The impact of human activity on the aquatic macroflora of Llangorse Lake, South Wales

Abstract

1. The first recorded effects of human activity on the aquatic flora of Llangorse Lake, South Wales, were the result of introductions of Elodea canadensis in the early 1900s and of Nymphoides peltata in 1936, altering the species balance of both submerged and floating plant communities. 2. The most significant impact on the lake in recent times has been effluent from the sewage treatment works, which discharged into the lake between the early 1950s and 1982, and the impact of a concurrent intensification of agriculture within the catchment, both leading to accelerated eutrophication. 3. The eutrophication of the lake resulted in a significant change in the submerged flora, which declined in diversity and extent to only a few stands of two species in 1982. 4. Following the diversion of the sewage effluent, the submerged flora recovered to a situation similar to that existing before the effects of accelerated eutrophication. 5. The emergent and floating plant communities did not reflect the eutrophication in the same way as the submerged flora, although Equisetum fluviatile has declined noticeably. 6. The floating and emergent communities, notably Phragmites australis reed swamp, have been significantly damaged in the immediate vicinity of mooring developments, but elsewhere the introduction of water‐based recreation cannot be demonstrated to have had a widespread detrimental effect. 7. The recovery of the submerged plant community is considered to be in part due to residual populations of the various species ‘lost’ from the main body of the lake existing in refugia in and around the lake. 8. The history of the lake is notable in terms of the recovery of the submerged flora and in the absence of dominants new to the system invading during the period of accelerated eutrophication. Copyright © 1999 John Wiley & Sons, Ltd.

Spatio-temporal changes in land cover and aquatic macrophytes of the Danube floodplain lake

“…There is a general agreement in the literature about the rapid spread of M. spicatum, e.g. in North America or Great Britain (Boylen et al, 1999;Wade, 1999). The results of Agami and Waisel (2002) suggested that a competitive relationship exists between the submerged species Najas marina and M. spicatum, in accordance with our findings (Fig.…”

“…Several studies have reported comparisons between the current species richness, abundance and distribution and historical levels of aquatic vegetation in lake ecosystem. These documented changes occurred mostly during the second half of the last century, in response to human impacts, mainly changes in water level (Egertson et al, 2004;Hellsten et al, 2006), eutrophication (Ozimek and Kowalczewski, 1984), the intensification of agriculture (Wade, 1999;Duigan et al, 2006), stocking of herbivorous fish (Hutorowicz and Dziedzic, 2008) and changes in land use along the lakeshores and catchments (Papastergiadou et al, 2007(Papastergiadou et al, , 2008Partanen et al, 2009).…”

Spatiotemporal Dynamics of Submerged Aquatic Vegetation in a Deep Lake from Sentinel-2 Data

“…Generally, it is critical to be able to disentangle the bijective interactions of natural and human determinants in influencing macrophyte distribution and dominance [12]. Several works have been done to investigate the contribution of human impacts on such changes [13][14][15][16][17]. On the contrary, only few studies have investigated non-nutrient drivers of macrophyte growth and distribution [18,19] or focused on their natural successional patterns [11,20].…”