Predicted impacts of climate change on growth rate and distribution of aquatic fungal diseases

Dr Mariska Laubscher¹, Dr.  Kevin Christison², Prof. Nico Smit¹

¹North West University, Potchefstroom, South Africa, ²Department of Agriculture, Forestry and Fisheries, Directorate: Aquaculture Research and Development, Cape Town, South Africa

Aquatic diseases caused by fungi and the fungal-like oomycetes have gained more interest over the past few years.  The phylum Oomycota, is a group of fungus-like eukaryotic microorganisms with a world-wide distribution.  This phylum includes genera such as Aphanomyces, Saprolegnia and Achlya, also known as water moulds.  These water moulds are commonly found in most natural water systems including aquaculture systems. Some oomycetes have been reported as either primary or secondary pathogens of aquatic animals which may become more susceptible to oomycete infections as a result of compromised immunity or reduced disease resistance.  Climate fluctuations such as an increase or decrease in water temperatures and pH are important contributing physical environmental parameters driving clinical infections and geographical spread of pathogens and their carrier or reservoir hosts.  The aim of this study was to determine the effect of temperature and pH on the growth rate of oomycetes species.  Oomycetes were isolated from clinically infected hosts, and from the environment using hemp seed bait stations.  Axenic cultures were obtained.  Following molecular identifications, cultures were inoculated onto Potato dextrose agar (PDA) and incubated at 5 different temperatures, ranging from 5 to 25 °C. The optimal growth temperature was used to incubate cultures on media with different pH levels.  Radial colony growth was monitored daily to determine the growth rate for a period of 7 days.  Preliminary data suggested that growth is favoured by higher temperatures it is therefore predicted that climate change will increase infection rates and distribution of fungal infectious diseases.

Biography:

I am a Qualified Microbiologist with an interest in the environment and clinical laboratories.  In December 2016 I graduated from a Philosophiae Doctor Degree in Microbiology at Stellenbosch University, this was then coupled with a Magister Scientiae Degree (cum laude) in Biodiversity and Conservation Biology, a Honneurs Baccalaureus Scientiae Degree in Water Science and a Baccalaureus Scientiae Degree in Microbiology and Zoology. I am currently a registered post-doctoral fellow at North West University.  My research include the development of diagnostic tools to detect aquatic fungal disease agents.  I have a special interest in aquatic fungi and fungal-like organisms.