Marine microbial community dynamics as a tool for

measuring the response of sub-Antarctic

ecosystems to climate change

Nasipi Mtsi

MSc, Rhodes University

Southern Ocean

Prince Edward Islands • Marion Island and Prince Edward Island, covering an area

of approx. 270km², located 2400km southeast of Cape Town(pristine).

• Climate(rain, snow, humidity, cloud cover, wind).

• 3 seal species and 4 penguin species, ocean dependent.

• Nutrients from the island flow into the ocean near the islands.

• Freshwater is less dense and retained with its nutrients in this shallow area in-between the islands - island mass effect.

• This then results in a phytoplankton bloom and top predators are heavily reliant on this.

Aim: To survey the marine microbial communities in the Prince Edward Islands

surrounding waters

Why?

• Microbes are the base of the food web-

phytoplankton

• Unknown territory

• Situated in the Southern Ocean-understand its

response to climate change

Phytoplankton and microbes response

• Coastal samples 2012, Marine surveys 2013 and

2018, ACE 2016

• Methodology(sampling, processing )

Results

Venkatachalam et al. 2018

Results

Venkatachalam et al. 2018

Results A

B

Venkatachalam et al. 2018

• SAF 2012,13, 15

show similar

pattern

Microbial

patterns similar

• SAF movement

in 2014 mostly

northward

• Mixing of both

warm SASW and

cold AASW

Changes in

microbial

patterns

Results

Venkatachalam et al. 2018

Conclusion SAF position influence the occurrence of phytoplankton blooms

SAF position influences the microbial community composition

Microbes can be used to map the origin of the water and

understanding the oceanography(fronts, eddies, current), most

importantly the influence of climate change

Future work

2018 sampling, sampled APF

Mapping PEIs using phytoplankton

Acknowledgements

• Prof. RA Dorrington

• Dr. S Venkatachalam

• Dr. GF Matcher