The Outbreak of Toxic Blue-Green Algae in Northern Ireland

According to the Northern Ireland Environment Agency (NIEA, cited in BBC, 2023), there have been 168 confirmed reports of toxic blue-green algae in waterways across the province since May 2023. There is particular concern over Lough Neagh (Fig.1) which is the largest lake in the British Isles (Greene, 2023). The current levels of blue-green algae recorded in this lake have not been as high since the 1970s (Greene, 2023). This essay explores the causes of this harmful algal bloom and its threats to both the people and environment of NI.

Figure 1.The locations of toxic blue-green algae found in NI (green dots). Adapted from BBC (2023).

The Causes: Cultural Eutrophication, Climate Change, and Invasive Species

There are several factors which have caused this outbreak of algae in Lough Neagh. For example, fertilizer runoff from agricultural activity, along with wastewater and sewage, have increased the levels of nitrates and phosphates within the lake, causing algae to grow rapidly (BBC, 2023) (Fig.2). This process is known as cultural eutrophication (Miller and Spoolman, 2018). According to the NIEA (cited in Corr, 2023), 62% of the phosphorus pollution, which has caused this outbreak of algae, is from agriculture, 22% is from wastewater and 12% from septic tanks.

Figure 2. Blue-green algae in Lough Neagh. Source: BBC (2023).

However, climate change has also contributed to this harmful algal bloom (Department of Agriculture, Environment and Rural Affairs, (DAERA), 2023). Anthropogenic activities, such as the burning of fossil fuels which emit greenhouse gases, such as carbon dioxide into the atmosphere, have caused global atmospheric temperatures to increase by approximately 1°C during the last century (Marshak, 2019: 902). According to Lindsey and Dahlman (2020), large bodies of water, such as lakes, seas and oceans have absorbed much of this heat, causing water temperatures to increase over time. The water temperature in Lough Neagh is 1°C higher than it was in 1995 due to climate change (Cullen, 2023). In June 2023, the UK experienced its hottest June on record (Met Office, 2023) and the water in Lough Neagh reached a record-breaking temperature of 17.4°C, which increased the rate of algae growth (BBC, 2023).

An invasive species, known as Zebra Mussels, is another factor which has led to the harmful algal bloom within Lough Neagh. This organism entered Britain and Ireland by sticking to the hulls of ships that were travelling from Eastern Europe (Canal and River Trust, 2020; Pollox et al., 2003). Zebra Mussels feed on plankton and therefore increase the clarity of water (Canal and River Trust, 2020). According to DAERA (cited in BBC, 2023) the water in Lough Neagh, prior to this algae bloom, was 3 times clearer than it was in 2019, due to the presence of Zebra Mussels. This has allowed more sunlight to penetrate the water surface, which has increased the rate of algal photosynthesis and thus, contributed to the recent algal bloom within Lough Neagh (BBC, 2023).

The threats to the environment and people of NI

Algal blooms can kill other aquatic organisms by starving them of oxygen and sunlight and clogging the gills of fish and invertebrates (Miller and Spoolman, 2018; NOAA, 2016). According to NOAA (2016), algal blooms can also produce toxins that can kill mammals and birds, which has been happening in Lough Neagh (Fig.3). Therefore, the current algal bloom is threatening the local ecosystem around this lake.

Figure 3. A bird being killed due to toxins released from Lough Neagh. Source: Sky News (2023).

However, algal blooms can also cause direct harm to humans. The toxins that they release can cause skin irritations, severe stomach upsets and can even lead to death (UK Centre for Ecology and Hydrology, n.d.). This has made Lough Neagh unsafe for recreational activities and consequently, a local swimming group has had to stop using this lake, creating a negative impact on their mental and physical health (BBC, 2023).

Lough Neagh supplies 40% of NI’s drinking water and is home to the largest commercial wild eel fishery in Europe (BBC, 2023). However, the Head of Drinking Water Regulation at NI Water has assured the public that there is no health risk in drinking treated water from Lough Neagh (BBC, 2023). There is a huge difference between direct contact with blue-green algae in raw water and the water we get from our taps (BBC, 2023). The Chief Scientific Advisor at the Food Standard Agency in NI has also said there is no risk in eating fish that is harvested from Lough Neagh by commercial fisheries, but that people should exercise caution with regards to eating fish caught by private anglers from the lake (BBC, 2023).

Conclusion

The outbreak of toxic blue-green algae in Lough Neagh, NI is a complex issue that has been caused by an array of factors, and poses a huge threat to both the environment and the people of NI. The NIEA are currently developing a plan to address this situation (BBC, 2023). However, they argue that it is going to be difficult to resolve this issue with no MLAs in Stormant to push for investments (BBC, 2023). Therefore, the current ecological crisis in Lough Neagh is being worsened by NI’s political crisis.

Reference List

BBC (2023) Blue-green algae map shows extent of Lough Neagh problems, Available at: https://www.bbc.co.uk/news/uk-northern-ireland-66896942 (Accessed: 4/11/2023).

BBC (2023) Lough Neagh: Environmentalists hold 'wake' after algal blooms, Available at: https://www.bbc.co.uk/news/uk-northern-ireland-66835897 (Accessed: 4/11/2023).

BBC (2023) Lough Neagh: 168 confirmed algae reports in Northern Ireland since May, Available at: https://www.bbc.co.uk/news/uk-northern-ireland-66883500 (Accessed: 4/11/2023).

Canal and River Trust (2020) Zebra Mussel, Available at: https://canalrivertrust.org.uk/things-to-do/canal-and-river-wildlife/canal-and-river-invasive-species/zebra-mussel (Accessed: 4/11/2023).

Corr, S. (2023) Ireland's biggest freshwater lake 'is making people sick and killing animals', campaigners claim, Available at: https://www.irishmirror.ie/news/irish-news/irelands-biggest-freshwater-lake-is-30972766?int_source=nba (Accessed: 4/11/2023).

Cullen, L. (2023) Climate change: Lough Neagh temperature rises 'alarmingly', Available at: https://www.bbc.co.uk/news/uk-northern-ireland-66516358 (Accessed: 4/11/2023).

DAERA (2023) Blue-Green Algae, Available at: https://www.daera-ni.gov.uk/blue-green-algae (Accessed: 4/11/2023).

Greene, T. (2023) Lough Neagh ‘dying in plain sight’ due to vast algal blooms, Available at: https://www.theguardian.com/uk-news/2023/aug/23/lough-neagh-dying-in-plain-sight-say-campaigners-due-to-vast-algal-blooms (Accessed: 4/11/2023).

Lindsey, R. and Dahlman, L. (2020) Climate Change: Ocean Heat Content, Available at: https://www.climate.gov/news-features/understanding-climate/climate-change-ocean-heat-content (Accessed: 4/11/2023).

Marshak, S. (2019) ‘Global Change in the Earth System’ in Schindel, J. et al. (eds.) Earth: Portrait of a Planet, 6th Edn (New York: W.W. Norton & Company): 876-913.

Met Office (2023) UK will have its hottest June on record, Available at: https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2023/hottest-june-on-record (Accessed: 4/11/2023).

Miller, T.G. and Spoolman, S.P. (2018) ‘Water Pollution’ in Miller, T.G. and Spoolman, S.P. Living in the Environment 19th Edn (Boston: Cengage): 540-571.

NOAA (2016) What is a harmful algal bloom? Available at: https://www.noaa.gov/what-is-harmful-algal-bloom (Accessed: 4/11/2023).

Pollox, B. et al (2003) ‘Zebra mussels (Dreissena polymorpha) in Ireland, AFLP-fingerprinting and boat traffic both indicate an origin from Britain’ Freshwater Biology, 48 (6): 1127-1139.

Sky News (2023) Lough Neagh, Available at: https://www.youtube.com/watch?v=UaoonJRYc7k (Accessed: 4/11/2023).

UK Centre for Ecology & Hydrology (n.d.) Algal blooms and human health, Available at: https://www.ceh.ac.uk/our-science/projects/algal-blooms-and-human-health (Accessed: 4/11/2023).