Investigating the effect of nickel concentration on phytoplankton growth to inform the assessment of ocean alkalinity enhancement

Ocean alkalinity enhancement (OAE) is a proposed method for removing carbon dioxide (CO2) from the atmosphere by the accelerated weathering of (ultra-) basic minerals to increase alkalinity – the chemical capacity of seawater to store CO2. During the weathering of OAE-relevant minerals relatively large amounts of trace metals will be released and may perturb pelagic ecosystems. Nickel (Ni) is of particular concern as it is abundant in olivine, one of the most widely considered minerals for OAE. However, so far there is limited knowledge about the impact of Ni on marine biota including phytoplankton. To fill this knowledge gap, this study tested the growth and photo-physiological response of 11 marine phytoplankton species to a wide range of dissolved Ni concentrations (from 0 nmol/L to 50,000 nmol/L). We found that the phytoplankton species were not very sensitive to Ni concentrations under the culturing conditions established in our experiments, but the responses were species-specific. The growth rates of 6 of the 11 tested species showed small but significant responses to changing Ni concentrations. Photosynthetic performance, assessed by measuring the maximum quantum yield (Fv/Fm) and the functional absorption cross-section (σPSII) of photosystem II, was also only mildly sensitive to changing Ni in 3 out of 11 species and 4 out of 11 species, respectively. The limited effect of Ni may be partly due to the provision of nitrate as the nitrogen source for growth, as previous studies suggest higher sensitivities when urea is the nitrogen source. Furthermore, limited influence may be due to the relatively high concentrations of organic ligands in the growth media in our experiments. These ligands reduced bioavailable Ni (i.e., “free Ni2+”) concentrations by binding the majority of the dissolved Ni. Our data suggest that dissolved Ni does not have a strong effect on phytoplankton under our experimental conditions, but we emphasize that a deeper understanding of nitrogen sources, ligand concentrations and phytoplankton composition is needed when assessing the influence of Ni release associated with OAE. We discuss if applications of OAE with Ni-rich minerals may be safer in regions with high organic ligand concentrations and low concentrations of urea as such boundary conditions may lead to less impact of Ni on phytoplankton communities.

Phytoplankton community structure changes in Thi Nai lagoon (South - Central Vietnam) from 2004 to 2020

Phytoplankton species composition, abundance, biodiversity indices and their influence by environmental conditions were examined in Thi Nai lagoon using data from four surveys in 2004, 2008, 2009 and 2020. A total of 367 taxa of phytoplankton belonging to ten groups was recorded, of which diatoms were dominant with over 60% of the total species. In Thi Nai lagoon, the number of phytoplankton species decreased from the upper lagoon (283 taxa) to the lagoon mouth area (224) and was lowest in river stations (139). The species number was much lower in the rainy season (<95 species) and increased from 2004 to 2020. Among the biodiversity indices, Shannon, ∆, s∆+, Λ+ and sФ+ were lower in the rainy season, whereas ∆*, ∆+ and Ф+ had lower values in the dry season. For long-term analysis, the differences were especially significant at upper and lower lagoon for ∆, ∆*, ∆+, s∆+ and sФ+. In the dry season, the mean density of phytoplankton was lower at the river stations and upper lagoon, but higher at the lower lagoon and the lagoon mouth area. There was a clear difference of species assemblages between the two seasons with average dissimilarities in each area ranging from 94.16% to 95.57%. During 2004–2020, the difference in ratios between the main phytoplankton groups were small over years but there was a complete change in dominance of particular species, assemblage dissimilarities were from 73.4 to 77.9, greatest between 2009 and 2020. The lagoon was low in biodiversity for the whole investigated time indicated by taxonomic index ∆+. Among biodiversity indices, species richness (S), taxonomic indices (∆*, s∆+), and phylogenetic indices (Ф+, sФ+) were more sensitive to the changes of the aquatic environment than other traditional indices.

Assessing relationship of degradation of coastal zones and phytoplankton species structure of Lake Uvildy and Lake Turgoyak (South Ural, Russia)

The current paper aims at analyzing the species structure of the phytoplankton community of two reservoirs on the territory of South Ural. The given water bodies are of different trophicity, namely, oligotrophic Lake Turgoyak and oligomesotrophic Lake Uvildy. Both lakes, being natural monuments, are subject to intensive recreational use. A large flow of tourists is a serious problem for the ecological state of the water bodies coastal areas. Also, tourist activities can affect the state of aquatic biocenoses. In this work, the degree of recreational degression of the selected study sites was assessed. The analysis was carried out according to the state of landscapes, vegetation and trampledness of the surveyed area. Based upon the research the current paper reveals spatial patterns in the distribution of recreational load on the coastal geosystems and the level of anthropogenic transformation of the territory. Mainly due to the high density of recreational centres and camping areas, the coastal area is characterized by a high degree of regression. Some signs allow forecasting changes in the species composition of phytoplankton communities and the trophic status of the lakes depending on the degradation of the coastal zones. Diatoms (Bacillariophyta) have been dominant in plankton phytocoenosis of Turgoyak and Uvildy. At the same time, in the oligomesotrophic lake (Uvildy), the number of diatom species is significantly reduced in areas with a higher degree of regression. Thus, diatoms are sensitive indicators of anthropogenic impact on aquatic ecosystems. Green and blue-green algae biodiversity has grown in the water body. However, no relationship was found between their species diversity and the level regression. But the following tendency is observed for the oligotrophic Lake Turgoyak. The species diversity of green algae grows with an increase in the degression degree. To forecast the further state of the studied water bodies, the revealed patterns in the change of the phytoplankton species structure depending on the degradation level of the coastal territories can be used as eutrophication signs.

Abundance of Plankton in the Waters of Geger Beach, Badung Regency, Bali

Geger Beach is located in Peminge traditional village area, Sawangan, Nusa Dua, Bali which is a tourism area and there is seaweed cultivation managed by local people. Such human activity will affect the quality of the waters which will result in an increase in nutrients and organic matter which can further lead to changes in the structure of plankton. The purpose of this study is to find out the types of plankton and the abundance of plankton found in the waters of Geger Beach using the pour method. This research was conducted in March 2021. Sampling is conducted once a week at three observation points. The total phytoplankton species obtained as many as 32 species consisting of 6 classes, namely Bacillariophyceae (23 genera), Xanthophyceae (1 genus), Cyanophyceae (3 genera), Ulvophyceae (1 genus), Conjugatophyceae or Zygnematophyceae (2 genera), Coscinodiscophyceae (2 genera). The dominant type of phytoplankton found during the study was the Gyrosigma fasciola species in the Bacillariophyceae class. Meanwhile, the total zooplankton obtained by 11 species consisting of 5 classes, namely Maxillopoda (3 genera), Hexanauplia (3 genera), Magnoliopsida, Branchiopoda, and Copepoda (1 genus). The dominant type of zooplankton found during the study was the Cyclops sp. species in the Maxillopoda class. The average abundance of phytoplankton is 120 cells/l, while the average abundance of zooplankton is 20 cells/l. The average diversity value of phytoplankton is 2,7, while the diversity of zooplankton is 1,4. The average dominance index value of phytoplankton is 0,06, while the average zooplankton dominance index is 0,25.

Multivariate approach to determine the ecological preferences of phytoplankton in Uppanar estuary, southeast coast of India

In the present study, the phytoplankton diversity and distribution was studied in relation seasonal variation of environmental parameters in the Uppanar estuary. Samples were seasonally collected (i.e., pre-monsoon: July-2018 and summer: June-2019) from six stations. A total of 62 phytoplankton species belonging to three classes, 20 orders, 26 families and 36 genera were and among the three phytoplankton taxa, diatoms topped the list with 41 species followed by Dinoflagellates (17 species) and blue green algae (4 species). The maximum number of phytoplankton species (36) and diversity value (H’) 3.976 was recorded in the stations near river mouth (UE-6) during summer and minimum species number (21) and maximum species richness (d) 6.923 was recorded in stations close to industrialr zone (UE-1) during monsoon. The maximum species evenness (J') 0.928 was recorded at stations near river mouth (UE-6). BIO-ENV (Biota-Environmental matching) and CCA results confirmed that the environmental parameters such as Dissolved oxygen, Turbidity, Salinity, Water pH, Chlorophyll, Silicate, TN and TP as best match (ρω = 0.968) in determining phytoplankton distributions. The results of present study helps to develop an understanding on the phytoplankton distribution based on physico-chemical parameters, which will form a reliable tool in bio-monitoring studies.

Metabarcoding Analysis of Harmful Algal Bloom Species in the Western Pacific Seamount Regions

The Western Pacific is the most oligotrophic sea on Earth, with numerous seamounts. However, the plankton diversity and biogeography of the Western Pacific in general and the seamount regions in particular remains largely unexplored. In this project, we quantitatively analyzed the composition and distribution patterns of plankton species in the Western Pacific seamount regions by applying metabarcoding analysis. We identified 4601 amplicon sequence variants (ASVs) representing 34 classes in seven protist phyla/divisions in the Western Pacific seamount regions, among which Dinoflagellata was by far the most dominant division. Among the 336 annotated phytoplankton species (including species in Dinoflagellata), we identified 36 harmful algal bloom (HAB) species, many of which displayed unique spatial distribution patterns in the Western Pacific seamount regions. This study was the first attempt in applying ASV-based metabarcoding analysis in studying phytoplankton and HAB species in the Western Pacific seamount regions, which may facilitate further research on the potential correlation between HABs in the Western Pacific seamount regions and coastal regions.

Development of a Fast Liquid Chromatography Coupled to Mass Spectrometry Method (LC-MS/MS) to Determine Fourteen Lipophilic Shellfish Toxins Based on Fused–Core Technology: In-House Validation

Prevalence and incidence of the marine toxins (paralytic, amnesic, and lipophilic toxins) including the so-called emerging toxins (these are, gymnodimines, pinnatoxins, or spirolides among others) have increased in recent years all over the world. Climate change, which is affecting the distribution of their producing phytoplankton species, is probably one of the main causes. Early detection of the toxins present in a particular area, and linking the toxins to their causative phytoplankton species are key tools to minimize the risk they pose for human consumers. The development of both types of studies requires fast and highly sensitive analytical methods. In the present work, we have developed a highly sensitive liquid chromatography-mass spectrometry methodology (LC-MS/MS), using a column with fused-core particle technology, for the determination of fourteen lipophilic toxins in a single run of 3.6 min. The performance of the method was evaluated for specificity, linearity, precision (repeatability and reproducibility) and accuracy by analysing spiked and naturally contaminated samples. The in-house validation was successful, and the limit of detection (LOD) and quantification (LOQ) for all the toxins were far below their regulatory action limits. The method is suitable to be considered in monitoring systems of bivalves for food control.