Publications by authors named "Yohan D Louis"

Awareness of plastic pollution in marine habitats, such as coral reefs, has grown in recent years. Several studies have shown that tiny particles resulting from plastic breakdown, especially microplastics, can potentially harm corals. However, to date, there is very little evidence regarding the impact that nanoplastics (<1 μm) can have on the physiology and health of corals, particularly soft corals.

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The Mediterranean is known for its marine biodiversity, especially gorgonian forests. Unfortunately, these are experiencing rapid declines due to climate change, manifested by repeated marine heat waves resulting in mass mortality events since the early 1990 s. To better understand why gorgonians are declining, more systematic approaches to investigate the exact causes are needed, and pathology may aid in this goal.

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Article Synopsis
  • Coral reefs are experiencing a rapid decline in biodiversity due to climate change and increased disease outbreaks, making it difficult to assess the dynamics of coral diseases in the Maldives.
  • A study around Thudufushi Island evaluated four coral diseases over a 12-year period, finding an overall increase in disease prevalence, particularly skeletal eroding band (SEB), which showed the largest rise since the last assessment in 2010.
  • The research highlights a significant rise in coral diseases, with a recommendation for a national monitoring protocol to understand and predict future disease trends in the region.
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Article Synopsis
  • Microplastic pollution threatens coral reefs, which are already struggling with climate change, particularly heat stress, but the impact of microplastics on coral health is not well understood.
  • In a study on Pocillopora damicornis, corals were exposed to varying concentrations of polyethylene microplastic beads and temperatures, revealing ingestion and egestion but no immediate visual stress responses.
  • The findings showed that while heat stress is the main concern for coral health, microplastics could compound the negative effects of thermal stress, suggesting the need for better management of ocean temperature to protect coral ecosystems.
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Massive coral bleaching episodes induced by thermal stress are one of the first causes of coral death worldwide. Overproduction of reactive oxygen species (ROS) has been identified as one of the potential causes of symbiosis breakdown between polyps and algae in corals during extreme heat wave events. Here, we propose a new strategy for mitigating heat effects by delivering underwater an antioxidant to the corals.

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Chlorophyll a fluorescence is increasingly being used as a rapid, non-invasive, sensitive and convenient indicator of photosynthetic performance in marine autotrophs. This review presents the methodology, applications and limitations of chlorophyll fluorescence in marine studies. The various chlorophyll fluorescence tools such as Pulse-Amplitude-Modulated (PAM) and Fast Repetition Rate (FRR) fluorometry used in marine scientific studies are discussed.

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Corals show spatial acclimatisation to local environment conditions. However, the various cellular mechanisms involved in local acclimatisation and variable bleaching patterns in corals remain to be thoroughly understood. In this study, the modulation of a protein implicated in cellular heat stress tolerance, the heat shock protein 70, was compared at both gene (hsp70) and protein (Hsp70) expression level in bleaching tolerant near-coast Acropora muricata colonies and bleaching susceptible reef colonies, in the lagoon of Belle Mare (Mauritius).

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Gene expression biomarkers (GEBs) are emerging as powerful diagnostic tools for identifying and characterizing coral stress. Their capacity to detect sublethal stress prior to the onset of signs at the organismal level that might already indicate significant damage makes them more precise and proactive compared to traditional monitoring techniques. A high number of candidate GEBs, including certain heat shock protein genes, metabolic genes, oxidative stress genes, immune response genes, ion transport genes, and structural genes have been investigated, and some genes, including hsp16, Cacna1, MnSOD, SLC26, and Nf-kB, are already showing excellent potential as reliable indicators of thermal stress in corals.

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