Lydia King

Bio: Lydia King is an academic researcher from Lancaster University. The author has contributed to research in topics: Nutrient & Water Framework Directive. The author has an hindex of 10, co-authored 17 publications receiving 681 citations.

Nutrient limitation of phytoplankton and periphyton growth in upland lakes

Abstract: SUMMARY 1. Thirty small upland lakes in Cumbria, Wales, Scotland and Northern Ireland were visited three times between April and August 2000. On each occasion water chemistry was measured and phytoplankton bioassays were performed in the laboratory to assess growth-rate and yield limitation by phosphorus and nitrogen. In addition, yield limitation of periphyton growth was investigated twice, in situ, using nutrient-diffusing substrata. 2. Over the whole season the percentage frequency of P, N and co-limitation was 24, 13 and 63%, respectively, for phytoplankton rate limitation and 20, 22 and 58%, respectively, for phytoplankton yield limitation. 3. A clear response of periphyton yield to nutrient additions was found in 75% of all cases and of these, co-limitation was most common (54%). Average percentage frequency for P and N limitation was 26 and 20%, respectively. 4. Phytoplankton and periphyton showed seasonal changes in nutrient limitation within sites. In particular, co-limitation became progressively more common as the season progressed. 5. The response of phytoplankton growth rate to ammonium and nitrate addition was identical, but ammonium was a slightly better source of nitrogen than nitrate for phytoplankton yield on 7% and for periphyton yield on 10% of the occasions. However, the magnitude of the effect was small. 6. The concentration of dissolved inorganic nitrogen (DIN) and the molar ratio of DIN to total dissolved phosphorus (TDP), appeared to be the main environmental factors controlling the extent of nitrogen or phosphorus limitation at a given site. Nitrogen limitation was more likely than phosphorus limitation where the DIN was <6.5 mmol m−3 and the ratio of DIN : TDP was <53. Co-limitation was the most likely outcome at a DIN concentration <13 mmol m−3 and at a DIN : TDP molar ratio <250. Above these values phosphorus limitation was most likely. 7. The relatively high frequency of nitrogen limitation and co-limitation at higher N : P ratios than previously reported, may result from the inability of nitrogen-fixing cyanobacteria to thrive in these upland lakes where pH and the concentration of phosphorus tended to be low and where flushing rates tended to be high.

Recommendations for sampling littoral diatoms in lakes for ecological status assessments

Abstract: This review summarises the existing literature and outlines the theoretical basis for using standard methods for sampling diatoms from rivers to sample littoral diatoms and other phytobenthos from standing waters. The European Union's Water Framework Directive has created a statutory obligation for EU Member States to monitor macrophytes and phytobenthos in lakes. Although there has been a considerable amount of work using phytobenthos (especially diatoms) to monitor river water quality in Europe, there are fewer studies on the use of phytobenthos for monitoring in lakes. European standard methods for sampling diatoms from rivers should be suitable, with only minor modifications, for sampling littoral diatoms from lakes and other standing water bodies. These recommendations should be applicable to all temperate regions.

Nitrogen stable isotope ratios in surface sediments, epilithon and macrophytes from upland lakes with differing nutrient status

Abstract: Summary 1. Thirty small upland lakes in Cumbria, Wales, Scotland and Northern Ireland were each visited once during June and July 2000. From each lake, samples of surface sediment epilithon, macrophytes and total dissolved nitrogen (TDN) were collected for nitrogen stable isotope analysis. As part of a wider programme, samples were also collected for chemical analysis and bioassays. 2. Considerable variation was found in δ15N values in all measured nitrogen compartments. Some regional variation was evident but was generally weak. Sediment and epilithon δ15N were positively correlated with δ15N of TDN, suggesting that baseline nitrogen isotope ratios influence those in some organic matter compartments in the lakes. 3. Sediment δ15N was higher when inorganic nitrogen concentration in the water was low, possibly reflecting reduced isotope fractionation under these conditions. However, this was not the case for epilithon or macrophytes. Sediment δ15N values were also negatively related to annual nitrogen deposition. 4. Sediment, epilithon and macrophyte δ15N values all showed significant relations to nutrient limitation in the lakes as determined by algal bioassays. We suggest that sediment δ15N might be developed as a simple integrating measure of the degree of nitrogen limitation in lakes.

Epilithic algal communities and their relationship to environmental variables in lakes of the English Lake District.

Abstract: 1. The relationship between epilithic algal communities and 17 environmental variables from 17 oligo- to eutrophic lakes in the English Lake District was explored using canonical correspondence analysis (CCA). Total phosphorus (TP) and calcium (Ca) concentration were the most important variables accounting for species distribution. 2. Weighted-averaging regression and calibration models with tolerance downweighting and classical deshrinking were developed to infer TP, Ca, dissolved inorganic carbon (DIC) and conductivity from the relative abundance of 138 epilithic algal taxa. 3. The ranges of the environmental variables covered by the models are 0.8-49.2 μg L−1 for TP, 2.2–13.0 mg L−1 for Ca, 0.5–8.6 mg L−1 for DIC and 38–124 μS cm−1 for conductivity. Within these limits the models can be used to infer chemical properties of lakes from epilithic communities in the English Lake District. 4. The major advantages of using transfer functions based on epilithic communities are the low logistic requirements and the integrative character of algal samples compared to direct point measurements of chemical parameters of the lakes.

Validation of diatoms as proxies for phytobenthos when assessing ecological status in lakes

Abstract: Research to develop tools to assess the ecological status of phytobenthos, as required in Annex V of the European Union Water Framework Directive, has focussed largely on diatoms Diatoms are often the most abundant and diverse group of algae within the phytobenthos and have been used widely for other monitoring purposes However, there is little empirical justification for the use of diatoms as proxies for the wider phytobenthos In this paper, we re-examine an existing dataset compiled largely from littoral samples from standing waters in the English Lake District and compared transfer functions for total phosphorus, dissolved inorganic carbon, conductivity and calcium concentration generated from diatoms and non-diatoms separately and together The results show that transfer functions generated from diatoms alone are as powerful as transfer functions generated from diatoms and non-diatoms combined, while transfer functions generated from non-diatoms alone are less effective These results provide support for the use of diatoms as proxies for phytobenthos when ecological status is being assessed

Metarhizium spp., cosmopolitan insect-pathogenic fungi: mycological aspects.

Abstract: Publisher Summary The chapter focuses on mycological aspects of the genus Metarhizium . The genus includes several species, varieties within species, and individual isolates with broad ranges of physiological traits—including host range. The interactions of these fungi with their hosts, and the large literature on their use for pest control, largely define the scientific and popular concepts of Metarhizium spp. Fungi of the hyphomycete genus Metarhizium have been isolated from infected insects and soil. Although some isolates of these fungi have rather restricted host ranges, the group is better known for its ability to kill a wide spectrum of insects, including insects in at least seven orders. The common name for Metarhizium -induced disease is “green muscardine,” based on the encrustation of insect cadavers with green conidia. The rapid increase in research on Metarhizium , followed by sustained high scientific output, can be explained by several important worldwide attitude changes and the initiation of several promising Metarhizium -based pest-control and molecular-biology efforts.

Multi-proxy studies in palaeolimnology

Abstract: Multi-proxy studies are becoming increasingly common in palaeolimnology. Eight basic requirements and challenges for a multi-proxy study are outlined in this essay – definition of research questions, leadership, site selection and coring, data storage, chronology, presentation of results, numerical tools and data interpretation. The nature of proxy data is discussed in terms of physical proxies and biotic proxies. Loss-on-ignition changes and the use of transfer functions are reviewed as examples of problems in the interpretation of data from multi-proxy studies. The importance of pollen analysis and plant macrofossil analysis in multi-proxy studies is emphasised as lake history cannot be interpreted without knowledge of catchment history. Future directions are outlined about how multi-proxy studies can contribute to understanding biotic responses to environmental change.