Diel Variations in Cell Abundance and Trophic Transfer of Diarrheic Toxins during a Massive Dinophysis Bloom in Southern Brazil

Abstract

Dinophysis spp. are a major source of diarrheic toxins to marine food webs, especially during blooms. This study documented the occurrence, in late May 2016, of a massive toxic bloom of the Dinophysis acuminata complex along the southern coast of Brazil, associated with an episode of marked salinity stratification. The study tracked the daily vertical distribution of Dinophysis spp. cells and their ciliate prey, Mesodinium cf. rubrum, and quantified the amount of lipophilic toxins present in seston and accumulated by various marine organisms in the food web. The abundance of the D. acuminata complex reached 43 × 104 cells·L−1 at 1.0 m depth at the peak of the bloom. Maximum cell densities of cryptophyceans and M. cf. rubrum (>500 × 104 and 18 × 104 cell·L−1, respectively) were recorded on the first day of sampling, one week before the peak in abundance of the D. acuminata complex. The diarrheic toxin okadaic acid (OA) was the only toxin detected during the bloom, attaining unprecedented, high concentrations of up to 829 µg·L−1 in seston, and 143 ± 93 pg·cell−1 in individually picked cells of the D. acuminata complex. Suspension-feeders such as the mussel, Perna perna, and barnacle, Megabalanus tintinnabulum, accumulated maximum OA levels (up to 578.4 and 21.9 µg total OA·Kg−1, respectively) during early bloom stages, whereas predators and detritivores such as Caprellidae amphipods (154.6 µg·Kg−1), Stramonita haemastoma gastropods (111.6 µg·Kg−1), Pilumnus spinosissimus crabs (33.4 µg·Kg−1) and a commercially important species of shrimp, Xiphopenaeus kroyeri (7.2 µg·Kg−1), only incorporated OA from mid- to late bloom stages. Conjugated forms of OA were dominant (>70%) in most organisms, except in blenny fish, Hypleurochilus fissicornis, and polychaetes, Pseudonereis palpata (up to 59.3 and 164.6 µg total OA·Kg−1, respectively), which contained mostly free-OA throughout the bloom. Although algal toxins are only regulated in bivalves during toxic blooms in most countries, including Brazil, this study indicates that human seafood consumers might be exposed to moderate toxin levels from a variety of other vectors during intense toxic outbreaks.

Marine Heatwaves, Sewage and Eutrophication Combine to Trigger Deoxygenation and Biodiversity Loss: A SW Atlantic Case Study

“…Santa Catarina Island bays have moderate to high eutrophication pressure (Cabral et al, 2020). The combination of organic enrichment and eutrophication (Bricker et al, 2008) can cause low oxygen levels in the rivers (Pagliosa et al, 2006) and harmful algal blooms in marine shelf waters (Alves and Mafra, 2018).…”

“…Nutrient inputs often boost algal blooms in systems with long water residence time, such as lagoons and bays (Bricker et al, 2008). In South Brazil, harmful algal blooms, deoxygenation and human diseases (e.g., gastroenteritis, mycosis, conjunctivitis) have frequently been associated with sewage pollution and nutrient enrichment from agricultural land run-off Alves and Mafra, 2018;. One of the few studies about the interactive effects of eutrophication and high temperatures in Brazil showed a major decline in the physiological performance of a macroalga, indicating that individuals inhabiting densely urbanized areas are more susceptible to warm water episodes (Gouvêa et al, 2017).…”

DSP Toxin Distribution across Organs in Mice after Acute Oral Administration

“…The worldwide incidence of diarrheic shellfish toxins poses a threat to public health, with a consequent marine environment effect and great economic impact on the seafood industry [ 10 , 29 , 30 ]. In vivo toxicity differences were observed for the toxins of this group, both intraperitoneally [ 14 , 31 ] and orally [ 15 ].…”

Diarrhetic Shellfish Toxin Monitoring in Commercial Wild Harvest Bivalve Shellfish in New South Wales, Australia

“…Mussels generally accumulate DSTs more readily than oysters (e.g., Pitcher et al [ 49 ]) and while during this study pipis were the main species affected by DSTs in NSW, oyster samples from South Australia have shown DSTs above the regulatory limit [ 46 ]. Worldwide, new cases and outbreaks of DST are still occurring (e.g., British Columbia [ 60 ], China [ 61 ], Brazil [ 62 ]). While the occurrence of DSTs has been variable in NSW [ 3 , 29 , 45 ], a DST event in Tasmania during 2016 was responsible for a recall of mussels from a location that was not previously known to be impacted by DSTs [ 63 ].…”