Broads Authority

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Uk, Russia
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Madgwick G.,University College London | Madgwick G.,University of Stirling | Emson D.,University College London | Sayer C.D.,University College London | And 4 more authors.
Freshwater Biology | Year: 2011

1.We investigate long-term (>200years) changes to the composition and spatial structure of macrophyte communities in a shallow, eutrophic lake (Barton Broad, eastern England) and consider the implications for lake restoration. 2.Historical macrophyte data were assembled from a variety of sources: existing plant databases, museum herbaria, journal articles, old photographs and eyewitness accounts. Additionally, two types of sediment core sample were analysed for plant macro-remains and pollen; bulk basal samples from multiple core sites analysed to provide information on 'pre-disturbance' macrophyte communities and two whole cores analysed to determine historical change. 3.Prior to the late 1800s, macrophyte communities were diverse and included a multilayered mosaic of short-stature submerged taxa and taller submerged and floating-leaved species. With the progression of eutrophication after around 1900, the former community was displaced by the latter. Diversity was maintained, however, since an encroaching Schoenoplectus-nymphaeid swamp generated extensive patches of low-energy habitat affording refugia for several macrophytes otherwise unable to withstand the hydraulic forces associated with open water conditions. When this swamp vegetation disappeared in the 1950s, many of the 'dependent' aquatic macrophytes also declined leaving behind a sparse, species-poor community (as today) resilient to both eutrophication and turbulent open waters. 4.The combination of historical and palaeolimnological data sources offers considerable benefits for reconstructing past changes to the aquatic vegetation of lakes and for setting restoration goals. In this respect, our study suggests that successful restoration might often be better judged by reinstatement of the characteristic structure of plant communities than the fine detail of species lists; when nutrients are low and the structure is right, the right species will follow. © 2011 Blackwell Publishing Ltd.


Hunter P.D.,University of Stirling | Gilvear D.J.,University of Stirling | Tyler A.N.,University of Stirling | Willby N.J.,University of Stirling | Kelly A.,Broads Authority
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2010

The ecological status of shallow lakes is highly dependent on the abundance and composition of macrophytes. However, large-scale surveys are often confined to a small number of water bodies and undertaken only infrequently owing to logistical and financial constraints. Data acquired by the Compact Airborne Spectrographic Imager-2 (CASI-2) was used to map the distribution of macrophytes in the Upper Thurne region of the Norfolk Broads, UK. Three different approaches to image classification were evaluated: (i) Euclidean minimum distance, (ii) Gaussian maximum likelihood, and (iii) support vector machines. The results show macrophyte growth-habits (i.e. submerged, floating-leaved, partially-emergent, emergent) and submerged species could be mapped with a maximum overall classification accuracy of 78% and 87%, respectively. The Gaussian maximum likelihood algorithm and support vector machine returned the highest classification accuracies in each instance. This study suggests that remote sensing is a potentially powerful tool for large-scale assessment of the cover and distribution of aquatic vegetation in clear water shallow lakes, particularly with respect to upscaling field survey data to a functionally relevant form, and supporting site-condition monitoring under the European Union Habitats (92/43/EEC) and Water Framework (2000/60/EC) directives. Copyright © 2010 John Wiley & Sons, Ltd.


PubMed | Institute Dr Nowak, Natural England, Netherlands Institute of Ecology, Freshwater Research and 5 more.
Type: | Journal: Water research | Year: 2016

Lanthanum (La) modified bentonite is being increasingly used as a geo-engineering tool for the control of phosphorus (P) release from lake bed sediments to overlying waters. However, little is known about its effectiveness in controlling P across a wide range of lake conditions or of its potential to promote rapid ecological recovery. We combined data from 18 treated lakes to examine the lake population responses in the 24 months following La-bentonite application (range of La-bentonite loads: 1.4-6.7tonnesha(-1)) in concentrations of surface water total phosphorus (TP; data available from 15 lakes), soluble reactive phosphorus (SRP; 14 lakes), and chlorophyll a (15 lakes), and in Secchi disk depths (15 lakes), aquatic macrophyte species numbers (6 lakes) and aquatic macrophyte maximum colonisation depths (4 lakes) across the treated lakes. Data availability varied across the lakes and variables, and in general monitoring was more frequent closer to the application dates. Median annual TP concentrations decreased significantly across the lakes, following the La-bentonite applications (from 0.08mgL(-1) in the 24 months pre-application to 0.03mgL(-1) in the 24 months post-application), particularly in autumn (0.08mgL(-1) to 0.03mgL(-1)) and winter (0.08mgL(-1) to 0.02mgL(-1)). Significant decreases in SRP concentrations over annual (0.019mgL(-1) to 0.005mgL(-1)), summer (0.018mgL(-1) to 0.004mgL(-1)), autumn (0.019mgL(-1) to 0.005mgL(-1)) and winter (0.033mgL(-1) to 0.005mgL(-1)) periods were also reported. P concentrations following La-bentonite application varied across the lakes and were correlated positively with dissolved organic carbon concentrations. Relatively weak, but significant responses were reported for summer chlorophyll a concentrations and Secchi disk depths following La-bentonite applications, the 75th percentile values decreasing from 119gL(-1) to 74gL(-1) and increasing from 398cm to 506cm, respectively. Aquatic macrophyte species numbers and maximum colonisation depths increased following La-bentonite application from a median of 5.5 species to 7.0 species and a median of 1.8m to 2.5m, respectively. The aquatic macrophyte responses varied significantly between lakes. La-bentonite application resulted in a general improvement in water quality leading to an improvement in the aquatic macrophyte community within 24 months. However, because, the responses were highly site-specific, we stress the need for comprehensive pre- and post-application assessments of processes driving ecological structure and function in candidate lakes to inform future use of this and similar products.


Spears B.M.,UK Center for Ecology and Hydrology | Mackay E.B.,UK Center for Ecology and Hydrology | Yasseri S.,Institute Dr Nowak | Gunn I.D.M.,UK Center for Ecology and Hydrology | And 13 more authors.
Water Research | Year: 2015

Lanthanum (La) modified bentonite is being increasingly used as a geo-engineering tool for the control of phosphorus (P) release from lake bed sediments to overlying waters. However, little is known about its effectiveness in controlling P across a wide range of lake conditions or of its potential to promote rapid ecological recovery. We combined data from 18 treated lakes to examine the lake population responses in the 24 months following La-bentonite application (range of La-bentonite loads: 1.4-6.7 tonnes ha-1) in concentrations of surface water total phosphorus (TP; data available from 15 lakes), soluble reactive phosphorus (SRP; 14 lakes), and chlorophyll a (15 lakes), and in Secchi disk depths (15 lakes), aquatic macrophyte species numbers (6 lakes) and aquatic macrophyte maximum colonisation depths (4 lakes) across the treated lakes. Data availability varied across the lakes and variables, and in general monitoring was more frequent closer to the application dates. Median annual TP concentrations decreased significantly across the lakes, following the La-bentonite applications (from 0.08 mg L-1 in the 24 months pre-application to 0.03 mg L-1 in the 24 months post-application), particularly in autumn (0.08 mg L-1 to 0.03 mg L-1) and winter (0.08 mg L-1 to 0.02 mg L-1). Significant decreases in SRP concentrations over annual (0.019 mg L-1 to 0.005 mg L-1), summer (0.018 mg L-1 to 0.004 mg L-1), autumn (0.019 mg L-1 to 0.005 mg L-1) and winter (0.033 mg L-1 to 0.005 mg L-1) periods were also reported. P concentrations following La-bentonite application varied across the lakes and were correlated positively with dissolved organic carbon concentrations. Relatively weak, but significant responses were reported for summer chlorophyll a concentrations and Secchi disk depths following La-bentonite applications, the 75th percentile values decreasing from 119 μg L-1 to 74 μg L-1 and increasing from 398 cm to 506 cm, respectively. Aquatic macrophyte species numbers and maximum colonisation depths increased following La-bentonite application from a median of 5.5 species to 7.0 species and a median of 1.8 m to 2.5 m, respectively. The aquatic macrophyte responses varied significantly between lakes. La-bentonite application resulted in a general improvement in water quality leading to an improvement in the aquatic macrophyte community within 24 months. However, because, the responses were highly site-specific, we stress the need for comprehensive pre- and post-application assessments of processes driving ecological structure and function in candidate lakes to inform future use of this and similar products. © 2015 The Authors.


Okamura B.,Natural History Museum in London | Ayres K.,University of Reading | Salgado J.,University College London | Davidson T.A.,University of Aarhus | And 4 more authors.
Aquatic Ecology | Year: 2013

The aim of this pilot study is to test the hypotheses that sediment cores can provide evidence for metapopulation dynamics and that these can be linked with site characteristics. We focus on temporal patterns of incidence and abundance of overwintering stages (statoblasts) produced by the freshwater bryozoan Cristatella mucedo, an organism characterised by a metapopulation ecology, in sediment cores retrieved from 18 UK lakes. Runs and goodness-of-fit tests provided evidence for population instability, periods of low abundance and absence, and of asynchrony-all signatures of metapopulation dynamics. Further hypothesis testing indicated that extinction risk is greater in more isolated sites and in sites of smaller size. Absence of statoblasts from the top sections of spatially separated, replicate cores provided independent evidence for extinction in one site. Our study demonstrates how the abundances of sedimentary-bound propagules may be analysed initially for metapopulation dynamics and subsequently how this may lead to working hypotheses regarding the drivers of such dynamics. The sediment archive represents a unique historical record whose potential for characterising metapopulation dynamics has previously been untapped but is broadly relevant for understanding the population biology of freshwater organisms. © 2013 Springer Science+Business Media Dordrecht.


Boyle J.F.,University of Liverpool | Sayer C.D.,University College London | Hoare D.,Broads Authority | Bennion H.,University College London | And 5 more authors.
Journal of Paleolimnology | Year: 2016

Tributyltin (TBT), an aqueous biocide derived from antifouling paint pollution, is known to have impacted coastal marine ecosystems, and has been reported in the sediment of the Norfolk and Suffolk Broads, a network of rivers and shallow lakes in eastern England. In the marine environment, the 1987 TBT ban resulted in expanded use of alternative biocides, raising the question of whether these products too have impacted the Broads ecosystem and freshwaters in general. We examined the lake sediment record in the Norfolk and Suffolk Broads for contamination by copper (Cu), an active biocide agent, and zinc (Zn), a component of booster biocides, to assess their occurrence and potential for causing environmental harm in freshwater ecosystems. After the introduction of leisure boating, there was a statistically significant difference in Cu enrichment between heavily and lightly boated sites, whereas no such difference existed prior to that time. At the heavily boated sites, the onset of Cu enrichment coincided with a period of rapid increase in leisure boating. Such enrichment has been maintained to the present day, with some evidence of continued increase. We conclude that Cu-based antifouling has measurably contaminated lakes exposed to boating, at concentrations high enough to cause ecological harm. Similar findings can be expected at other boated freshwater ecosystems elsewhere in the world. © 2016, The Author(s).


D.wood E.L.,University of Edinburgh | Matthews J.B.,Moredun Research Institute | Stephenson S.,Broads Authority | Slote M.,Norfolk Wildlife Trust | Nussey D.H.,University of Edinburgh
Parasitology | Year: 2013

Cyathostomins are the most prevalent equine intestinal parasites and resistance has been reported in these nematodes against all 3 licensed anthelmintic classes. Strategies need to be developed that are less dependent upon drugs and more reliant on management-based control. To develop these we need to understand natural transmission patterns better. Here, we analysed longitudinal fecal egg count (FEC) data from 5 pony populations used for conservation purposes. We tested how egg excretion varied amongst populations and individuals, and how this was affected by age and climate. There was evidence for consistency in FECs over time at the individual level; this was generally weak and accounted for <10% of the total variance. Animals <5 years old had higher FECs and there was profound seasonal variation in FECs, with highest levels recorded in spring/summer. Effects of monthly temperature and rainfall explained most, but not all, of the observed seasonal variation and associations between climate measures and FECs were stronger in younger versus adult animals. One population was occasionally treated with anthelmintics and analysis of this population suggested that treatment substantially altered the seasonal dynamics. This paper highlights the variability in strongyle egg excretion amongst individuals and the factors involved in this variation. Copyright © 2012 Cambridge University Press.

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