The impact of climate change on infection of salmonid fish with Saprolegnia

Lead Research Organisation: University of Aberdeen
Department Name: School of Medical Sciences

Abstract

Fish are very sensitive to changes in their environment and it is known that such changes can lead to increased stress and can alter the immune status of the fish, which in turn can lead to higher susceptibility to diseases. We will investigate the role of water temperature and oxygen changes on the incidence and severity of salmon and trout infection with Saprolegnia parasitica and Saprolegnia diclina. Both pathogens cause saprolegniosis, which is a deadly disease of salmonid eggs and fish. Saprolegniosis can often lead to losses of 10% or more in fish farms. Currently these oomycete pathogens rank amongst the top 3 of most relevant pathogens on rainbow trout and Atlantic salmon in the aquaculture industry of the UK.
Data on temperature and oxygen dependant pathogen dynamics and host immune response will be collected through experimental and field studies, which will provide a basis for predicting the likely impact of these pathogens as a result of climate change. Spatial analysis and mapping techniques will be used to identify baseline relationships between fish farm locations, environmental conditions in the river and pathogen abundance. Based on climate change predictions for the UK, we will try to predict how the impact of the pathogens in our study is likely to change over the next decades. The information generated from this project, which addresses all priority areas of the BBSRC/NERC joint call on Aquaculture: Fish Health & Disease, will ultimately allow better planning and design of mitigating strategies for farmers, which will be especially relevant after the enforcement of the EU-wide ban on the use of formalin in aquaculture. Changes in aquaculture management procedures, biosecurity and treatment (of intake water or fish) may allow fish farmers to counteract some of the expected impacts of these fish pathogens in response to climate change. The project will also allow making projections about the impact of CC and Saprolegnia infection on wild salmonid fish. This information will be important to inform future conservation strategies.

Technical Summary

Fish are very sensitive to changes in their environment and it is known that such changes can lead to increased stress and can alter the immune status of the fish, which in turn can lead to higher susceptibility to diseases. We will investigate the role of water temperature and oxygen changes on the incidence and severity of salmon and trout infection with Saprolegnia parasitica and Saprolegnia diclina.
Data on temperature and oxygen dependant pathogen dynamics and host immune response will be collected through experimental and field studies, which will provide a basis for predicting the likely impact of these pathogens as a result of climate change. We will develop a new real time-PCR quantification method to determine the number of zoospores in water and mucous of the fish. Furthermore, detailed gene expression analysis of known (pro)-inflammatory, immunological and stress-induced genes will be performed in head kidney, spleen and gill samples. Spatial analysis and mapping techniques will be used to identify baseline relationships between fish farm locations, environmental conditions in the river and pathogen abundance. Based on climate change predictions for the UK, we will try to predict how the impact of the pathogens in our study is likely to change over the next decades. The information generated from this project will ultimately allow better planning and design of mitigating strategies for farmers, which will be especially relevant after the enforcement of the EU-wide ban of the use of formalin in aquaculture. Changes in aquaculture management procedures, biosecurity and treatment (of intake water or fish) may allow fish farmers to counteract some of the expected impacts of these fish pathogens in response to climate change. The project will also allow making projections about the impact of climate change and Saprolegnia infection on wild salmonid fish. This information will be important to inform future conservation strategies.

Planned Impact

Who will benefit from this research?

(1) Pharmaceutical, biotechnology industries, the aquaculture industry (fish farmers), anglers, conservation organisations
How will they benefit?
With the proposed project we will provide novel knowledge on the Saprolegnia-host interaction in response to climate change, in particular diagnostics and quantification of pathogen spore levels in water, pathogenicity and host defence responses that will ultimately lead to control measures that are currently not available.
The results of our study will not only allow insights on the impact of CC on farmed salmonid species. Wild Atlantic salmon, brown trout and other salmonid species living in rivers in the UK are going to be exposed to the impact of CC as are farmed salmonids. The insights about how well salmonid species are capable of coping with CC associated environmental changes will allow making projections about the likely impact of CC associated water temperature changes in the future. The information generated under this project is likely to help future planning of conservation strategies.

What will be done to ensure that they have the opportunity to benefit?
We will communicate our research and results to colleagues and industry through our publications in the literature, through presentation at appropriate scientific meetings, and by making reagents generated as part of this project available to other researchers under structured material transfer agreements. We will take advantage of natural liaison opportunities that emerge from our membership of NERC and BBSRC Networks. We will also work together with the Research and Innovation unit at the University of Aberdeen and Cefas to identify findings that have clear potential for commercial exploitation. We will actively get fish farmers informed about our findings by giving seminars for fish farm health managers. The PI is giving such seminars on an annual basis at several companies (eg Marine Harvest, Landcatch, Novartis, Zoetis and MSD)

(2): The public
How will they benefit?
The general public will benefit from this research in a number of ways because our work will ultimately safeguard food production. We will however ensure that the public is informed about our research, forming part of a national effort by the science community to ensure greater scientific literacy among the general population.

What will be done to ensure that they have the opportunity to benefit?
Ensuring public awareness of our research and allowing a public education impact to be made, we will use our groups' web sites to communicate our science to the public. Key research outcomes from this proposal will be released by the University of Aberdeen's Communication sections as press releases.


(3) Policy makers and (non)-government bodies
How will they benefit?
Legislators and (non)-government bodies involved in wildlife conservation in UK and fish farming (such as Natural Heritage, DEFRA, SEPA, Scottish Salmon Producing Organisation, the British Trout Association etc.) will be able to use our generated data to better predict and avoid possible Saprolegnia parasitica outbreaks in the UK. In case we obtain clear evidence that climate change plays a major part in increased problems of saprolegniosis in salmonids, we would consult with legislators, relevant organisations and other policy makers across the UK to find solutions to minimize saprolegniosis in fish.

What will be done to ensure that they have the opportunity to benefit?
We already have good links with several representatives of these organisations and will actively approach them to consider our results.

Publications

10 25 50
publication icon
Derevnina L (2016) Emerging oomycete threats to plants and animals. in Philosophical transactions of the Royal Society of London. Series B, Biological sciences

publication icon
Sarmiento-Ramirez J (2016) Isolation of fungal pathogens from eggs of the endangered sea turtle species Chelonia mydas in Ascension Island in Journal of the Marine Biological Association of the United Kingdom

 
Description One of the project's objectives was the development of a diagnostic tool for S. parasitica. To achieve that goal 50 sets of primers were tested against several Saprolegniales and a fungus isolate. Only one primer combination turned out to be specific for S. parasitica. These primers were also blindly tested against isolates from a collaborator database. Furthermore, the usage of these primers on eDNA resulted in an adequate quantification of spores from S. parasitica in water samples.
From the environmental data we could see: a) Rivers in southwest were warmer than regional average in winter and cooler than regional average in summer. Temperatures showed greatest between-site variability in summer. This is strongly influenced by groundwater, that can mitigate against low flows and temperature change, but dependent on recharge levels, duration of heatwaves and drought periods. They possess alkaline waters due to chalk and limestone geology. Previous research indicates aquatic ecosystems in alkaline environments are more resilient than those in acidic environments. b) In Scotland, loch temperatures tend to be warmer in winter and cooler in summer than adjacent rivers. Temperatures show greatest between-site variability in summer. The loch temperature takes longer to respond to seasonal changes and rainfall events, due to the larger water volume. Lochs are dominated by surface flow while rivers are more susceptible to temperature and flow fluctuations. Lochs possess slightly acidic waters, due to underlying geology.
Almost all immune genes tested had no statistical difference between the farm with saprolegniosis problems and the low saprolegniosis incidence farm. The current project findings do not allow to ascertain temperature as a main cause for saprolegniosis in fish.

A diagnostic tool was developed. This tool allows a quick detection and/or quantification of S. parasitica in the field. Allowing farmers to put in place preventive measures.
This can be further used to identify saprolegniosis in fish.
Exploitation Route The data will be very useful for fish farmers to anticipate the impact of climate change on the occurrence of Saprolegniosis.
Sectors Agriculture, Food and Drink

 
Description BBSRC-LINK
Amount £1,200,000 (GBP)
Funding ID BB/P020224/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 06/2017 
End 05/2020
 
Description Cafe Scientifique 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact I presented our work on Saprolegnia infections in salmon farms and how we are looking into new methods too control saprolegniosis and other fish diseases.
Year(s) Of Engagement Activity 2018
 
Description Organising Microbiology School lectures at University of Aberdeen 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Every year I am organising a school lecture for secondary school children to learn about microbiology and show them a career option in sciences and in particular microbiology. Usually we get 100-250 children attending between the ages of 16-18 from several regional schools (Aberdeenshire)
Year(s) Of Engagement Activity 2008,2009,2010,2011,2012