Marine Megafauna and Microplastics (Guest Blog)

Marine Megafauna and Microplastics (Guest Blog)

January 15, 2019

Guestblog by Demi Kerkhof

From an early age, I felt a connection to and fascination for the ocean and its inhabitants. Whether it was snorkelling looking for fish, chasing waves bodyboarding, or messing around in tide pools it was a challenge to keep me out of the salt water and sun.

Now, at age 23, not much has changed. I’m pursuing my passions studying environmental sciences and biology and spending my free time surfing, scuba diving, or freediving and traveling as much as possible.

Currently I am chasing my dreams, figuratively and literally – I swim after manta rays and whale sharks as a job – working as a research assistant for the Marine Megafauna Foundation (MMF) in Mozambique. MMF focuses on studying marine megafauna – everything big in our oceans such as manta rays, whale sharks, leopard sharks, marine turtles, and more amazing creatures. Then we use what we learn to work with local and global communities to find and inspire sustainable, long-lasting conservation solutions.

All of our lives are in a way connected to the oceans.  As humans, our well-being and survival is dependent on the oceans - literally 50% of the oxygen we breathe is produced by them – to do so they need to be healthy and full of life. However, plastic in our oceans is a big issue for marine life. Daily, we are exposed to posts about plastics in our oceans, news of a stranded whale found with 6 kg of plastic in its stomach or videos of a turtle with a straw stuck in its nostril. Rumor has it that by 2050, there will be more plastic than fish in the sea. This is not a pretty future.

Unfortunately, even the Mozambican coastline has been affected by plastic pollution. Walking on the beach it is easy to see what that day’s tide brought in: bottle caps, pieces of flip flops, toothbrushes, lighters and much more. By closely observing the sand, in between the millions of grains, you can notice a lot of tiny colorful pieces: microplastics – a man-made nightmare.

Praia do Tofo, in the Inhambane province of Mozambique is special as we are lucky enough to have two of the species that we study – whale sharks and manta rays –  year-round (most other places on earth only have these species seasonally). Tofo is special because this region is subjected to unique oceanic currents that cause upwelling of nutrient rich water from the deep sea and enable year-round plankton blooms.


Contrary to a common misconception, whale sharks, despite their huge mouths cannot swallow children or any other large thing as their throats are no bigger than a human fist: same goes for manta rays. Both species are in fact filter feeders, meaning that they feed by filtering plankton out of the water. Plankton, is any small plant or animal in the ocean going wherever the current takes them as they are not strong nor big enough to swim against it, whale sharks and manta rays mainly feed on zooplankton, the animal kind: such as jellyfishes and fish eggs. Unfortunately, microplastics are about the same size as the zooplankton these gentle giants feed on, and they are unable to tell the difference between a piece of plastic and their food. Mantas and whale sharks will thus, ingest whatever happens to get into their mouth and is small enough for them to swallow. This means individuals will most likely have to feed more and for longer amounts of time to gain the same amounts of energy as nutritional uptake is more inefficient, depending on the plastic : plankton ratios in the water. Microplastics also carry toxins which can bio-accumulate in the fatty tissue of manta rays and whale sharks.

So, it is obvious that not much good comes from plastic. We used to call it the greatest human invention, as it was seen as useful and essential for our society to function. However, we are now beginning to recognize it as a curse. With increasing human pressure on marine life and the marine environment, it’s becoming more and more important for us to do something and change the current situation to reduce our impact on the worlds’ oceans!

We can help the ocean through research, conservation, and education as the Marine Megafauna Foundation and other organizations are currently doing. But, even as individuals can have a great impact! So here are a few simple life changes that can help the world’s seas:

  • Reducing plastic use: stop using disposable plastic water bottles. Instead, opt for a reusable bottle, say no to plastic straws when ordering a drink, and bring your own reusable bag, a linen one for example when going shopping. Use a bamboo toothbrush instead of a plastic one.
  • Making sustainable food choices: support sustainable fisheries, choose local by visiting farmers’ markets and opt for a vegetarian/vegan meal instead of one with meat.
  • Support sustainable brands: Such as The Bamboo Brush Society
  • Recycling: a simple step, inform yourself about the best way to recycle in your neighbourhood.

Whale shark

One day while out on the ocean, a snorkeler decided to touch a whale shark. Soon after she was stung in the face by a bluebottle (a type of jellyfish). Some might call that karma. This happened a few weeks back, here in Praia do Tofo. I reckon, if we continue the way we are with our oceans, karma might come for us all – just as the jellyfish did for that woman’s face: by changing together, we can make a difference and work towards a world where marine life and humans live in harmony and can flourish together.

Demi Kerkhof (Guestblogger)

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We want to thank Demi Kerkhof for her contribution, please give here a follow on Instagram to follow here adventures and please check out Marine Megafauna Foundation.  

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