Parasitic helminths of Halichoeres bivittatus (Pisces: Labridae) from the southwestern Gulf of México / Helmintos parásitos de halichoeres bivittatus (pisces: labridae) del suroeste del golfo de méxico

RESUMEN Un total de 326 helmintos parásitos fueron recuperados de 94 especímenes de Halichoeres bivittatus (Pisces: Labridae) en dos sitios de la zona arrecifal en los límites del Parque Nacional Sistema Arrecifal Veracruzano, Veracruz, México, el suroeste del Golfo de México: Punta Gorda (n = 51) y Mata de Uva (n = 43). Los peces fueron capturados entre mayo y septiembre de 2001. Cada muestra se analizó a nivel de comunidad componente e infracomunidad. Tres especies de helmintos se localizaron en intestino: Nicolla halichoeri (Digenea) considerándose nuevo registro de localidad, Procamallanus (Spirocamallanus) garnotus (Nematoda) es nuevo registro de hospedero, y las larvas de Tetraphyllidea gen. sp. (Cestoda) fueron los parásitos con mayor prevalencia e intensidad promedio para cada sitio. La riqueza de especies para ambos sitios fue de S = 3 y el índice de diversidad de Shannon-Wiener (Punta Gorda, H'= 0,42; Mata de Uva, H'= 0,49) fueron inferiores a los registrados para las comunidades hospedero-parásito de lábridos y de hospederos de la localidad. No hubo correlación entre el número total de especies o el número total de helmintos con respecto a la longitud total o el peso del hospedero. El análisis de las curvas de especies acumuladas para la comunidad componente sugirió, que el inventario de especies de helmintos estaba casi completo para ambos sitios. La abundancia de larvas del céstodo ubica a H. bivittatus como hospedero intermediario del parásito.

ABSTRACT A total of 326 parasitic helminths were obtained from 94 specimens of Halichoeres bivittatus (Pisces: Labridae) at two sites in the reef zone at the limits of the Veracruz Reef System National Park, Veracruz, Mexico, southwestern Gulf of Mexico: Punta Gorda (n = 51) and Mata de Uva (n = 43). Fish were caught from May to September 2001. Each sample was examined at the levels of the component community and infracommunity. Three parasitic helminth species were found in intestines: Nicolla halichoeri (Digenea: Plagiorchiida: Opecoelidae) is a new geographic record, Procamallanus (Spirocamallanus) garnotus (Nematoda) is a new host record, and larvae of Tetraphyllidea gen. sp. (Cestoda) were the parasites with the highest prevalence and the average intensity at both sites. Species richness (S = 3) and the Shannon-Wiener diversity index (H'= 0,42; 0,49) were lower than those previously estimated for the labrid host-parasite community in the study area. No correlations between the total number of species or the total number of helminths and the total length or weight of the host were observed. An analysis of the accumulated curve for the component community suggested that the inventory of helminth species was almost complete for both sites. The abundance of cestode larvae infers H. bivittatus is an intermediate host of the parasite.

Paralytic Shellfish Toxins of Pyrodinium bahamense (Dinophyceae) in the Southeastern Gulf of Mexico.

In September and November 2016, eight marine sampling sites along the coast of the southeastern Gulf of Mexico were monitored for the presence of lipophilic and hydrophilic toxins. Water temperature, salinity, hydrogen potential, dissolved oxygen saturation, inorganic nutrients and phytoplankton abundance were also determined. Two samples filtered through glass fiber filters were used for the extraction and analysis of paralytic shellfish toxins (PSTs) by lateral flow immunochromatography (IFL), HPLC with post-column oxidation and fluorescent detection (FLD) and UHPLC coupled to tandem mass spectrometry (UHPLC-MS/MS). Elevated nutrient contents were associated with the sites of rainwater discharge or those near anthropogenic activities. A predominance of the dinoflagellate Pyrodinium bahamense was found with abundances of up to 104 cells L-1. Identification of the dinoflagellate was corroborated by light and scanning electron microscopy. Samples for toxins were positive by IFL, and the analogs NeoSTX and STX were identified and quantified by HPLC-FLD and UHPLC-MS/MS, with a total PST concentration of 6.5 pg cell-1. This study is the first report that confirms the presence of PSTs in P. bahamense in Mexican waters of the Gulf of Mexico.

Spatio-temporal Variation of Harmful Planktonic Microalgae and Cyanobacteria Along the Central Coast of Campeche, Southeastern Gulf of Mexico.

To describe the phytoplankton species composition, spatio-temporal distribution and habitats during different seasons along the central coast of the state of Campeche, Mexico, southeastern Gulf of Mexico, eight shallow-water (ca 1 m) sites from the city of Campeche Southwest to Villamar were monitored monthly from September 2016 to June 2017 by taking water-bottle samples. Average water temperature varied between 22.2 and 30.9°C and average salinity between 26.6 and 35.0. The Kolmogorov-Smirnov test, the Bartlett's test and canonical correspondence analyses were applied. Sixteen potentially harmful microalgal species were found: five species are bloom-forming, nine are potentially toxic to humans, and two affect aquatic organisms. At all sampling sites, massive algal proliferations occurred in June (beginning of rainy season) caused by the dinoflagellates Heterocapsa sp. (2.6 × 105 cells/L) and Blixaea quinquecornis (2.0 × 104 cells/L) and from October to March (windy season) by the cyanobacterium Trichodesmium sp. (2.6 × 105 cells/L).

Effects of a Light Crude Oil Spill on a Tropical Coastal Phytoplankton Community.

Oiling scenarios following spills vary in concentration and usually can affect large coastal areas. Consequently, this research evaluated different crude oil concentrations (10, 40, and 80 mg L-1) on the nearshore phytoplanktonic community in the southern Gulf of Mexico. This experiment was carried out for ten days using eight units of 2500 L each; factors monitored included shifts in phytoplankton composition, physicochemical parameters and the culturable bacterial abundance of heterotrophic and hydrocarbonoclastic groups. The temperature, salinity, and nutrient concentrations measured were within the ranges previously reported for Yucatan Peninsula waters. The total hydrocarbon concentration (TPH) in the control at T0 indicated the presence of hydrocarbons (PAHs 0.80 µg L-1, aliphatics 7.83 µg L-1 and UCM 184.09 µg L-1). At T0, the phytoplankton community showed a similar assemblage structure and composition in all treatments. At T10, the community composition remained heterogeneous in the control, in agreement with previous reports for the area. However, for oiled treatments, Bacillariophyceae dominated at T10. Hydrocarbonoclastic bacteria were associated with oiled treatments throughout the experiment, while heterotrophic bacteria were associated with control conditions. Our results agreed with previous works at the taxonomic level showing the presence of Bacillariophyceae and Dinophyceae in oil-related treatments, where these groups showed the major interactions in co-occurrence networks. In contrast, Chlorophyceae showed the key node in the co-occurrence network for the control. This study aims to contribute to knowledge on phytoplankton community shifts during a crude oil spill in subtropical oligotrophic regions.

Diversity of Bacterioplankton and Bacteriobenthos from the Veracruz Reef System, Southwestern Gulf of Mexico.

Bacterial diversity was explored among field samples and cultured isolates from coral reefs within the Veracruz Reef System. Bacterioplankton and bacteriobenthos were characterized by pyrosequencing 16S rRNA genes. Identified sequences belonged to the kingdom Bacteria and classified into 33 phyla. Proteobacteria (likely SAR11 clade) dominated in collective field samples, whereas Firmicutes were the most abundant taxa among cultured isolates. Bioinformatic sorting of sequences to family level revealed 223 bacterial families. Pseudomonadaceae, Exiguobacteraceae and Bacillaceae were dominant among cultured isolates. Vibrionaceae, Alteromonadaceae, and Flavobacteriaceae dominated in reef-associated sediments, whereas Rickettsiaceae and Synechoccaceae were more highly represented in the water column. Bacterial communities from sediments were more diverse than from the water column. This study reveals cryptic bacterial diversity among microenvironmental components of marine microbial reef communities subject to differential influence of anthropogenic stressors. Such investigations are critical for constructing scenarios of environmentally induced shifts in bacterial biodiversity and species composition.

Morphological and phylogenetic data do not support the split of Alexandrium into four genera.

A recently published study analyzed the phylogenetic relationship between the genera Centrodinium and Alexandrium, confirming an earlier publication showing the genus Alexandrium as paraphyletic. This most recent manuscript retained the genus Alexandrium, introduced a new genus Episemicolon, resurrected two genera, Gessnerium and Protogonyaulax, and stated that: "The polyphyly [sic] of Alexandrium is solved with the split into four genera". However, these reintroduced taxa were not based on monophyletic groups. Therefore this work, if accepted, would result in replacing a single paraphyletic taxon with several non-monophyletic ones. The morphological data presented for genus characterization also do not convincingly support taxa delimitations. The combination of weak molecular phylogenetics and the lack of diagnostic traits (i.e., autapomorphies) render the applicability of the concept of limited use. The proposal to split the genus Alexandrium on the basis of our current knowledge is rejected herein. The aim here is not to present an alternative analysis and revision, but to maintain Alexandrium. A better constructed and more phylogenetically accurate revision can and should wait until more complete evidence becomes available and there is a strong reason to revise the genus Alexandrium. The reasons are explained in detail by a review of the available molecular and morphological data for species of the genera Alexandrium and Centrodinium. In addition, cyst morphology and chemotaxonomy are discussed, and the need for integrative taxonomy is highlighted.

Seasonality of the dinoflagellate Amphidinium cf. carterae (Dinophyceae: Amphidiniales) in Bahía de la Paz, Gulf of California.

Monthly phytoplankton samples were collected from January 2013 to December 2015 at a fixed sampling site in Bahía de La Paz, Gulf of California. During this study 26 samplings were Amphidinium cf. carterae positive. The highest densities of A. cf. carterae (754.2 × 103 to 1022.4 × 103 cells L-1) were recorded during a bloom detected in January 2015 when water temperatures were 20-22 °C. This dinoflagellate showed a well-marked seasonal variation, being found mainly from November to April. Blooms of the species were linked to the upwelled water due to the northwesterly wind. Cysts surrounded by a mucilaginous membrane of A. cf. carterae were found. We also observed these hyaline cysts inside zooplankton fecal pellets. Other benthic/tychoplanktonic dinoflagellates and diatoms, including some potentially toxic species were also found. The occurrence of blooms of A. cf. carterae in Bahía de La Paz could represent a risk for aquaculture activities and human health.

Cianobacterias potencialmente nocivas en los bancos ostrícolas de la laguna de Términos, sureste del Golfo de México / Potentially harmful cyanobacteria in oyster banks of términos lagoon, southeastern gulf of mexico

ABSTRACT Cyanobacteria inhabit hypersaline, marine and freshwater environments. Some toxic and non-toxic species can form harmful blooms. The aim of this study was to identify potentially harmful cyanobacterial species in the oyster banks of Términos Lagoon, the southeastern Gulf of Mexico. Six sample sites (up to 2-m depth) were monitored monthly from August 2012 to September 2013. Water temperature, salinity, pH, dissolved oxygen saturation (% DO), inorganic nutrients and abundance of cyanobacteria were determined. Temperature and salinity were characterized by marked seasonal differences (26.8 to 30.6 °C and 6.1 to 19.5, respectively). The pH values (ranging from 7.1 to 8.4) and the % DO (88.4 to 118.2 %) suggest a predominance of photosynthetic activity in the windy season (October-February). Elevated nutrient contents are associated with the period of increased river discharge, determined by water circulation and biogeochemical processes. Fourteen taxa were identified, of which Anabaena sp., Merismopedia sp., Oscillatoria sp. and Cylindrospermopsis cuspis produced blooms. Cyanobacterial abundances were on the order of magnitude of 106 cells L-1 in October 2012 at stations S1-S6, with an average value of 3.2x105 cells L-1 and a range of 2000 to 3.1x106 cells L-1 throughout the study period; however, they showed a remarkable absence during the windy season (October to January). Anabaena sp. and C. cuspis reached abundances of 1.9x106 and 1.3x106 cells L1, respectively. The latter caused the temporary closure of oyster Crassostrea virginica harvesting for 15 days in October 2012.

RESUMEN Las cianobacterias habitan en ambientes hipersalinos, marinos y de agua dulce. Algunas especies tóxicas y no tóxicas pueden formar florecimientos nocivos. El objetivo de este estudio fue identificar las especies de cianobacterias potencialmente nocivas en los bancos ostrícolas de laguna de Términos, sureste del Golfo de México. Seis sitios de muestreo (hasta 2 m de profundidad) fueron monitoreados mensualmente de agosto de 2012 a septiembre de 2013. Se midió la temperatura del agua, salinidad, pH, saturación de oxígeno, nutrientes inorgánicos y abundancia de cianobacterias. La temperatura y la salinidad se caracterizaron por marcadas diferencias estacionales (26,8 a 30,6 °C y 6,1 a 19,5, respectivamente). Los valores de pH (de 7,1 a 8,4) y la saturación de oxígeno disuelto (de 88,4 a 118,2 %) sugieren un predominio de la actividad fotosintética en la temporada de nortes (octubre-enero). Las concentraciones elevadas de los nutrientes están asociados al periodo de mayor descarga de los ríos, determinados por la circulación y los procesos biogeoquímicos. Se identificaron 14 taxa, de los cuales Anabaena sp., Merismopedia sp., Oscillatoria sp. y Cylindrospermopsis cuspis formaron florecimientos. Las abundancias de cianobacterias fueron del orden de magnitud de 106 células L-1 en octubre de 2012 en las estaciones S1-S6, con un valor promedio de 3.2x105 células L-1 y un rango de 2000 a 3.1x106 células L-1 a lo largo del periodo de estudio. Sin embargo, mostraron una ausencia notable durante la temporada de nortes (octubre a enero). Anabaena sp. y C. cuspis alcanzaron abundancias de 1.9x106 y 1.3x106 células L-1, respectivamente. Este último causó el cierre temporal de la colecta del ostión Crassostrea virginica durante 15 días en octubre de 2012.

Occurrence of Ostreopsis lenticularis (Dinophyceae: Gonyaulacales) from the Archipiélago de Revillagigedo, Mexican Pacific.

From December 2016 to May 2017, 22 phytoplankton surface samples were collected with a 20-µm mesh net at three islands of the Archipiélago de Revillagigedo (Partida, Socorro and San Benedicto), Mexican Pacific. The sites depth was approximately 20-80 m; the surface water temperature was 21-27 °C. The potentially toxic benthic dinoflagellate Ostreopsis lenticularis was present in all the samples. Cells had a lenticular to broadly oval shape, 65-100 µm long and 50-80 µm wide. The taxonomy of the genus Ostreopsis has been unclear due to equivocal ascribing some taxonomic features among species. The identification of specimens from the archipelago was made based on the most important taxonomic characteristics: the thecal plates, the presence of two types of thecal pores (larger and smaller), and the lack of cingulum undulation. The studied cells are compared with O. cf. siamensis, O. labens and O. marina. This is the first record of the species in the archipelago waters.

Increasing contribution of coccolithophorids to the phytoplankton in the northeastern Black Sea.

During 2005-2011, 418 phytoplankton samples were collected in Novorossiysk and Tuapse ports and near the resort cities of Anapa and Gelendzhik in the northeastern Black Sea. The maximal values of both abundance and biomass of phytoplankton related to high nutrient concentration, probably due to anthropogenic load, were observed at Novorossiysk (5.82×105cells/l, 1.492g/m3); in other bays values were about three times lower. The annual cycle included two to four phytoplankton abundance peaks. Emiliania huxleyi was the most abundant coccolithophorid (1.15×105cells/l offshore and 2.20×104cells/l in bays and ports). In spring-summer it contributed up to 90% of the phytoplankton abundance offshore. The maximal abundance of E. huxleyi was observed offshore of Gelendzhik (up to 1.32×106cells/l); the minimum was in the coastal zone in the port of Novorossiysk (on average 7.7×103cells/l). Generally, the species appears to avoid eutrophic waters.

Taxocoenosis of epibenthic dinoflagellates in the coastal waters of the northern Yucatan Peninsula before and after the harmful algal bloom event in 2011-2012.

Eutrophication causes the major impact in the coastal waters of the state of Yucatan. In general, loss of water quality and biological communities and massive development of toxic microorganisms are some of the consequences of this phenomenon. To reveal changes in species composition and cell abundance of the taxocoenosis of epibenthic dinoflagellates before and after a harmful algal bloom event in the water column that lasted about 150days (August-December 2011) in the Dzilam - San Crisanto area (northern Yucatan Peninsula, southeastern Gulf of Mexico) were the main objectives of the present study. In August 2011 and September 2012, sampling along 20 transects perpendicular to the coastline along the entire northern Yucatan coast, starting from 20 sampling sites from El Cuyo in the east to Celestún in the west, at a distance of 50, 150 and 250m from the coast, was carried out. Physicochemical characteristics measured before and after the bloom were within the ranges previously reported in the study area. Salinity was the most stable characteristic, with mean values of 36.25 and 36.42 in 2011 and 2012, respectively. Phosphates were the only parameter that showed a wide range with higher values before the bloom (0.03-0.54µM/l). A total of 168 macrophyte (seaweeds and seagrasses), sponge and sediment samples (105 in 2011 and 63 in 2012) that included associated microphytobenthos were taken by snorkeling from 0.7 to 5m depth. Six substrate types were distinguished: Chlorophyta, Phaeophyceae, Rhodophyta, Angiospermae (seagrasses), Demospongiae (sponges) and sediment. Chlorophytes dominated the collected samples: 38 samples in 2011 and 23 in 2012. Avrainvillea longicaulis f. laxa predominated before the bloom and Udotea flabellum after it. In total, 25 epibenthic dinoflagellate species from 11 genera were found. The genus Prorocentrum was the most representative in terms of the number of species. The highest total dinoflagellate cell abundances were observed in the sites with different types of macrophytes (up to 2441cells/g substrate wet weight in 2011 and up to 1068cells/g in 2012). The lowest cell densities were observed in the areas with scarce or no macrophytes on sandy seafloor. Before the bloom, Prorocentrum rhathymum (up to 4995cells/g) and P. cf. sipadanensis (up to 5275cells/g) were the most abundant, and after the bloom the latter was dominant (up to 3559cells/g); in 2012, both variety of substrates and dinoflagellate cell abundance diminished. A canonical correspondence analysis revealed significant relationships between the physicochemical variables and epiphytic/benthic dinoflagellate species either before or after the bloom. The pelagic bloom resulted in the loss of substrate for epiphytic dinoflagellates, which caused replacement of the dominant species and a decrease in cell abundance of the whole taxocoenosis.

Circadian rhythm of a red-tide dinoflagellate Peridinium quadridentatum in the port of Veracruz, Gulf of Mexico, its thecal morphology, nomenclature and geographical distribution.

A circadian rhythm of the dinoflagellate Peridinium quadridentatum was studied at a time-series station in the southwestern Gulf of Mexico, in May 2007. Different substrates (water column, the seagrass Thalassia testudinum, macroalgae, coral rubble and sandy sediment surface) were sampled at the site at 1.5-3.5m depth. In the samples of coral rubble, P. quadridentatum was scarce. In the water column, the species showed an abundance peak at 15:00. The cell abundance of P. quadridentatum in Thalassia samples increased from 15:00 until 18:00 (1.81×10(4)cells/gsubstratewet weight), and then continuously decreased until 06:00. Changes in P. quadridentatum cell abundance on macroalgae followed the same trend as on Thalassia, with the maximal value at 18:00. The higher abundance of P. quadridentatum (up to 1.40×10(4)cells/gSWW) in macroalgae samples showed the preference for seaweeds. P. quadridentatum has a neritic tropical-boreal distribution. A new combination is proposed: Peridinium quadridentatum var. trispiniferum.