Floración algal nociva del dinoflagelado Blixaea quinquecornis en el Perú / Harmful algal bloom of dinoflagellate Blixaea quinquecornis in Peru

Resumen En el presente trabajo, se registra por primera vez floraciones algales nocivas del dinoflagelado Blixaea quinquecornis (Abé) Gottschling, 2017 para aguas costeras del mar peruano. La determinación taxonómica de esta especie se realizó mediante microscopia de luz, electrónica de barrido y contraste interferencial diferencial (DIC). La fórmula tecal encontrada fue: pp, 3', 2a, 7'',5c, 5"' y 2''' 4s. Blixaea quinquecornis fue registrada en las bahías Sechura, Miraflores y Paracas entre el 2014 y 2017, usualmente con altas densidades de 3.2 x105 cel.L-1 (Miraflores) y 2.11x105 cel.L-1 (Paracas) en verano y 4.11 x104 (Paracas) en otoño 2016. Blixaea quinquecornis estuvo alternando con floraciones algales del dinoflagelado atecado Akashiwo sanguinea. El florecimiento de B. quinquecornis se observó con TSM entre 18.5 a 26.6 °C, salinidades entre 34.70 y 35.32 ups, pH entre 7.32 y 8.82 y oxígeno disuelto entre 3.8 y 12.5 mL/L. En Bahía Miraflores, la floración de B. quinquecornis fue asociado positivamente con el incremento de la TSM, salinidad y negativamente con la concentración de nitratos, mientras que las floraciones algales de A. sanguinea se correlacionó positivamente con la concentración de fosfatos y oxígeno disuelto. El registro de la floración de B. quinquecornis en las bahías de Miraflores y Paracas, coincidió con eventos de inusual calentamiento del mar asociado con el evento cálido El Niño 2015-2016.

Abstract In the present work, harmful algal blooms of the dinoflagellate Blixaea quinquecornis (Abé) Gottschling, 2017 are recorded for the first time for coastal waters of the Peruvian sea. The taxonomic determination of this species was done with light microscopy, Scanning Electron Microscopy (SEM), and Differential Interference Contrast (DIC) microscopy. The thecal formula is: pp, 3', 2a, 7'', 5c, 5"' and 2''' 4s. Blixaea quinquecornis was recorded in Sechura, Miraflores and Paracas bays between 2014 - 2016, mainly with algal blooms of 3.2 x105 cel.L-1 (Miraflores) and 2.11x105 cel.L-1 (Paracas) and 4.11 x104 cel.L-1 (Paracas) in autumn of 2016. Blixaea quinquecornis was found alternating with algal bloom produced by the athecate dinoflagellate Akashiwo sanguinea. The physicochemical variables associated with the bloom of B. quinquecornis were SST (18.5 to 26.6° C), salinities (34.7 to 35.325), pH (7.32 to 12.5), and dissolved oxygen (3.8 to 12.5 mL/L). The bloom of B. quinquecornis in Miraflores Bay was positively associated with the increase in SST, salinity and negatively with the concentration of nitrates, whereas the algal blooms of A. sanguinea were positively correlated with the concentration of phosphates and oxygen. The record of the bloom of B. quinquecornis in the 3 bays coincided with unusual sea warming event associated with the El Niño phenomenon 2015-2016.

Absence of hypoxia events in the adjacent coastal waters of Grijalva-Usumacinta river, Southern Gulf of Mexico.

Globally, oxygen concentration in many coastal areas is depleting. River nutrient discharges may produce hypoxia events. The Southern Gulf of Mexico receives the discharges of the Grijalva-Usumacinta River System, the second largest in the Gulf of Mexico. To evaluate the influence of river discharges on dissolved oxygen concentrations in the receiving coastal ecosystem, we studied the variation of physicochemical variables in the water column. During the dry season, the influence of the river waters to the coastal area is scarce, but during the rainy season the river plume reached ~9 km offshore. The lowest concentration of dissolved oxygen (3.6 mg L-1) was observed within the river plume. We concluded that, in the studied area, hypoxia events (oxygen concentrations ≤ 2 mg L-1) would occur during the rainy season, low winds and in deeper waters (>80 m depth).

Morphological observations of the marine planktonic dinoflagellate Phalacroma turbineum Kofoid et Michener (Dinophyta), with discussion on its taxonomy and distribution.

The marine planktonic thecate dinoflagellate Phalacroma turbineum Kofoid et Michener was found at two oceanic stations in the southern Gulf of Mexico and studied by light and scanning electron microscopy. This species is extremely rare and has not been reported since 1911. The terms reticules and septa are introduced here for structures of theca and cingulum of the species. The peculiar morphological characters of P. turbineum are described: (1) two separate pores that might represent flagellar pores, (2) right and left sulcal lists are united, (3) left sulcal list showed no apparent ribs, (4) a parasagittal list occurs in the hypotheca as continuation of the left sulcal list, (5) structural complexity of the cingulum, with septa along the cingulum, (6) strong ribs supporting the two cingular lists, (7) large and spaced reticules in the theca, with elevated ridges, and (8) an elongation of the hypotheca. No chloroplasts were detected. The morphology and taxonomy of P. turbineum are discussed, especially the possibility that the species may be considered as belonging to a new genus. Finally, although information is yet limited, we suggest that the species is distributed in equatorial and tropical zones of both the Atlantic and Pacific Oceans, in oceanic environments.

Toxic and harmful marine phytoplankton and microalgae (HABs) in Mexican Coasts.

Harmful Algal Blooms (HABs) are becoming an increasing problem to human health and environment (including effects on natural and cultured resources, tourism and ecosystems) all over the world. In Mexico a number of human fatalities and important economic losses have occurred in the last 30 years because of these events. There are about 70 species of planktonic and non-planktonic microalgae considered harmful in Mexican coasts. The most important toxin-producing species are the dinoflagellates Gymnodinium catenatum and Pyrodinium bahamense var. compressum, in the Mexican Pacific, and Karenia brevis in the Gulf of Mexico, and consequently the poisonings documented in Mexico are Paralytic Shellfish Poisoning (PSP) and Neurotoxic Shellfish Poisoning (NSP). Although there is evidence that Amnesic Shellfish Poisoning (ASP), Diarrhetic Shellfish Poisoning (DSP) and Ciguatera Fish Poisoning (CFP) also occur in Mexico, these problems are reported less frequently. The type of phytoplankton and epiphytic microalgae, their toxins and harmful effects as well as current methodology used to study these phenomena are presented in this paper. As an experienced group of workers, we include descriptions of monitoring and mitigation programs, our proposals for collaborative projects and perspectives on future research.