The influence of marine algae on iodine speciation in the coastaocean

Funding Information: This work was supported in part by grant CHE-1664657 from the National Science Foundation to CJC and FCK, the TOTAL Foundation (Paris) and the UK Natural Environment Research Council grants (NE/D521522/1, NE/ J023094/1, Oceans 2025 / WP 4.5) to FCK. We are also grateful for funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). We thank Dr. M. L. Carter, SIO for help with collection of water samples at Scripps Pier, César O. Almeda-Jáuregui, CICESE for Ocean Data View plots and Dr. Avery Tatters, USC for the initial culture of Lingulodinium polyedra. A fellowship from the Hanse-Wissenschaftskolleg to CJC is also gratefully acknowledged.Peer reviewedPublisher PD

The role of iron in potential algal-bacterial mutualism as related to harmful algae blooms

Phytoplankton blooms can cause acute effects on marine ecosystems either due to their production of endogenous toxins or due to their enormous biomass leading to major impacts on local economies and public health. Despite years of effort, the causes of harmful algal blooms (HAB) are still not fully understood. Our hypothesis is that bacteria that produce photoactive siderophores may provide a bioavailable form of iron to commensally associated phytoplankton, which could in turn affect algal growth and bloom dynamics. Here we report both laboratory-based studies using binary cultures of the dinoflagellate Lingulodinium polyedrum, a major HAB species, with Marinobacter algicola DG893, a phytoplankton-associated bacterium that produces the photoactive siderophore vibrioferrin and analysis of field collected data linking seawater iron concentrations, HAB phytoplankton numbers and bacterial populations. Together these results support the notion of a carbon for iron mutualism in some bacterial-algal interactions

Harmful Algae Monitoring on San Jorge Bay in Antofagasta, Chile

ICHA 2021/19th International Conference on Harmful Algae La Paz, Baja California Sur, Mexico (virtual meeting), October 10-15 2021チリの赤潮モニタリングにメタゲノム技術を取り入れて分析した内容の紹介です

Iron and Harmful Algae Blooms: Potential Algal-Bacterial Mutualism Between Lingulodinium polyedrum and Marinobacter algicola

Phytoplankton blooms can cause acute effects on marine ecosystems either due to their production of endogenous toxins or due to their enormous biomass leading to major impacts on local economies and public health. Despite years of effort, the causes of harmful algal blooms (HAB) are still not fully understood. Our hypothesis is that bacteria that produce photoactive siderophores may provide a bioavailable form of iron to commensally associated phytoplankton, which could in turn affect algal growth and bloom dynamics. Here we report a laboratory-based study of binary cultures of the dinoflagellate Lingulodinium polyedrum, a major HAB species, with Marinobacter algicola DG893, a phytoplankton-associated bacterium that produces the photoactive siderophore vibrioferrin. Comparing binary cultures of L. polyedrum with both the wild type and the vibrioferrin minus mutant of M. algicola shows that bacteria are necessary to promote dinoflagellate growth and that this growth promotion effect is at least partially related to the ability of the bacterium to supply bioavailable iron via the siderophore vibrioferrin. These results support the notion of a carbon for iron mutualism in some bacterial-algal interactions

The B-Vitamin Mutualism Between the Dinoflagellate Lingulodinium polyedrum and the Bacterium Dinoroseobacter shibae

Recent research has shown that in aquatic systems pairs of prokaryote and eukaryote species exercise symbiotic exchanges of metabolites that are essential for the proliferation of either species. Using dinoflagellate Lingulodinium polyedrum cultures and a factorial design, we examined its growth at different concentrations of vitamin B1 (thiamine) and B12 (cobalamin). When both vitamins were at their lowest concentrations tested, 0.033 pM of B1 and 0.053 pM of B12 the growth was limited. When axenic L. polyedrum was co-cultured with the bacterium Dinoroseobacter shibae, a known B1 and B12 producer, then L. polyedrum grew at the same rate as in culture media supplemented with B1 and B12. In the L. polyedrum vitamin—limited culture (V-L), the abundance of attached and free-living D. shibae was higher than in the vitamin—replete (V-R) culture. In the V-R and V-L co-cultures the measured particulate B12 (pB12) concentration of attached and free-living D. shibae were in the range of 4.7 × 10−19 to 3 × 10−18 and 8.4 × 10−21 to1.2 × 10−19 (mol cell−1), respectively. Without B12 or B7 (biotin) added to the culture medium of a co-culture of L. polyedrum and D. shibae, the measured dissolved B12 (dB12) concentration was more than 60 pM higher than necessary for un-limited growth rates of L. polyedrum. In the same culture we measured B7 in the L. polyedrum particulate fraction (pB7; 4.7 × 10−19 to 9.4 × 10−19 mol cell−1). We suggest that in response to the production of B1 and B12 by D. shibae to supply L. polyedrum requeriments, the latter produced B7, which is required by D. shibae, and in our culture was only produced by L. polyedrum when D. shibae was present. We propose that D. shibae can control L. polyedrum through the release of B1 and B12, and L. polyedrum can control D. shibae through the release of B7. D. shibae is also auxotroph for niacin and 4-amino-benzoic acid, not provided by the culture medium. Therefore, L. polyedrum might affect a similar control through the release of these specific compounds and organic substrate necessary for the growth of D. shibae

Monitoring bacterial composition and assemblage in the Gulf of Corcovado, southern Chile: Bacteria associated with harmful algae

Harmful Algal Blooms (HABs) have caused damage to the marine environment in Isla San Pedro in the Gulf of Corcovado, Chile. While rising water temperature and artificial eutrophication are the most discussed topics as a cause, marine bacteria is a recent attractive parameter as an algal bloom driver. This study monitored algal and bacterial compositions in the water of Isla San Pedro for one year using microscopy and 16S rRNA metabarcoding analysis, along with physicochemical parameters. The collected data were analyzed with various statistical tools to understand how the particle-associated bacteria (PA) and the free-living (FL) bacteria were possibly involved in algal blooms. Both FL and PA fractions maintained a stable bacterial composition: the FL fraction was dominated by Proteobacteria (α-Proteobacteria and γ-Proteobacteria), and Cyanobacteria dominated the PA fraction. The two fractions contained equivalent bacterial taxonomic richness (c.a. 8,000 Operational Taxonomic Units) and shared more than 50% of OTU; however, roughly 20% was exclusive to each fraction. The four most abundant algal genera in the Isla San Pedro water were Thalassiosira, Skeletonema, Chaetoceros, and Pseudo-nitzchia. Statistical analysis identified that the bacterial species Polycyclovorans algicola was correlated with Pseudo-nitzschia spp., and our monitoring data recorded a sudden increase of particle-associated Polycyclovorans algicola shortly after the increase of Pseudo-nitzschia, suggesting that P. algicola may have regression effect on Pseudo-nitzschia spp. The study also investigated the physicochemical parameter effect on algal-bacterial interactions. Oxygen concentration and chlorophyll-a showed a strong correlation with both FL and PA bacteria despite their assemblage differences, suggesting that the two groups had different mechanisms for interacting with algal species

Harmful Algae Blooms in Chile and Coastal Monitoring with Metabarcoding Analysis

The dinoflagellate Alexandrium catenella is a well-known paralytic shellfish toxin producer that forms harmful algal blooms (HABs) worldwide. Blooms of this species have repeatedly brought severe marine ecological and economic damages to Chile. A clear mechanism of HABs has been a long term debate. Algal-bacterial interaction is one of the recently discussed potential drivers for HABs. The present study isolated A. catenella strain from Quellón, which has been severely impacted by frequent A. catenella blooms, to study in-situ bacterial diversity in cultured A. catenella. We investigated intact bacteria that have survived for generations in culture A. catenella, postulating that they were essential for A. catenella survival. We monitored the intact bacteria in seawater from Quellón biweekly for two years using metabarcoding analysis. Our laboratory study discovered that the dominant attached bacteria for the culture A. catenella after maintaining years were of the genus of Paraglaciecola 49.86%, Spongiibacter 10.74%, Reichenbachiella 10.01%, and Thalassospira 5.89%. Our field studies showed evidence of the frequent presence of attached Paraglaciecola in seawater in Quellón. The other three bacterial genus were occasionally detected during the two year study period. The study suggests that these bacterial taxa are candidates for playing a pivotal role in A. catenella growth.XLIII Annual Meeting of the Society of Microbiology of Chile 2021 November 30 - December 2, 202

Environmental evaluation of the Reloncaví estuary in southern Chile based on lipophilic shellfish toxins as related to harmful algal blooms*

The Reloncavi estuary in southern Chile is famous for its aquaculture. However, recurring harmful algal blooms have adversely affected mussel production. Therefore, regular monitoring of algal toxins is urgently needed to better understand the contamination status of the estuary. In this study, we quantified 15 types of lipophilic shellfish toxins in Metri Bay in the Reloncavi estuary on a biweekly basis for 4 years. We identified algal species using microscopy and metabarcoding analysis. We also measured water temperature, salinity, chlorophyll-a, and dissolved oxygen to determine the potential relationships of these parameters with algal toxin production. Our results revealed the presence of a trace amount of pectenotoxin and the causal phytoplankton Dinophysis, as well as yessotoxin and the causal phytoplankton Protoceratium. Statistical analysis indicated that fluctuations in water temperature affected the detection of these toxins. Additionally, metabarcoding analysis detected the highly toxic phytoplankton Alexandrium spp. in some samples. Although our results suggest that the level of lipophilic shellfish toxins in Metri Bay during the study period was insignificantly low using our current LC-MS method, the confirmed presence of highly toxic algae in Metri Bay raises concerns, given that favorable environmental conditions could cause blooms

A Chilean Harmful Algal Bloom Monitoring Program using Metabarcoding Analysis by SATREPS-MACH

This video introduces steps of Harmful Algae monitoring in Chile performed by the SATREPS-MACH project. It includes the procedures from sampling to data summary. The video is created to present to the public what Harmful Algae are and how toxic algae are being monitored. The video also aims to explain to scientists how to use metabarcoding analysis for monitoring algal species. This film answers these questions visually step by step. See more information about the SATREPS-MACH project: https://www.mach-satreps.org