Natural Hazards


The proliferation of Cyanobacterial blooms: A toxic blue tide

Dr Assaf Sukenik is Senior Scientist at Kinneret Limnological Laboratory of the Israel Oceanographic and Limnological Research. His research interests concern the physiology and biochemistry of freshwater and marine algae, Cyanobacteria and algal toxins, the water quality of freshwater ecosystems.

What are cyanobacteria and what is their natural habitat?

Cyanobacteria (from the Greek word κυανοσ =blue), also known as blue-green algae, constitute the largest, most diverse, and most widely distributed group of photosynthetic oxygenic (oxygen-evolving) prokaryotes[1]. They acquire their energy through photosynthesis, thus are often referred to as algae, although their prokaryotic characteristics (for example, their DNA is not enclosed in a nucleus) differentiate them from eukaryotic[2] algae. The blue-green colour of cyanobacteria is given by their suite of photosynthetic pigments, which differ from that of eukaryotic algae.

Cyanobacteria are also among the oldest organisms on Earth. They appear in fossil records, in sedimentary rocks deposited in shallow seas and lakes 3.5 billion years ago. They played a major role in raising the level of free oxygen in the atmosphere of early Earth and contributed to the evolution of plants. Sometime in the late Proterozoic, or in the early Cambrian, about half a billion years ago, cyanobacteria began to take up residence within certain eukaryotic cells, providing organic compounds for the eukaryotic host via photosynthesis in return for a home in a process known as endosymbiosis[3].

Cyanobacteria are found in a diverse range of habitats, [Read More]

Hazard chains: from anthropic oil spills to ecosystem pollution. Can tiny organisms be the solution?

Hazard chains: from anthropic oil spills to ecosystem pollution. Can tiny organisms be the solution?

Hello to everyone. Today I have the personal pleasure to interview Dr. Grégoire Michoud. He is a friend and a brilliant scientist working on ecosystem microbial ecology. In the interview, Grégoire will talk to us about oil spills in the marine system, a specific anthropic hazard that can evolve into a natural hazard with terrible environmental consequences.

Grégoire Michoud is a Post-Doctoral Scientist at KAUST (Saudi Arabia), since 2015. He obtained his Ph.D. from the Université de Bretagne Occidentale, in Brest France. His primary research interest focuses on the characterization of the coping mechanisms of microbes in extreme environments (deep sea, brine pools, hydrocarbon pollution) by genomics and cultures approaches. His work has application in hazard chain from anthropic sources to natural targets.



Hello Grégoire, please tell us a bit about environmental issues related to oil spills.

When it comes to oil spills, widespread publicized releases are rare events and represent just 10% of the overall release in the marine ecosystem. The remaining 90% is actually due to ship activities or other land-based industries that contribute to the pollution. One example of rare oil spill is the Deep Water Horizon case where, in a relative short time, a huge amount of oil was released into the Gulf of Mexico. However, in the vast majority of situations, small quantities of oil can be released from random events adding up to a considerable pollution.

[Read More]