User:Eitamh/Windermere

Introduction
Aside from being a popular tourist and recreational destination, Windermere is a Site of Special Scientific Interest. Windermere has been the site of a lot of scientific study, and the Freshwater Biological Association and the Centre for Ecology and Hydrology have both had laboratories at the lake for over 50 years. The North Basin is also a sampling site for the UK's Environmental Change Network. Windermere is the largest natural lake in England and the lake suffers from certain pressures, such as eutrophication, warming due to climate change, and invasive species. These characteristics make Windermere an ideal location for long term ecological studies and monitoring the effects of climate change on the lake.

During the last major ice age, 13,000 years ago, Windermere was created, along with the other lakes in the English Lake District. The lakes were created by glaciers eroding deep valleys as they travelled across the area now known as the English Lake District. The erosion of the rock and deposition of moraines created the system of lakes that all experience a similar climate with varying geology, lake morphology, and biodiversity, creating an ideal system of lakes for scientific studies. Windemere itself consists of two basins, the North Basin and the South Basin. The North Basin has a surface area of 8 km2 and a watershed area of 180 km2, and the South Basin has a surface area of 6.7 km2 and a watershed area of 250 km2.

Current Research
Over 600 papers and reports have been published on the English Lake District, starting in the early 20th century and continuing today, and Windermere is the most studied out of all those lakes. S. C. Maberly and J. A. Elliot's 2012 Special Issue paper brings together many of the important studies published about Windermere, focusing on microbes, zooplankton, phytoplankton, and fish, and mostly consisting of findings from long-term monitoring of the lake and its watershed. Because of the long-term monitoring and compilation of multiple, specific studies in this issue, the authors were able to put together a relatively comprehensive analysis of the changes occurring to Windermere overtime. This issue found that local influences, such as rainfall, altered land use, wind, and non-native plant species had a greater impact on the lake than regional stressors, such as large-scale weather patterns and the Gulf Stream position in the Atlantic Ocean. This issue was also able to explore the bottom-up and top-down interactions that relate to those local and regional stressors, further impacting and changing the lake structure and ecology. Overall, this special issue emphasizes the importance of long-term monitoring to track lakes' responses to changes in their environment and to climate change.

Fish
The fish populations in Windermere are also well-studied and ecologically important. Trout, charr, perch, and pike have each dominated the lake at one point in its history. Human effects, such as fishing and experimental manipulations of the fish population have changed the dominant fish species over time. A study by Winfield et al. looked at the changes in pike prey over time from 1976 to 2009. Pike are the top predator in Lake Windermere, so they have a large effect on the species in the lower trophic levels. Over the time studied, pike began eating more percid perch, esocid pike, and cyprinid roach and less Arctic charr and brown trout. The changes in pike diet are correlated with climate change and an increase in eutrophication, and this could affect the food web structure of the lake.

Phytoplankton and Eutrophication
J. Alex Elliot's paper "Predicting the impact of changing nutrient load and temperature on the phytoplankton of England’s largest lake, Windermere" focuses on the phytoplankton population in Lake Windermere. In this paper, Elliot uses the PROTECH (Phytoplankton RespOnses To Environmental CHange) model to assess the phytoplankton community in Windermere under different changes in water temperature and changes in nutrient load. The study measured mean chlorophyll a concentrations annually and in the fall, spring, and summer. The chlorophyll concentration represents the amount of phytoplankton, diatoms, and cyanobacteria present in the lake water. The timing of the spring diatom bloom as well as the number of days exceeding the World Health Organization (WHO) derived risk threshold for cyanobacteria chlorophyll a concentrations were also measured. The study concluded that Windermere diatoms produced the largest amount of chlorophyll in the spring, an increase in temperature led to an earlier diatom bloom, and cyanobacteria, which peaked in the summer and fall, increase with both increasing nutrients and increasing temperature. Overall, the effects from the increasing temperature were lessened by a lower input of nutrients, suggesting that local management of nutrient inputs, such as from agriculture and sewage, can lessen the effects of warming on phytoplankton.

Another study by McGowen et al. looked at algae abundance since 1850 to determine the primary causes of algae growth in Windermere. Primary production, which is caused by algae and phytoplankton, has increased fivefold since 1850. The study showed that human causes, such as sewage and agriculture were the primary causes in the increase in algae abundance, and climate change was the secondary reason. Sheep farming and the nitrogen fertilizers involved and the growing human population in the area are the main effects humans have had in the increase in nutrients in Windermere, leading to the growth of algae and phytoplankton.

Biomanipulation
D.G. George's paper "Top-down versus bottom-up control in planktonic systems: some case studies from the English Lake District" looks at food web interactions in Windermere and nearby lakes. In this paper, George looks at five examples taken from long-term studies, the longest lasting 40 years, where outside factors affect the entire food web in a lake, either as a top-down effect or a bottom-up effect. George found that bottom-up effects, such as increasing the nutrient load to a lake by war-time ploughing, are more effective in changing the zooplankton abundance in a lake than top-down effects, such as the commerical perch fishery. Time was also found to be an important part of trophic interactions. These results could be used to determine how people working to preserve Windermere's ecosystem through biomanipulation should procede.

Glacial History and Ice Cover
A paper by Avery et al. titled "A new varve sequence from Windermere, UK, records rapid ice retreat prior to the Lateglacial Interstadial (GI-1)" studied annual laminated sediments, or varves, to record the retreat of the Windermere glacier and the transition into the Lateglacial Interstadial period. This study looks at data still available today in the lake's sediments to map events in history. Sediment coring, radiocarbon and radionuclide dating, and multiple kinds of imaging were used to obtain the data required for this analysis. Four cores were analyzed, adding to the library of studies already conducted from similar sediment analysis of the lake. This study shows that the Windermere glacier retreated north of the separation between the two basins of Lake Windermere between 225 and 700 vyr before the Lateglacial Interstadial, and the glacier may have started receding as early as 1500 years before the Lateglacial Interstadial. This information about the deglaciating of the valley contributes to information about how Lake Windermere formed. The authors hope that the additonal information added by these four new cores from the Windermere sediment will lead to further coring in Windermere and other lakes in the UK to contribute to more ice retreat studies and establish Windermere as an important archive for these studies.

One study by D.G. George used data from 1933 to 2000 to relate local air temperature and the North Atlantic Ossillation to the number of days Windermere was covered by ice each year. The models used in this study to accurately predict the number of ice days each year show that Windermere's ice cover has been affected by the North Atlantic Ossillation for at least 130 years and that Windermere can be used as a good indicator of climate change that can be applied to lakes elsewhere.