Why are they so many dead fish on Discovery Bay beach?
- Written by October 29, 2015
The presence of a number of dead fish in the water near DB pier and washed up on the beach have caused concern for local residents.
A number of readers contacted Around DB with photos, wanting to know the reason.
DBer Kae Nebbs said on Tuesday morning she saw many fish swimming around the pier, but yesterday there were dozens floating dead in the water.
DB resident and Director of Operations at environmental charity Plastic Free Seas, Dana Winograd, talks to Around DB and gives her expert opinion on the situation.
"There are many reasons which could contribute to fish die-off, which was experienced yesterday in Discovery Bay.
The most common reason is reduced oxygen in the water. This phenomenon is of concern because it can be an indication of how we are affecting the environment around us and longer term, there are far-reaching implications.
Algal blooms - a rapid growth of algae - can happen when there is an excess of nutrients in the water. Although there are many reasons this can happen, common causes are the chemical fertilisers in agricultural runoff and nutrients from sewage outflows. Algal blooms (including the infamous red tide) are known to occur year round in Hong Kong.
Algae are short lived, and when they die and begin to decay, the process consumes dissolved oxygen in the water which can result in low oxygen levels. Some fish cannot survive in areas where there is a decrease in the dissolved oxygen content level. In a few situations, the algae themselves do produce toxins which can be deadly.
Plastic Free Seas has been in contact with the Agriculture, Fisheries and Conservation Department (AFCD). Testing was done this morning but we do not have any results yet. The tests may give an indication of the problem, but one thing is for certain, we should be more aware of how our behaviour on land can affect the sea around us."
Note: This article is an updated version of the previous article that was published on our website. It clarifies Dana's opinion on the subject.
Photo credit: Kae Nebbs
Another DB resident Fred Boot sent photos of the beach being cleaned up this morning.