Buglife responds to ‘Further Information’ – Objection maintained
Buglife – The Invertebrate Conservation Trust would like to make the additional comments on the above application while maintaining the objection outlined in previous comments dated 13th May 2025.
These comments are in response to the additional information submitted by the applicant, with reference to ‘4b Aquatic Ecology – Loch Ness Macroinvertebrate Survey Update’ written by AECOM (dated August 2025). This report provides additional survey data and assessment with regards to the impacts of water fluctuations on the aquatic invertebrate communities in Loch Ness.
Buglife welcome that further sampling of aquatic macroinvertebrates has been undertaken to supplement the data presented within the Environmental Impact Assessment Report (EIAR) (March 2025).
Comprehensive surveys require spring and autumn sampling but as only spring sampling was undertaken at most locations, some taxa or species are likely to have been missed. However, the increased sampling areas does provide a more representative data set to assess the impacts of the proposals. Buglife outline below our continued concerns with the impact assessment that has been provided with these updated surveys.
Inappropriate and inadequate assessment of aquatic macroinvertebrates
As stated in our previous comments, and which applies to the updated report, the only metric that has been used to appropriately assess the value of invertebrates in freshwater lochs is the CCI, an index that accounts for community richness as well as species rarity (Ref 1). The evaluation of the importance of the invertebrate communities in Loch Ness by other metrics is not valid as they are not appropriate for use in still water bodies.
The updated report states that “the conclusion reached in the EIAR that the impact of increased fluctuation of water levels in Loch Ness on resident macroinvertebrate communities, would result in a Negligible effect is still applicable”. Buglife reiterate, the EIAR did not identify key taxa that are intolerant of excessive water fluctuations as part of the impact assessment and therefore no assessment has been made on how drawdown would impact the invertebrate communities present. The updated report states that “The taxa identified through these surveys have been analysed in terms of their tolerance to increased water level fluctuations and been found to be considered tolerant…” and yet no evidence is presented of how the assessment of the tolerance of different taxa has been made with reference to the available scientific literature. The updated assessment takes species or families that have been deemed ‘tolerant’ to water fluctuations in the EIAR (where no evidence is presented for this tolerance) and determined that other species/families will also be tolerant to water fluctuations because they occupy a similar ecological niche. This is a hugely assumptive approach as although different species all live within the littoral zone habitat, their differing ecology and life histories means their ability to track water levels or be impacted by water fluctuations at different stages of their life cycle will vary.
As an example, the report highlights seven cased caddisfly families that were recorded in the data presented in the EIAR. Just one species, the Cinnamon Sedge Caddisfly (Limnephilus marmoratus) was discussed with regard to the impacts of water fluctuations, with the conclusion that this species would not be adversely impacted by drawdown effects. Buglife does not agree with this conclusion which refers to the spring egg laying behaviour observed of Cinnamon Sedge Caddisflies inhabiting temporary water bodies. As Loch Ness is a permanent water site, the adults will lay in summer and therefore there is concern that eggs and larvae could be vulnerable to drawdown, with larvae known to live amongst submerged vegetation (Ref 2).
The updated survey report specifically refers to cased caddisflies, in the family Leptoceridae, of which the assessment concludes that as the species in this family “occur in similar ecological niches” to the other cased caddisfly families recorded, it can be implied that this family will also suffer “Negligible effect resulting from increased water fluctuations in Loch Ness”. This conclusion appears to be based on the Cinnamon Sedge Caddisfly being determined to be tolerant, so all caddisflies are tolerant. Caddisflies are a group that can be sensitive to water fluctuations (Ref 3) but as the ecology of different species and families varies, it is not reasonable to assume that all species and families will have the same tolerance. For example, within the Leptoceridae family, some species are only able to crawl rather than swim and some have heavy cases as opposed to lighter cases which impacts their mobility. These species would not be able to track water fluctuations and would become stranded. Within the Leptoceridae family, the main genera that are able to swim were not represented in the samples collected.
With regard to the Vulnerable Arctic-alpine Pea Clam (Euglesa conventus), a Scottish Biodiversity List species present in Loch Ness, the updated report correctly asserts that this species will not be subject to impacts from water fluctuations as it lives in deeper water habitats. However, as Buglife highlighted in our previous comments, it was the potential impacts from changes in water pressure and temperature that may occur due to the scheme that requires assessment.
Adverse impacts on aquatic macroinvertebrates in Loch Ness from water fluctuations
The updated report repeats the conclusion of the EIAR that there will be a negligible impact on aquatic invertebrate communities from the increased water fluctuations due to the scheme. Buglife highlight that this conclusion is not founded in evidence. Buglife reiterates that the premise in the EIAR and repeated in the updated report that more frequent water fluctuations, resulting in wetter marginal habitat could provide benefits to invertebrates is contrary to scientific evidence. As presented in detail in our previous comments, the scientific evidence illustrates the detrimental impact of increased water fluctuations leading to impoverished invertebrate communities (Refs 4 & 5). Reduction in species diversity and abundance would have wide eco-system impacts considering the pivotal role invertebrates have in the food chain. It is therefore vital that the impacts are understood and that an adequate assessment is provided before a decision is made on these proposals.
To summarise, the aquatic invertebrate data submitted for the scheme is now more representative of the communities inhabiting the littoral zone of Loch Ness that will be impacted by habitat loss and water fluctuations from the scheme. However, no assessment is provided, based on evidence, of how water fluctuations will impact these communities and the resulting wider eco-system impacts. The evidence we have presented in our comments highlights that there are likely to be adverse impacts, that will lead to overall biodiversity loss from the proposals.
Craig Macadam
Co-Leader and Director of Conservation
E-mail: scotland@buglife.org.uk
References
- Chadd, R. and Extence, C. 2004. The conservation of freshwater macroinvertebrate populations: a community-based classification scheme. Aquatic Conssrv: Mar. Freshw. Ecosyst., 14: 597-624.
- Clifford C, Friend K, Skipp S, Wallace I, Price BW (2023) The genome sequence of the cinnamon sedge caddisfly, Limnephilus marmoratus (Curtis, 1834). Wellcome Open Res. Feb 8;8:64. doi: 10.12688/wellcomeopenres.18753.1.
- Carmignani, J.R. and Roy, A.H. (2017). Ecological impacts of winter water level drawdowns on lake littoral zones: a review. Aquat. Sci. 79: 803–824.
- Smith, B.D., Maitland, P.S. and Pennock, S.M. (1987). A Comparative Study of Water Level Regimes and Littoral Benthic Communities in Scottish Lochs. Biological Conservation 39: 291-316.
- Trottier, G., Turgeon, K., Boisclair, D., Bulle, C. and Margni, M. et al. (2022). The impacts of hydropower on freshwater macroinvertebrate richness: A global meta-analysis. PLoS ONE 17(8): e0273089.