Milad Pourdanandeh Hosseini
About Milad Pourdanandeh Hosseini
Who am I?
I work as a PhD candidate in the Signals in the Sea working group (pelagial.se), with Erik Selander as supervisor.
I am broadly interested in ecology and ecophysiology, especially in aquatic environments, but also biostatistics, experimental design and science communication.
Twitter/X: @pour__Milad
Research
My research focuses on phytoplankton responses to chemical cues released by copepods, called copepodamides, and the consequences of these responses at individual to ecosystem scales.
Copepods, and their chemical scent, have been shown to induce a wide variety of different defensive mechanism. They induce toxin production in harmful algae, bioluminescence (svenska: mareld), shortening of chain forming diatom colonies, altered swimming behaviour in motile dinoflagellates and changes in the diel feeding behaviour of marine protists.
Thesis projects
Published:
- Copepodamides in freshwater copepods, compared to in marine copepods (published in Scientific Reports https://doi.org/mf4s)
- We have previously found bioactive copepodamides (i.e., capable of inducing physiological and/or behavioral effects in phytoplankton and protists) in almost all studies of herbivorous/omnivorous marine copepods, the exception being a purely carnivorous copepod (Paraeuchaeta norvegica) which almost exclusively contained only the copepodamide scaffold. However, it has been unknown how prevalent copepodamides are in freshwater copepods and if these differ in chemical composition compared to marine copepods.
- The effects of copepod chemicals cues on Diarrhetic shellfish poison-causing microalgae (published in Harmful Algae https://doi.org/nz3q)
- Copepod chemical cues have been shown to induce toxins in a variety of marine algae, but we do not know if this is also the case for the toxic dinoflagellate Dinophysis sp. which produce diarrhetic shellfish toxins that affect marine organisms and cause diarrhetic shellfish poisoning in humans. Here, we induced cultures of two species of Dinophysis to three concentrations of copepodamides and one live grazing copepod treatment.
Works in progress:
- Drivers of toxin production in harmful algae (in prep, soon to be submitted)
- I am currently finishing up a meta-analysis on the relative induction effects of top-down (grazing pressure) and bottom-up (nutrient availability of nitrogen and phosphorous) on toxin production in two important genera of harmful microalgae (Alexandrium & Pseudo-nitzschia).
- Copepodamide mediated induction of toxins and bioluminescence in additional dinoflagellates (in prep, soon to be submitted)
- Copepodamides induce defences such as toxins and bioluminescence in several marine dinoflagellates. Here we exposed previously untested species, Protoceratium reticulatum, Gymnodinium catenatum, and Alexandrium catenella and measured their toxin and bioluminescence response. We also assessed if increased toxin or bioluminescence production correlated with any changes in growth rate, indicating a cost of the defence.
- Costs of toxicity and bioluminescence in marine dinoflagellates (partially piloted)
- Toxin production and bioluminescence in marine dinoflagellates have been shown to, at least partly) be due to grazing pressure from zooplankton such as copepods. These responses are predicted to have an inherent energy cost, which we will attempt to quantify in terms of growth.
- The effect of copepod chemical cues on thecal plates of dinoflagellates (partially piloted)
- Thecal plates of dinoflagellates in laboratory cultures have been described as "thin" and "weak" by some dinoflagellate taxonomists, compared to cells found in nature. We will study if this is a plastic response to the lack of grazing, and if exposure to grazing pressure from copepods and/or their chemical cues can trigger the cells to reinforce their thecal plates and make them thicker.
- Method development for fragile dinoflagellates (planned)
- When we want to expose cultures to several pulses of copepodamides over time, usually to create an environment with more stable copepodamide concentrations, we cannot simply add the compounds to the medium directly, because they are dissolved in methanol and would poison our algae. We therefore coat a new culture vessel with the compounds (dissolved in methanol), evaporate the methanol (either by itself or by flushing it with nitrogen gas), and finally decant the culture into the newly coated vessel. However, several species of dinoflagellates seem to be very sensitive to the decantation, affecting their growth. I will therefore investigate new methods of repeatedly exposing cells to copepodamides in the same vial/flask. The general idea is to instead coat the compounds onto a glass rod/plate, which is attached/suspended from the vessel cap. This would enable us to expose the cultures to new pulses of copepodamides without disturbing the cells as much as we do now.
Projects outside my thesis
- The fate of the methane released by the sabotage of the Nord Stream pipelines (published in Scientific Reports https://doi.org/m4c6)
- I was part of the University of Gothenburg researcher led scientific expeditions to the Nord Stream pipeline explosion site in 2022 and 2023, where we sampled the area in a variety of ways to determine what happened to the methane released. I was in charge of sampling zooplankton and phytoplankton.
- The effect of the methane released by the Nord Stream pipeline sabotage on plankton communities (in prep)
- Led by Carina Bunse at the Department of Marine Sciences, this project aims to determine whether the methane released from the Nord Steam pipelines affected the plankton communities, focusing on bacteria, phytoplankton and zooplankton.