For the past few days, I have been thinking of how we’d be surviving without the aquatic ecosystem. Frankly, we’d all be dead by now, needless to say that every pillar/factor of the environment is dependent on each other; they complement each other.
Humans, as they strive to live a better life, often interact mostly with the environment, leaving an impact, both negative and positive. Sadly, according to Environmental Economics, for optimum economic development, there is a higher probability of a compromise on the state of the environment, and vice versa. For the same reason, the environment has been adversely affected, from pollution to land degradation etcetera. My focus today however, is on how our own actions have affected the aquatic ecology, quoting from the most recent cases.
On 27th January, 2021, The Kenya Marine and Fisheries Research institute (KEMFRI) banned the consumption of fish from L. Nakuru (Kenya) citing poisoning of the fauna in Lake Nakuru biotic community. It is alleged that the fish from the lake start rotting three hours after the catch. How is that even possible? The report presented to the Ministry of Agriculture after a study showed that raw sewage and industrial waste flowed in the lake for a long time, a situation that worsened six months after the Rift Valley lakes started flooding.
On 6th February, 2021, barely ten days after fish in L. Nakuru being declared unfit for human consumption, the fishermen and community around the Nyanza L. Victoria region woke up to a scenario, that they could only describe as ‘unseen.’ On that Saturday morning, they woke up to find thousands of fish (especially) the Nile Perch washed ashore, with quite a number still floating, lifeless, on water. Coincidentally, on the same day, the same scenario was experienced in Chile, where thousands were mysteriously washed ashore. The Chile’s National Fishing Service said that they found chlorophyll in the water. Experts also got concerned that the change in water temperatures and water quality could be the cause. (CGTN, 2021)
But, how do raw sewage and industrial waste; chlorophyll and change in water temperatures among other factors negatively affect the aquatic ecosystem?
I. Raw Sewage and Industrial Waste.
Raw sewage and industrial waste contain high amounts of nitrates and other nutrients. When they are directed into the waters, they lead to what we call eutrophication and upswelling of oxygen deficient waters. Eutrophication basically is the gradual increase in the concentration of phosphorous, nitrogen, and other plant nutrients in aging aquatic ecosystem such as lakes and oceans. Eutrophication is perquisite for growth of algae and other microorganisms. As far as some fish feed on these algae and microorganism, most algal blooms produce toxins which in turn affect the food chain leading to death of the animals, and, inhibit the supply of sunlight at the lower depths. Moreover, it leads to large anoxic areas, especially on tidal flats. An anoxic condition is brought by the depletion of the oxygen levels in water. Lack of oxygen causes the fish to suffocate and eventually die. Or at times, they are forced to move upwards to the water surface to avoid suffocation and in turn are directly hit by heat from the sun leading to their death.
II. Presence of Chlorophyll and change in water temperatures.
Plants require chlorophyll for photosynthesis; therefore, sea plants are not exempted. When water is rich in chlorophyll, then there is higher concentration of the algal bloom. A dense algal bloom produces a surplus of oxygen on a summer afternoon. However, during the night, the bloom attempts to take more oxygen out of the water, lowering the dissolved oxygen in water. On the other hand, fish are able to detect a slight change in temperatures and acts accordingly. Adverse temperatures stress the fish out. In an attempt to find a suitable habitat away from the adverse temperatures, they find themselves to the shores on shallow waters.
The only solution to such problems is coming up with the best policies and legislations which govern the disposal of industrial wastes and treatment of sewages. Ecological Sanitation (ECOSAN) principles should also be upheld to make sure that the sewages are recycled instead of being channeled to the aquatic ecosystem.
Failure to quickly mitigate the loss of aquatic life only derails the efforts of SDGs (Goals no. 2,6, and 14) and Agenda 21 (Goals 2, 6, 12 and 14) on the Food Sustainability and clean environment. Let this be a social responsibility.