Invasive Species

For the first time in the life of the Lough Corrib, a serious threat exists to the natural habitat of the lake’s fish, wild animals and fauna.

Non-native species are species that have been introduced, either intentionally or unintentionally, to a habitat they do not normally exist in. Some of these species live in natural harmony with the native species and cause no adverse problems.

Invasive species are a group of non-native species that thrive in the natural habitat of Lough Corrib and out-compete the natural flora and fauna.

Invasive species are considered the greatest threat to the future of Lough Corrib as a unique, bio-deverse habitat for some of Ireland’s most beautiful birds, fish and flowers.

Zebra Mussel

Dreissena polymorpha - Zara Brady

Dreissena polymorpha is a small, but prolific, mussel introduced into the Shannon Estuary in the 1990s by the movement of boats. Zebra mussels live in freshwater and have spread from the Shannon Estuary, principally via recreational water use into unconnected water bodies, such as Lough Corrib. Their arrival in Lough Corrib has led to significant changes in native fish communities and changes in aquatic plant growth.

They are filter feeders and remove much of the plankton that juvenile fish depend upon and mask the water bodies natural response to eutrophication. They can result in toxic algal blooms which impact on drinking water. They DO NOT MAKE THE WATER CLEANER!

They attach to any hard surface, such as boats, buoys and water intake pipes, where they form very dense clusters. As such, they can cause problems by blocking out-pipes and clogging cooling systems.

Curly Leaved Waterweed

Lagarosiphon major

Lagarosiphon major grows in water up to 5 metres deep. It is commonly sold as an oxygenating plant for artificial ponds. It has had a serious impact on Lough Corrib where it has grown with such vigour it has already excluded the native flora from the bays in which it is established. It restricts angling, boating and other water based activities.

It spreads by fragmentation. Plant fragments can easily be spread from one waterbody to another on the hull of boats, trailers, outboard motors or angling equipment.

In October 2009, the Irish Times published the following letter from the Hon. Secretary, on the subject of Lough Corrib and Zebra Mussels

26th October 2009

To the Editor,

Sadly we have come to the end of an era in our household. The water pump that draws our domestic water from
Annaghkeen Bay in Lough Corrib has succumbed to the dreaded Zebra Mussel. The foot valve is infested with mussels;
they have colonized the pipes and infiltrated the pressure pump.

I can remember the coming of the rural electrification scheme to this townland in the mid-1950’s and the excitement
of having running water for the first time. On the subject of rural electrification, Sean Lemass announced to the
Senate in March 1945:
“I hope to see the day that when a girl gets a proposal of marriage from a farmer, she will enquire not so much about the number of cows but rather concerning the electrical appliances she will require before she gives her consent, including not merely electric light but a water heater, an electric clothes boiler, a vacuum cleaner and even a refrigerator.”

In March 2006, I attended a conference in a Claregalway entitled Zebra Mussels & other Alien Invaders.
Dr. Doug Jensen of the University of Minnesota spoke about the very serious consequences we faced, and initiatives
which were adopted in USA to combat the scourge of these mussels.

The Irish Government might have acted then to ban boat movement from infected waters (e.g. Shannon-Erne Waterway)
to the Western Lakes (unless certified as steam-cleaned and out-of-water for a specified period). Instead, notices about
Zebra Mussels were erected at slipways and launching areas.
What a joke! The Mayfly Season came and so did the anglers – in their hundreds.

At the slipway at Annaghkeen there were cars with registrations from Clare, Longford, Roscommon, Cavan, Limerick,
Leitrim – all launching boats and engines into the Corrib. And exactly the same occurred in 2007, 2008 and 2009.

Trojan work has been carried by the various local agencies and fishing clubs to combat the influx of these zebra mussels,
but sadly there is a segment of the boating fraternity that display total disregard of the dangers presented to Lough Corrib
from these mussels. Zebra mussels can be transported on ropes, on landing nets, on the boots of fishermen,
and even people walking along the shore. It is much more advisable for visiting anglers to hire boats locally.

When boat owners personally experience the impact of the mussels on their pcokets, I wonder will they begin to take stock?
The discovery that the lower unit of their outboard engine is encrusted with zebra mussels will make them a bit annoyed.
But when the chap who services their engine tells them that the water intakes and inside the housing as far as the
pump impeller is similarly encrusted, they are going to be rather unhappy.

Zebra Mussels have already caused problems to water treatment facilities on the River Shannon. Pipes have been obstructed, water for human consumption tainted by the mussels and the waste left in their wake. Public and Group Water Schemes operating on the Corrib may be similarly affected within a very short period.

Sixty years is a short lifetime to see the water come bubbling and sparkling out of brand new tap. It is short time to be an eye-witness to the irreversible changes of a lake’s ecology. But we really have come to the end of an era.
Ní gá ach sracfheachaint a thogail chun an fhírinne a fheiceail.
Translation: It isn’t necessary but to take a glimpse to see the truth.

Yours faithfully,

Zara Brady
Lough Corrib

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