Getting to know freshwater ecosystems around Swansea

After our blog post introducing the FIRE lab at Swansea University and our research backgrounds, I was keen to further explore and share about the local freshwater environments around Swansea. As a freshwater ecologist, I was enthused to explore the flora and fauna inhabiting local waterbodies across the region. Luckily, Swansea and its surrounding area support various aquatic ecosystems which harbour an array of exciting biota.

Situated on the south coast of Wales, Swansea is located a short 10-minute drive away from Crymlyn bog (see map below). This has been classified as a ‘Special Area of Conservation’ under the European Union’s Habitat Directive. It is renowned as a ‘quaking bog’, where the surface underfoot begins to ripple like a waterbed. Here is a short video capturing the characteristics of a ‘quaking’ bog from near Carnedd Llewellyn in Wales. Crymlyn bog supports different flora rare to many parts of Europe, including swamp sawgrass (Cladium mariscu) and the black alder tree (Alnus glutinosa). It seems like a great place for our first lab field trip! If you’ve visited the bog, please do share a photo or story with us below in the comments or tweet us on Twitter @FIRELabTweets.

Swansea and freshwater environments surrounding it.

The River Tawe flows through the heart of the city and into Swansea Bay. The lower Tawe valley historically supported intense industrial activity working different types of metal (namely copper, lead, zinc and nickel), while coal mining used to be extensive in the middle of the river catchment (National Resources Wales, 2015). Pollution in the Tawe was so extreme in the post-war period that angling associations reported the river as being uninhabitable for fishes (O’Hara, 2017). More recently, industry and mining have reduced across the Tawe catchment (National Resources Wales, 2015).

The Tawe estuary is of crucial ecological importance for migratory Atlantic salmon (Salmo salar) and Brown trout (Salmo trutta), that swim up the Tawe towards the headwaters to spawn. The construction of the Swansea barrage along the Tawe in 1992 initially caused concern for the migratory salmonid populations (Blacklidge and Mee, 1993). There were improvements in the fish pass and the introduction of an aeration system (to heighten oxygen levels) towards the turn of the century to improve the conditions of migratory fish (and other aquatic biota). The exact benefits that the Swansea barrage improvements have had for the river ecosystem remains unclear, with the presence of barriers along the Tawe still presenting a key human pressure on the ecosystem (National Resources Wales, 2016). Notwithstanding, today the Tawe still supports an important salmonid fishery, with salmon and trout laying up to 1.8 million eggs annually and anglers catching hundreds of adults each year (approximately 650 individual fish in 2010; National Resources Wales, 2015).

Moving upstream, the Tawe headwaters are situated in the Brecon Beacons National Park (Brecon Beacons, 2018). The park attracts 12 million visitors annually and supports various rare species dependent on freshwater, including otters (Lutra lutra – Strachan, 2015), the native white-clawed crayfish (Austropotamobius pallipes – Brecon Beacons, 2018) and great crested newts (Triturus cristatus – Brecon Beacons, 2018). Many of the streams within the Brecon Beacons are classified as supporting a ‘Good Ecological Status’, defined as a European benchmark of ecosystem health to strive towards within the European Union’s Water Framework Directive (National Resources Wales, 2016).

Pictures of fauna dependent on freshwater ecosystems in the Brecon Beacons  National Park (from left): Otter (photo source); White-clawed Crayfish (photo source); Great Crested Newt (photo source).

Another fascinating aquatic environment in the Tawe catchment headwaters is the Ogof Ffynnon Ddu (OFD) cave system lying 300 metres below ground! OFD is the third longest cave in Great Britain and among the 50 longest caves in the world (Jefferson et al., 2004). The OFD harbours an array of ‘stygofauna’ (animals living underground), with at least 62 taxa recorded in the cave system’s aquatic environment, including  10 crustaceans and 11 beetles (some pictured below), many of which are rare on a national scale (Jefferson et al., 2004; Robertson et al., 2008).

Examples of stygofauna inhabiting Ogof Ffynnon Ddu (from left): Crangonyx subterraneus (photo source); Trechoblemus micros (photo source).

I hope that you have enjoyed learning about freshwater ecosystems around Swansea! Myself and the FireLab team are very keen to explore aquatic environments across the region and learn about how local communities engage and interact with these fascinating ecosystems. So if you have any thoughts, further information on this post, or suggestions on what freshwater environments you’d recommend visiting in the region, please do get in touch via twitter (@FIRELabTweets or @JWhite211).

Dr James White.

References

Blacklidge, R. H and Mee, D. M (1992) The results of tawe barrage post-impoundment Salmon and sea trout telemetry study 1992. National Rivers Authority Report, PL/EAW/93/2. National Rivers Authority, Cardiff. Available online through <http://www.environmentdata.org/archive/ealit:3345&gt;. [Accessed 7/11/2018].

Brecon Beacons (2018) Breacon Beacons – Our National Park. Available online through <http://www.breconbeacons.org/&gt;. [Accessed 7/11/2018].

Jefferson, G.T., Chapman, P., Carter, J. and Proudlove, G. (2004). The invertebrate fauna of the Ogof Ffynnon Ddu cave system, Powys, South Wales, UK. Cave and Karst Science, 31(2). 63-76.

National Resources Wales (2015) Know Your River – Tawe Salmon and Sea Trout catchment summary. National Resources Wales Report. Available online through <https://cdn.naturalresources.wales/media/681492/know-your-river-river-tawe-salmon-and-sea-trout-catchment-summary.pdf&gt;. [Accessed 7/11/2018].

National Resources Wales (2016) Tawe to Cadoxton management catchment summary. National Resources Wales Report. Available online through <https://naturalresources.wales/media/679388/2016-updated-_tawe_catchment_summary_nrw.pdf&gt;. [Accessed 7/11/2018].

O’Hara, G. (2017). River Pollution. In: The Politics of Water in Post-War Britain (pp. 85-115). Palgrave Macmillan, London.

Robertson, A.L., Johns, T., Smith, J.W.N. and Proudlove, G.S. (2008). A review of the subterranean aquatic ecology of England and Wales. Environment Agency Science Report, SC030155/SR20. Environment Agency, Bristol.

Strachan, R. (2015) Otter Survey of Wales 2009-10. National Resources Wales Report. Available online through <https://naturalresources.wales/media/4590/osw-5-english-24-06-2015.pdf&gt;. [Accessed 7/11/2018].