Pule Mpopetsi

MSC Candidate
Pule Mpopetsi


Interacting effects of elevated temperature and acidification on early life history stages of dusky kob (Argyrosomus japonicus).

The burning of fossil fuels, cement manufacturing and deforestation are some of the anthropogenic activities that result in the emission of greenhouse gases into the atmosphere and cause rapid change in global climate. Two of the consequences of this change include ocean warming and ocean acidification.  Ocean warming is as a result of the ocean acting as a heat sink absorbing most of the atmospheric heat and thereby increasing sea surface temperatures.  Ocean acidification on the other hand is largely as a result of the ocean acting as carbon sink, absorbing most of the atmospheric CO2, causing imbalance in ocean’s chemistry and dropping its pH. Most studies on the effects of these two environmental parameters on aquatic organisms focused on one variable at a time, either temperature or pH alone. There are few studies on the interacting effects of these two parameters on aquatic organisms, even fewer on marine vertebrates such as fish.

The aim of this study is therefore to look at the interacting effects of elevated temperature and acidification on the early life history stages of dusky kob (Argyrosomus japonicus), a commercially and recreationally valuable fish species found off the coast of South Africa. Adults of this species are found in marine habitat and spawn nearshore. The juveniles (+/- 20mm in length) recruit into the estuaries towards the upper reaches and when they get to about 150mm in length, they migrate back into the sea.

This study will simulate temperature and pH (CO2-induced acidification) levels predicted for the year 2100. Some of the responses to be measured will include metabolism, growth rates and survival. Data from this study can be used to make inferences about the likely impacts of global climate on this species and other aquatic organisms.

Registered: Rhodes University (Department of Ichthyology and Fisheries Science) (DIFS)

Supervisor: Dr Warren Potts (DIFS)
Co supervisors: Dr Nikki James (SAIAB) and Dr Amber Childs (DIFS)