Ireland’s freshwaters: a world of wonder and discovery awaits you
Ireland’s freshwaters are host to an amazing world of animals, plants and other organisms. These organisms, many of whom are dependent on good water quality, can tell us much about our environment. The EPA uses this information as part of its water quality reporting. EPA Ecologist Hugh Feeley describes the wonderful web of life that exists just below the surface of our rivers, lakes, streams and wetlands…
How many times have you passed a river, lake or stream and considered what lies beneath? I’ve been lucky enough to have spent the past ten years or so involved in both research, and monitoring and assessment of our streams, rivers, lakes and wetlands. This work has taken me to all four corners of the island and every day is different. I try to expect the unexpected and to paraphrase a quote from Albert Einstein:
“The important thing is not to stop questioning. Curiosity has its own reason for existing…It is enough if one tries merely to comprehend a little of this mystery every day……”
Embracing this idea, I enjoy nothing better than to find something new. Every time I arrive at a river or a lake the professional in me wants to get on with the job in hand and move on, another site ticked off on my list, but the biologist in me is curious to know what lurks beneath the riffles or the waves.
Stonefly – nymphs and Insects
I remember the first time I saw the nymph of the large stonefly Perla bipunctata that grows up to 35 mm in length and lives in many of our rivers as an immature nymph for over three years before becoming a flying adult; I had never considered such a large and beautiful insect could exist, and in Ireland! Suddenly a world of discovery and wonder opened before me. I had caught a bug, one of discovery, that has shaped my career to date.
I have been lucky enough to encounter a vast array of amazing animals and plants that live in Irish freshwater throughout my career. The aquatic insects are my favourite, but there are all sorts of other weird and wonderful biota, namely algae, fungi, plants, invertebrates and fish, inhabiting our rivers, lakes and streams.
Animals that use hairs to move and feed
Ophrydium versatile, a ciliate protist, best described as a microscopic animal recognisable by their hair-like ‘cilia’ which they use for movement and for feeding. These animals have a mutually beneficial (symbiotic) relationship with green algae found in lakes containing dissolved limestone. This is but one of a remarkable number of organisms that form colonies and make their home in our waterways up and down the country.
Bladderworts – carnivorous plants that feed on plankton
We have a diverse array of freshwater plants in Ireland, and although it’s an area I’ve only recently ventured into I’m amazed at what there is to find. Thanks to my colleagues in the EPA Ecological Monitoring and Assessment Unit, I have recently discovered the remarkable aquatic plant known scientifically as Utricularia, or commonly as bladderworts. These are carnivorous plants relatively common in Irish lakes, feeding mainly on Daphina, a small planktonic animal, using sophisticated mechanical bladder-like traps which take only a split second to activate.
Similarly, only recently have I started to take notice of our freshwater sponges. There are relatively common animals found in our rivers and lakes. Sponges and algae have a mutually beneficial symbiotic relationship, and are green because of the algae. The sponge, using its complex structure, provides a safe place for the algae to grow and, in turn, the algae processes sunlight into energy and provides food to the sponge. I’ve also recently discovered that there is a fly, or more accurately a spongefly (or Sisyridae), whose larvae feed exclusively on freshwater sponges! This discovery shouldn’t have surprised me but it did..
Insects that have been living on earth for 250 million years
The list of insects found in our waterways is well over 3,000 species and they come in a variety of shapes and sizes, with some looking like they have come out of the latest sci-fi movie! This diversity, however, is a result of millions of years of evolution and adaption to their environment. Stoneflies, ubiquitous across Irish rivers and many lakes, are over 250 million years old, dating back to the Permian period during the age of the supercontinent Pangaea, when all our current continents were joined together, and predating infamous dinosaurs, such as Tyrannosaurus rex, by 180 million years. Aquatic insects are amazingly adaptable; some eat algae, some eat leaf material and some eat other animals, creating a complex food-web that ensures the healthy functioning of our freshwater ecosystems.
Insect life: camouflage, adaptability and armour
Many of these insects have remarkable adaptions, including camouflaged pigmentation, adaptable life strategies and other weird and wonderful survival and reproductive tactics. As larvae, the caddisflies create elaborate cases made from a variety sand, gravel, stones, twigs and leaves, in which they live, each constructed specifically, with many case formations unique to a species or family. Probably the most amazing features of aquatic insects is their transition from immature larval stage (which can last from anywhere between a few months to several years), to the reproductive adult stage. This transformation, triggered by a combination of temperature, morphological development and genetics, allows insects to not only reproduce successfully but to also spread to new waterways and expand their range.
Landscapes to inspire a sense of wonder
Even if you are not interested in the wonderful life that makes their home in our waters, it can be worth just admiring the beauty of our landscapes, which are only enhanced by the presence of healthy freshwaters. Whether it is the beautiful view of the Killarney lakes from Lady’s View in the heart of Killarney National Park, or an old bridge crossing a meandering river, we are surrounded by an array of history and cultural heritage, a sense of place, a sense of wonder, and even a sense of home, which are vital to the satisfaction felt by society but is often taken for granted. I believe this is what drives our interest and quest for knowledge of the nature within, and the eagerness of some of us to preserve our wildlife and ecosystems for the experience they provide us, and for their protection for future generations.
Insects: drumming in different dialects to attract a mate
The adults also have amazing behaviours during their often-fleeting time alive. For example, the stoneflies have a mate-locating behaviour known as ‘drumming’. This behaviour involves the male creating a low frequency ‘drum’ sound by striking its abdomen off the underlying substrate. Females respond in kind until they find each other and mate. What’s amazing about this drumming behaviour is that the drumming frequency produced is species and sex specific. More amazingly is that research has highlighted that the drum produced by the same species in different geographic areas has resulted in different ‘dialects’; something one would never associate with freshwater insects.
Invasive species and loss of our highest quality waters
Unfortunately, I write this article in the context of change. Every year the threat grows from invasive species being introduced to our freshwaters, endangering our native species and the natural balance which makes our rivers and lakes thrive.
The introduction of the Zebra mussel, for example, has been detrimental to the normal healthy functioning of so many of our lakes and rivers, with new waterbodies affected each year. More recently disease has threatened our native and protected white-clawed crayfish.
More worryingly, the dramatic loss of our highest quality waters since the 1980s, as highlighted by the latest EPA Water Quality Report, is alarming and needs urgent attention. Human activities, such as effluent release, pesticides and fine sedimentation, continue to put pressures on our freshwaters. The new ‘Blue Dot’ programme in the forthcoming River Basin Management Plan will protect the health and wellbeing of our most precious and healthiest waters. Their protection, restoration and enhancement is not only the responsibility of the Government, its agencies or the European Union, but something that should be the responsibility of every member of society, as we all benefit.
I want my children, and their children, to be able to discover all our freshwater species just as I have. I write this piece with optimistic enthusiasm for our freshwaters future being bright and unpolluted.
Next time you walk long a lake shore, stand on a bridge overlooking a river, or jump from stone to stone to cross a babbling brook just stop and think of what life lurks below. Whether it is the simple joy of just turning over a rock in a river and seeing a stonefly, such as Perla bipunctata, or a mayfly, such as Ecdyonurus, for the first time, discovering the amazing freshwater pearl mussel, or just enjoying the beauty and tranquillity waterways provide us, the important thing is to be curious, to not stop questioning and most of all to comprehend a little of that mystery with surrounds us each day. In its simplest terms, and put so eloquently by Sir David Attenborough when he said:
“an understanding of the natural world and what’s in it is a source of not only great curiosity but great fulfilment”
So, if you do one thing this year, go experience and enjoy your local river, lake or stream, and most of all go discover the world of wonder that exists below the riffles and the waves for yourself – you never know what you may find!
Hugh Feeley, EPA Ecology Unit
EPA Ecological Monitoring and Assessment: The EPA Ecology team monitor the ecological health of Ireland’s waters. The organisms that live there are important indicators of water quality. The outcome of these scientific assessments are reported in EPA Water Quality Reports.
Dr Hugh Feeley is a freshwater ecologist who recently joined the environmental monitoring team at the EPA. Hugh has over ten years’ experience studying and assessing Irish freshwaters and has a special interest in the ecology of stoneflies. Currently, he is involved in assessing the ecological quality of Ireland’s freshwaters, and you may find him splashing about in a river or lake near you soon.