The marine epiphytic dinoflagellate Gambierdiscus is a toxicologically important genus responsible for ciguatera fish poisoning, the principal cause of non-bacterial illness associated with fish consumption. The genus currently contains species exhibiting either globular or anterior-posteriorly compressed morphologies with marked differences in cell shape and plate arrangement. Here we report a third globular, epiphytic and tychoplanktonic species from the coasts of Ubatuba, Brazil. The new species can be distinguished from G. yasumotoi and G. ruetzleri by its broader first apical plate that occupies a larger portion of the epitheca. Accordingly, phylogenetic trees from small subunit (SSU) and large subunit (LSU) ribosomal DNA sequences also showed strongly supported separation of the new species from the G. yasumotoi / G. ruetzleri group albeit with short distance. The molecular phylogenies, which included new sequences of the planktonic species Goniodoma polyedricum, further indicated that the globular species of Gambierdiscus formed a tight clade, clearly separated (with strong bootstrap support) from the clade of lenticular species including the type for Gambierdiscus. The morphological and molecular data in concert support the split of Gambierdiscus sensu lato into two genera. Gambierdiscus sensu stricto should be reserved for the species with lenticular shapes, highly compressed anterioposteriorly, with short-shank fishhook apical pore plate, large 2' plate, low and ascending cingular displacement, and pouch-like sulcal morphology. The new genus name Fukuyoa gen. nov. should be applied to the globular species, slightly laterally compressed, with long-shank fishhook apical pore plate, large 1' plate, greater and descending cingular displacement, and not pouch-like vertically-oriented sulcal morphology. Fukuyoa contains the new species Fukuyoa paulensis gen. et sp. nov., and F. yasumotoi comb. nov. and F. ruetzleri comb. nov.

Significance: Many different types of plankton bloom in the coastal ocean. Some produce harmful toxins, whereas others are considered important contributors to primary production and ecosystem dynamics. Routine ocean color sensors can reveal a dense bloom or “red tide” from space but cannot differentiate types of plankton. The Hyperspectral Imager for the Coastal Ocean on the International Space Station allowed for new “hyperspectral” approaches to identify pigments and assess biophysical forcing associated with different blooms. Consistent with field and molecular observations, imagery revealed dense surface patches of Mesodinium rubrum , a ciliate that uses the chloroplasts from its cryptophyte algal prey to photosynthesize. For the first time, to our knowledge, the distribution and abundance were mapped based on the unique yellow fluorescence properties of its signature pigment phycoerythrin.

The effect on phytoplankton dynamics of nutrient inputs from rivers within the highly eutrophic Pearl River Estuary (PRE) in China is well understood. However, the role that typhoons play in enhancing or reducing phytoplankton blooms is less well known. The primary factors controlling phytoplankton dynamics in the PRE in June–July 2009 were determined by coupling satellite remote sensing data with field observations during two successive typhoons: Nangka and Soudelor. The results revealed that the magnitude of chlorophyll a concentration (Chl) near the PRE was controlled by several key factors. (1) Vertical mixing of seawater induced by Typhoons Nangka and Soudelor led to a sudden decrease in Chl and phytoplankton abundance near the PRE, especially in picophytoplankton. (2) Following the typhoon events, increased nutrient availability associated with significant freshwater runoff promoted phytoplankton (especially Synechococcus) growth, recovery, and blooms in and near the PRE. (3) Increased freshwater input or easterly winds enhanced the extension of highly abundant phytoplankton with brackish water from the estuary into the adjacent nearshore water. (4) Phycocyanin‐rich Synechococcus was endemic and a dominant picophytoplankton group in the estuarial brackish water. We propose a mechanism that describes the interactions of vertical mixing, terrestrial precipitation, freshwater discharge, nutrient inputs, and winds on short‐term phytoplankton dynamics in and near the PRE during typhoon season.

Significance: Symbioses between marine plankton species are diverse and widespread both spatially and taxonomically. However, the nature and function of such relationships in natural assemblages are severely underexplored due to technical challenges. Consequently, as an example, the relationship between the ciliate Mesodinium rubrum and its observed cryptophyte endosymbiont is varied and debated, from enslaving chloroplasts to exploiting an organelle complex. Applying environmental transcriptomics and other methods to a natural bloom of M. rubrum revealed an unsuspected relationship, “host farming symbiont,” in which the host helps to transport nutrients from the environment, promotes symbiont cell proliferation, and benefits from the symbiont’s photosynthesis.

The Dinophysis genus is an ecologically and evolutionarily important group of marine dinoflagellates, yet their molecular phylogenetic positions and ecological characteristics such as trophic modes remain poorly understood. Here, a population of Dinophysis miles var. indica was sampled from South China Sea in March 2010. Nuclear ribosomal RNA gene (rDNA) SSU, ITS1-5.8S-ITS2 and LSU, mitochondrial genes encoding cytochrome B (cob) and cytochrome C oxidase subunit I (cox1), and plastid rDNA SSU were PCR amplified and sequenced. Phylogenetic analyses based on cob, cox1, and the nuclear rRNA regions showed that D. miles was closely related to D. tripos and D. caudata while distinct from D. acuminata. Along with morphology the LSU and ITS1-5.8S-ITS2 molecular data confirmed that this population was D. miles var. indica. Furthermore, the result demonstrated that ITS1-5.8S-ITS2 fragment was the most effective region to distinguish D. miles from other Dinophysis species. Three distinct types of plastid rDNA sequences were detected, belonging to plastids of a cryptophyte, a haptophyte, and a cyanobacterium, respectively. This is the first documentation of three photosynthetic entities associated with a Dinophysis species. While the cyanobacterial sequence likely represented an ectosymbiont of the D. miles cells, the detection of the cryptophyte and haptophyte plastid sequences indicates that the natural assemblage of D. miles likely retain more than one type of plastids from its prey algae for temporary use in photosynthesis. The result, together with recent findings of plastid types in other Dinophysis species, suggests that more systematic research is required to understand the complex nutritional physiology of this genus of dinoflagellates.