Llyn Tegid

Also within

Gwynedd County Eryri / Snowdonia National Park

Geology & landscape

Geological Feature: Geological Fault

Birds & fish recorded

Birds

Fish

Description

Description Located in a glacially cut basin on a geological fault line, Llyn Tegid is the largest natural Welsh lake. It reaches 42 metres in depth and the underlying rocks are predominantly acidic. Llyn Tegid is considered a nationally important site in ecological terms, its value is enhanced by the amount of research invested in its fish populations by Liverpool University. Aquatic vegetation is limited along the rocky shores to species such as shoreweed Littorella uniflora and water starworts Callitriche spp.. More sheltered stretches have an interesting flora including floating pondweed Potamogeton natans, branched bur-reed Sparganium erectum, and the uncommon floating water plantain Luronium natans. The invertebrate fauna of Llyn Tegid is typical of exposed oligo-to mesotrophic lakes. Eight species of gastropod occur, including the rare Myxas glutinosa. A range of fish species are present including perch, pike, roach, grayling and the unique Gwyniad Coregonus clapeoides pennantii, a subspecies of European whitefish. The brown trout population has been reduced because the lowering of the water level in 1995 has restricted its spawning shallows. Llyn Tegid is of limited ornithological interest; small numbers of duck such as pochard and wigeon overwinter while great crested grebe breed.

Species mentioned