Here, we present the interannual distribution of Dinophysis acuminata and Protoceratium reticulatum over a 10-year period in the Reloncavi Fjord, a highly stratified fjord in southern Chile. A realized subniche approach based on the Within Outlying Mean Index (WitOMI) was used to decompose the species’ realized niche into realized subniches (found within subsets of environmental conditions). The interannual distribution of both D. acuminata and P. reticulatum summer blooms was strongly influenced by climatological regional events, i.e., El Nino Southern Oscillation (ENSO) and the Southern Annual Mode (SAM). The two species showed distinct niche preferences, with blooms of D. acuminata occurring under La Nina conditions (cold years) and low river streamflow whereas P. reticulatum blooms were observed in years of El Nino conditions and positive SAM phase. The biological constraint exerted on the species was further estimated based on the difference between the existing fundamental subniche and the realized subniche. The observed patterns suggested that D. acuminata was subject to strong biological constraint during the studied period, probably as a result of low cell densities of its putative prey (the mixotrophic ciliate Mesodinium cf. rubrum) usually observed in the studied area.

Interannual Variability of Dinophysis acuminata and Protoceratium reticulatum in a Chilean Fjord: Insights from the Realized Niche Analysis.

The Latin America and Caribbean HAB status report based on OBIS and HAEDAT maps and databases.

In southern Chile, Alexandrium catenella is the main species generating HABs and over time it has expanded its range since it was first recorded in the Magallanes region in 1972. In 2016 a severe bloom of an Alexandrium species occurred, which was notable for its intensity and geographical extent, extending into new areas to the north of the Patagonian fjords including areas along the open Pacific Ocean coast. Given the exceptional nature of this event, we verified the taxonomic classification of the species that generated the bloom and evaluated the influence of the range expansion process on its genetic structure and population diversity. This was achieved by isolating clones collected in 2014 from cyst beds located at the northern limit of its then known distribution, along with clones isolated from the water samples taken during the 2016 bloom. These clones were characterized genetically with LSU rDNA and AFLPs molecular markers. Phylogenetic analyses showed that all clones were aggregated in the Group I of the A. tamarense species complex, which confirmed that A. catenella was the species responsible for the 2016 bloom. High genetic diversity was observed within populations though there were no significant differences between populations. Furthermore, genetic structure showed an isolation by distance relationship among populations, and several analyses consistently indicated a high divergence among the population groups derived from both cysts and vegetative cells. Despite this study not finding the patterns expected for species range expansion (i.e. diversity gradient and/or high population divergence), the genetic diversity and structure indicated that these were influenced by the geographic distance effect and the physical restrictions to gene flow, along with the demographic processes that occurred during the distinct phases of the life cycle of A. catenella.

/pdf/population-genetic-structure-at-the-northern-edge-of-the-5dfg25tzvo.pdf

Population Genetic Structure at the Northern Edge of the Distribution of Alexandrium catenella in the Patagonian Fjords and Its Expansion Along the Open Pacific Ocean Coast

Niche differentiation of Dinophysis acuta and D. acuminata in a stratified fjord.

Phytoplankton blooms, including harmful algal blooms (HABs), have serious impacts on ecosystems, public health, and productivity activities. Rapid detection and monitoring of marine microalgae are important in predicting and managing HABs. We developed a toolkit, the Suitcase Lab, to detect harmful algae species in the field. We demonstrated the Suitcase Lab’s capabilities for sampling, filtration, DNA extraction, and loop-mediated isothermal amplification (LAMP) detection in cultured Alexandrium catenella cells as well as Chilean coastal waters from four sites: Repollal, Isla Garcia, Puerto Montt, and Metri. A LAMP assay using the Suitcase Lab in the field confirmed microscopic observations of A. catenella in samples from Repollal and Isla Garcia. The Suitcase Lab allowed the rapid detection of A. catenella, within 2 h from the time of sampling, even at a single cell per milliliter concentrations, demonstrating its usefulness for quick and qualitative on-site diagnosis of target toxic algae species. This method is applicable not only to detecting harmful algae but also to other field studies that seek a rapid molecular diagnostic test.

/pdf/suitcase-lab-new-portable-and-deployable-equipment-for-rapid-4wtrm2lkqt.pdf

Suitcase Lab: new, portable, and deployable equipment for rapid detection of specific harmful algae in Chilean coastal waters

The Aysen region (43°-47oS) has been prone to intensive summer blooms of toxic microalgae and complex toxin profiles in the shellfish. However, their winter distribution, toxin profile, and resting cysts in sediments are poorly known. Frequently detected toxins are: Paralytic Shellfish Toxins (PST); lipophilic toxins, including Diarrheic Shellfish Toxins (DST), Amnesic Shellfish Toxin or Domoic Acid (DA). During a cruise, carried out in winter 2012, samples were collected at 24 stations for phytoplankton analysis and analysis of toxins in mollusks, and at 5 stations, additional samples were taken for toxin analysis in plankton and resting cysts in sediments. The results confirm the presence of microalgae associated with toxins in winter, and a higher sensitivity of the relative abundance (RA) than the cellular density, as a parameter of distribution of the microalgae. The maximum RA values were level 2 (low), for Alexandrium catenella and Protoceratium reticulatum ; level 1 (rare) for Alexandrium ostenfeldii , Dinophysis acuminata and D. acuta ; levels 3 (regular) and 4 (abundant) for Pseudo-nitzschia spp. seriata complex and Pseudo-nitzschia spp. delicatissima complex, respectively. Only PST in plankton and yessotoxins in mo llusks were detected, whereas cyst densities of A. catenella and P. reticulatum in sediments were 4 and 103 cysts mL -1 of wet sediment, respectively. The analyzed parameters showed a bigger inter-annual variability during the winter period, as it has been reported for the summer.

/pdf/winter-distribution-of-toxic-potentially-toxic-phytoplankton-3xvlk72d19.pdf

Winter distribution of toxic, potentially toxic phytoplankton, and shellfish toxins in fjords and channels of the Aysén region, Chile

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Winter distribution of toxic, potentially toxic phytoplankton, and shellfish toxins in fjords and channels of the Aysén region, Chile