Climate Change

Posidonia oceanica, commonly known as Neptune grass or Mediterranean tapeweed, is a seagrass species that is endemic to the Mediterranean Sea. It forms large underwater meadows that are an important part of the ecosystem.
Posidonia oceanica, commonly known as Neptune grass or Mediterranean tapeweed, is a seagrass species that is endemic to the Mediterranean Sea. It forms large underwater meadows that are an important part of the ecosystem.

Seagrasses are natural carbon dioxide sink, thanks to symbiotic bacteria

Seagrasses need nutrients to thrive, particularly nitrogen (N). Up to now, it has been assumed that the nitrogen is taken up by the seagrasses through leaves and roots from the surrounding seawater and sediment.

However, in many of the regions where seagrasses are most abundant, there is little nitrogen to be found. Furthermore, while nitrogen is abundant in the sea in its elemental form (N2), seagrasses cannot use it in this form. 

Climate Change & the Growing Crisis of Our Oceans

Partically bleached coral in the Mediterranean Sea, Cape Carbonara, Sardinia. Photo by Lorenzo Moscia
Partially bleached colony of the madreporarian Cladocora caespitosa, one of the most important hard corals in the Mediterranean, at Cape Carbonara, Sardinia

Climate change is increasing the crisis of our seas, already under pressure due to several human activities. Rising temperatures are affecting and changing the underwater environment all over the world. The Mediterranean Sea, unfortunately, is no different from other seas. A group of specialists, coordinated by Greenpeace Italy, are monitoring the situation in the waters around Italy. Lorenzo Moscia reports.

Rising sea temperatures have prompted marine species in the Mediterranean to move deeper into the ocean depths.
Rising sea temperatures have prompted marine species in the Mediterranean to move deeper into the ocean depths.

Mediterranean species move deeper to flee rising sea temps

Due to climate change, the average temperature in the Mediterranean Sea rises by one degree every thirty years, and this rate has been increasing. Because of this, the marine creatures there have been shifting their habitats to the deeper, cooler depths of the ocean.

Researchers reached this conclusion after reviewing research involving the depth distribution of 236 marine species like fish, crustaceans and mollusks collected in previous bottom-trawl surveys.

A new approach to enhance coral resilience comprise of selective sexual propagation, coral probiotics and environmental hardening, to enhance coral’s stress resilience and allow reefs to regrow under changed environmental conditions.
A new approach to enhance coral resilience comprise of selective sexual propagation, coral probiotics and environmental hardening, to enhance coral’s stress resilience and allow reefs to regrow under changed environmental conditions.

Restoring coral to health

Corals are able to respond to changes in their environment through acclimation (the physiological process of becoming accustomed to a new condition) and adaptation and researchers believe natural populations may already be adapting to increasing sea surface temperatures.

Vlad Karpinsky / CC BY-NC-ND 2.0
File photo: Reef scene in Fiji. Source: Vlad Karpinsky / CC BY-NC-ND 2.0

Fiji's coral reefs rebounds

On 20 February 2016, tropical cyclone Winston struck Fiji. It was described as the most destructive cyclone ever to strike in the Pacific. With winds of up to 280km/h, the coral reefs in the Namena Marine Reserve and Vatu-i-Ra Conservation Park off Fiji were completely destroyed.

To understand how cyclones affect coral reefs and how fast the reefs recover, the team at Wildlife Conservation Society (WCS) Fiji conducted three surveys at different times—one month after, six months after and in December 2020 (more than four years after the cyclone).

Natural bleaching susceptibility is manifested in the biochemistry of both the coral and its algal symbiont.

Unravelling how some corals resist bleaching

Researchers at Michigan State University and the University of Hawaii at Manoa have been uncovering clues as to why some corals bleach while others are resistant, information that could help reefs better weather warming waters in the future.

The team analysed the biochemistry of corals using mass spectrometers to understand what set resistant corals apart from susceptible ones. The scientists found that two different communities of algae lived within the corals. Inside the algae cells were compounds known as lipids.

Researchers conclude the northward range shift demonstrates the young white sharks are being subjected to a loss of suitable thermal habitat

Climate change shifts the range of white sharks

Researchers conclude the northward range shift demonstrates water temperatures within their preferred temperature range of juvenile white sharks are becoming harder to find.

The animals have historically remained in warmer waters in the southern California Current; Between 1982 and 2013, the northernmost edge of the juveniles' range was located near Santa Barbara (34° N).

Help protect the Coral Reefs

Our coral reefs are now under threat not only from the global warming, pollution and exploitation but also by the conduct of divers in these sensitive areas. The reefs are now calling for our protection both when we dive and as contributors to the ongoing struggle to preserve these unique ecosystems for future generations.