Changes in aquatic macrophyte communities in Loch Leven: evidence of recovery from eutrophication?

Dudley, Bernard; Gunn, Iain; Carvalho, Laurence; Proctor, I.; O’Hare, Matthew T.; Murphy, K. J.; Milligan, A. L.

doi:10.1007/978-94-007-4333-5_6

Cited by 5 publications

(7 citation statements)

References 31 publications

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“…Changes in a lake's aquatic vegetation can be determined from historical botanical data yet, with a few exceptions (Sand-Jensen 1997;Davidson et al 2005;Madgwick et al 2011;Dudley et al 2012), such records rarely exist for time periods (decades to centuries) sufficient to assess human impacts. An alternative, or indeed complementary, tool for assessing long term changes in vegetation is the palaeoecological record.…”

Section: Introductionmentioning

confidence: 99%

Sedimentary macrofossil records reveal ecological change in English lakes: implications for conservation

et al. 2017

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Aquatic macrophytes play a key role in providing habitat, refuge and food for a range of biota in shallow lakes. However, many shallow lakes have experienced declines in macrophyte vegetation in recent decades, principally due to eutrophication. As changes in macrophyte composition and abundance can affect overall ecological structure and function of a lake, an assessment of the timing and nature of such changes is crucial to our understanding of the wider lake ecosystem. In the typical absence of historical plant records, the macro-remains of macrophytes preserved in lake sediments can be used to assess long-term changes in aquatic vegetation. We generated recent (150-200 years) plant macrofossil records for six English lakes subject to conservation protection to define past macrophyte communities, assess trajectories of ecological change and consider the implications of our findings for conservation targets and strategies. The data for all six lakes reveal a diverse submerged macrophyte community, with charophytes Electronic supplementary material The online version of this article (doi:10.1007/s10933-017-9941-7) contains supplementary material, which is available to authorized users. as a key component, in the early part of the sedimentary records. The stratigraphies indicate considerable change to the aquatic vegetation over the last two centuries with a general shift towards species more typically associated with eutrophic conditions. A common feature is the decline in abundance of lowgrowing charophytes and an increase in tall canopyforming angiosperms such as fine-leaved Potamogeton species, Zannichellia palustris and Callitriche species. We hypothesise, based on findings from longterm datasets and palaeoecological records from enriched shallow lakes where plants are now absent, that the observed shifts provide a warning to managers that the lakes are on a pathway to complete macrophyte loss such that nutrient load reduction is urgently needed. It is the sound understanding of present-day plant ecology that affords such reliable interpretation of the fossil data which, in turn, provide valuable context for current conservation decisions.

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Section: Introductionmentioning

confidence: 99%

Sedimentary macrofossil records reveal ecological change in English lakes: implications for conservation

et al. 2017

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“…Historical (Jupp et al 1974;Dudley et al 2012b) and palaeoecological (Haworth 1972;Salgado et al 2010;Bennion et al 2012) records reveal progressive nutrient-enrichment in Loch Leven throughout the nineteenth and twentieth centuries from oligo-mesotrophic to eutrophic conditions. In particular, the loss of Isoetes lacustris prior to ca.…”

Section: Study Sitementioning

confidence: 99%

“…This accords with the core LEVE11 diatom record , which shows a marked shift to a planktonic dominated assemblage throughout the twentieth century, including Aulacoseira ambigua and Stephanodiscus hantzschii. Moreover, historical macrophyte surveys from 1905 to 2008 (Dudley et al 2012b) attest to the continued eutrophication of Loch Leven during much of the twentieth century. Nutrient-enrichment was driven by increased inputs of TP to the loch which rose from an estimated 6 t TP year -1 in the early 1900s to around 20 t TP year -1 in 1985 .…”

Section: Palaeo-inferred Testate Amoeba Ecologymentioning

confidence: 99%

Refining the palaeoecology of lacustrine testate amoebae: insights from a plant macrofossil record from a eutrophic Scottish lake

et al. 2017

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Arcellinida (lobose testate amoebae) preserve well in lake sediments and have shown great potential as palaeolimnological indicators, but a limited understanding of their ecology prevents more indepth interpretations of both contemporary and fossil assemblages. Loch Leven, Scotland, has a well-documented history of nutrient-enrichment and associated lake biological change, creating a temporal gradient along which testate amoeba ecology can be investigated. Plant macrofossil data from a dated sediment core (LEVE14) indicate that a transition from oligomesotrophic to eutrophic conditions occurred over at least the last 200 years, enabling direct comparisons to be drawn with fossil testate amoeba assemblages from the same core. Cluster analysis and principal components analysis show that testate amoebae and macrophytes responded synchronously to an early phase of nutrient-enrichment after ca. AD 1200, and to anthropogenic water-level lowering and further enrichment after ca. AD 1830. The results of indicator species analysis (IndVal) support the suggestion inferred previously that Cucurbitella tricuspis is an indicator of nutrient-enrichment, while the association of some less abundant taxa, specifically Difflugia amphora and Mediolus corona, with eutrophic environments is also corroborated. Overall, the testate amoeba assemblage response appears to reflect a complex interaction of factors which were ultimately driven by eutrophication. These include variations in microhabitat associated with changing plant structure and sedimentary conditions influenced by macrophyte community succession. In particular, a shift from an oligo-mesotrophic macrophyte assemblage composed of isoetid plants to one dominated by Potamogeton spp. and dense stands of Characeae is suggested to influence the relative proportions of sediment dwelling and plant-associated testate amoebae. The results highlight the utility of testate amoebae as benthic indicators of lake nutrient-enrichment and demonstrate the value of using multi-proxy palaeolimnological data to refine the ecology of lesser-studied palaeoecological groups.

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“…This led to a significant lowering of the chlorophyll a:TP ratio in the lake (Figure 1) and an associated reduction in the frequency of algal blooms. This caused a temporary improvement in water clarity and an increase in the abundance of submerged macrophytes (Johnson & Walker, 1974;Dudley et al, this volume). However, as P inputs to the lake continued to increase (May et al, this volume), algal growth outstripped loss processes, even with the increase in zooplankton grazing, and algal blooms became more common, again.…”

Section: Consequencesmentioning

confidence: 99%

“…These blooms decreased water clarity, lowering the aesthetic, economic and amenity values of the lake, and reducing the depth to which rooted, submerged vegetation was able to grow (May & Carvalho, 2010;Dudley et al, this volume). The blooms also limited the ability of the lake to support other ecosystem services, such as supplying clean water and providing good quality habitat for aquatic birds, especially those that are dependent on underwater plants (Allison & Newton, 1974).…”

Section: Introductionmentioning

confidence: 99%

Managing ecosystem services at Loch Leven, Scotland, UK: actions, impacts and unintended consequences

May

Spears

2011

Hydrobiologia

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Corresponding author: Linda May Email lmay@ceh.ac.uk; telephone +44 (0)131 445 8537; fax +44 (0)131 445 3943 Keywords:Lake management, brown trout, rainbow trout, Daphnia, nutrient load, pesticide pollution, cost This paper has not been submitted elsewhere in identical or similar form, nor will it be during the first three months after its submission to Hydrobiologia. 2 AbstractRivers, lakes and wetlands are good examples of ecosystems that provide multiple, concurrent, services to mankind. Human society has often exploited these systems by enhancing one ecosystem service at the expense of another. Loch Leven, Scotland, UK, is a good example of this. Over the past 150 years, the lake has been subjected to hydrological modification, fish stocking and pollution control to improve the delivery of key goods and services. This study uses historical records to explore the results of these interventions on the ecosystem services that were targeted for improvement and the knock-on effects on other services provided by the lake. The results suggest that, when management changes are being considered to enhance particular ecosystem services, the potentially damaging effects on other ecosystem services should be taken into account. This requires a better understanding of the role of ecosystem function in delivering ecosystem services, and of the links between multiple ecosystem services, than is currently available. While further research is clearly needed, the value of long term datasets in providing knowledge and understanding through 'hindsight' should not be underestimated. The study concludes that successful management actions are likely to be those that incorporate lessons learned from previous decisions.3

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Changes in aquatic macrophyte communities in Loch Leven: evidence of recovery from eutrophication?

Cited by 5 publications

References 31 publications

Sedimentary macrofossil records reveal ecological change in English lakes: implications for conservation

Sedimentary macrofossil records reveal ecological change in English lakes: implications for conservation

Refining the palaeoecology of lacustrine testate amoebae: insights from a plant macrofossil record from a eutrophic Scottish lake

Managing ecosystem services at Loch Leven, Scotland, UK: actions, impacts and unintended consequences

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