Heavy metals in aquatic crustaceans

Dr Anna Iglikowska from the Faculty of Biology, UG.

Dr Anna Iglikowska from the Faculty of Biology, University of Gdańsk, was awarded the prize in the Miniatura 5 competition of the National Science Centre. Her project, entitled: 'Testing bioaccumulation of heavy metals in aquatic crustaceans from the group of Ostracoda,' will observe the impact of water contamination with metals on the bioaccumulation of heavy metals in the tissues of Ostracoda and on the survival, number of eggs laid, the viability of offspring and also their behaviour. The project has received funding of 49 500.00 PLN.

Ostracods are small crustaceans that play an important role in aquatic ecosystems. They provide food for other aquatic invertebrates, including birds and fish. Some species of bivalve molluscs are very tolerant of their environment and may inhabit reservoirs heavily polluted with e.g. heavy metals. They may then tend to accumulate contaminants in their body tissues, a process known as bioaccumulation.

- 'Ostracods are known to be sensitive to heavy metals and are therefore widely used in ecotoxicology, e.g. in the form of commercial Ostracodtoxkit® biotests. However, these tests only check whether the organisms survived in a metal-contaminated environment or not, while so far there is no data on bioaccumulation of heavy metals in ostracods,' says dr Anna Iglikowska from the Department of Genetics and Biosystematics, Faculty of Biology, University of Gdańsk. - 'In my research, I will try to assess the accumulation of two heavy metals, i.e. zinc (Zn) and copper (Cu), by ostracods under laboratory conditions. Both Zn and Cu are essential elements for living organisms, but in higher concentrations, they can exhibit toxic effects, inhibit protein production, block enzyme function and cause physiological disorders.'.

Pictured is an Ostracoda, the species Heterocypris incongruens, on which the UG scientist's experiment will be conducted.

Zinc is a metal strongly associated with anthropogenic pollution in urban areas, is a component of many metal alloys, and is also used as an additive in paints, varnishes, rubbers and plastics. Cu, on the other hand, is used in the manufacture of electrical cables, roofing, water supply systems and the production of fungicides.

- 'By determining the concentration of Zn and Cu in ostracods' tissues, we want to estimate whether and to what extent these organisms accumulate heavy metals from the external environment (i.e. from water). If ostracods are characterised by a high accumulation potential, this could mean that predators feeding on the molluscs may biomagnify metals in the tissues. Over the years, this can lead to toxic concentrations of metals being exceeded in the body, with consequent disturbing effects on the physiology, health, viability and fertility of the predator. Since ostracods also feed on fish eaten by humans, there is a risk that such a heavy-metal-laden dinner will also appear on our plates,' adds dr Anna Iglikowska.

In the laboratory experiment, ostracods will be bred for six weeks, covering their entire life cycle from eggs to adults. The organisms will be reared in three concentrations of Zn and Cu, with environmental and higher concentrations. The effect of different combinations of concentrations of the two metals will also be studied. After six weeks, live adults and juveniles will be harvested and the Zn and Cu concentrations analysed using a Microwave Plasma Atomic Emission Spectrometer (MP-AES 4210). MP-AES is a type of emission spectroscopy in which an inductively coupled plasma produces excited atoms and ions that emit light radiation at wavelengths specific to the element. The intensity of emission from different wavelengths of light is proportional to the concentration of elements in the sample, therefore the MP-AES method will enable not only the detection of the presence of selected heavy metals but also the estimation of their concentrations in the tissues of organisms.

In addition, data on the influence of Zn and Cu on the functioning of ostracods will be monitored daily in the experiment. The effects of metal contamination on the survival rate, number of eggs laid, the viability of the offspring, length of the developmental cycle and behaviour of the ostracods will be observed.

- 'Thanks to the results of our experiment it will be possible to establish the relationship between heavy metal concentration in the environment and accumulation of these metals in tissues, and to determine at what concentration of Zn and Cu potential changes in the viability, fertility, development and behaviour of ostracods may occur,' explains dr Anna Iglikowska.

Elżbieta Michalak-Witkowska / Press Office UG