסולת באזורנו על מנת למזער את הפגיעה העתידית .
Technical Report
Full-text available
This is a 2021 update to a NOAA guidance document originally published in 2003.
Article
Full-text available
Blooms and coastal inundations of pelagic Sargassum have caused major problems to coastal communities and ecosystems throughout the tropical Atlantic over the past decade. Understanding Sargassum growth, movement, and mortality is essential to being able to predict and mitigate these events. In principle, tropical cyclones that occur in this area could have an impact on all three processes. In a recent article, Sosa‐Gutierrez et al. (2022, https://doi.org/10.1029/2021GL097484) investigated the potential impacts of tropical cyclones (TCs) on pelagic Sargassum using satellite‐based Sargassum maps and 86 hurricane tracks during 2011–2020. Their statistical analysis showed an average drop of 40% in Sargassum coverage under TC trajectories, which was attributed to possible sinking of Sargassum. Here, we discuss implications of these findings, and advocate continued research on how storms and other physical factors influence the dynamics of growth, movement, and mortality in this ecologically and economically important macroalgae.
Preprint
Full-text available
The massive Sargassum algae strandings observed over the past decade are the new natural hazard that currently impacts the island states of the Caribbean region (human health, environmental damages, and economic losses). This study aims to improve the prediction of the surface current dynamic leading to beachings in the Lesser Antilles, using clustering analysis methods. The input surface currents including windage effect were derived from the Mercator model and the Hybrid Coordinate Ocean Model 10 (HYCOM). Past daily observations of Sargassum stranding on Guadeloupe coasts were also integrated. Four representative current regimes were identified for both Mercator and HYCOM data. The analysis of the backward current sequences leading to strandings showed that the recurrence of two current regimes is related to the beaching peaks observed respectively in March and in August. A decision tree classifier was built and its accuracy reaches 73.3% with 0.04°-scale HYCOM data and 50.8% with 0.08°-scale Mercator data. This significant accuracy difference highlights the need of very small-scale current data (i.e., lower than 5 km scale) 15 to assess coastal Sargassum hazard in the Lesser Antilles. The present clustering analysis predictive system would help improve this risk management in the islands of this region.
Article
Green turtles foraging in coastal areas are exposed to land-based chemical pollutants that accumulate in the habitats to which they show high site fidelity. However, prior to coastal recruitment, they may be exposed to a different range of chemical threats. The recent development of species-specific in vitro bioassays for marine turtles allows for an effect-based assessment of toxicological endpoints. Blood was collected from green turtles of two life-stages, ‘recent recruits’ and ‘coastal residents’, in Hervey Bay and Moreton Bay. Organic contaminants were extracted from blood using the QuEChERS method, and cytotoxicity of the extracts measured in green turtle skin cells. Although not statistically significant, extracts from ‘coastal residents’ exhibited greater mean toxicity compared to ‘recent recruits’, possibly indicative of increased chemical accumulation from coastal habitat exposure. The bioassay results also indicated that turtles foraging in Hervey Bay are at greater risk of chemical exposure than those foraging in Moreton Bay.
Chapter
Full-text available
Um dos grandes desafios do setor da construção civil é a busca pela redução de resíduos oriundos dos mais diversos processos da produção industrial. Desta forma, é estimulada, no âmbito científico, a busca por alternativas que visam o reaproveitamento desses resíduos como matéria-prima na construção. Aliado a esta ideia, o 7º Encontro Nacional de Aproveitamento de Resíduos na Construção (ENARC) é um evento que visa incentivar a divulgação e discussão de ideias que possam embasar e desenvolver o setor da construção, levando em conta a ótica de preservação ambiental, redução de impactos e o reaproveitamento de resíduos.
Article
Various types of floating macroalgae and other floating matters have been reported in the global oceans and inland waters, and their remote detection has relied primarily on passive optical sensors. These sensors provide multiple spectral bands and frequent revisits, yet they all suffer from clouds. Synthetic aperture radar (SAR) imagers are active sensors that overcome this obstacle, yet their capacity in detecting macroalgae and other floating matters is generally unknown. Here, through statistical analysis and comparison of the Sentinel-2/MultiSpectral Instrument (MSI) and Sentinel-1/SAR imagery, we attempt to fill this knowledge gap. The types of floating matters considered in this study include macroalgae (Ulva Prolifera in the Yellow Sea, Sargassum horneri in the East China Sea, and Sargassum fluitans/natans in the Caribbean Sea), cyanobacteria (Microcystis, Nodularia spumigena, and Trichodesmium), dinoflagellates (green and red Noctiluca), organic matters (sea snots and brine shrimp cysts), and marine debris (driftwood). Of these, the only floating matter that can be definitively detected in Sentinel-1/SAR imagery is U. prolifera, followed by the occasional detection of S. fluitans/natans and driftwood. In all detection cases, the macroalgae features always appear in Sentinel-1/SAR imagery with positive contrast from the surrounding waters. Because of the all-weather measurements, SAR observations can therefore complement those from the optical sensors in monitoring and tracking U. prolifera and S. fluitans/natans in their respective regions.
Article
Full-text available
An in-water survey for immature endangered and threatened sea turtles in the coastal waters of southwest Florida during 1997-2003 yielded 191 Kemp's ridley (Lepidochelys hempi), 15 loggerhead (Caretta caretta), 13 green (Chelonia mydas), and one hybrid hawksbill (Eretmochelys imbricata)-loggerhead turtle. Mean carapace lengths were 40.3 cm minimum straightline carapace length (MSCL) for Kemp's ridley, 65.5 cm MSCL for loggerhead, and 51.6 cm MSCL for green turtles. Fibropapilloma tumors were found on seven of the green turtles and one loggerhead turtle. The mean growth rate of recaptured Kemp's ridleys was 6.3 cm/yr. The nearshore waters of Gullivan Bay in the Ten Thousand Islands are an important developmental habitat for the highly endangered Kemp's ridley turtle, and to a lesser degree, immature loggerhead and green turtles. © 2004 by the Marine Environmental Sciences Consortium of Alabama.
Article
Full-text available
Although the usual diet of Chelonia mydas comes from algae and sea grasses (plant material), animal material has been found in samples taken over the past 35 yr. The small black-brown protein sponge Chondrosia chucalla resembles the alga Codium arabicum in size, color, and texture, and both grow next to each other on the reefs. We hypothesize that turtles are actively seeking and eating these sponges and not mistaking them for C. arabicum. Both protein and silica sponges occur in the diet of Chelonia, but only 6.8% of the time are eaten in addition to their usual plant diet. Thirty different kinds of other animals were found in the samples, including Cnidaria, Mollusca, Crustacea, Insecta, Echinodermata, squid, fish, tumor flesh, and other animals but in low frequency (5%). Most of the miscellaneous nonfood debris items were terrestrial leaves, plastic, paper, string, fibers, hair, and paint chips but also in low frequency (<7%). Among animal food items known to have nutritional value, the protein sponge C. chucalla could be contributing an important nutritive factor, but this needs further research.
Article
Full-text available
Sea turtle hatchlings emerge from subsurface nests on oceanic beaches, crawl to the ocean, and swim out to sea. Once in the water, hatchlings at first swim almost continuously (a period called the frenzy). In this laboratory study, we compared the duration and diel pattern of frenzy and postfrenzy swimming activity among loggerhead, green turtle, and leatherback hatchlings from beaches in southeastern Florida. The frenzy of all species lasted one day (24 h). After the frenzy, hatchlings continued to swim during the day. Green and loggerhead hatchlings eventually became inactive at night, but leatherback hatchlings typically swam between 15-45% of the dark period. Because the frenzy is temporally similar in all species, its function may also be the same: escape from shallow waters near shore. Postfrenzy differences in diel activity may reflect contrasts among species in foraging, predator avoidance, and energy conservation strategies.
Article
Full-text available
Article
Full-text available
To collect data on green turtles Chelonia mydas near the Marquesas Keys, Florida, USA, we conducted haphazard, unmarked, nonlinear transect (HUNT) surveys from a moving vessel. During HUNTs, we recorded green turtle locations and made opportunistic captures. We found a unique foraging assemblage of subadult and adult green turtles in open-water seagrass habitat (3 to 5 m deep) at the eastern Quicksands, west of the Marquesas Keys. At an adjacent area in the Marquesas Keys (Mooney Harbor), we observed juvenile green turtles foraging in shallow seagrass habitat (<2 m). During 267 km of HUNTs, 370 green turtles (153 adults, 216 subadults, 1 juvenile) were recorded from the eastern Quicksands. At the Mooney Harbor site, 190 juvenile green turtles were sighted during 309 km of transects. Green turtles captured at the eastern Quicksands were adult and subadult animals that ranged from 69.3 to 108.5 cm straight carapace length (SCL; mean ± SD = 88.4 ± 10.6 cm, n = 31). Green turtles captured in Mooney Harbor were juveniles ranging from 27.0 to 59.3 cm SCL (mean = 44.0 ± 7.8, n = 41). Six repeatable, linear transects were surveyed during 3 sampling events at the eastern Quicksands. During these transects, 238 green turtles were observed. These spatial data were used in a nearest-neighbor analysis, which indicated that the distribution of green turtles at the eastern Quicksands was non-random and clumped. We hypothesize that adult and large subadult green turtles use deeper water habitats than juveniles, and this size-class partitioning may be due to differing habitat requirements and predation risk. Our analyses indicate that green turtles found at the eastern Quicksands form foraging herds.
Article
Full-text available
We used a turtle-mounted video and data-logging system (Crittercam; National Geographic Society, USA) to study underwater behaviour and dive patterns of green turtles, Chelonia mydas, at a coastal foraging area in the Gulf of California, Mexico, Between August 1997 and June 2002, units were deployed 36 times on 34 green turtles ranging from 64.1 to 96.7 cm in straight carapace length and 38.6 to 120.5 kg in weight. A total of 89.5 h of video was recorded with corresponding dive data (1065 total dives). Foraging was observed during 8 deployments (28 events) at depths of 3.0 to 32.0 m and occurred while turtles were swimming in the midwater column and stationary on the seafloor; 4 marine algae and 5 invertebrate prey species were identified. Resting behaviour was seen during 9 deployments (33 dives) as turtles set on the seafloor at depths of 7.0 to 26.5 m. Overall, 6 dive types were observed and labeled Type 1 to Type 6 dives. Green turtles foraged during Type 1, Type 3, and Type 5 dives, whereas they rested only during Type 1 dives. In addition to elucidating the importance of specific habitats and resources in neritic foraging areas, our results confirm that a variety of underwater behaviours can be reflected by 1 specific dive profile. These data indicate caution should be exercised when ascertaining in-water activity solely based on the appearance of dive profiles.
Article
Full-text available
The quantity and distribution of Sargassum in the Sargasso Sea, as estimated by various investigators, is reviewed. There has apparently been no significant change in the biomass of Sargassum from 1933 to 1981, except for an area northeast of the Antilles (20 to 25°N, 62 to 68°W), where measurements made in November 1977 and November 1980 were about 0.1% of values measured in February and March 1933. Because of the lack of change in the Bermuda, Bahamas, or Gulf Stream regions, the effect does not appear to be due to pollution or to broad climatic changes; it is most likely due to a seasonal change in Sargassum abundance or to a long-term shift of currents defining the southwestern boundary of the Sargasso Sea.
Book
Full-text available
This book is available for purchase, The 1993 version is available on the page at http://distancesampling.org/downloads/distancebook1993/index.html
Article
Full-text available
Green turtles Chelonia mydas are endangered, long-lived marine reptiles that display an ontogenetic shift in diet and habitat use during development. During their early life stage, juvenile green turtles in the southwestern Pacific inhabit the pelagic zone where they feed omnivorously on neustonic material. At approximately 44 cm curved carapace length they recruit to inshore foraging habitats where they become primarily herbivorous. In this study we investigate the change in stable isotope (delta C-13 and delta N-15) composition of green turtle epidermal tissue throughout their life history to examine this ontogenetic shift in diet and habitat as it occurs in a southwestern Pacific green turtle population. Turtles that had recently recruited to foraging grounds in Moreton Bay, Australia had significantly higher delta N-15 isotopic signatures when compared with all other life history groups examined and significantly lower delta C-13 when compared with all age classes other than pelagic juveniles. Adult and large immature turtles had similar isotopic signatures and were both significantly enriched in C-13 when compared with hatchlings and small immature turtles. These results support previous observations that suggest pelagic juveniles are foraging in a different habitat and at a higher trophic level than turtles captured in the neritic environment. This is the first study to capture the entire life history of green turtles in terms of foraging ecology and supports the ontogenetic shift previously observed in traditional diet and behavioral studies of green turtles.
Article
Full-text available
The pelagic juvenile stage of sea turtles is poorly studied. We present a growth model and estimates for duration of the pelagic juvenile stage for loggerhead sea turtles Caretta caretta in the North Atlantic based on length-frequency analyses and sizes of young-of-the-year stranded in the Azores. The size-specific growth model is a monotonic, nonlinear, declining function. The growth model is consistent with growth rates calculated from recaptures of tagged loggerheads. Loggerheads leave the pelagic habitat and recruit to neritic habitats over a range of sizes from 46 to 64 cm curved carapace length (CCL). From this size range and the growth model, we estimate the duration of the pelagic stage varies from 6.5 to 11.5 yr. Nonparametric smooths of the size frequency distributions of loggerheads in pelagic (n = 1692) and neritic (n = 1803) habitats intersect at 53 cm CCL, which is equivalent to an 8.2 yr duration for the pelagic stage. More growth data from loggerheads <2 yr old would strengthen the database for our growth model and perhaps lengthen our estimates of the duration of the pelagic stage. Incorporating our estimates for duration of the pelagic juvenile stage into the stage-based population model developed for North Atlantic loggerheads would have a major effect on estimates of population growth.
Article
Full-text available
Operational longline fishery characteristics, bycatch information, and loggerhead turtle satellite tracks were all used in conjunction with remotely sensed sea surface temperature data to identify the environmental area where the majority of loggerhead turtle bycatch occurred in the Hawaii-based longline fishery during 1994 to 2006. In the first quarter of each calendar year from 1994 to 2006, the majority of shallow longline sets and associated loggerhead turtle bycatch were above 28°N, which corresponds to the area near the North Pacific Subtropical Frontal Zone. Based on the thermal ranges of bycatch, sets and the satellite-tagged turtles, it was recommended that shallow sets should only be deployed in waters south of the 18.5°C (∼65.5°F) isotherm to decrease loggerhead turtle bycatch. This recommendation formed the basis for the TurtleWatch tool, a map providing up-to-date information about the thermal habitat of loggerhead sea turtles in the Pacific Ocean north of the Hawaiin Islands. TurtleWatch was released to fishers and managers in electronic and paper formats on December 26, 2006, to assist in decision making during the first quarter of 2007. Fishery information from 2007 was later compared with data for the years 2005 to 2006 to assess the response of the fishery to TurtleWatch. The observed fleet movement during the first quarter of 2007 was to the north of the 18.5°C (∼65.5°F) isotherm (i.e. in the area recommended for avoidance by the TurtleWatch product) with increased effort and lower bycatch rates. We discuss possible reasons for this decrease in turtle bycatch north of the frontal zone together with future research directions which may lead to refinement of the TurtleWatch product.
Article
Full-text available
Large-mesh tangle nets were used to collect marine turtles in Waccasassa Bay, near the Cedar Keys, Florida, from June 1986 to October 1995. Tagging records were analyzed to determine the species composition, population structure, and seasonal occurrence of Kemp's ridley, Lepidochelys kempii, loggerhead, Caretta caretta, and green, Chelonia mydas, turtles. Additional information on local movements, morphometrics, growth, population estimation, and diet was provided for Kemp's ridley turtles. Subadult green turtles dominated the catch on the seagrass shoals of Waccasassa Reefs. Subadult Kemp's ridley turtles and, to a lesser degree, subadult and adult loggerhead turtles were primarily captured near the oyster bars of Corrigan Reef. Marine turtles were caught in these nearshore waters from April to November. Recaptures indicate that some Kemp's ridley turtles remain in the vicinity of Corrigan Reef during their seasonal occurrence and return to this foraging area annually. Seasonal and annual size distributions of Kemp’s ridley turtles were investigated and regression equations were developed for carapace morphometrics. Carapace growth averaged 4-5 cm/yr for Kemp's ridley turtles, but growth analyses were confounded by the extrapolation of annual estimates from short-term recaptures. Population estimates for the Kemp's ridley mark-recapture data indicated a mean annual population size of 159 turtles at Corrigan Reef with presumably high rates of immigration and emigration by larger subadult turtles. Examination of fecal samples indicated that crabs were the primary food items of Kemp's ridley turtles captured near oyster bars.
Article
Full-text available
We used satellite imagery from the European Space Agency (ESA) Medium Resolution Imaging Spectrometer (MERIS) optical sensor to make the first mapping of the full distribution and movement of the population of Sargassum in the Gulf of Mexico and the western Atlantic. For most of the years for which we have data (2002 to 2008), the results show a seasonal pattern in which Sargassum originates in the northwest Gulf of Mexico in the spring of each year, and is then advected into the Atlantic. The Sargassum appears east of Cape Hatteras as a ‘Sargassum jet’ in July and ends northeast of the Bahamas in February of the following year. This pattern is consistent with historical surveys from ships. MERIS provides a spectral band that greatly improves the discrimination of floating vegetation from confusing signals such as cloud and sunglint.
Article
Full-text available
A diet analysis was conducted on the gastrointestinal contents of 10 oceanic green turtles, Chelonia mydas, collected as bycatch mortalities in pelagic fisheries. Size distribution of the green turtles ranged from 30 to 70 cm curved carapace length (CCL). Prey items found indicated pelagic green turtles to be carnivorous with some omnivorous tendencies, foraging within the first 100 m of the water column. Most frequent identifiable prey items were Zooplankton, pelagic crustaceans, and mollusks (listed in order of frequency of occurrence, which ranged from 80% to 40% frequency): Pyrosoma spp., Lepas spp. (goose barnacles), amphipods, Carinaria spp. (sea snails), and Cavolinia spp. (sea butterflies). Other coelenterates such as salps, ctenophores, and cnidarians (jellyfish) were also identified. Plastics and anthropogenic debris were commonly found (70% frequency, mean = 4% of gastrointestinal content by volume). The turtles examined consisted of two distinct morphotypes corresponding to the central Pacific and the eastern Pacific green turtle populations. Genetic analysis confirmed turtles of the central Pacific morphotype to be of Hawaiian origin and at least one of the eastern Pacific morphotype turtles to have a mtDNA haplotype found in the population nesting in the Revillagigedo archipelago off Mexico. Other eastern Pacific morphotypical turtles had a different common Mexican haplotype found among the nesting populations throughout Mexico and the Galápagos. Turtles of the central Pacific morphotype were distributed north of the Hawaiian Islands, and turtles of the eastern Pacific morphotype were all encountered south of Hawai'i, suggesting a dichotomy in the oceanic distribution of these two populations. Our records of green turtles as large as 70 cm CCL in pelagic waters suggest that some green turtles, mainly those with eastern Pacific green turtle morphology and mtDNA haplotype, delay their recruitment to nearshore (neritic) habitats or move back and forth between neritic and open ocean waters as adults.
Article
Full-text available
The Hawaii-based longline fishery oper-Historically, the Hawaii longline ates over a large area in the central fishery has set longlines considerably North Pacific, from the equator to lat-shallower than 100 m to target sword­ itude 45°N, between longitudes 130°W fish (Xiphias gladius) or substantially and 180°W. In 2000, 125 vessels were deeper than 100 m to target bigeye active in the fishery, producing total tuna. Incidental hookings of logger-landings estimated at 24 million head turtles have been reported in pounds and exvessel (wholesale) reve-the Hawaii longline fishery observer nues of $50 million. The target species data, which cover about 5% of the include bigeye tuna (Thunnus obesus), total annual effort. Analyses of these yellowfin tuna (T. albacares), and alba-data found that loggerhead turtles core tuna (T. alalunga), and swordfish were caught only when gear was set (Xiphias gladius). shallow enough to target swordfish, Caught incidentally with these target primarily in the northern portion of species are leatherback (Dermochelys the fishing ground. No loggerhead sea coriacea), loggerhead (Carretta carretta), turtles were caught when longline gear olive ridley (Lepidochelys olivacea), and was set deep to target bigeye tuna, green (Chelonia mydas) sea turtles. primarily in the southern portion of Over the period 1994–99, it was es-the fishing ground. These analyses sug­ timated that an annual average of 418 gest that a ban of shallow sets in the loggerhead, 112 leatherback, 146 olive fishery since 1 April 2001 may reduce ridley, and 40 green sea turtles were future incidental catches of loggerhead caught in the Hawaii-based longline sea turtles. However, analyses based fishery (McCracken 1). only on observer data suffer from the limited observer coverage and the de­ pendence between depth of setting and area fished. For example, swordfish are targeted at night in the north, whereas tuna are targeted during the day in the south. To better understand the depths inhabited by sea turtles, we used div­ ing depth distributions collected from satellite-linked dive recorders attached to two loggerhead and two olive ridley sea turtles caught and released in the Hawaii-based longline fishery. Al­ though other studies on the dive depths of olive ridley and loggerhead sea tur­ tles have been conducted in the Pacific, these have been conducted with sea turtles in coastal areas rather than in the oceanic central Pacific (Sakamoto et al., 1993; Beavers and Cassano, 1996).
Article
Full-text available
We studied the feeding ecology of juvenile loggerhead turtles Caretta caretta in the western Mediterranean based on the contents of the digestive tract of 54 turtles (range of CCL: 34±69 cm) seized in Barcelona (Spain) in 1991. Turtles had been captured in ®shing trawls, but speci®c information about dates and localities is not available. Despite this limitation, we obtained interesting evidences about the foraging strategies of loggerheads, with potentially important conservation implications. We report 33 new taxa in the diet. Results indicated that western Mediterranean loggerheads feed in an opportunistic way. Numerically, ®sh made up the most important prey group, followed by pelagic tunicates, crustaceans, molluscs and other invertebrates. The importance of ®sh as a food resource has been rarely reported, and several lines of evidence indicated that ®sh were possibly consumed as discarded by-catch. This raises the question over whether or not western Mediterranean ®sheries are an important food source for juvenile loggerheads. The number and diversity of prey increased with turtle size, this may re¯ect the lack of prey selectivity of juvenile loggerheads coupled with a higher retention of food remains in larger turtles. Discounting prey that could be consumed as discarded by-catch, dietary data suggest that most, if not all, loggerheads of our sample were captured in neritic habitats. However, many turtles contained remains of both pelagic and benthic-demersal prey. These observations support the existence of an intermediate neritic phase in loggerheads' developmental shift from pelagic±oceanic to benthic±neritic foraging habitats, as previously suggested. During this phase, loggerheads would feed upon both pelagic and benthic prey.
Article
A total of 2,632 dolphin Coryphaena hippurus, 250 to 1,530 millimeters fork length (FL), were captured by hook and line off the southeastern United States and from the Gulf of Mexico in 1980 and 1981. Eighty-four percent (2,219) of the stomachs contained ingested materials consisting of 13,383 individual items, displacing 57,648 milliliters, and representing 248 different categories. Fishes occurred in 77.6% of the stomachs, invertebrates in 27.5%, and miscellaneous items (Sargas-sum, tar balls, plastics, etc.) in 50.6%. Much of the material indicated that dolphin frequently feed at the surface and ingest fishes, crustaceans, insects, plants, and inorganic items that are associated with floating Sargassum. Index of relative importance (IRI) revealed unidentified fish, balistids, crustaceans, carangids, exocoetids, teuthidiEs (squids), syngnathids, coryphaenids, stomatopods, and diodontids as the 10 most important foods in the diet. Sargassum, which occurred in 48,6% of the stomachs, was considered to be consumed incidental to normal foods. The diets differed with size of dolphin (8 size classes), area of collection (10 areas), and season (4 seasons). The ascaridoid nematode Hysterothylacium pelagicum sp. n. and an unidentified digenetic trematode were found in the digestive tracts. Nematodes were far more numerous and occurred more frequently than did trematodes. Infestation rate seemed to be more associated with size of dolphin than with season or area of collection. © 1984, The Japanese Society of Fisheries Science. All rights reserved.
Article
We report clinical and pathological characteristics of a case of systemic infection with Paecilomyces lilacinus in a sea turtle as well as the morphological and cultural features of this rarely diagnosed opportunistic pathogen. Clinically, the animal showed multiple yellow nodules in the skin. After several weeks of illness it died and was submitted for necropsy. Macroscopical and histological examination revealed a systemic mycotic infection causing granuloma formation in several organs. Moreover an acute mycobacterial infection of the lung was diagnosed. It was considered to be secondary to the fungal infection. Microbiology confirmed a systemic mycotic infection. The morphological characteristics of the fungal culture allowed the identification of the organism as Paecilomyces lilacinus.
Article
Digestive tract contents were examined from 101 dead Kemp's ridley turtles, Lepidochelys kempi, found stranded on south Texas beaches from 1983-1989. Fifty turtles were wild and 51 had been head-started (captively-reared) for 6-9 months. Fifty-one were found on bay (inshore water) and 50 on Gulf of Mexico (offshore water) shorelines. Ogren (1989) stated that juveniles (<20 cm carapace length) are surface feeders and consume a variety of food items, while subadults (20-60 cm carapace length) and adults (>60 cm carapace length) are predominately benthic feeders and eat mostly crabs. It appears, from analysis of gut contents, that wild and head-started turtles are foraging in water depths of less than 50 m and that they will consume items discarded from shrimp trawls and smaller trawls fishing for bait items. Significant differences occur between various dietary parameters measured for wild and post-release head-started turtles. However, there are similarities between the diets of both groups and head-started turtles appear to be adapting to feeding in the wild. Size and habitat differences are primary causes of dietary divergences among L. kempi.
Article
The caloric value of posthatching yolk (7,949 ± 132 cal/g AFDM) and hatchlings minus yolk (6,712 ± 29 cal/g AFDM) from one Caretta caretta clutch did not change from hatching through 96 hours after emergence from the nest. There was a considerable decrease in the relative (yolk dry mass/hatchling dry mass) amount of posthatching yolk per turtle, whereas the dry mass of hatchlings did not change through time. The greatest decrease in yolk occurred between hatching and emergence. As growth and storage of fat were not evident in hatchlings, we suggest that posthatching yolk functions to support the metabolic demands of hatching, possible delayed activity in the egg cavity, digging to reach the nest surface, and initial swimming from the nesting beach. Based on an energetic consideration of hatchling dispersal from the nesting beach, posthatching yolk can support "frenzied" swimming activity during the first few days after emergence. The quantity of yolk is not sufficient for logger-head hatchlings from the south Georgia coast to reach a major oceanic current, such as the Gulf Stream.