Cutting of Our Lady's Island Lake

flashjohn

http://www.youtube.com/watch?v=E04TtKrMEoM

ytpe2r5bxkn0c1

Any commentary? Is it remedial or preventative works?

I thought it was usual to run off every now and again if the fresh water element is too high, in order to maintain the brackish nature of the lake.

flashjohn

http://www.boards.ie/vbulletin/showthread.php?p=89141096

ytpe2r5bxkn0c1

Sorry, am I missing something? Is this just a video showing the annual draining or some commentary on the wildlife impact. Apologies for being thick but is there an issue or query here, or is it a "some video I took recently" item?

flashjohn

Its a popular nature spot?

http://en.wikipedia.org/wiki/Lady%27s_Island_Lake

ytpe2r5bxkn0c1

flashjohn wrote: »

Its a popular nature spot?

http://en.wikipedia.org/wiki/Lady%27s_Island_Lake

Very much so and keeping the brackish nature intact is vital to that.

flashjohn

???

ytpe2r5bxkn0c1

flashjohn wrote: »

???

To maintain the unique habitat there is an annual cut to allow the water, which is becoming too fresh, to run off.

Capercaille

I would presume it would also maintains the water levels at optimal levels for the breeding terns (sandwich, common and roseate) and the gulls (black headed and med). The lake is full at the moment.

Decoda

http://www.ourladysisland.ie/conservation_plan_our_ladys_island.php

See page 73 for the reasons for the cut. Mainly to do with water levels and as Caper says the bird habitats.

D

Birdnuts

The funny thing is that on most lakes bird numbers tend to go up as water levels go down. Shallower water and more exposed mud make for better feeding. Obviously though you have to maintain the water at a certain level for the benefit of fish and to keep islands ground predator proof etc.

recedite

Decoda wrote: »

http://www.ourladysisland.ie/conservation_plan_our_ladys_island.php

See page 73 for the reasons for the cut. Mainly to do with water levels and as Caper says the bird habitats.
D

This from P.5 explains why they have been doing it for hundreds of years, it acts as a fish trap/fish farm;

It is once in four or five years opened, evacuating itselfe into the sea, a passage being cut by command of Squire Cod, of Castletowne, which during a few months continuing open, flowes and ebbs, whereat enters aboundance of fry or small fish, untill by violence of Tempest the Gappe is by running sand obstructed, wherein that yong Fish detained becomes extraordinary great and fatt, especially Base and Mullet, Whitings, Herrings, incomparable large, solid, and thicke, Flounders, extraordinary great fatt Eeles, &c

Then on P.73 it mentions that eutrophication has become a problem since 1980's, so that means emptying out all the smelly water in the spring and then allowing a large volume of water to build up for the summer which would dilute the pollutants. Anyone who has kept a goldfish in an bowl will understand what is going on.

The serious aquarist however will favour filtration, water treatment and smaller more frequent water changes, all these being less disruptive to the ecosystem. Hence the author of the document calls for a more permanent engineering solution.

A little further north at the East Coast Nature Reserve, at Kilcoole marshes, the water levels are maintained by a simple enough sluice gate placed on the drainage ditch exiting the marsh to the sea. This is optimum for the wildlife and management of the ecosystem. If this was applied at Lady's Island, the water would soon cease to be brackish, but would also probably be a richer albeit freshwater ecosystem.

At Lady's Island lake, I'm guessing there is no stream exiting the lake, and the water simply filters through the shingle embankment, leaving all the pollutants/nutrients behind in the lake.

flashjohn

There is no stream exiting the lake. It is man made every year. It was usually done by local farmers using horses and various tools. It is looked after by council now who contract in the work. They used to let the tide in and out of the lake and it would gradually block up the passage again. I think they block it up now once drained. Last weeks cut blocked up in a few hours, however high winds coming from south means they have to wait to unblock it again. Very little water drained out, but it did relieve the threat of the road on Our Lady's Island being flooded.

Capercaille

recedite wrote: »

This from P.5 explains why they have been doing it for hundreds of years, it acts as a fish trap/fish farm;


Then on P.73 it mentions that eutrophication has become a problem since 1980's, so that means emptying out all the smelly water in the spring and then allowing a large volume of water to build up for the summer which would dilute the pollutants. Anyone who has kept a goldfish in an bowl will understand what is going on.

The serious aquarist however will favour filtration, water treatment and smaller more frequent water changes, all these being less disruptive to the ecosystem. Hence the author of the document calls for a more permanent engineering solution.

A little further north at the East Coast Nature Reserve, at Kilcoole marshes, the water levels are maintained by a simple enough sluice gate placed on the drainage ditch exiting the marsh to the sea. This is optimum for the wildlife and management of the ecosystem. If this was applied at Lady's Island, the water would soon cease to be brackish, but would also probably be a richer albeit freshwater ecosystem.

At Lady's Island lake, I'm guessing there is no stream exiting the lake, and the water simply filters through the shingle embankment, leaving all the pollutants/nutrients behind in the lake.

There is alot of tillage around Lady's Island, no doubt a major contributor to pollution of the lake. Changing the water from brackish to a fresh water lake might not be a good idea however. It might have an effect on the internationally important tern Colonies, especially the Roseate terns.

ytpe2r5bxkn0c1

The brackish nature of the lake is what makes it what it is. It would be an environmental disaster at a European level if this was lost.

Capercaille

Kaylin Melted Tablet wrote: »

The brackish nature of the lake is what makes it what it is. It would be an environmental disaster at a European level if this was lost.

Lady's Island lake along with Tacumshin lake are the finest example of coastal lagoon in the Country.

OpenYourEyes

If I remember correctly (and it might essentially be what some people above have said) but the SAC and SPA designations are in conflict in terms of the management they require - cutting the lake benefits the SPA interests, but hurts the SAC interests, and not cutting the lake would be detrimental to the site as an SPA but would benefit the SAC habitat.

An unusual and difficult balance to strike, but it's a great and unique site nonetheless

flashjohn

http://www.youtube.com/watch?v=kco8w9vNCcQ Part 2

recedite

Normally a coastal lagoon is freshwater. Brackish habitat is to be found in an estuary. It was mentioned in the document that locals complain about the smell from rotting (freshwater) pondweed after the seawater is let in every year. But on the other hand, making the cut is the only method they have at the moment to prevent the road from flooding, so they tolerate the smell.

Some here are saying that the brackish nature is what makes the lake what it is, which may be the case, but I'd suggest that the sudden wild fluctuations from near 100% freshwater to near pure seawater once a year is neither natural nor beneficial to the wildlife and vegetation there. Its only a good idea if you are farming flounders and eels on an annual cycle.

It would be an interesting site for a more detailed case study though. Someone would need to measure the various effects over say two years.