Category Archives: Nature

Nature interest category

Spare a thought for the jellyfish

Did you ever spare a thought for the jellyfish? I certainly haven’t, but there is far more to a jellyfish than meets the eye. Jellyfish have been quietly living their lives, roaming the great oceans of the world for at least 500 million years. They evolved during the Cambrian Explosion, a short period in the Earth’s history that saw a great flurry of evolutionary activity. While other organisms joined this evolutionary rat-race to go on to become dinosaurs and a myriad of other creatures, the jellyfish, happy with its lot, shunned evolution and retired to the peace and quiet of the high seas. This may, in part, be due to the fact that they are without brains, or at least brains as we typically think of them. Their bodies, of which more than 95% is water, comprise two basic layers of cells. One forms a loose network of nerves called the ‘nerve net’ which is considered the most basic of all nervous systems identified in multi-cellular organisms. This primitive system allows jellyfish to sense their environment, such as changes in water chemistry indicating food, light sensors to detect the presence of light, and balance sensors to let them know if they are facing up or down. Basic, but effective weaponry, which has allowed jellyfish to prosper down through the millennia.

Lions_Mane_resize
Lion’s Mane (Photo: Damien Haberlin)

It is a misconception that jellyfish just aimlessly sail the high seas at the whim of ocean currents and tides, for the manner in which certain species are geographical spread suggest they have some habitat preferences. Around the Irish coasts, for example, the barrel jellyfish each year forms enormous smacks (a ‘smack’ is the collective noun given to a group of jellyfish) off Rosslaire and Wexford Harbour, but is rarely seen elsewhere in such numbers. And the Lion’s Mane jellyfish seems to prefer the cooler waters off the coast of Dublin.

The knowledge of jellyfish around Irish coasts has increased in recent years thanks to research done by Tom Doyle, Damien Haberlin and colleagues at the Coastal Marine Research Centre at University College Cork, research that was spurred on by the apparent worldwide population explosion of jellyfish.  It is thought that the removal of top level predators through over-fishing may have created conditions to allow jellyfish to flourish. Similarly, changes ascribed to climate change have also been implicated for this increase. There is no hard evidence to show that jellyfish have increased in any great numbers in Irish waters, however, the closure of beaches in Dublin in 2005 due to a Lion’s Mane jellyfish infestation, has raised the issue in the collective consciousness.

If your only encounter with a jellyfish is an unexpected eye-to-eye one when swimming, you could be forgiven for not being their greatest fan. Not all jellyfish are small unspectacular blobs of jelly, but they come in a variety of shapes and sizes. The Lion’s Mane is a majestic reddish-brown gelatinous bulk over 1 metre in diameter with masses of long tentacles. Also spectacular are the wonderfully coloured and shaped Compass and Blue Jellyfishes, both roughly the size of a dinner plate. The Barrel Jellyfish is a huge mass of solid ghost-white jelly. Tom Doyle and his colleagues found one specimen that was 80cm in diameters and weighted in at 35kg. Now that’s a lot of jelly(fish).

Snorkeling Church Bay copy resize
Jellyfish (Photo: Damien Haberlin)

Then there are the other jelly-like creatures found around the Irish coast. The wonderfully named ‘Portuguese Man-O-War’ which has a Cornish pastie shaped balloon as a float. Riding the waves with the balloon above water, it somehow resembles an old warship at full sail. But the Portuguese Man-O-War is not a jellyfish, nor is it even a species. Rather it is a colony of creatures that work together to eke out a living, much in the same way that marine corals do; scientifically they are referred to as Siphonophorae and are related to jellyfish, corals and others. But as its name suggests, give the Portuguese Man-O-War a wide berth for its body and tentacles, which can extend for 50m, contain a serious sting. Portuguese Man-O-War made the news headlines in 2012 when some were found washed ashore in Waterford and Cork, but fortunately they normally live further south and only venture north when unusual weather conditions persist.

White Strand resize
Jellyfish (Photo: Damien Haberlin)

But there are many other, less spectacular Siphonophorae living in Irish waters, beautifully shaped jellyfish of varying sizes, each with its own delicate shape and function. And jellyfish do serve important functions; because of their sheer abundance they eat vast quantities of plankton, crustaceans and fish, and in return vast quantities of jellyfish are themselves preyed upon, thus fuelling the marine food web. And jellyfish can be quite the delicacy; the leatherback turtle apparently likes nothing better than to feast on jellyfish, and has been known to swim all the way from the Caribbean to Irish waters searching them out.

So next time you meet a jellyfish spare a thought for how they have done so well for themselves in this rat race of life on earth.

The Barrow River at Ballytigelea

Running along the eastern bank of the River Barrow is the old tow-path. Built in the 18th Century to tow barges plying the waterway, it has long since become redundant for its original use. The picturesque tow-path is now used by locals as an amenity, and is increasingly promoted as an amenity to encourage activity holiday-makers to visit the villages that straddle the Kilkenny and Carlow border; Goresbridge, Borris, Graiguenamanagh and St. Mullins, beautiful unspoiled villages with unique Irish charm.

Barrow Track 1 resize
The River Barrow at Ballytigelea

Ballytigelea Bridge provides access to one of the nicest stretches of the Barrow. Downstream the river flows along the wonderful semi-natural deciduous woodlands of Borris Demesne, linear patches of wet alluvial woodland backing onto to majestic ancient oaks. North of the bridge the river valley opens onto pastoral farmland with beautiful luxuriant species-rich hedgerows and areas of waterlogged ground and pools, each with their own special character. The grassy tow-path is maintained to keep it free for walkers, but the level of intervention is minimal, so it retains is natural feel.

Barrow Track 3 resize
In places the tow-path retains a natural feel
Ballytigelea Lock resize
Elsewhere it is beautifully maintained

 

 

 

 

 

 

This is a strange time of year. Winter is almost upon us yet on some pet days it still feels like summer. Today along the Barrow the temperature was in the high teens with plenty of bright sunshine. A flock of about 20 swallows were feeding over the river, a surprise, for in most years by now they would have left on their migration south.

Near Ballytigelea Lock, red admirals were basking in the warm sun and, much to my delight, I also came across a couple of comma butterflies. These look for all the world like small tortoiseshell butterflies  with badly frayed wings. But the comma is a relatively new addition to the Irish fauna. It was first recorded 2007 or 2008 in  County Wexford where it gained a foothold and has continued to expand its range. It now occurs over most of Wexford and has spread into Waterford, Wicklow and Dublin, and is expanding northwards along the river network. There are established populations along the Slaney and Barrow Rivers, and Ballytigelea seems to mark the limit to its range at the moment. I hadn’t seen a comma so far this year, so seeing one so late in the season was an unexpected treat.

Comma resize
The comma, a relatively new addition to the Irish fauna

The juxtaposition of butterflies basking in the sun and shrubs laden with autumn fruits is a reminder of the changing season. The autumn colours are everywhere; the rusty brown bracken and bramble, vivid red dog rose and guilder rose berries, the carmine guelder rose foliage and the curious vivid orange spindle seeds breaking out from their deep pink shell. Less spectacular but more abundant are the blackberries, haws and sloes, and even the crab apples are almost the size of eating apples this year. A natural bonanza for the birds this winter.

Bracken resize
Bracken
IMG_2143 resize
Guelder rose
woody nightshade resize
Woody nightshade
Spindle cropped resize
Spindle

 

The natural tow-path along the Barrow is a wonderful resource for local and visitor alike, and serves as a huge natural artery for wildlife. Walkers, joggers, anglers and boaters all use and enjoy the amenity, in perfect harmony. The low-level management of the tow-path and the discrete signage make for a experience in keeping with the character of the amenity. It came as a shock to me, therefore, to read a notice pinned on a gate at Ballytigelea, that Waterways Ireland are seeking planning permission to resurface the tow-path with limestone filling. There may be some sound reason why Waterways Ireland are seeking to do this, but for me this would be a huge act of vandalism and totally unnecessary. The Barrow tow-path is an extremely valuable natural asset for the locality – by all means help and promote greater use of the resource, but lay off changing the character of the experience. I’m sure there are better ways of spending the money.