Water sports enthusiasts know they should not endanger swimmers – and there are rules and regulations to make sure they don’t – but many may ignore the fact that the sea is home to other life forms that also need protection: marine species.

Among existing water sports, recreational boating may be doing most harm to underwater life for a number of reasons, the top one being anchor damage.

“Anchoring has the biggest impact, especially on vulnerable species such as seagrass ones and where there is not enough berthing space or pontoons,” claims marine biologist Alan Deidun.

“One might think the sea is a free- for-all, unaware of the ecological importance of the area.”

Anchors physically damage seabeds, seagrass and coral reefs.

Mġarr ix-Xini is particularly at risk. The area is home to coral and false coral species, sea horses and Posidonia oceanica, a seagrass species that is endemic to the Mediterranean and is an important part of the marine ecosystem.

“The installation of at least a small, floating pontoon would minimise this problem within the densely-populated [with boats] creek,” claims Deidun.

The second-most problematic aspect is the anti-fouling paints used on boats. This is a specialised coating applied to the hull of a boat to slow the growth of organisms that can attach to it and affect its performance and durability. There is a high concentration of these paints, which are toxic to marine life, in yacht marinas.

Release of fuel through leakages is also an issue, as is the disposal of the content of bilge tanks.

“There is currently no legislation on this. For example, often at Għadira, boats dispose of their wastewater a few hundred metres away from the bay’s mouth, which is useless, as the currents might draw the waste into the bay.”

The building of yacht marinas also affects water quality as sea-water may turn milky white and become extremely turbid, cutting off light penetration which is necessary for underwater vegetation.

Scuba-diving can also harm marine species, especially those found in caves.

“Exhaled air trapped in bubbles affects the highly-adapted specialised species dwelling in caves,” explains Deidun.

A particular diving apparatus called ‘rebreather’ would avoid this problem.

Exhaled air trapped in bubbles affects the highly-adapted specialised species dwelling in caves

Divers can also hit branching erect species such as coral, sea squirts and sponges with their fins.

“These are very delicate and are easily broken off when hit. Manual touching can also damage them. This has happened to a great extent at Dwejra, where the lace coral within the Coral Cave has mostly fallen off .”

Inexperienced divers, who still have to get to grips with buoyancy control, can disturb sandy seabeds, especially where the sand is fine, meaning it has a high proportion of silt and clay. This type of sand takes more time to settle than coarse sand, making water turbid for a longer period of time.

Divers can also generate underwater noise pollution ­– as they use a special equipment that generates sound to attract the attention of fellow divers – and light pollution by using torches during night dives to visit caves and places accustomed to a low-light intensity.

Jet skis can also harm the environment through fuel residue and oil leakages, and also through possible collisions with marine mammals and reptiles.

“Turtles are vulnerable to collisions when they surface to breathe,” says Deidun.

Paddle boats, canoes and snorkelling are very low-impact sports, as they are unlikely to affect branching erect species and don’t release hydrocarbons (fuel and engine oil) into the water column.

“The non-branching species, called encrusting species, stand a low chance of being impacted by man, as they lie low along the seabed and are calcareous, that is very strong. Coralline red algae is one such group of resilient species.”

Another possibly dangerous ‘sport’ is harpoon fishing, which can affect individual small fish. However, if practised responsibly, it should not have a big impact.

“One should be very selective, and choose species that are mature or not that rare. One should also go for species that are not so ‘charismatic’, such as the big dusky grouper, which are important to the diving industry.

“Fish caught should be eaten and, obviously enough, harpooning should not be practised in swimmers’ zone.”

A little more responsibility could lessen the impact of recreational boating and diving in no small way. Deidun says that anchoring should be restricted to sandy seabeds, so as not to impinge on Posidonia beds.

Diving within caves should be supervised and only done by experienced divers and, ­preferably, using the appropriate ­equipment.

Posidonia Oceanica

Posidonia oceanica, commonly known as Neptune Grass, is a seagrass species that is endemic to the Mediterranean Sea and is an important part of the ecosystem. Here are some facts about it:

• The genus Posidonia is named after Poseidon, the Greek god of the seas, while oceanica refers to its former wide distribution.

• It is abundant in the Mediterranean, however there is evidence that the population is declining in the western Mediterranean.

• It is a large, long-living but very slow-growing seagrass.

• It is an important habitat-forming species and provides habitat for many species. It forms nursery grounds for the juveniles of many commercially important fish and vertebrates.

• The meadows composed of this species are considered the basis of the richness of Mediterranean coastal waters, due to the surface area they occupy and to the essential part they play at biological level in maintaining the coastal equilibrium.

• In autumn, the seagrass sheds some of its leaves, much of which ends up on the shore to form seaweed banks that comprise a different habitat.

• Posidonia grows best in clean waters, and its presence is a marker of lack of pollution.

• It is threatened at depth by mechanical damage from trawling, boat anchoring and turbidity.

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