Whole lake responses to species invasion mediated by climate change

Lead Research Organisation: NERC Centre for Ecology and Hydrology
Department Name: Parr

Abstract

Lake ecosystems face multiple stresses including nutrient enrichment, climate change and invasion of nonindigenous species. This latter stress is widely recognised as having a major impact on biodiversity and the functioning of ecosystems worldwide and its effects are increasing because human activity has enhanced rates of dispersal and climate change is opening new niches at high latitudes. Windermere, comprising two basins, is England's largest lake and one of the best studied in the world with detailed records extending back for up to 70 years. A marked deterioration in water quality has been observed in the last 10 to 15 years despite continued removal of a key nutrient, phosphorus, at the wastewater treatment works. For example, summer algal blooms have increased and concentrations of oxygen at depth have decreased. The numbers of the rare and protected fish, the Arctic charr, have also declined dramatically in recent years. These changes have coincided with the population expansion of a lower-latitude, nonindigenous species, the roach. In this project we will test the hypotheses that the roach expansion is a result of the documented warmer waters in Windermere and that the population increase has triggered a 'trophic cascade' leading to greater predation on the zooplankton, which in turn has reduced the algae from control by their grazer. We will also test whether the decline in Arctic charr numbers results from competition with roach, since both feed on the zooplankton. We are in a unique position to assess the long term ramifications of multiple stressors because of the wealth ecological and environmental data and preserved samples collected from Windermere for most of the last century. The project will involve targeted, detailed analysis of the long-term data, analysis of the historical archived fish and zooplankton samples, identification of food sources of the different fish populations and food-web structure using stable isotope analysis and studies of fish gut contents, hydroacoustic analysis to estimate fish density and location and modelling to estimate roach ecological niche, zooplankton grazing and algal growth. The project is relevant to current general ecological issues such as the importance of top-down-control, the effects of multiple stressors and possible species extinction caused by species invasion. The results will also be highly relevant to the management of lakes since if our hypotheses are correct, nutrient removal will need to be even more stringent in the face of climate change and disruption of food-chains caused by invasion of nonindigenous species.
 
Description Whole lake responses to species invasion mediated by climate change Ongoing analysis of long-term data and stable isotope analysis of long term archived material has shown substantial shifts in food web structure consequent on environmental perturbation in the two basins of Windermere. A new method to quantify size classes of preserved zooplankton samples has been developed and is being applied to the long-term samples to assess whether changes in fish populations can be linked to changes in zooplankton size-structure as hypothesised. A paper (Smyntek et al) used empirical and mechanistic models to produce a better method of accounting for changes in delta13C content of the baseline (zooplankton) populations by taking account of how the phytoplankton discriminate against delta 13C as a function of pH. This will improve estimate of baseline zooplankton delta 13C and hence improve estimates of foodweb interactions.
Exploitation Route The work highlighted the disruptive effect an expansion of a non-native species can have on lake water quality by triggering new trophic interactions. This is relevant to lake management as phosphorus reduction will need to be more severe in order to meet environmental targets.
Sectors Agriculture, Food and Drink,Environment

 
Description One day workshop exploring the lessons learnt from research on Windermere for practitioners concerned with effects of invasive species and climate change on lakes. Beneficiaries: Representatives from Environment Agency, Natural England, Natural Resources Wales, Scottish Natural Heritage and Cumbria Freshwater Invasive Non-Native Species attended and gave presentations.
First Year Of Impact 2013
Sector Agriculture, Food and Drink,Environment
Impact Types Policy & public services

 
Description Nitrate Vulnerable Zones
Geographic Reach National 
Policy Influence Type Participation in a advisory committee
Impact The work helped guide Defra decide which lakes should be in nitrate vulnerable zones in order to protect the environment, but taking into account the cost to the farming community.
URL https://www.gov.uk/guidance/nutrient-management-nitrate-vulnerable-zones
 
Description Cumbrian Lakes Research Forum 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Over 40 delegates from 15 organisations attended to hear about the research being carried out on Cumbrian lakes from NERC funded grants.
Year(s) Of Engagement Activity 2015
 
Description Guest lecture to students at Wolverhampton University 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Undergraduate students
Results and Impact Guest lecture on protected freshwater fish species
Year(s) Of Engagement Activity 2017
 
Description Presentation at international conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation on effects of climate change at an international fisheries management conference.
Year(s) Of Engagement Activity 2017
 
Description Presentation on lake research and monitoring to the U3A 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Presentation for about an hour to the University of the Third Age group in Cockermouth explaining the different types of monitoring and research that we undertake.
Year(s) Of Engagement Activity 2017
 
Description Presentation to Environment Agency Fisheries practitioners 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Seminar by Dr Ian Winfield to Environment Agency Fisheries practitioners.
Year(s) Of Engagement Activity 2017
 
Description Presentation to West Cumbria Rivers Trust on the Arctic charr 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Presentation to the West Cumbria Rivers Trust on the Arctic charr
Year(s) Of Engagement Activity 2018
 
Description Presentation to local natural history group on the Arctic charr 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Presentation to local natural history group on the Arctic charr in Windermere.
Year(s) Of Engagement Activity 2017