NH
Natural Hazards

Archives / 2019 / July

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]

NH10 Multi-Hazards: The Latest EGU Natural Hazards Sub-Division

NH10 Multi-Hazards: The Latest EGU Natural Hazards Sub-Division

Earlier this year, the EGU Natural Hazards Division approved the addition of a new sub-division focused on the theme of ‘multi-hazards’. The Science Officers representing this sub-division, Joel Gill (British Geological Survey) and Marleen de Ruiter (IVM-VU Amsterdam), reflect on why this sub-division is necessary and how you can get involved.

Many regions are affected by multiple natural hazards, with hazards and/or their impacts not always occurring independently. The Sendai Framework for Disaster Risk Reduction, therefore, advocates for ‘multi-hazard’ approaches to disaster risk assessment and reduction. The UN defines ‘multi-hazard’ as follows: 

“Multi-hazard means (1) the selection of multiple major hazards that the country faces, and (2) the specific contexts where hazardous events may occur simultaneously, cascadingly or cumulatively over time, and taking into account the potential interrelated effects” (UNDRR Terminology, 2017).

[Read More]