A non-invasive method of microplastics pollution quantification in green sea turtle Chelonia mydas of the Mexican Caribbean.

Due to the amply exposure of marine turtles to marine plastic pollution, this is a reason that the green sea turtle Chelonia mydas makes a good candidate species as a bioindicator for plastic pollution. Turtle feces were collected at Isla Blanca on the northeast Caribbean coast of the Yucatan Peninsula, Mexico. Microplastic extraction was done following Hidalgo-Ruz et al. (2012) and Masura et al. (2015) methods. After organic matter degradation of the feces samples, microplastics were identified and quantified by stereomicroscope. Their morphostructure was analyzed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, while their composition was determined by Fourier transform infrared spectroscopy and Raman spectroscopy. Microplastics (MP) abundance ranged from 10 ± 2 MP·g-1 to 89 ± 3 MP·g-1. Kruskal Wallis test (KW = 70.31, p < 0.001) showed a significant difference between 22 green turtles analyzed. Most of the microplastics were fiber type. Blue, purple, and transparent fibers were the most abundant. The identified microplastics were nylon (polyamide), PVC, polypropylene, polyester, and viscose (cellulose). The non-invasive method used here allowed the detection of microplastic pollution and is promising for long-term microplastic pollution monitoring.

Widespread microplastic pollution across the Caribbean Sea confirmed using queen conch.

The Caribbean Sea is reported to have one of the highest levels of plastic pollution of any marine ecosystem. Much less is known about the levels of microplastics as an emerging pollutant in the marine environment, especially in the water column and benthic substrates where they can be easily ingested by marine organisms. This study was carried out to quantify marine microplastics in the Wider Caribbean using the mollusk, queen conch (Aliger gigas). We analyzed feces collected from queen conch, a non-lethal method of sampling, to investigate microplastic pollution in eleven sites across the Wider Caribbean. Microplastics were extracted by degradation of organic matter from feces with peroxide (30%) over 48 h. Microplastics were then analyzed by stereomicroscope and scanning electron microscope. Microplastics were found to be present in the feces of all 175 queen conch sampled, and in statistically different abundances among sites, but with no obvious geographical pattern. The highest and lowest levels were found in Central America; the highest being in Belize (270 ± 55 microplastics/queen conch) and Alacranes, Mexico (203 ± 29 microplastics/queen conch), whilst the lowest levels were found in Puerto Morelos, Mexico. Fibers, mostly between 1000 and 1500 µm in size, were the most frequent microplastic particle types at every site and represented between 60 and 98% of all microplastic particles found. Our results suggest that the use of queen conch feces is a suitable method for detecting benthic microplastic pollution, and have confirmed that microplastic pollution of marine benthos is widespread across the Wider Caribbean.

Variación espacio-temporal de la ictiofauna del Parque marino Xel-Há, Caribe mexicano y su relación con parámetros fisicoquímicos / Spatio-temporal variation of the ichthyofauna in Xel-Ha, Mexican Caribbean Marine Park and its relationship to physico-chemical parameters

Resumen:Xel-Há es un parque ecoturístico marino donde no se permite ningún tipo de extracción de flora o fauna. Una de las principales atracciones turísticas en este parque son los peces de arrecife, no existiendo trabajos publicados sobre la comunidad íctica para este sitio. En este estudio se analizó la variación espacio-temporal de la comunidad íctica en diferentes zonas del parque marino Xel-Há. Para ello, se realizaron censos visuales durante un año en 21 transectos fijos de 100x5 m, distribuidos en cinco zonas del parque: "Bocana", "Centro", "Brazo Norte", "Cueva" y "Río", que incluyen la bocana del mar, canales de manglares y un sitio con aportes de agua dulce. Para caracterizar la comunidad de peces, se estimaron los descriptores ecológicos: riqueza de especies, diversidad, abundancia y densidad a partir del promedio de los censos y se compararon entre zonas y tres temporadas (lluvias, "nortes" y secas). El grado de similitud entre zonas y temporadas se evaluó mediante un análisis de escalamiento multidimensional no métrico. El reemplazo en la composición de especies entre temporadas fue determinado con la presencia-ausencia de peces. Además, se aplicó un análisis de componentes principales para evaluar si las variables fisicoquímicas como temperatura, salinidad y concentración de oxígeno disuelto influyen en la variación de las comunidades de peces. Se registró un total de 22 641 individuos que correspondieron a 63 especies, siendo "nortes", la temporada donde se presentó la mayor abundancia (7 991 organismos). Las especies mejor representadas basados en su abundancia total y frecuencia de aparición fueron: Haemulon sciurus, H. flavolineatum, Lutjanus griseus, Acanthurus coeruleus, Abudefduf saxatilis y Gerres cinereus. La diversidad incrementó de lluvias a secas y comparando entre zonas la riqueza de especies y diversidad fue menor en "Río". Entre temporadas, el 54 % de las especies fueron residentes durante todo el año; se observaron cuatro especies exclusivas para lluvias y tres para secas. La diversidad fue el único descriptor que permitió observar variación entre temporadas. El oxígeno disuelto fue la variable que más influyó en la variación de la comunidad de peces entre zonas. El parque Xel-Há, alberga cerca del 20 % de la biodiversidad de peces reportada para el Caribe mexicano y la predominancia de juveniles de varias especies confirma su importancia como sitio de crianza.

Abstract:Xel-Ha is a private marine park where the extraction of flora and fauna is not allowed. Here, reef fish are one of the main touristic attractions, but there are no published surveys focused on fish community in this site. In this study we analyzed the spatio-temporal variation of the fish community in different areas of the marine park Xel-Há. Abundance and richness were estimated during one-year period (2012-2013); visual censuses using fixed transects of 100x5 m each distributed in 21 transects along five sites were established in different zones: "Bocana", "Center", "North branch", "Cave" and "River", including the inlet mouth to the sea, brackish mangrove channels and a zone with freshwater influence. To characterize the fish community, we used species richness, abundance, diversity, and density compared among zones and climatic seasons (rain, "norths" and dry). The similarity among zones and seasons was estimated using a multidimensional scaling analysis. The replacement on the species composition among seasons and sites was realized based on the presence-absence of fish. The influence of physicochemical variables such as temperature, salinity and dissolve oxygen concentration in the fish community was estimated by a principal component analysis. A total of 22 641 individuals were recorded corresponding to sixty-three species over the year. Abundance was higher during the windy season (locally named "norths") with 7 991 organisms. The most representative species according with abundance and frequency of occurrence were: Haemulon sciurus, H. flavolineatum, Lutjanus griseus, Acanthurus coeruleus, Abudefduf saxatilis, and Gerres cinereus. Diversity increased from the rainy to the dry season; species richness and diversity was lower in "River" than other sites in Xel-Ha. Most species (54 %) species were residents through the year. Four non-shared species were observed during the rainy season and three in dry season. Dissolved oxygen was the most influential variable on the fish community composition among zones. Xel-Ha houses nearly 20 % of fish biodiversity reported for the mexican Caribbean, and the predominance of juveniles of several species confirms its role as a nursery area. Rev. Biol. Trop. 64 (4): 1353-1367. Epub 2016 December 01.

[Turbinella angulata and Busyconperversum (Mesogasteropoda: Turbinellidae and Melongenidae) population and reproductive dynamics in the Campeche Bank, Mexico]. / Dinámica poblacional y reproductiva de Turbinella angulata y Busycon perversum (Mesogasteropoda: Turbinellidae y Melongenidae) en el Banco de Campeche, México.

Turbinella angulata and Busycon perversum are two marine gastropods that support the 90% of conch fisheries in the Gulf of Mexico, nevertheless there is no information available to support a management strategy for both species. The aim of this work was to obtain preliminary fishery information to promote management actions for both species in the Campeche Bank. The population of conchs was sampled in 12 transects (150x1.5m) by SCUBA diving from April 2008 to March 2010. All conchs were collected and siphonal length (SL) was measured. These samples were complemented with data from the commercial catches, analyzing a total of 2 832 individuals of T angulata. Siphonal length varied between 63 and 282mm. Sex ratio was of 0.98:1 female:male. The von Bertalanffy growth equation parameters were: L infinity =346mm; K=0.30 and t(0)=-0.24. Spawning extended from January to May with a long resting stage from June to September for over 80% of the adult population. The first gonadic maturity (L50) was at 210mm (SL) for females and 200mm for males. For B. perversum a total of 1655 individuals were analyzed. Siphonal length varied between 78 and 291mm with significant differences between male and female (p<0.05). Sex ratio was of 1:0.25 female:male. The growth parameters obtained were: Linifinity=360mm; K=0.35 and t(0)=-0.19. The spawning period was from August to December with resting stage from January to April. The L50 was 215mm (LS) for females and 190mm for males. Both species presented one recruitment pulse. These results will be useful to design management schemes based on population dynamics and reproductive attributes.

Insight of EDX analysis and EFTEM: are spherocrystals located in Strombidae digestive gland implied in detoxification of trace metals?

Digestive tubules of Strombidae are composed by three cell types: digestive cells, vacuolated cells, and crypt cells. The last one is characterized by the presence of intracellular granules identified as spherocrystals. Such structures are known to occur in basophilic cells of gastropod digestive gland, where they are supposed to be involved in the regulation of some minerals and in detoxification. In this study, energy-dispersive X-ray analysis (EDX) and energy filtered transmission electron microscopy (EFTEM) were used to determine the elemental content of spherocrystals in two Strombidae, Strombus gigas and Strombus pugilis. In freshly collected individuals of both species, the following elements were detected: Ca, Fe, Mg, P, and Zn. Aluminum and Mn were also detected in S. gigas. Their presence in spherocrystals indicates that, in Strombidae, spherocrystals are involved in the regulation of minerals and essential trace metals. In order to answer the question "are spherocrystals involved in nonessential trace metals scavenging?," artificial cadmium and lead exposure by both waterborne and dietary pathways was applied to S. pugilis. No evidence of cadmium (Cd(NO(3))(2)) or lead (Pb(NO(3))(2)) provided by food was found in spherocrystals. Cadmium provided in water (Cd(NO(3))(2) and CdCl(2)) causes structural modifications of the digestive gland; however, this element was not trapped in spherocrystals. These results suggest that spherocrystals are not involved in detoxification of such nonessential trace metals.

Occurrence of Apicomplexa-like structures in the digestive gland of Strombus gigas throughout the Caribbean.

The queen conch, Strombus gigas, is a marine resource of ecological and economical importance in the Caribbean region. Given its importance in this region, and the critical status of most populations, the reproductive biology of this species has been studied to support management decisions. It was from these studies that a generalized sporozoan infection was detected. This study describes the geographic distribution of a coccidian (Apicomplexa) parasite infecting the digestive gland of S. gigas throughout the Caribbean. The parasite was present in every location sampled. Based on histological analysis, the parasites from all locations are similar and appear to complete their life cycle within the digestive gland. The highest occurrence of the parasites was registered in samples from Puerto Rico (54 parasites per field) and Martinique (45 parasites per field). The lowest incidence was registered on the Mexican coast of Yucatan peninsula, at Alacranes and Chinchorro with 17 parasites per field. Data showed significant differences among sites (Kruskal Wallis H=106.957; p ≤ 0.05). The abundance of parasites found in the digestive ducts and in the faeces suggests the liberation of parasites to the environment. A gradual decrease in abundance was found from East to West of the Caribbean sea.