Air pollution & contamination Marine & freshwater Poster

Ramage, Calum // Assessing the impacts of environmental contaminants on the Olifants River, Kruger National Park: from sediments to crocodiles


The aim of this poster is to give the audience an explanatory introduction to my research. My target audience is simply a broad range of researchers with a scientific background who may have an interest in environmental sciences. Due to current circumstances, no data has yet been collected. The poster therefore merely explains the purpose and relevance of my research and briefly describes the methodology I will be implementing in order to achieve my research objectives.



Kruger National Park (KNP), South Africa, is one of the largest and most biodiverse game reserves in Africa and is home to hundreds of species of great conservation importance. However, its geographic location downstream of the Olifants River, one of the most polluted rivers in Southern Africa, present many threats to the wildlife.

The Olifants flows through intensive mining, agricultural and industrial landscapes before reaching KNP, acquiring on the way a diverse cocktail of highly toxic and persistent trace elements (e.g. Pb and Hg), industrial persistent organic pollutants and numerous toxic pesticides (e.g. DDT) (1).

2.1. Problem: Several large-scale fish and crocodile mass mortalities have occurred since 2007 (2).

Disease, infections and ill-health are also commonly observed amongst the aquatic wildlife.

Toxic contaminants are accumulating in the sediments and aquatic organisms of the Olifants.

These toxicants can ultimately threaten survival, population viabilities and ecosystem function (3, 4). Very few studies have investigated the relationship between environmental contaminants and wildlife health in the Olifants. Environmental monitoring has also fallen short: regular sediment monitoring is not conducted, and hundreds of potentially toxic pesticides and chemicals have rarely or never been measured in the Lower Olifants River.

2.2. Main objectives

Assess the current state of environmental contamination of the Lower Olifants River leading into KNP, focusing on trace elements and pesticides. Determine the health implications of exposure to contaminants for the aquatic organisms of the Lower Olifants River.

3. Methods: An integrated and holistic environmental assessment of the Lower Olifants River, Kruger National Park.

3.1. Chemical Monitoring of the environment

  • Water and sediment samples to map the presence and distribution of contaminants from potential upstream pollution sources through KNP.
  • Microtox Solid Phase Tests (using Vibrio Fisherii) to test whole effluent sediment toxicity and highlight potential synergistic pollutant interactions.

3.2. Bioaccumulation monitoring

  • Bioaccumulation monitoring of bioindicator species to inform on the longer-term presence and bioavailability of contaminants in the system.
  • Invertebrate, fish and crocodile tissue samples collected at different locations along the river will be analysed for the presence of contaminants.

3.3. Species health assessments

  • A multi-species, multi-trophic ecosystem health assessment to inform on the biological responses and impacts of exposure on aquatic organisms.
  • The diagram illustrates the biological endpoints chosen to assess wildlife health with the help of a multi-level suite of biochemical, cellular and organ-level biomarkers:
    • histological tissue alterations
    • genotoxicity, neurotoxicity
    • immunological response
    • endocrine disruption
    • oxidative stress
    • biotransformation
    • gut microbiome


Environmental and animal tissue samples will be analysed for inorganic and organic contaminants using high performance mass-spectrometry techniques (ICP-MS, GC-MS and LC-MS/MS).

Invertebrate community species richness and abundance will inform us on their survival.


1. Heath et al. Water Research Commission, 2010, WRC No. TT 452/10;

2. Ashton. Aquat Conserv. 2010, 20, 5, 489-493 ;

3. Gerber et al. Sci. Total Environ. 2016, 550, 522-533 ;

4. du Preez et al. Ecotoxicol. Environ. Saf. 2018, 148, 930-941.

Calum Ramage

Originally half Scottish and half English, Calum grew up as a nature and wildlife enthusiast in rural France. He has always been quite driven to help protect the natural world against the numerous threats it faces. So far, Calum’s quest has taken him around the world and back, through arid deserts and tropical islands working on various conservation and ecology projects. Next stop (much to his poor mother’s dismay): fish and crocodile wrestling in Kruger National Park, South Africa.

Calum’s Envision profile


Organisation: University of Nottingham