www.postersession.com

The Combined Effects of Ocean Acidification and

Varying Concentrations of Heavy Metals in Dotilla

fenestrata (sand bubbler crab) in Durban Bay,

Richards Bay and uMlalazi EstuaryBabatunde Adeleke, Gan Moodley and Deborah Robertson-Andersson

University of KwaZulu-Natal, School of Life Sciences

Introduction – Its Business as Usual!

� Estuarine ecosystems globally are expansively being altered and endangered due to growing

impacts of anthropogenic activities and global climate change.

� These result in over-enrichment and bioaccumulation of toxic waste within these systems.

� Heavy metals are of great concern because they cause several biological alterations in organisms

depending on their concentrations and duration of exposure (Figueira et al. 2012).

� GCC is expected to have substantial effects on release, fate, behaviour, and exposure of toxicants

(Noyes et al. 2009).Automobile Emissions

Agricultural

Runoff

Shipping & Harbour Activities

Global Climate Change

Ocean Acidification

Industrialization

Weathering Activities

Industrial Effluent DischargeDurban Bay Drainage System

Relevance of the Study Study Sites

How Far We Have Gone…Sampling

Sample Preparation

DryingGrinding

Acid

DigestionScintillating

Vials

Sample StorageICP-MS Analysis

� Contributing to our knowledge of interactive effects of near-future ocean acidification (climate stressor)

with heavy metal levels (chemical stressor) in the crab, Dotilla.

� Relationship between heavy metals uptake and bioaccumulation in the crabs vis-à-vis increasing

ocean acidity (lowered pH).

� Acute toxicity LC50 levels for Dotilla fenestrata when exposed to ocean acidity-heavy metal

combinations.

� Serves as ecotox assessment model for periodic monitoring of heavy metal levels using crab, sediments

and water as indicators.

� Crabs, Water and Sediments were collected from the three study sites

� Crabs were dissected for tissues (hepatopancreas, gills, muscle and skeleton)

� Crab tissues and sediment were prepared for heavy metal analysis by nitric acid digestion.

Work in Progress…

� Acute toxicity LC50 levels for Dotilla fenestrata when exposed to simulated ocean acidity-

heavy metal (Cd and Pb) combinations.

� Haemolymph Osmolality.

� Determine the relationship between Cd and Pb uptake and bioaccumulation in the crabs

vis-à-vis increasing ocean acidity.

Benefits to Ethekwini Municipality� Creates awareness of the impacts of pollution due to increasing anthropogenic activities

� Pollution monitoring and control using crabs as a potential bioindicator

� Informs environmental conservation strategic plan

� Informs environmental policy reform

References

Figueria E, Cardoso P, Freitas R., 2012. Ruditapes philippinarum exposed to cadmium: toxicological

effects and bioaccumulation patterns. Comp Biochem Physiol C 156:80–86

Noyes PD, McElwee MK, Miller HD, Clark BW, Van Tiem LA, Walcott KC, Erwin KN, Levin ED (2009)

The toxicology of climate change: environmental contaminants in a warming world. Environ Int

35:971–986