Mass fish deaths and marine life found stranded on coasts… In April 2016 alone cases have been seen in Cambodia, India, Vietnam, Spain, Turkey amongst others. In addition, reports of turtles dying en masse, dolphins and sharks stranded on beaches have added to concerns for marine life. So what are the causes?

Climate change and global warming is a major player to the issue and the effect on sea life has started to catch more than the scientific community’s attention due to increased visual evidence and media reports.  (Cases have not just been seen in the last year but for over a decade [3,4]). These mass extinction events are indeed on the increase. It is not an alarmist flawed perception of a natural phenomenon, but a reality [1,2].

The reasons under current scientific investigations for these mass die-offs include:

  • extreme heat
  • lack of oxygen in the water [5]
  • increase of dead zones where the oxygen levels are too low to support marine life
  • sudden increases in algae or plankton which reduces oxygen and interferes with gills, normally caused by sudden changes in temperature
  • pollutants/ waste runoff (human and animal)
  • natural disasters

In April this year, Vietnam saw its own case with dead fish washing up on beaches. Whilst the government investigated and said there was no link to a local steel work which began operations circa 4 months previously, they did comment that the other reason could be a sudden and increased algae bloom [7].

“A harmful algal bloom (HAB) is an algal bloom that causes negative impacts to other organisms via production of natural toxins, mechanical damage to other organisms, or by other means. HABs are often associated with large-scale marine mortality events and have been associated with various types of shellfish poisonings.” (Wikipedia)

What causes increased harmful algal bloom? Contributors include increased temperatures and sunlight, and an increase of nitrogen and phosphorus (by-products of industrialization).

Environmental agencies have a priority to understand the causes to ensure measures and remediation are put in place.

So how can we help to remediate the issue? Climate change agreements will certainly help and the number of countries signed up to #ParisAgreement following COP21 gives hope.

On an individual level, awareness of and pressure on local industries to reduce emissions; our own efforts to reduce demand on the meat industry (to reduce agricultural farming); and simply our own efforts to save energy will play a helpful part. The average Bangladeshi uses 300 watts of power per annum. The average American or UK around 12,000 (source – National Geographic  November 2015 issue).

Follow the link to see easy things we can do to help our oceans and climate:

Photography source: Google images labeled for non-commercial reuse with modification.

Further Reading

[1] Rise in Mass Die-offs Seen Among Birds, Fish and Marine Invertebrates in Science Daily (2015)

[2] Recent Shifts in the Occurrence, Cause, and Magnitude of Animal Mass Mortality Events by Samuel B. Fey and al. PNAS (2014).

[3] Oceanic Dead Zones Continue to Spread by David Biello. Scientific American (2008)

[4] Mass Animal Deaths for 2016. Note that EwA does not affiliate itself to any of the opinions expressed in referred site. The site is quoted as it has a comprehensive list of mass animal deaths.

[5] New Research Reveals Extreme Oxygen Loss in Oceans During Past Climate Change by Sarah Moffitt. The Guardian (2015).

[6] Dead Zone – National Geographic’s Encyclopia Entry 

[7] Vietnam Says No Proof Formosa Steel Plant Linked to Mass Fish deaths by Reuters (2016)

by Sharan BahraSharan 

The photographs in this article are Google images found using the filter ‘labeled for non-commercial reuse with modification’.

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