A recent study by the Malpelo Foundation revealed that about seven species of sharks off the Colombian Pacific coast are contaminated with mercury. This phenomenon, linked to illegal gold mining and other human activities, poses a serious threat to both marine fauna and human health.
The indiscriminate use of mercury in illegal gold mining has caused an environmental crisis in the region. This heavy metal, used to separate gold from sediments, is released into aquatic ecosystems through rivers like the Patía and other tributaries, eventually reaching the ocean. Once in the sea, mercury converts to methylmercury, a highly toxic substance that accumulates in marine organisms.
Sharks, as top predators, ingest contaminated fish and accumulate mercury in their tissues throughout their lives, a process known as bioaccumulation. As they move up the food chain, the concentration of the metal increases, a phenomenon known as biomagnification. This endangers species such as the scalloped hammerhead shark (Sphyrna lewini) and the pelagic thresher shark (Alopias pelagicus), classified as Critically Endangered by the International Union for Conservation of Nature (IUCN).
Consequences for Health and the Ecosystem
The study found levels of mercury above those permitted by the World Health Organization (WHO) in several shark species. This poses a risk to coastal communities that consume their meat, as mercury affects the nervous system, especially in children and pregnant women.
Additionally, the contamination also impacts shark breeding areas in mangroves and estuaries, harming the reproduction of these species. Pregnant females can transfer mercury to their embryos, reducing the survival rates of the offspring.
Urgent Measures to Mitigate the Problem
Given this situation, researchers recommend restricting shark consumption, strengthening controls on illegal mining, and raising awareness among communities about the risks of mercury. International collaboration is crucial to address this crisis and protect the marine biodiversity of the Colombian Pacific.
Environmental authorities have called for action to implement mitigation strategies, including the restoration of affected habitats and the promotion of sustainable economic activities that do not rely on the illegal extraction of resources. Meanwhile, researchers continue monitoring mercury levels in marine ecosystems to assess the evolution of the problem and take preventive measures in the presence of sharks contaminated with mercury.
Sharks are not the only ones with high tuna concentrations
According to experts, the amount of mercury in fish is related to their position in the food chain. This means that predatory fish, larger and longer-lived, such as swordfish, sharks, bluefin tuna, or pike, are considered to have the highest concentrations. This phenomenon is known as bioaccumulation.
It is estimated that a can of tuna contains around 15 micrograms of mercury, which is below the recommended mercury limit for an adult of 110 micrograms per week. For this reason, it is recommended not to consume more than seven cans of canned tuna per week, although stricter recommendations are needed for vulnerable populations.
Due to mercury intake through the consumption of these fish, experts ensure that including naturally detoxifying foods in the daily diet, such as garlic, onion, and broccoli, will help eliminate toxins from the body.
Source: Nicole Andrea Vargas – Mongabay, Ecoticias.
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