The Blackwater is catching!

I’ve always been passionate about “the Irish Rhine”, Munster’s Great River, the Blackwater. I’m proud to know it so intimately, having swum every inch of it between Ballyhooly and the sea (the bottom 70 km of its 170 km course). The Blackwater Valley is truly stunning: with breathtaking scenery around every corner, and peace. Exploring it at a swimmer’s pace is a great way of appreciating, and from a unique angle. It’s a shame that, until recently, I was one of very few people to have experienced this, so I’m delighted that members of Blackwater Triathlon Club have started pushing out their distances in the water and are making good use of the beautiful river on our doorstep! Over the last two weekends, they started catching the bug…

Cregg/Castlehyde to Fermoy Rowing Club

The first swim, from just upstream of Castlehyde House to Fermoy Rowing Club, a distance of about 4 km, was last Monday morning. Dave Mulcahy, Declan O’Keeffe and I had been doing this swim once a year for the last few years, but this was the first time that a decent-sized group took on the challenge…


Setting off in dribs and drabs from the riverbank just upstream from Castlehyde.

The swim was a great opportunity for many to challenge themselves with their longest swim to date, which it was for most of the 15 swimmers who completed it. It was also a good opportunity for my boyfriend, Wagner, to get to grips with kayaking for a bigger group of swimmers, which it turns out mightn’t be as tough as listening to them talking about swimming!


Wagner getting used to the kayak…and listening to swimmers talking about swimming!

The swim was thoroughly enjoyed by all who took part, so much so that the possibility of an organised event is on the cards for next year, though maybe starting just below the fast water…

Blackwater Sub-aqua Club to Clondullane

The second swim took place last Sunday. It was a little longer, at 5 km, but seven dedicated swimmers took up the challenge (that number would likely have been higher had Cork not been playing Waterford in hurling at the same time). We had plenty of safety back-up for this swim, with Wagner kayaking again, as well as Declan’s daughter Anna and one other also kayaking, and Iain MacCallum accompanying us in a boat. Again, all completed the swim and are looking forward to doing it again!

foto (2)

Assembling on the Blackwater Sub-aqua Club slipway, just downstream of the town.

What’s next?

Now that appetites have been wet for longer swims in the river, we may be able to get a group to try out the 7 km from Cappoquin to Villierstown, in the tidal reach of the Blackwater. From there, who knows, let’s hope that it’s just the start of great long-distance swimming culture on our great river!

Yes, I’m still here!

I haven’t posted in a while, but I am still here! The last week and a bit have been very busy with a college field course. We had a great 3 days doing ecological research in Garretstown (one of our less regular swimming spots), Castlefreke (not advisable to swim here) and Glengarriff (home of the Gaddin’ About Garnish swim). I seemed to be one of the few people to get the reports in on time so that leaves me with almost 3 full weeks to study for the summer exams, or maybe get distracted and actually do some swimming!

In my absence from blogging, though, I have actually been doing some swimming for a change. On Sunday, I travelled to the University Arena in Limerick for some long course training with Fermoy SC and have been swimming regularly with them over the last few weeks. As well as that, the weather has been improving so Dave Mulcahy and I headed for a swim in the Blackwater on Tuesday. The water temperature was much higher than expected (about 8ºC) but there was a strong flow which was reflected in our 0.5 km splits of 16 minutes and 5 minutes for our 1 km dip! Hopefully the trend in increasing temperatures and increasing swimming will continue over the next few weeks, and maybe I might get some study done as well…

Ba mhaith liom ádh mór do ghuí ar gach duine atá ag déanamh a scrúduithe béil sa Ghaelainn agus sna teangacha eile an tseachtain, mo dheirfiúr ach go h-áirithe. Go n-eirí go geal libh go léir!

Entries open for two great swims in June…

Promotion – Owen O'KeefeThis week entries opened for two great swims this June. On the evening of Friday, 14 June, the Martin Duggan Memorial Swim will take place over a 2 km course on the River Blackwater in Fermoy. This swim began as the Blackwater Swim in 1999 and, 10 years later, changed its name in memory of Martin Duggan, a local schoolboy who drowned tragically in the river on 12 July 2012. All information relating to entry criteria, etc., can be found on the event website (linked above). One aim of the swim has been to encourage people of all ages, but especially young people, to take part in open water swimming and learn to enjoy swimming outdoors in a way that is safe. Another aim of the swim is to show the people of Fermoy that our beautiful River Blackwater is not something to be feared and avoided, but rather something to be respected and enjoyed.

Photograph – George O'Keefe

The second wave of 2 km swimmers during the in-water start for the Martin Duggan Memorial Swim in 2010.

Any money left over after the all of the costs of running the event have been covered are donated to the Blackwater Sub-Aqua Club Search & Recovery Unit who are based here in Fermoy and who have provided great support for this swim over the last few years.

Another swim that supports its local water rescue services is the Myrtleville to Church Bay Swim which raises money for Crosshaven RNLI. This swim is also 2 km in length and is organised by the Myrtleville Swimmers. This year’s swim takes place on Sunday, 16 June and entry is through the Myrtleville Swimmers website (linked above).

Photograph – Myrtleville Swimmers

The crowd just before the start of the Church Bay Swim in 2012. I believe that I came third in this race, behind Chris Mintern and Ned Denison.

Despite the protracted winter and ever-elusive spring, their is a great sense of optimism about the 2013 open water season with some new events being created and existing events raising their profiles. Let’s hope it lives up to expectations!

A Bit of a Whinge…

There’s really very little going on at the moment – the winter has been dragging on and on this year with double figure temperatures still very elusive and frost most mornings. From taking to the gang at the Sandycove Swimmers spring dinner the other night, it sounds like practically nobody is swimming in the sea at the moment! Because of this, I’ve pretty much nothing to write about so I’ll just have a bit of a whinge instead…

Last year, works began on the Fermoy South Drainage Scheme. The aim of this scheme is to “save” the town from floods which happen once or twice a year. So far, the whole project has cost, I believe, some where in the region of €37 million (with no guarantee of effectiveness), has caused untold disruption in the town, more so than any flood has, not to mention the total loss of the aesthetic appeal of the town, mostly through the loss of trees.

Photograph – Owen O'Keefe

Flood prevention works on Ashe Quay, Fermoy as seen from the bridge on 5 April 2013.

My main issue with the project is that it seems to be part of an ongoing process of Fermoy turning its back on the river. Were it not for the River Blackwater, the town wouldn’t even be here and it is still the source of a huge amount of revenue in the town, especially during the summertime with visiting coarse and game fishermen and oars-people. The total abandonment of the plan of what works were to be done when has meant that there has been a big reduction in parking in the town centre and extremely limited access to the river. This has affected both Fermoy Rowing Club, who may even have to cancel the Fermoy Regatta which is one of the busiest days of the year in Fermoy, and swimmers who haven’t been able to get in and out of the river. It remains to be seen when the whole affair might be completed – it won’t be anytime soon.

On the plus side, though, we have gotten a nice new slipway out of the whole project. This new slipway is located on Barnane Walk, immediately in front of Fermoy Rowing Club, and should make it safer and easier for large groups to get in and out of the water…

Photograph – Owen O'Keefe

New slipway at Fermoy Rowing Club just after opening on 4 April 2013.

On a related subject, entries are now open for the Martin Duggan Memorial Swim 2013 on Friday, 14 June at Fermoy Rowing Club. You can enter online or on paper and all relevant information can be fount here: Enter | Martin Duggan Memorial Swim

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Back to the Blackwater

I’ve done virtually no open water swimming so far this year. I did a quick dip in Sandycove a few weeks ago which I wrote about in My first sea swim of the year… but nothing else since. I’ve been trying to concentrate on my fitness, etc. in the pool and worry about the open water when it [eventually] warms up enough to be able to do proper swims. For the last few years, Dave Mulcahy and I have been aiming to be back in the Blackwater for about St. Patrick’s Day. Though it has been a cold March so far, Dave and I decided that we’d better get in before we put it off for another month!

Photograph – Owen O'Keefe

First river swim of the year in the Blackwater on St. Patrick’s Day.

So just before the parade on Sunday, we headed down to the Rowing Club where we got changed. It was to be my first time to use the new slipway, which is not quite finished but suitable for use. Dave had already had the privilege of using the new slipway, and was among the first to do so, during the Fermoy Christmas Day Swim last December. It was a dry, bright morning but a cool one at the same time. There was a slight westerly breeze, which was a nice change from the chilling north-easterly which we’d had for the last week or so. Another nice change was being able to walk all of the way into the water, a much easier entry than we previously had!

My first few strokes felt good, even if I found it a little hard to take a breath. I decided that it would be better to lift my head up for a few strokes and then go back to normal swimming again. After a minute or two, my hands and feet became quite sore, as did my face. I felt like getting out but then thought of my ice swimming friends and other, colder swims that I’d managed before and decided to keep calm and keep swimming. After about 200 m, which took about 6 minutes swimming against the current, I decided that I’d done enough and decided to head back to the slipway at my ease.

Photograph – Owen O'Keefe

Dave on the new slipway at the Rowing Club on St. Patrick’s Day 2013.

Dave turned at the same time as me and we arrived back at the slipway having swum for about 10 minutes. Dave and I estimated the water temperature at about 6ºC so I was pleased enough to have done 10 minutes at that temperature. Hopefully, it will start warming up soon and we will be able to do longer swims!

As Nuala Moore often reminds me, the swim isn’t over until you are dry, dressed and regaining body heat. On this occasion, I managed to get dressed reasonably quickly (this was a great achievement for me) and my feet, which were very painful on exiting the water, starting to warm up pretty quickly. Things didn’t go so well for Dave, however, who discovered that his pants were locked into the Rowing Club! He then had to endure the walk of shame back to his car and drive home to ask Brigid, his wife, to collect them from the clubhouse after the parade. He won’t make that mistake again…

It was an enjoyable swim, all in all, and it feels good to have finally been in the river. It can only get warmer from here and, hopefully, I’ll start to see the results of my winter “quality rather than quantity” training in the pool.

Freshwater Pearl Mussel

If you read Donal Buckley‘s blog, you might notice a lot of physical and biomechanical references. If you read Karen Throsby‘s blog, you’ll notice a lot of sociological analysis of open water and English Channel swimmers in particular. As you go on reading my blog, you might find out more about the zoological and ecological side of swimming. This post is actually an essay that I wrote on one species of freshwater pearl mussel that I’ve become familiar with from swimming in the River Blackwater, though it’s usually empty shells that I come across. I’m sure that most will find this a bit boring but others might find it interesting so here it is anyway (in time, I will get around to writing about some of the more “exciting” species that swimmers encounter):

Margaritifera margaritifera (Linnaeus, 1758)


The phylum Mollusca is among the most diverse of the animal phyla in terms of morphology (Passamaneck et al., 2004). Molluscs exhibit a great variety of body forms, but there is one external feature that distinguishes molluscs from other members of the animal kingdom, i.e. the mantle. The mantle encloses many of the vital organs of molluscan organisms and is specialised for a variety of purposes in the various mollusc groups, e.g. cephalopods such as squid use their mantle for jet propulsion (Pörtner, 2002), but the mantle of most molluscs is used for the secretion of a hard, calcareous shell.

Sharma et al. (2012) described the class Bivalvia as the second largest class of the phylum Mollusca. The bivalves are characterised by a laterally compressed body enclosed by two hinged valves (shells) and the lack of the radula-like tongue common in other molluscs (Sharma et al., 2012). This group includes clams, oysters, scallops and mussels and is distributed over a global range.

The subclass Palaeoheterodonta is distinct from other bivalves in that both valves are of the same size and shape and the hinge teeth are arranged in a single row. There are two orders within the paleoheterodonts: Trigonioida (marine) and Unionoida (freshwater). A common family among the unionoids is the family Margaritiferidae. Byrne et al. (2009) found that the most widespread margaritiferid species found in Irish rivers is Margaritifera margaritifera, commonly referred to as the freshwater pearl mussel or “river oyster” in certain areas.

English: Freshwater pearl mussel (Margaritifer...

Freshwater pearl mussels (Margaritifera margaritifera) in the Navarån Västernorrland river in Sweden.

Biology: Form & Function

The external morphology of the adult freshwater pearl mussel is similar to that of most other freshwater bivalves. The entire body is enclosed between two kidney-shaped brown or black coloured valves (Degerman et al., 2009). The body is laterally compressed and the posterior end is elongated. The radial depression on the surface of the shell is called the sulcus. Mature specimens can measure 12 cm to 15 cm in length (Skinner et al., 2003) but Degerman et al. (2009) reported that a specimen measuring 17.6 cm was recorded in the county of Jämtland in Sweden.

The valves articulate at a dorsal hinge, which is secured by a ligament. Just ventral to the hinge is the umbo; this is the oldest and thickest part of the valve and growth rings can be seen radiating from it (Nyström et al., 1995). A cross section of a shell reveals three discrete layers; the periostracum, the prismatic layer and the nacreous layer, which lines the internal surface of the shell and is better known as mother-of-pearl (Jacob et al., 2008). The shell is secreted by the epithelial cells of the mantle (Jacob et al., 2008) and serves to protect the mussel’s delicate ctenidia (gills) and other soft body parts from predators and debris moving in the water.

All of the mussel’s soft body parts are located between the two shells and enveloped by the mantle. The mantle’s edge has three distinct pallial lobes; the outer lobe, which secretes the shell, the sensory lobe and the inner lobe, which is muscular. At the posterior end, the inner pallial lobes of the left and right mantles separate to form the incurrent (inhalant) and excurrent (exhalant) siphons. The excurrent siphon is dorsal to the incurrent siphon. Water and food particles are inhaled into the mantle cavity via the incurrent siphon and water and wastes expelled from the mantle cavity via the excurrent siphon (Degerman et al., 2009).

Inside the mantle cavity, a pair of large, feather-shaped ctenidia can be seen extending posteriorly from the visceral mass. The ctenidia of M. margaritifera are specialised for two purposes. The primary function of the ctenidia is to provide a surface for gaseous exchange (Carroll & Catapane, 2007). The respiratory surface area is maximised by a large number of ctenidial plates extending from a central ctenidial axis. The flow of water over the ctenidia is maintained by the movement of cilia on the surface of the ctenidial plates (Carroll & Catapane, 2007). Water flows from the ventral incurrent chamber to the dorsal excurrent chamber, counter to the flow of the blood, thus maximising gaseous exchange. The cilia and grooves on the surface of the ctenidia also play a role in the selection and sorting of food particles from inhaled water (Ward et al., 2003).

Margaritifera margaritifera, like all bivalves, has an open circulatory system. The heart has three chambers (two auricles and one ventricle) and is enclosed by a pericardium. The haemolymph (blood) leaves the heart via a posterior aorta and an anterior aorta. The oxygen-carrying glycoprotein in the haemolymph of M. margaritifera (and most other molluscs) is haemocyanin, and unlike haemoglobin in the erythrocytes of other animals, haemocyanin is suspended freely in the haemolymph (Streit et al., 2005). Gaseous exchange occurs across the ctenidial plates of the gills.

As is the case with other filter-feeding bivalves, M. margaritifera has a complete, though relatively simple, digestive tract. Food particles collected on the gills move proximally towards the mouth, where they are further sorted by the labial palps, before entering the mouth (Ward & Shumway, 2004). M. margaritifera lacks the radula-like tongue characteristic of most molluscs. The mouth and oesophagus are ciliated and serve merely to direct food particles to the stomach (Helm et al., 2004). Mechanical digestion in the stomach is accomplished by a crystalline style, projecting into from an associated sac. This sac is ciliated and the rhythmic motion of the cilia causes the style to rotate, grinding food particles against the gastric shield located on the wall of the stomach (Helm et al., 2004). These food particles then pass to the sorting caecum and enter the digestive diverticula for further digestion. Following digestion, waste products are egested into the excurrent chamber via the anus and are expelled into the water via the excurrent siphon.

The three largest muscle masses of M. margaritifera are the two adductor muscles and the foot. The adductor muscles’ function is to close the shell of the mussel and/or to hold it closed (Itoh et al., 2007). The anterior adductor muscle is located near the mouth, while the posterior adductor muscle is located just posterior to the visceral mass on the dorsal side. The foot of M. margaritifera is recognisable as a large muscular mass projecting anteriorly from the ventral surface of the visceral mass. Its function is to allow the mussel to burrow into the substrate. It achieves this by first extending longitudinally into the substrate, then expanding transversely to form an anchor and finally contracting longitudinally, pulling the entire animal into the substrate (Germann et al., 2011).

Life History & Ecology

Reproductive circle of the Freshwater Pearl Mussle

Reproductive cycle of the freshwater pearl mussel.

Margaritifera margaritifera is widely known for its longevity. Bauer (1987) found that the main maximum life expectancy of European specimens was 93 ± 9 years. However, it is thought that, given the right conditions, they can live for more than 200 years. One specimen, believed to be as much as 280 years old was found in Sweden (Degerman et al., 2009). The reason for this longevity becomes clear when one considers the reproductive strategy of the mussel.

Margaritifera margaritifera is normally dioecious (Moorkens, 1999) but does not exhibit any external sexual dimorphism (Bauer, 1987). Given certain environmental cues, the male mussel releases sperm aggregates into the water and they are then carried by the water current to the female (Degerman et al., 2009). The fertilised eggs develop on the gills of the female for period of a few weeks before being released into the water as larvae known as glochidia (Skinner et al., 2003). A female can produce several million glochidia each time she reproduces, which can amount to as many as 200 million glochidia if she lives out a normal life span (Bauer, 1987).

Glochidia resemble adult mussels but their shells are open as they drift, suspended in the water column (Skinner et al., 2003). The glochidia are parasitic and must encyst on the gill filaments of a juvenile salmonid fish, e.g. Salmo salar or Salmo trutta, if they are to survive (Skinner et al., 2003). Having survived this stage, the glochidia release from the gills of their host and drop to the riverbed, where they burrow into the substrate and develop for a further 5 years (Moorkens, 1999) before returning to the surface. Mussels reach maturity after about 20 years and once they reach this stage, there is a high probability that they will survive into old age (Bauer, 1987). Bauer (1987) also noted that there is no post-reproductive stage in the life cycle of M. margaritifera, meaning that adults can continue to reproduce into old age.

Margaritifera margaritifera inhabits riverine systems across Eurasia and North America, where it can be found partially buried in the substrate (Skinner et al., 2003). Degerman et al. (2009) described, in detail, the habitat requirements of this species. They point out that populations of M. margaritifera are only known in fast-flowing, clean rivers with stable substrata and where there is a healthy stock of host fish. Skinner et al. (2003) noted that the ideal substratum for this species is coarse sand or fine gravel. They also note that this substratum must be stable and that there should be little or no silt in the interstitial spaces. Shallow water near riffles is favourable as it is more oxygenated and there is less sedimentation.

Hastie & Young (2003) cited Ziuganov et al. (1994) in describing the relationship between M. margaritifera and salmonid fishes as mutually beneficial: the salmonids receive clean water and spawning beds in return for hosting the parasitic glochidia of the mussels. While juvenile mussels may be at risk of predation by fish, adult mussels generally have no natural predators (Degerman et al., 2009).

Margaritifera margaritifera is listed as critically endangered worldwide (IUCN, 2012) and critically endangered in Ireland (Byrne et al., 2009). The widespread and direct exploitation of M. margaritifera for its nacreous pearls and the overfishing of its host fishes have had a long-term effect on the species. More recently, the pollution of rivers and the construction of man-made dams has led to the destruction of much of the mussel’s habitat (Watters, 1995). Extensive conservation projects are underway in Ireland, the UK and across Europe (Skinner et al., 2003).

English: Stamp from Deutsche Post AG from 2002...

Freshwater pearl mussel on a German stamp in 2002.


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  • Byrne, A., Moorkens, E.A., Anderson, R., Killeen, I.J. & Regan, E.C., 2009. Ireland Red List No. 2 – Non-Marine Molluscs. National Parks and Wildlife Service, Department of the Environment, Heritage and Local Government, Dublin, Ireland.
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River Blackwater explored on “Abhainn” tonight…

At 19:30 tonight, the second episode of Series Four of “Abhainn” will be broadcast on RTÉ One. This programme will follow the course of the River Blackwater in Munster from its source in the Mullaghareirk Mountains on the Cork/Kerry border to where it enters the sea at Youghal Bay on the Cork/Waterford border. Swimming in the Blackwater in Fermoy will feature about halfway through. Here is the trailer for the series:

The programme will be broadcast in Irish but there will be English subtitles. Cláracha Gaeilge are doing a great job with these series about Ireland’s rivers. Past episodes can be found on RTÉ Player and the one about the An Laoi (the River Lee) is well worth the watch of you get a chance.

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