BIO-INDICATORS AND THEIR INFLUENCE ON CADMIUM ELIMINATION

Greetings and welcome back dear readers of this wonderful platform, the scientific approach does not stop, so this time we will be referring to the role of some species that act as bio-indicators and exert a direct action in the elimination of chemicals, specifically we will be talking about how some marine species are able to remove cadmium present in the depths of the waters.

In this sense and as has been constant throughout my transcendence in this platform is a content that is usually published through the outreach spaces of the #StemSocial community, where the scientific theme is the transversal axis that moves this conglomerate of users.

In this sense, it is necessary to understand that human development has been exerting direct negative actions on the different ecosystems that make up our planet, so that we have not had the vision to respect the carrying capacity of the different ecosystems and consequently, we have entered a state of imbalance that increases with the passing of the days and that projects terrifying effects on our planet, effects that are manifested in the form of melting of the polar ice caps, greenhouse effect, acid rain, soil erosion, among other problems.

Consequently, in a certain way our planet has looked for a way to face the diverse attacks that the human species has exerted on it and one of these alternatives are the bio-indicators, which are nothing more than a large group of plant species among which we can find fungi or animals and whose presence in an ecosystem is determined according to certain biological characteristics, which are present as a measure of response to the possible environmental impacts that can be exerted by certain practices on it.

Hence, these species are mainly used as a way of evaluating the environmental quality of ecosystems, for which each of the bio-indicators must meet a series of guidelines or requirements for their use, among which we can highlight their dispersion, their abundance in the territory, their capacity for sedentarism and their tolerance to various pollutants in concentrations similar to those of the ecosystem and which do not produce lethal effects.

At this point and referring to the process of bio-absorption of heavy metals, algae and seagrasses, have always had this priority character to deal with these situations, which is mainly due to certain properties they exert on their cell wall, where the electrostatic attraction and the formation of complex compounds are essential for the extraction and transformation of these metals.

Properties that are attributable to the presence of carboxylic groups on the cell wall, in addition, we can find sulfonic acids present in the fucoidan, understood as sulfated polysaccharides present in algae, likewise we cannot forget the presence of hydroxyl groups of the respective polysaccharides that end up generating complex groups that facilitate the absorption of heavy metals.

However, beyond the above, recent studies have shown that some species of fish found in the seabed have the capacity to act as bio-indicators, specifically with regard to the transformation or absorption of cadmium.

At this point, it is necessary to understand that exposure to Cadmium, a heavy metal that is naturally present in soils but that is dragged by the leaching process of water, usually accumulates in the seabed, without forgetting that the process of decomposition of rocks is also capable of releasing this metal, also industrial processes in the manufacture of pigments, galvanizing, paint manufacturing and graphic arts, are sources that release this heavy metal into our environment.

Similarly, the paper industry and overexposure to nickel-cadmium battery waste contribute large concentrations of the material, which increases environmental damage, so that as a society we are constantly exposed to this chemical element, which can cause environmental and health problems.

Consequently, it seems that the existing regulations on this element have not been sufficient, since it still reaches aquatic bodies through wastewater from homes and industries, also the surface waters of rivers, lagoons and streams are exposed to the accumulation of the same by the leaching process or otherwise after the dumping of waste as contaminated fertilizers, a situation that undoubtedly exposes the lives of humans to the toxicity of this element.

In this sense, if we make a metabolic review of the effects of Cadmium at the level of human beings, we realize that it is capable of producing adverse effects as it causes alterations at the metabolic level and in its absence limits the mobility, hence people with concentrations of change in their body have chronic pain, demineralization of bones or anxiety and is also considered highly carcinogenic.

Based on the above, recent studies have shown how the Pleco fish, whose scientific name is Hypostomus plecostomus, can be used as a toxicity indicator for this chemical element in different aquatic scenarios.

In this sense, through the biology department of the Faculty of Sciences of the National University of Colombia, tests have been carried out with the participation of more than 30 adult specimens of the aforementioned fish and they have been methodologically exposed to the metal in controlled laboratory conditions, which allows manipulating the concentrations with which they are working, establishing variations in the concentration ranging from 1, 5, 10, 50 and 100 micrograms of change per liter of water, which have been subjected to a comparative process with fish in water without exposure to the metal (control sample).

Consequently, the experimental conditions were previously controlled so that the species at the experimental level were acclimatized individually through the implementation of fish tanks made from PVC pipes that simulated the shelters they are used to having in their natural habitat, so that the temperature was kept controlled around 24 °C.

If we analyze the results obtained, we realize that the responses to the pollutant were identified through bio-markers that are nothing more than biochemical variations at the cellular, physiological or behavioral level that can be metrics assumed through a living being and these are able to give a valid response to the toxic agent.

In this sense, metal concentrations at the gill level, oxygen consumption and ingestion rates were evaluated, without forgetting the protein concentration in the liver, remembering that when these metals bind to heavy metals they can generate a controversial change in the properties and consequently the body ends up discarding it. Similarly, the experimental species were subjected to a process of evaluation of cholinesterase levels, assuming that this enzyme helps the entire nervous process to function efficiently and to react to the presence of foreign or toxic substances.

At this point, the variations of Cholistenerase, protein functions and oxygen consumption rates were the variables that brought clear and imminent answers about the concentration of the metal in the Pleco fish species.

Consequently, it has been identified that the fish has the capacity to react positively to the presence of Cadmium and theoretically the researchers assume that this aquatic species is capable of assuming or facing Cadmium intoxication since it directs the same contaminant to the kidney and from there it is capable of producing its excretion.

Although the research is still in progress, some relevant results have been advanced that allow identifying how the same species of the planet, struggle to improve the conditions of the habitat where it develops and thus provide better conditions to our planet to improve the carrying capacity and the resources present in it.

[1] Eulogio Soto y Gerardo Leighton Biological indicators of soft bottom marine ecosystems and their importance in environmental monitoring programs. Article: Online Access

[2] María Teresa García Córcoles Marine bioindicators in the environmental study and transfer of chemical contaminants to the food chain. Article: Online Access

2. For more information related to the areas of science, technology, engineering and mathematics, do not hesitate to visit #stemsocial and #stem-espanol, they are communities that promote scientific advances in these areas