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The genus Coolia A. Meunier 1919 has a global distribution and is a common member of epiphytic dinoflagellate assemblages in neritic ecosystems. Coolia monotis is the type species of the genus and was the only known species for 76 years. Over the past few decades, molecular characterization has unveiled two species complexes that group morphologically very similar species, so their limits are often unclear. To provide new knowledge on the biogeography and species composition of the genus Coolia, 16 strains were isolated from Bahía de La Paz, Gulf of California. The species were identified by applying morphological and molecular approaches. The morphometric characteristics of all isolated Coolia species were consistent with the original taxa descriptions. Phylogenetic analyses (large subunit [LSU] rDNA D1 / D2 and internal transcribed spacer [ITS] 1 / 5.8S / ITS2) revealed a species assemblage comprising Coolia malayensis, C. palmyrensis, C. tropicalis, and the C. cf. canariensis lineage. This is the first report of Coolia palmyrensis and C. cf. canariensis in Mexico and C. tropicalis in the Gulf of California. Our results strengthen the biogeographical understanding of these potentially harmful epiphytic dinoflagellate species.

Monthly phytoplankton samples were collected from January 2013 to December 2015 at a fixed sampling site in Bahia 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 Bahia de La Paz could represent a risk for aquaculture activities and human health.

Cyanotetras (Hindák, 1988), es un género poco conocido, planctónico y/o metafítico, propio de pequeños reservorios de agua continental, ligeramente eutróficos. Hasta la fecha, sólo se han descrito tres especies. El propósito del presente estudio es reportar dos taxa del género Cyanotetras encontrados en el Lago de Catemaco, Veracruz (México); incluyendo, además, la propuesta de una nueva variedad. Se recolectaron muestras en once sitios en el Lago de Catemaco, para evaluar la composición de la taxocenosis fitoplanctónica, así como las características de las variables físico-químicas. Se describen los taxa del género Cyanotetras halladas en el Lago de Catemaco: C. crucigenielloides, C. aerotopa, así como una nueva forma, C. crucigenielloides var. mexicana. Esta última fue abundante (2-165 x 10³ céls L⁻¹ ), en tanto que, C. aerotopa y C. crucigenielloides fueron especies raras (2-16 x 10³ céls L⁻¹ ). Debido a que no hay suficientes investigaciones del género Cyanotetras y sus respectivas especies, es necesario seguir realizando estudios de estas especies en el Lago de Catemaco, sobre todo, para C. crucigenielloides var. mexicana, la cual fue una especie abundante, debido a que no hay suficientes investigaciones sobre taxa pertenecientes a este género., Cyanotetras (Hindák, 1988), is a poorly known planktonic and / or metaphytic genus of cyanobacteria, typical of small, slightly eutrophic reservoirs. To date, only three species have been described. The purpose of this study is to report two taxa of this genus found in Catemaco lake, Veracruz (Mexico), and to propose a new variety. Water samples were collected at eleven sites in Catemaco lake, to evaluate the composition of phytoplankton taxocenosis, as well as the characteristics of the physicochemical variables. This study described the species of the genus Cyanotetras, found in Catemaco lake: C. crucigenielloides, C. aerotopa, as well as a new form, C. crucigeniellodes var. mexicana. was an abundant species (2 - 165 x 10³ cells L⁻¹ ). Cyanotetras aerotopa and C. crucigenielloides were rare species (2-16 x 10³ cells L⁻¹ ). It is important to continue studying these species in Catemaco lake to improve the knowledge of the genus., Facultad de Ciencias Naturales y Museo, Comisión de Investigaciones Científicas de la provincia de Buenos Aires

8 pages, 2 tables, 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, Support to DMA from the NOAA ECOHAB program (Grant #NA15NOS4780181) is gratefully acknowledged. Support to EG, AR, NS from the COPAs project (CTM2017-86121-R) is acknowledged. IGL and CJBS are COFFA-IPN and EDI-IPN fellows, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

RESUMEN. La irradiancia juega un papel importante sobre la distribucion de los grupos funcionales del fitoplancton a traves de la zona eufotica. Con el proposito de caracterizar la variabilidad ambiental de la zona eufotica (tres niveles de irradiancia: 100, 10 y 1%) y su influencia sobre estos grupos funcionales, estos son abordados en este estudio. Asimismo, se determinaron los cambios en la estructura de los grupos funcionales del microfitoplancton como respuesta a la variabilidad en las condiciones hidrologicas. De esta manera, se presentan los resultados de la distribucion vertical de la comunidad microfitoplanctonica en tres niveles de luz de la zona eufotica durante un ciclo anual (junio 2000-junio 2001) en un punto de muestreo dentro de Bahia de La Paz (24° 21.284 N; 110° 26.294 O). Se identificaron un total de 62 taxa: 45 especies de diatomeas (72.58 %); 11 de dinoflagelados (17.74 %), 3 de silicoflagelados (4.83 %), 1 ciliado (1.61%), 1 de cianofitas (1.61%), 1 de cocolitoforidos (1.61%). La mayor abundancia de diatomeas se registro en superficie, mientras que los dinoflagelados dominaron en el nivel con 10% de la irradiancia superficial; los silicoflagelados, aunque en menor magnitud, se asociaron al limite de la zona eufotica. A traves del tiempo se registro la dominancia de diatomeas, seguidas por dinoflagelados en todos los niveles de irradiancia. Las condiciones ambientales durante el periodo calido (>23°C) favorecieron a dinoflagelados autotrofos, mientras que el periodo de homogenizacion en la columna de agua (diciembre-abril) favorecio dinoflagelados heterotrofos del genero Protoperidinium sobre la termoclina o debajo de la misma. La integracion de asociaciones durante el periodo de homogeneidad en la columna de agua no fue clara debido a la mezcla de comunidades de fitoplancton provenientes de diferentes profundidades. Distribution of functional groups of phytoplankton in the euphotic zone during an annual cycle in Bahia de La Paz, Gulf of California ABSTRACT. Irradiance plays an important role in the distribution of functional groups of phytoplankton in the euphotic zone. To characterize the environmental variability of the euphotic zone (in three levels of irradiance, 100, 10 and 1%) and its influence on the functional groups, the latter were studied. Similarly, changes in the structure of the microphytoplankton functional groups were determined as a response to the variability of hydrological conditions. Thus, results of the vertical distribution of microphytoplankton at three light quantity levels during an annual cycle (June 2000-June 2001) at a fixed sampling site in Bahia de La Paz (24° 21.284 N; 110° 26.294 W) are presented. A total of 62 taxa were identified: 45 diatom species (72.58%), 11 dinoflagellate species (17.74%), 3 species of silicoflagellates (4.83%), 1 ciliate species (1.61%), 1 cyanophyte (1.61%), and 1 coccolithophorid (1.61%). A higher abundance of diatoms was observed in the uppermost surface layer, while dinoflagellates were more abundant at the 10% irradiance level of the euphotic zone lower limit; silicoflagellates, although in a lesser magnitude, associated with the limit of the euphotic zone. Diatoms usually dominated, followed by dinoflagellates; this occurred at all three light quantity levels of the euphotic zone through the year. Environmental conditions during the warm period (>23°C) favored dinoflagellates; during the water-column homogenization period (December-April) conditions favored heterotrophic Protoperidinium species inhabiting the layers above or below the thermocline. However, the integration of species assemblages during the period of the homogenous water column was not clear due to mixing of different phytoplankton assemblages coming from different depth levels.

Ditrichocorycaeus anglicus (Copepoda; Poecilostomatoida), nuevo basibionte de Pseudohimantidium pacificum (Bacillariophyceae) en Bahia de La Paz, Golfo de California RESUMEN . En muestras recolectadas en la Bahia de La Paz se observo que copepodos Ditrichocorycaeus anglicus son utilizados como basibiontes por diatomeas Pseudohimantidium pacificum . Un especimen de D . anglicus de nueve recolectados en marzo de 2016 presento alta intensidad epibionte por P . pacificum (108 celulas de adheridas a lo largo del cuerpo); tres tuvieron baja intensidad epibionte (5-7 diatomeas por individuo). La temperatura superficial del mar presento un intervalo de 19–23 oC en las estaciones de muestreo donde se observo esta asociacion copepodo–diatomea.

From December 2016 to May 2017, 22 phytoplankton surface samples were collected with a 20-μm mesh net at three islands of the Archipielago 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.

Primer registro del dinoflagelado Prorocentrum panamense (Prorocentrales, Dinophyceae) en el Pacifico Mexicano recolectado en el Archipielago de Revillagigedo Se reporta por primera vez el dinoflagelado Prorocentrum panamense en la costa del Pacifico de Mexico. Diez celulas de P . panamense se encontraron en muestras de red procedentes de aguas superficiales en tres islas del Archipielago de Revillagigedo donde se recolectaron muestras en marzo de 2017. Los sitios de muestreo tenian una profundidad aproximada de 60-70 m y la temperatura superficial del agua estaba entre 21 y 23 oC.

The phytoplankton community of tuna farms in Bahía de La Paz, southern Baja California, Mexico was studied. Samples were taken from tuna farms near San Juan de la Costa, Rancheros del Mar and from a station in El Mogote, away from the influence of these farms. Water samples were collected monthly (June 2006-May 2007) with a van Dorn bottle at different depths in San Juan de la Costa (0, 25 and 50 m), Rancheros del Mar (0, 15 and 30 m) and El Mogote (0 m) to measure temperature, dissolved oxygen, inorganic nutrients, and chlorophyll-a and to determine phytoplankton composition and abundance. The index of simple dominance, Shannon-Weaver diversity, and Pielou evenness were estimated. The water column was stratified from June to September (~27.5°C) and mixed from October to May (~18.5°C). Nutrient concentrations at the three sampling sites did not increase significantly. Nanophytoplankton dominated, followed by microplanktonic diatoms, and the highest diatom abundance occurred during the warm period. The phytoplankton community was more diverse in San Juan de la Costa than in Rancheros del Mar. In the latter, a superficial bloom of the cyanobacterium Trichodesmium erythraeum (1630×103 cel L-1) occurred in September, and in San Juan de la Costa the diatom Pseudo-nitzschia fraudulenta reached the highest abundance (183.8×103 cel L-1) in July.

Historical records of ciguatera in Mexico date back to 1862. This review, including references and epidemiological reports, documents 464 cases during 25 events from 1984 to 2013: 240 (51.72%) in Baja California Sur, 163 (35.12%) in Quintana Roo, 45 (9.69%) in Yucatan, and 16 (3.44%) cases of Mexican tourists intoxicated in Cuba. Carnivorous fish, such as snapper (Lutjanus) and grouper (Epinephelus and Mycteroperca) in the Pacific Ocean, and great barracuda (Sphyraena barracuda) and snapper (Lutjanus) in the Atlantic (Gulf of Mexico and Caribbean Sea), were involved in all cases. In the Mexican Caribbean, a sub-record of ciguatera cases that occurred before 1984 exists. However, the number of intoxications has increased in recent years, and this food poisoning is poorly studied in the region. Current records suggest that ciguatera fish poisoning in humans is the second most prevalent form of seafood poisoning in Mexico, only exceeded by paralytic shellfish poisoning (505 cases, 21 fatalities in the same 34-year period). In this study, the status of ciguatera in Mexico (epidemiological and treatment), and the fish vectors are reviewed. Dinoflagellate species Gambierdiscus, Ostreopsis, and Prorocentrum are related with the reported outbreaks, marine toxins, ecological risk, and the potential toxicological impact.

On 19–20 August 2014, a moderate proliferation of dinoflagellates was detected in the southwestern part of Bahia de La Paz. The phytoplankton community within this red tide was composed of 60 microalgae taxa and was characterized by the presence of unarmored dinoflagellates such as Levanderina fissa and Polykrikos hartmannii . The proliferation occurred during low tide after a period of windy and rainy days. Densities of L. fissa varied from 163 to 265 × 10 3 cells L –1 and for P. hartmannii varied from 16 to 33 × 10 3 cells L –1 . Low densities were estimated on September and October samplings. Both species showed a great variation both in size and form. As part of the phytoplankton species composition during this proliferation, two taxa of dinoflagellates are new records for the Pacific coast of Mexico ( Ankistrodinium semilunatum and Sclerodinium calyptroglyphe ), one in the Gulf of California ( Pronoctiluca acuta ), and one in the Bahia de La Paz ( Prorocentrum robustum ). Cyanobacteria were an important group observed during this proliferation. The symbiotic association between a cyanobacterium Synechococcus sp., the stramenopile protist Solenicola setigera , and the diatom Leptocylindrus mediterraneus was observed for the first time in this bay. Proliferacion de Levanderina fissa y Polykrikos hartmannii (Dinophyceae: Gymnodiniales) en Bahia de La Paz, Golfo de California, Mexico Se detecto una proliferacion moderada de dinoflagelados en la porcion suroeste de la Bahia de La Paz del 19 al 20 de agosto de 2014. La comunidad del fitoplancton dentro de este florecimiento estuvo compuesta de 60 taxa y se caracterizo por la dominancia de Levanderina fissa y Polykrikos hartmannii . La proliferacion ocurrio durante la marea baja y despues de dias lluviosos. La abundancia de L. fissa vario de 163 a 265 × 10 3 cels L –1 y P. hartmannii vario de 16 a 33 × 10 3 cels L –1 . Densidades bajas fueron estimadas durante los muestreos de septiembre y octubre. Ambas especies mostraron una gran variacion en su forma y su tamano celular. Como resultado de la composicion especifica del fitoplancton encontrado durante esta proliferacion, dos taxa de dinoflagelados fueron nuevos registros para la costa Pacifica de Mexico ( Ankistrodinium semilunatum y Sclerodinium calyptroglyphe ), un taxon para el Golfo de California ( Pronoctiluca acuta ) y un taxon para la Bahia de La Paz ( Prorocentrum robustum ). Las cianobacterias fueron un grupo importante durante esta proliferacion. La asociacion simbiotica entre una cianobacteria Synechococcus sp., el protista stramenopiles Solenicola setigera y la diatomea Leptocylindrus mediterraneus se observo por primera vez en la bahia.

The coccolithophorid Scyphosphaera apsteinii is here reported for the first time from waters off the west coast of the Baja California Peninsula. Scypho­sphaera apsteinii is the type species of the genus Scyphosphaera and had hitherto been recorded only in the Atlantic and Indian Oceans, the Gulf of Mexico, the Mediterranean, and the Caribbean Seas. Specimens were found in samples collected in nets off Isla de Guadalupe in January 2013. This recording thus extends the geographical distribution of S. apsteinii from the Central Pacific (Hawaii) to the Eastern Pacific (NW Mexico).

The gymnodinioid marine dinoflagellates Torodinium robustum and T. teredo are reported for the Gulf of California. This is the first record of Torodinium teredo on the Pacific coast of Mexico. Both species were found mainly during the winter-spring in seawater at 19–27.5 °C. Torodinium robustum was the most frequent species. Morphological features of T. robustum and T. teredo varied widely and specimens observed in live samples and fixed in Lugol's solution were easily recognizable. Short description and microphotographs were provided for each species.

As part of a continuing toxic microalgae monitoring program, phytoplankton samples were collected on 16-17 August 2012 at several sampling sites in the southern part of the Bahía de La Paz. A bloom of the dinoflagellate Cochlodinium polykrikoides was detected. Abundance of C. polykrikoides ranged from 73 to 276×10(3) cells L(-1) on the first day to 980-1425×10(3) cells L(-1) on the second day. Study of live specimens showed great variation in cell size and form, mainly as single cells or chains of two cells. Live cells were 30-47 μm long and 20-35 μm wide (n=30). Seawater temperature during the bloom was 29-30°C. Low densities of Cochlodinium convolutum, Cochlodinium helicoides, and Cochlodinium shuettii were also found in the samples of the bloom event. These high densities of C. polykrikoides did not lead to fish die-offs in the bay.

From mid-August to mid-September 1998, a dinoflagellate bloom in a shrimp pond near La Paz, Baja California Sur, was studied. Daily samples were taken of phytoplankton, dissolved oxygen, nutrient concentrations, photosynthetic pigments and proteins. The bloom occurred at temperatures of 29.7 to 33.2 °C. High densities of a Scrippsiella-like dinoflagellate (15.9 × 106 cells/L) occurred on the first day of sampling, reaching a peak of 249 × 106 cells/L on Day 13, and declining to 4 to 7 × 106 cells/L by Day 26. Chlorophyll a varied from 8.63 mg/m3 on Day 4 to 141.38 mg/m3 on Day 13. Total nitrogen varied widely (0.2–11.50 μM) while phosphates peaked only once on Day 13 (4.14 μM). Proteins ranged from 523 to 6387 μg/L; the latter value occurred two days after the maximal peak of nitrates and coinciding with the highest level of phosphates. Fertilizers added to the ponds increased nutrient concentration and stimulated phytoplankton growth. In turn, the food supply to cultured shrimp noticeably increased throu...

"The naked marine dinoflagellates Cochlodinium convolutum and C. helicoides are reported for the first time in the Gulf of California. They occurred in seawater at 21-24.5°C. Cochlodinium convolutum was found in both bottle and net samples; its abundance ranged from 400-2200 cells L¿1. A total of 96 specimens of C. convolutum and 23 specimens of C. helicoides were examined from the net phytoplankton samples. A short description is given for each species, and photomicrographs provide information about the main morphological characteristics."

A strain of Gymnodinium catenatum Graham (GCCV-7), isolated from the Gulf of California, was submitted to conditions with different nitrogen-to-phosphorus ratios (5.4, 9.2, 23.5, 44.7, and 74.3) to determine the effect of these ratios on the growth, toxicity, and variations in toxin profile. No differences in toxicity and toxin profile were found among the treatments. Highest cell density occurred at the N:P ratio of 23.5:1, yielding 33% more cells than the 44.5:1 and 74.3:1 treatments, which in turn had 34% and 30% more cells than the 5.4:1 and 9.2:1 treatments. Toxin cell quota and variations in toxin composition were clearly related to growth rates. Toxicity remained relatively invariable because of changes in toxin composition rather than changes in the toxin cell quota during the different growth stages. The data suggest that changes in the N:P ratios do not stimulate production of toxins or changes in toxin profiles, but do affect cell density, and that cellular toxin dynamics is related to the growth stage.

Se presentan los cambios en la distribucion espacial de la comunidad fitoplanctonica en Bahia Concepcion, B.C.S. de 1991 a 1993. Se estimo la abundancia total, la variacion espacio-temporal por fracciones de tamano (nano y microfitoplancton) y se describe su estructura. Se determinaron 235 taxa, en donde las diatomeas fueron el grupo con mayor riqueza de especies (131). Los generos mas importantes fueron Chaetoceros, Rhizosolenia y Nitzschia . El segundo grupo en importancia fue el de los dinoflagelados (92 especies), representados principalmente por Protoperidinium, Ceratium y Prorocentrum ; el tercer grupo fueron los silicoflagelados (9 especies), principalmente del genero Dictyocha . Las diatomeas dominaron en la temporada fria cuando la columna de agua se mantiene homogenea, en tanto que los dinoflagelados prosperaron durante la temporada calida cuando la columna de agua estuvo estratificada. De este ultimo grupo, 10 especies son toxicas o potencialmente toxicas. La abundancia fitoplanctonica total no mostro un comportamiento estacional definido, sin embargo, las variaciones interanuales mostraron un decremento de aproximadamente 25% durante 1992 y 1993, asociado con anomalias positivas de temperatura. A pesar de que las abundancias totales disminuyeron, la contribucion porcentual de la fraccion nanofitoplanctonica se mantuvo. Ecological indicators of the phytoplankton community structure in Bahia Concepcion, Gulf of California, Mexico Seasonal changes in the spatial distribution of the phytoplankton community were determined in Bahia Concepcion, B.C.S., from 1991 to 1993. The total abundance and the seasonal variations of phytoplankton size fractions (nanno and microphytoplankton) as well as its structure were determined. A total of 235 taxa were identified. Diatoms were the best represented group due to their high species richness (131). The most important genera were Chaetoceros, Rhizosolenia and Nitzschia . The second important group were dinoflagellates (92 species), represented mainly by Protoperidinium, Ceratium and Prorocentrum . The third numerically important group were the silicoflagellates (9 species). The most representative genus of this group was Dictyocha . A major presence of the diatoms was observed during the cold months with a homogeneous water-column. Major presence of dinoflagellates was recorded during the warm season when the water-column appeared stratified. Ten species of dinoflagellates were considered as toxic or potentially toxic. Total phytoplankton abundance did not show a clear seasonal pattern; nevertheless, the interannual variations exhibited an important decline of about 25 % during 1992 and 1993. These changes were related to positive anomalies of temperature. Altough phytoplankton abundance diminished, the percentage contribution of nannophytoplankton was stable.

Analisis del contenido intestinal de Anadara tuberculosa (Sowerby, 1833) a traves de cortes histologicos Se examino el contenido intestinal de 30 especimenes de Anadara tuberculosa recolectados en la costa pacifica de la Peninsula de Baja California en abril, mayo, junio y octubre de 2000 y se hicieron cortes histologicos de intestino y estomago; se encontraron 1002 estructuras. De estas, 917 correspondieron a diatomeas (91.5%), de las cuales, la diatomea bentonica Paralia sulcata (45.3%) y las diatomeas planctonicas Thalassiosira spp. (42.9%) y Thalassionema nitzschioides (2.7%) fueron las mas frecuentes. El silicoflagelado Dictyocha sp. (1.6%) fue poco abundante. Asimismo, se encontraron 85 estructuras (8.5%) que consistieron en huevos de bivalvos (1.8%), espiculas de esponjas (0.4%) y material no identificado (6.3%). Los cortes histologicos representan una nueva alternativa para el estudio del contenido estomacal e intestinal para este bivalvo.

Primer registro de Erythropsidinium agile (Gymnodiniales: Warnowiaceae) en el Pacifico Mexicano Se registra por primera vez Erythropsidinium agile , un dinoflagelado de la Familia Warnowiaceae para el Pacifico Mexicano, dentro de Bahia de La Paz (Golfo de California). Se observaron 26 ejemplares de E. agile , principalmente en muestras de fitoplancton de red para el periodo de estudio (Junio, 2006 a Junio, 2010). En muestras de botella se estimaron densidades entre 80 y 1000 cel. L –1 . Los ejemplares de E. agile mostraron gran variacion en forma, tamano y coloracion; se presentaron principalmente en el periodo invierno-primavera, cuando la columna del agua esta homogenea, a temperaturas entre 19 y 22 °C y rica en nutrientes.

Se observaron cinco estados de desarrollo del dinoflagelado Gyrodinium falcatum en muestras de Bahia de La Paz. Aunque esta especie fue observada a lo largo del ano, fue mas abundante durante el periodo de inviero a primavera, cuando la columna de agua es homogenea. G. falcatum fue observada como epifita de la diatomea Chaetoceros coarctatus . Life stages of Gyrodinium falcatum (Dinophyceae) in Bahia de La Paz, Gulf of California Five stages of development of the dinoflagellate Gyrodinium falcatum were observed in field samples from Bahia de La Paz. Although this species was observed throughout the year, it was more abundant in the winter-spring period when the water column is homogeneous. G. falcatum was observed as epiphyte on the diatom Chaetoceros coarctatus .

Dinoflagelados en estanques de cultivo de camaron bajo condiciones tipicas de produccion Durante el cultivo del camaron se busca que las diatomeas sean el fitoplancton preponderante; sin embargo, frecuentemente surgen florecimientos algales nocivos, v.gr., de dinoflagelados. Nuestro objetivo fue identificar los taxa de dinoflagelados presentes y aquellos potencialmente nocivos bajo condiciones tipicas de produccion en una granja camaronera. Para ello se tomaron muestras mensuales (junio-octubre de 2003) de fondo (microfitobentos) y de superficie (arrastres). Se identificaron 46 taxa de dinoflagelados; los mas frecuentes fueron Protoperidinium cf. pacificum, Scrippsiella trochoidea, Prorocentrum minimum , taxa formadores de florecimientos nocivos; asimismo, se identificaron taxa potencialmente toxicos ( Prorocentrum rhathymum, P. micans, Dinophysis caudata, D. tripos ). En ningun caso hubo problemas en los estanques. Los dinoflagelados fueron menos abundantes al final del ciclo de cultivo del camaron.

This review presents a detailed analysis of the state of knowledge of studies done in Mexico related to the dinoflagellate Gymnodinium catenatum, a paralytic toxin producer. This species was first reported in the Gulf of California in 1939; since then most studies in Mexico have focused on local blooms and seasonal variations. G. catenatum is most abundant during March and April, usually associated with water temperatures between 18 and 25 ºC and an increase in nutrients. In vitro studies of G. catenatum strains from different bays along the Pacific coast of Mexico show that this species can grow in wide ranges of salinities, temperatures, and N:P ratios. Latitudinal differences are observed in the toxicity and toxin profile, but the presence of dcSTX, dcGTX2-3, C1, and C2 are usual components. A common characteristic of the toxin profile found in shellfish, when G. catenatum is present in the coastal environment, is the detection of dcGTX2-3, dcSTX, C1, and C2. Few bioassay studies have reported effects in mollusks and lethal effects in mice, and shrimp; however no adverse effects have been observed in the copepod Acartia clausi. Interestingly, genetic sequencing of D1-D2 LSU rDNA revealed that it differs only in one base pair, compared with strains from other regions.

Primer registro de Ceratium dens Dinophyceae) en el Golfo de California El dinoflagelado Ceratium dens , originalmente descrito del Oceano Indico, se registra por primera vez en el Golfo de California y en el Pacifico Mexicano. Se examinaron todos los registros disponibles de C. dens . La distribucion geografica de esta especie es principalmente en aguas tropicales y subtropicales. La presencia de C. dens durante el otono de 2009 en las aguas del Golfo de California parece relacionarse con condiciones del Evento de El Nino.

En México existe poca información sobre las asociaciones simbióticas entre diatomeas y ciliados, así como con otras especies de microalgas y particularmente con crustáceos planctónicos marinos. Es por ello que en este trabajo se presenta el primer registro de la diatomea Pseudohimantidium pacificum en epibiosis con el copépodo Farranula gibbula y otras asociaciones entre microalgas y ciliados marinos en la Bahía de La Paz. Las muestras biológicas se recolectaron mediante una red de plancton con una luz de malla de 20 µm, en diversas áreas de la Bahía de La Paz. Se encontraron 62 copépodos machos de F. gibbula, de los cuales 27 presentaban sobre su caparazón un ramillete compuesto por la diatomea epibionte P. pacificum. Los valores promedio de abundancia de P. pacificum por estación de muestreo variaron entre 16 y 82 ejemplares/copépodo. Otras diatomeas penales fueron observadas como epibiontes de copépodos del género Acartia. Asimismo se encontraron asociaciones simbióticas adicionales entre ciliados, microalgas y cianobacterias, destacando las siguientes: Chaetoceros coarctatum-Vorticella oceanica, Leptocylindrus mediterraneus-Solenicola setigera. Se registra por primera vez la agrupación entre la diatomea Fragilariopsis doliolus y el silicoflagelado Dictyocha pentagona con un ciliado de tipo Vorticella.

Blooms of the ciliate Myrionecta rubra are quite common in Bahia de La Paz. In June and July 2005 two blooms of this species were sampled to determine abundance, plankton biomass, nutrients, dissolved oxygen, and temperature. During the bloom in June, surface temperature ranged from 19.0 °C to 19.6 °C and dissolved oxygen from 4.2 mg l -1 to 4.7 mg l -1 . During the second bloom, surface temperature as 24.2 °C and dissolved oxygen was 6.7 mg l -1 . At 25 m depth, conditions were 20.0 °C and 3.5 mg l -1 , respectively. At the surface, nutrients were low, except for ammonium (1.14 µM – 2.27 µM). High densities of M. rubra (2.14 × 106 cells l -1 ), chlorophyll a (55.6 µg l -1 ), chlorophyll c (6.0 µg l -1 ), and alloxanthin (8.1 µg l -1 ) were recorded. This last pigment is characteristic of the cryptophyte group, suggesting an association of the ciliate with this algal group. Winds from the southeast varied from 3 to 4.5 m s -1 in June and 1.7 to 4.8 m s -1 in July. The presence of this bloom under low thermal stratification and with the highest density of the ciliates at the surface during the onset of the bloom suggest that southeastern winds mixed the shallow water column, brought up nutrients from the bottom sediments, and induced high concentrations of the cryptophytes. Proliferaciones de Myrionecta rubra en Bahia de La Paz, Golfo de California, al inicio del verano de 2005 Las proliferaciones del ciliado Myrionecta rubra son frecuentes en Bahia de la Paz. Durante junio y julio de 2005 se registraron dos proliferaciones de esta especie en tres sitios de esta bahia. Durante estos eventos se tomaron muestras para determinar abundancia, biomasa planctonica, nutrientes, oxigeno disuelto y temperatura. En junio, la temperatura oscilo entre 19.0 °C y 19.6 °C y el oxigeno entre 4.7 mg l -1 y 4.2 mg l -1 . En julio fue de 24.2 °C y 6.7 mg l -1 y disminuyo a 20.0 °C y 3.5 mg l -1 a 25 m de profundidad. Los nutrientes fueron bajos, siendo unicamente altos los de amonio en superficie (1.14-2.27 µM). Se presentaron valores altos de biomasa, expresada como clorofila a (55.6 µg l -1 ), clorofila c (6.0 µg l -1 ) y de aloxantina (8.1 µg l -1 ); este ultimo, es caracteristico de criptofitas asociadas con el ciliado M. rubra , el cual alcanzo densidades maximas de 2.14 x 106 celulas l -1 . Los vientos dominantes de junio fueron del sureste (3.0 m s -1 - 4.5 m s -1 ) y de 1.7 m s -1 - 4.8 m s -1 en julio. La debil estratificacion y la presencia en superficie de M. rubra durante la tarde, sugieren que los vientos del sureste promueven la mezcla de la columna de agua. Esto propicia la remocion de nutrientes de los sedimentos hacia la superficie, promoviendo el incremento de la abundancia de la criptofita.

Un total de 17 nuevos registros de dinoflagelados planctonicos fueron encontrados para las aguas del Golfo de Tehuantepec. De estos, los Dinophysiales Histioneis costata y Dinophysis expulsa son nuevos registros para el Pacifico Mexicano. Se incluyen registros fotograficos de 20 especies, a excepcion de Gonyaulax milneri de la que se presenta de su primera descripcion. En este trabajo se presenta el primerregistro fotografico de Histioneis pieltainii . La distribucion general de estas especies es principalmente de aguas subtropicales a tropicales. New records of planktonic dinoflagellates from the Gulf of Tehuantepec, Mexico Seventeen new records of planktonic dinoflagellates for the Gulf of Tehuantepec are presented. From these, the Dinophysiales Histioneis costata , and Dinophysis expulsa are new records for the Mexican Pacific. All but one species, Gonyaulax milneri (first description) were documented with photographic images. The first image of Histioneis pieltainii is recorded in this work. General distribution of these taxa is mainly in subtropical and tropical waters.

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.

Se presentan cuatro nuevos registros de dinoflagelados y el reporte de dos dinoflagelados desnudos planctonicos para la Bahia de La Paz y el Golfo de California. Los Brachidiniales Asterodinium gracile y Brachidinium sp. son nuevos registros para el Pacifico Mexicano y Brachidinium capitatum es nuevo registro para el Golfo de California. Se conoce poco acerca de la distribucion y morfologia de estas especies ya que son raras y se han reportado en pocas ocasiones. A. gracile y Kofoidinium pavillardii son consideradas especies de la flora de sombra. En este trabajo se documentaron fotograficamente todas las especies. New records of naked dinoflagellates from the Gulf of California, Mexico Four new records of naked planktonic dinoflagellate and two rare taxa were found in Bahia de La Paz, Gulf of California. The Brachidiniales Asterodinium gracile and Brachidinium sp. are new records for the Mexican Pacific and Brachidinium capitatum is a new record for the Gulf of California. Little is known about the distribution and morphology of these species since they are rare and have been scarcely reported in the worldwide literature. A. gracile and Kofoidinium pavillardii are considered as members of the shade flora. All species are photographically documented.

Benthic/epiphytic dinoflagellates were monitored every 2 wk from May to December 2005 in the Veracruz reef zone, Gulf of Mexico. This assemblage was characterized by low species diversity (at least 17 species from 11 genera) and high abundance: Amphidinium cf. carterae (41 172 cells g -1 substrate wet weight), Prorocentrum lima (29 756 cells g -1 ), Coolia monotis (2724 cells g -1 ), Ostreopsis heptagona (1202 cells g -1 ); P. lima was the dominant species. Clear sea- sonal population dynamics occurred, with the highest abundance in May-June, and the dynamics differed at 2 neighbouring sampling sites. In August to December dinoflagellate abundance de- creased considerably. Most of the epiphytic dinoflagellates did not show any significant preference for a macrophyte substrate (23 macroalgal and 2 seagrass species) or for any species or major algal group, although the seagrass Thalassia testudinum appeared to be the most abundant and perma- nent host species. The highest abundance of P. lima occurred on the chlorophyte Ulva fasciata (30 879 cells g -1 ) and T. testudinum (31 467). Dinoflagellates were usually scarce on dead coral (Acro- pora sp. and Millepora alcicornis) fragments (0 to 5039 cells g -1 ) and surface bottom sediments (2 to 84), and were slightly more abundant on living Diploria strigosa (329 to 1830) and more numerous in a fringing reef zone compared to a reef lagoon near an offshore island. Dinoflagellate abundance was not correlated with any measured physical or chemical parameter (temperature, salinity, pH, dis- solved oxygen, nitrates, nitrites, ammonium, phosphates, precipitation or wind speed and direction). There is a high potential for outbreaks of ciguatera in the studied area.

"As part of a continuing microalgae monitoring program, phytoplankton samples were collected from 19 August 2014 to 25 February 2015 at a fixed sampling site in the southern part of the Bahía de La Paz, Mexico. The armored dinoflagellate Oxytoxum caudatum was observed mainly in net samples of phytoplankton. Study of live specimens did not show great variation in cell size or shape. Cells were 24-38 μm long and 12-16 μm wide (n= 30). This is the first record of O. caudatum in the Gulf of California."

In vitro experiments were performed with Gymnodinium catenatum Graham strains isolated from three locations in the Gulf of California to determine the variability in toxicity and toxin profiles. Strains were cultivated in GSe at 20° C ± 1° C, 150 μmol photons·m -2 ·s -1 (12:12 light:dark cycle), and harvested during different growth phases. Growth rates were higher than in previous studies, varying between 0.70 and 0.82 day -1 . The highest cell yields were reached at 16 and 19 days, with maximum densities between 1090 and 3393 cells· mL -1 . Bahia de La Paz (BAPAZ) and Bahia de Mazatlan (BAMAZ) were the most toxic (101 pg STXeq-cell 1 ), whereas strains from Bahia Concepcion (BACO) were the least toxic (13 pg STXeq·cell -1 ). A strain isolated from cyst germination was one of the least toxic strains. No significant changes in toxin content with culture age were observed (0.2 and 0.6pmol paralytic shellfish poisoning·cell -1 ). All strains contained neosaxitoxin (NEOSTX), decarbamoyl-saxitoxin (dcSTX), decarbamoyl-gonyautoxin-2,-3, (dcGTX2-3), N-sulfocarbamoylsaxitoxin (Bl), N-sulfo-carbamoylneosaxitoxin (B2), and N-sulfo-carbamoylgonyautoxin-2,-3 (C1-2). Bahia Concepcion strains had the highest content of Cl; BAPAZ and BAMAZ strains had a higher percentage of NEOSTX. Differences in toxin composition with culture age were observed only in BAMAZ and BAPAZ strains. Cultures with a higher percentage of long chains had more NEOSTX, while those with a higher proportion of short chains had a lower content of NEOSTX. Gulf of California strains are characterized by a high proportion of NEOSTX, and seem to have evolved particular physiological responses to their environment that are reflected in the toxin profile, suggesting different populations.

Surface aggregations and beach strandings of a species of krill, Nematoscelis difficilis Hansen, were observed in June 2003 at locations along the shore of Bahia de La Paz in the Gulf of California. For 10 days before the krill die-off, a steady wind blew from the south at speeds between 4 and 5 m/sec. For that period, satellite images showed water temperatures between 18 and 22 °C along this coast, which is low compared with typical seasonal water temperatures of 26 to 28 °C for June. Phytoplankton biomass, determined by pigment concentration and cell counts, was the highest in the area in June. The diatom Chaetoceros debilis represented more than 96% of the phytoplankton community. Nutrients were in relatively higher concentrations. These data suggest that upwelling conditions occurred and the diatom bloom was in its final phase. Based on this limited data set, we present a hypothetical scenario describing the sea-surface aggregations and beach strandings of N. difficilis.

Se presenta una lista taxonómica con anotaciones de aproximadamente 605 especies y taxones infraespecíficos de dinoflagelados principalmente de vida libre comprendidos en 91 géneros que han sido reportados para el Pacífico Mexicano en la literatura publicada, algunas tesis, reportes no publicados y datos originales. Las referencias de la literatura entre 1878 y 2005 (en total, 311) están incluidas en la bibliografía, y en las notas taxonómicas concernientes a los taxa proporcionados, donde se consideró apropiado. La presencia de ilustraciones está dividida en tres categorías (dibujos, fotografías en microscopio óptico, y fotografías en microscopio electrónico de barrido) y se indica la distribución de los taxa en el Pacífico Mexicano. La nomenclatura y 193 especies y taxa infraespecíficos. Cuatro nuevas combinaciones: Histioneis pieltainii (B. F. Osorio) Okolodkov comb. nov., Latifascia subantarctica (Balech) Okolodkov comb. nov., Peridiniella globosa (P. A. Dang.) Okolodkov comb. nov. y Protoperidinium curtipes (Jörg.) Balech f. asymmetricum (Matzen.) Okolodkov comb. nov. Veintinueve nomina nuda son revelados. Los géneros mas importantes son Protoperidinium (111 especies), Ceratium (63), Dinophysis (41), Gonyaulax (25), Oxytoxum (22), Gymnodinium (22), Prorocentrum (21), Alexandrium (17), Ornithocercus (12) y Amphidinium (12). Para conocer la diversidad real de las especies de dinoflagelados en el Pacífico Mexicano, se necesitan hacer más estudios sobre las especies atecados de los Gymnodiniales, los dinoflagelados bentónicos y epifíticos, el ‘‘grupo Diplopsalis’’, el género Protoperidinium y los géneros recientemente descritos de la familia Podolampadaceae.

Gymnodinium catenatum Graham is a paralytic shellfish poison (PSP) producer that was described for the first time from the Gulf of California in 1943. During the last decade, its distribution along the Mexican Pacific coastline has increased. In Bahia Concepcion, a coastal lagoon on the western side of the Gulf of California, G. catenatum has been linked to significant PSP concentrations found in mollusks. In this study, we describe the saxitoxin profile of 16 strains of G. catenatum , and catarina scallops ( Argopecten ventricosus ) from Bahia Concepcion. Toxins were analyzed by HPLC with post-column oxidation and fluorescence detection. The average toxicity of the G. catenatum strains was 26.0±6.0 pg and 28.0±18.0 pg STX eq/cell after 17 and 22 days of growth, respectively. Ten toxins were recorded, but only dcSTX, dcGTX2, dcGTX3, C1, and C2 were always present in all strains at both growth stages. Since toxin profiles in scallops were similar to the cultures, biotransformations are not significant in catarina scallop. NeoSTX, GTX2, GTX3, and B2 were present in some G. catenatum strains and their presence varied with the age of the culture. In scallop samples, dcSTX, dcGTX2, and dcGTX3 were the most abundant toxins, and from the C-toxin group, only C2 was found. This unique toxin profile can be used as a biomarker for this population, when compared with strains of G. catenatum from other geographic regions.

Hyotissa hyotis specimens were collected at Espiritu Santo Island, Gulf of California, from March 1998 to March 1999. Water temperature was recorded, gut-content samples were obtained, phytoplankton abundance was estimated, and the reproductive status was inferred through the gonadic index. Gut content included phytoplankton, mostly diatoms (86.5%) and dinoflagellates (13.5%). The highest phytoplankton frequency in gut contents occurred from March to May, along with a growing phytoplankton abundance in seawater, matching the period of gonad development and the seasonal rise in temperature. Phytoplankton comprised diatoms (73.3%), dinoflagellates (10.4%), nannoplankton (18.8%), cyanobacteria (3.3%), and silicoflagellates (2.2%). The gonadic index suggests that this population has an annual reproductive pattern. Gonad development takes place from March to April, with the population ripening between April and July, matching the seasonal temperature rise from 22 °C to 27 °C, and spawning from July to...

Samples of epiphytic diatom assemblages found on prop roots of red mangrove (Rhizophora mangle) from four sites were collected at two tidal levels of exposure on two different dates from the cool season (autumn, spring). The overall floristic analysis yielded 171 diatom taxa, including 16 new records for the Baja California peninsula. Diversity estimates were among the highest ever measured for benthic diatoms using Shannon's (mean H′ = 4.89) and Simpson's (0.945) indices. Many species scored high on the Biological Value Index (BVI), thus reflecting their numerical importance within the assemblages. According to diversity values and overall species composition, all sampling sites represented a similar habitat consisting of three types of substrates: prop roots, epiphytic macroalgae, and sediments. These values are considered to represent stability in the diatom assemblages living on red mangrove prop roots. Thus, the conditions determined by periodic tidal exposure are not to be considered extrem...