Marine dinoflagellate assemblage in the Galápagos Marine Reserve

Abstract

It is likely that harmful algae blooms (HABs) have increased in frequency, intensity and geographic distribution in the last decades in response to anthropogenic activities but, there are still some areas in the globe where data is scarce increasing the lack of understanding of distributional patterns of HABs in these areas. The Galapagos Islands are renowned for their unique biological diversity, high levels of endemism, and the unique currents and oceanographic features that allow a variety of habitats to exist. However, marine dinoflagellates community has a lack of representation in biodiversity assessment. In that sense, this study aims to provide key information about dinoflagellates diversity and abundances, related to physical parameters, in the Galapagos Marine Reserve. Samples were collected in April 2016 at 2, 5 and 10 miles north, south east and west on four Islands (Santa Cruz, Santa Fé, Seymour and Pinzón) belonging to southern Galapagos Marine Reserve, 48 sampling sites. A total of 155 species were observed, 26 of them potentially toxic. Among these genera, Tripos, Protoperidinium and Dinophysis were the most diverse. At species level, T. furca, Oxytoxum tesselatum and Podolampas bipes were observed in more than 60% of the samples. It is important to mention the presence of benthic species in the water column such as Ostreopsis sp., Gambierdiscus sp. and Prorcentrum lima. In addition, water samples were taken at 0, 15 and 30 meters in 21 sampling sites where no blooms of toxic species were found, just Karlodinium sp. was registered in low abundances (3940 cells. L-1) at 2 miles, 30 meters depth northern Seymour Island. According to Sorensen Index, the community structure was homogenous, with slight differences in Santa Fé Island, associated to oceanographic variability. These results represent the first register of several species in the area and highlights the high diversity values of dinoflagellates. The presence of toxic species should be considered by policy makers regarding the implementation of phytoplankton monitoring programs in order to prevent ecological, sanitary and economic impacts in the islands considering the high species diversity and tourism influx