Information Source: Mason & Macdonald, 2009
As mentioned, industrial development and activities are a major threat to the Smooth-coated Otter population. However, they impact the otter population in more than one way, by polluting the water in their various habitats.
Waterways and wetlands are often polluted by eutrophication. It is usually caused by the discharge of fertilizers, sewage or detergents from agricultural runoff and industrial waste.
Eutrophication in a wetland
Image Credit: Alexandr Trubetskoy
Dead fish caused by aquatic hypoxia due to eutrophication
Besides fertilizers, due to the widespread use of pesticides in agriculture, non-biodegradable pesticides are frequently discharged into water bodies. Pesticide pollution is incredibly dangerous, as it can lead to the poisoning of the aquatic prey of the otters. The outcome of this impact is two-fold, as it will cause a reduction in prey biomass, and the risk of poisoning the otters from feeding on the contaminated prey. Specifically, pesticide and runoff pollution leads to the decline of fish species, which affects the diet of the otters. Furthermore, from eating the contaminated fish, organochloric and heavy metal contamination will enter into the otters’ digestive system and interfere with their normal physiology.
Another form of pollutant is sediments and silt. Deforestation causes the siltation of hill streams, whereby clastic rocks flow into the water, greatly reducing the quality of otter habitats.
The mentioned pollutants render the otter habitats unsustainable and inhabitable, leading to the decline in their population.
Lastly, in the context of Singapore, trash thrown into the rivers by humans pose a hazard to the Smooth-coated Otters. These include plastic bags and wrappers, PET bottles, Styrofoam, fishing lines and hooks. Mistaking trash for food, the otters might Ingest plastic, which would a blockage in their intestines, or even suffocate them. Styrofoam, when ingested by the otters, will produce styrene in their system. Styrene is a hazardous chemical which affects the nervous system and causes cancer in both humans and animals.
A Smooth-coated Otter enjoying his Styrofoam lunch… Maybe not.
Video Credit: Fast Snail