Ireland’s freshwater landscape encompasses over 12,000 lakes and extensive river networks, primarily shaped by Pleistocene glaciation. Standard aquatic surveys consistently target riffle zones, boulder substrates, and macrophyte beds, systematically overlooking specialised microhabitats such as seeps, temporary streams, turloughs, and those with groundwater sources including springs and the hyporheic zone of rivers that may harbour unique invertebrate communities.
Using Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies) as focal taxa, this talk examines distributional gaps and discusses species found in some of Ireland’s specialised aquatic habitats, based on recent surveys carried out at various locations across Ireland.
Q&A with Dr Helen Barber-James
Dr Helen Barber-James joined National Museums NI in January 2022 as Senior Curator of Natural Sciences. Previously, she was Senior Curator in the Department of Freshwater Invertebrates at the Albany Museum in Grahamstown, South Africa, where she was based for many years. Her research interests focus on biodiversity, systematics, biogeography and ecology of freshwater invertebrates, in particular the freshwater insect groups the Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies). These insect groups are frequently encountered during ecological studies of freshwater ecosystems, and play an important role as bioindicators of the state of the aquatic environment they inhabit.
In the past, Helen’s research focus has been on African freshwater ecosystems, and she has expanded this to include those in the UK and Ireland. She has carried out several externally funded surveys of Irish freshwater ecosystems, looking at the biodiversity of the organisms living in them, and adding voucher material to the museum collections through this work. Making museum natural history collections and their associated data available for research purposes is of fundamental importance as past collections contain hidden treasures of biological information. Adding new voucher material to expand these collections is essential for ongoing tracking of species changes over time. Vouchers allow not only geo-localities to be recorded, but can be used to investigate changes in body size, wing length, fecundity and other more subtle metrics.
1. Some mayflies, stoneflies and caddisflies are good indicators of unpolluted water. Are they also good indicators of invertebrate diversity in general in freshwater habitats?
Yes, mayflies, stoneflies and caddisflies are widely known as indicators of biodiverse freshwater habitats. They are good ‘umbrella’ species in this sense; the presence of river-flies in a habitat strongly indicates the presence of other freshwater invertebrates (e.g. water-bugs, water-beetles, aquatic Diptera larvae). Therefore, a high diversity of river-flies indicates a high diversity of other invertebrates. That is at least the rule in most freshwater habitats. The rule doesn’t hold quite so well for specialist habitats, because in extreme conditions diversity is just generally low! In these habitats the presence of specialised river-flies may however indicate the presence of other specialised invertebrates (just not necessarily a high diversity of species).
2. What is being done, or can be done, to protect important freshwater habitats in Northern Ireland?
In terms of what is being done currently, there are several Areas of Special Scientific Interest (ASSIs) in Northern Ireland which contain important freshwater habitats and are already being protected. In terms of what needs to be done, I personally think Northern Ireland sorely needs stronger environmental regulation on pollution and agricultural runoff as it affects freshwater habitats. I have been told that the intensification of farming in recent decades has coincided with the introduction of alarming quantities of new ammonia into the water cycle. This will surely have a negative effect on our freshwater invertebrates if not regulated. Alien invasive aquatic species, such as the zebra mussel, compound these effects, taking habitat from our native species. Much attention is being given to such species, but it is difficult or impossible to contain them once they have taken hold.
3. You mentioned using a grapnel to sample for freshwater invertebrates. Can you say more about this sampling method?
A grapnel is essentially a multi-pronged hook attached to a long rope. You can buy grapnels online (e.g. from NHBS) or construct one yourself using wire coat hangers. In biological fieldwork, they’re primarily used by botanists studying floating freshwater plants. To use a grapnel, you throw the hooked end into a body of water and allow it to sink into a patch of vegetation. When you reel it back in, the prongs snag plant material, which can then be examined in a white tray. Grapnels thereby enable researchers to access plant species that would otherwise be difficult to reach. For me, the real advantage is that the grapnel doesn’t just retrieve plants—it also brings back a host of “hitchhiking” freshwater invertebrates. Working together, then, botanists can collect material they would miss by searching only along the margins, and freshwater entomologists like me can sample species that are beyond the reach of a standard pond net. It’s a valuable addition to our toolkit and has already proved effective. More broadly, it highlights the benefits of collaboration across natural history disciplines – I would never have thought to use a grapnel had I not seen botanists employing one.
4. In the surveying that you’ve been doing, what are you seeing in terms of the abundance of river-flies?
Well in comparison to South Africa, where I lived previously, abundance is a lot lower! But that’s perhaps not unexpected. What I have definitely seen is a clear positive correlation between how clean a river is and the abundance of riverflies living within it. There is also a considerable variation in abundance over the seasons which one has to consider when surveying. I should also emphasise that when analysing the water quality of freshwater habitats, diversity is generally a much better metric than abundance. Riverfly populations can in some cases be very large but simultaneously dominated by relatively few species – that’s not what we want. It’s much more reassuring to see a large number of different species all co-existing.
Literature References
- Dalton et al. (2024) ‘Lakes In Ireland – Mirrors of Change’: https://dspace.mic.ul.ie/items/b58af794-56eb-4376-bd6a-c92042a45064
- Feehan et al. (2008) ‘The Bogs of Ireland: An Introduction to the Natural, Cultural and Industrial Heritage of Irish Peatlands’: https://researchrepository.ucd.ie/entities/publication/7e656399-0617-4d13-ac3a-0a7deb879e69a
- Feeley et al. (2016) ‘The Stonefly (Plecoptera) of Ireland. Distribution, Life histories & Ecology’: https://www.researchgate.net/publication/290394655_The_Stonefly_Plecoptera_of_Ireland_-_Distribution_Life_Histories_Ecology
- Feeley et al. (2020) ‘Ireland Red List No. 13: Stoneflies (Plecoptera)’: https://www.researchgate.net/publication/338572504_All-Ireland_Red_List_13_Stoneflies_Plecoptera
- Kelly‐Quinn and Regan (2012) ‘Ireland Red List No. 7: Mayflies (Ephemeroptera)’: https://archive.nationalredlist.org/files/2012/12/Ephemeroptera-Red-list.pdf
- Kelly-Quinn and Reynolds (2020) ‘Ireland’s Rivers’ [print only]
- Lucey and Cocchiglia (2014) ‘Distribution of sponges (porifera: Spongillidae) in southern Irish rivers and streams’: https://muse.jhu.edu/pub/423/article/835480/summary
- Macadam and Bennett (2016) ‘A Pictorial Guide to British Ephemeroptera’ [print only]
- Macadam et al. (2022) ‘British and Irish Stoneflies (Plecoptera): Keys to the Adults and Larvae, with notes on their Distribution, Life Histories and Ecology’ [print only]
- O’Connor (2015) ‘A Catalogue and Atlas of the Caddisflies (Trichoptera) of Ireland’: https://irishbiogeographicalsociety.com/pdf/OConnorCaddisflies-Trichoptera-ofIreland.pdf
- O’Connor and O’Connor (2025) ‘New records of Irish sponge flies (Neuroptera: Sisyridae)’: https://irishbiogeographicalsociety.com/pdf/ARTICLE3BullIBS48OConnorOConnor2025Sisyridae.pdf
Further Info
- Riverflies: The Canary of Our Rivers (entoLIVE blog): https://biologicalrecording.co.uk/2023/09/18/riverflies/
- Guardians of our Rivers: Monitoring Rivers with Freshwater Invertebrates (entoLIVE blog): https://biologicalrecording.co.uk/2025/02/27/guardians-of-our-rivers/
- SmartRivers: Using Freshwater Invertebrates to Monitor River Health (entoLIVE blog): https://biologicalrecording.co.uk/2023/12/04/smartrivers/
- Ain’t No Mountain High Enough: Impacts of Climate Change on Aquatic Insects (entoLIVE blog): https://biologicalrecording.co.uk/2023/02/09/aquatic-insects/
- There is a Riverfly Partnership tutor in Northern Ireland – Lisa Kirkwood. Anyone interested in putting together a Riverfly monitoring group can get in touch with us at Riverfly Partnership HQ (info@riverflies.org) and we will link you up.
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