The Malta Independent 4 December 2020, Friday

The Mediterranean Sea: A biodiversity and plastic hotspot - marine biologist

Giulia Magri Tuesday, 20 August 2019, 08:03 Last update: about 2 years ago

Over the summer months, the main news headlines highlighted the issue of trees being cut down and uprooted. Environment issues are not a new topic, but more and more people are discussing the environmental impact of the uprooting of such trees, especially on an island which lacks open green spaces to begin with. Yet, there has not been as much discussion on the environmental importance of our Mediterranean Sea. The Malta Independent spoke with marine biologist and lecturer Alan Deidun to highlight how the Mediterranean Sea has changed over time due to the increase in population, invasion of alien species and climate change.

Despite only covering around 1% of the global ocean surface area, the Mediterranean Sea hosts around 10% of all marine species in the world, marine biologist and University academic Alan Deidun told The Malta Independent.

Deidun said that while the Mediterranean flourishes with such biodiversity, it is also a plastic hotspot, being one of the areas in the world most affected and polluted due to the high concentration of plastics found.


The Malta Independent met with Deidun to discuss how the Mediterranean Sea has changed due to further urbanisation of the countries around it, and the damage caused by single use plastics.

 “Plastic has become man’s blueprint. It damages the Mediterranean, and damages sectors which are heavily reliant on the Mediterranean Sea,” explained Deidun. “Aesthetically, macro litter is bad for business where the sea plays a vital tool, as plastic litter is an eyesore.” He goes on to explain that once this litter sinks to the seabed, it smothers marine communities such as coral, and ultimately traps them.

“We have gone down 300 meters behind Filfla, and all you see are whole coral communities blanked with nylon rope from previous fishing seasons, where nylon ropes are cut and are not recovered.”

The biggest threat of all is micro and nano plastics, which end up in our food chain, he said.

“The smaller pieces of plastic are then absorbed or eaten by zooplankton, which are then consumed by smaller fish, which after time end up on our plate. In most recent studies, plastic particles have been found in human stool for the first time. We need to be more concerned about our marine life, even if it is from a selfish perspective; as the waste we are throwing into the sea is the same waste we will consume.”

Would you say there is enough focus on the importance of the sea and the marine biodiversity?

The public’s perception of marine environment is quite anonymous, and at times the sea is really overlooked. Although we are an island our marine area is very big, and just taking into consideration our territorial waters the ratio is 14.1 - all this without considering the fisheries zone or search and rescue area. When we discuss environmental issues and climate change, we must see what is happening to our seas and we should have a much greater interest and appreciation on the role the ocean plays in our lives.

We normally think of trees providing us oxygen, but at least half of the oxygen we breathe comes from the ocean, where we find phytoplankton producing oxygen,

Subconsciously we have a link to the sea, as we draw ourselves closer to the presence of the sea which can bring about feelings of nostalgia and memories. The sea has both a direct and indirect tie to the island’s economy. Directly - fishing, aquaculture, whilst indirectly - tourists come to our beaches, and restaurants serve the daily catch of the fishermen. There is also a booming diving industry. Many Maltese do not know enough about the sea and are hesitant to learn more.


What changes have you seen in the past 10-20 years in marine biodiversity due to climate change?

As temperatures continue to rise, this has an impact on our seas. It is the third consecutive summer, where by the end of it we will see the water temperatures going as high as above 30 degrees. There is no exact maximum threshold as to how high the temperature can go up before causing damage, but we do know that there are some species which suffer when the temperatures rise; especially species found in shallow areas where it gets very hot. Many algae disappear by the end of summer. Also when there is a prolonged heat wave, a mass of hot water sits on cold water; and over time the hot water pushes further down and ends up effecting species which are normally oblivious to such high temperatures.

Another main impact of climate change would be the invasion of alien species entering the Mediterranean Sea and causing harm to our native marine life. Most alien species keep a low profile and are not always an issue, but then there are a few, such as the lionfish, which displace the native species and have an ecological impact which can translate into having a bigger economical crash. There are also harmful algae which are harming the sea grass species, such as the posidonia, the lung of our Mediterranean Sea. The sea grass is vital as it keeps the sea transparent, provides oxygen and is also a place for other species to lay their eggs. This grass covers less than 2% of the Mediterranean. Anchoring and pollution harms these meadows as well.

Going back to the lionfish, there was also a time when one could buy a lionfish in a pet shop and release it back into the sea, not being aware of the harm or impact on the biodiversity. Another example of this is the release of crayfish into fresh water valleys, such as Chadwick Lakes, which they are running a riot and impacting indigenous species such as the native frog and fresh water crab. We must continue to raise awareness and monitor aquarium releases and customer behaviour.

You said that we see alien species entering our waters, but do we ever see our own native species migrating and moving to other parts of the Mediterranean?

In terms of our own native species we have a particular species of fish, the salema, better known as xilpa which is slowly being replaced by the alien rabbit fish. The native fish are moving yes; so now we find that species which were exclusively known in the East Mediterranean are now moving west, whilst those known in the South are moving north. This could also be happening with the dolphin fish, lampuki because catches have dwindled in recent years and this might be because there are more fishermen moving in our area catching this fish. Previously Maltese fishermen were specialised in catching this fish, but now there are other nationalities. It might be that this fish is moving because its prey species are also travelling through different routes; therefore their own routes are changing.


Does the overcrowding of beaches during the summer impact our marine life?

The main issue of overcrowding would be trampling, on both land and sea. On land coastal communities, we see that the native sand dunes, gharam tar- ramel, over time have been trampled on, either by people driving over them or camping on them. Currently one can find such sand dune ramilites on few beaches such as Golden Bay, Ramla l-Hamra in Gozo, the Bird Sanctuary in Ghadira and Santa Marija in Comino.An example of trampling at sea would be when one finds fragile communities such as algae or coral found on a shallow reef and people would trample over them.

Another issue apart from overcrowding would be the ever-increasing number of boats during the summer months. Anchoring destroys sea grasses and leaves shallow holes behind, and dumping the discharge of the boat pollutes the sea. One must also remember that the noise caused by the boats are amplified underwater, and many times scares or disorientates slow moving species. Such boats also end up colliding with migrating animals; earlier this summer we had a loggerhead turtle hit by a boat propeller. Although Nature Trust rescued the turtle it ended up dying due to injuries.

What can one do to decrease the harm and damage being caused to the Mediterranean Sea?

I would start from the very basics; that being raising more awareness and fostering a more ocean literate society. Ocean literacy is all about making people more aware about the ocean’s role in our lives. One example would be how the ocean plays a role as a climate regulator, taking the heat from the tropics to the poles to regulate the temperature. If this were to switch off, we would see extreme changes in our climate. 

We need to remember that the impacts of climate change are not exclusive to the land. if we have a healthier ocean, we have a better chance of fighting climate change. We should not take our sea for granted, and always be prepared for any massive pollution event which can affect us negatively, such as a massive oil spill. We are to a certain extent prepared, as there is constant training happening and there is partnership between University and Civil Protection, where training is being handled.

Such preparation is extremely important, especially since we get 60 per cent of our drinking water from the sea; so god forbid there ever is a massive oil spill.






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