Looking below the surface

CO2 you later, corals!

How are those corals looking?

Where? When? Why, are they changing? What can we do about it? Is what we're doing working? Are we actually helping?

OK, there are countless questions facing any conservationist, and the answer is always the same: Get good information... and coffee.

Up to date, accurate data is key for any action to be successful. We've got to know what we're dealing first before we can decide what to do next.

At WWF we strive to protect the most vulnerable ecosystems on the planet. Teams of scientists are working all over the world to get high quality, in-depth information to guide our actions, so all the time, effort and money we invest can help us ensure a sustainable future where humans live in harmony with nature.

Our innovative research on seascape mapping and monitoring with satellite imagery has just been published in  Remote Sensing in Ecology and Conservation  (there's a  blog post  too). We're proud of it and would like to share our journey with you.

Come with me to northern Mozambique ..

Loading... The green line surrounds the Quirimbas National Park, a recently designated UNESCO Biosphere Reserve.

Back in 2002 (when I was just a child), WWF helped establish the Quirimbas National Park to protect 7500 sq. km of rich  miombo* forests  (a natural home for 4 of the 5 " big five " species) as well as the neighboring marine area full of magnificent coral reefs, islands,  mangroves  and abundant marine life (including all  5 species of protected marine turtles ).  It is now a UNESCO Biosphere Reserve.  

*cool miombo fact: Miombo is a local name for Brachystegia species - a tree that sheds leaves in the dry/winter season, then regrows fresh leaves in red and golden colours just before the rains come. It looks like Autumn but it's actually Spring.

Another tough day on the water for a local Quirimbas Fisherman. To feed his family in the long term, local resources must be managed sustainably. ©WWF-Mozambique

Importantly, Quirimbas is also home to more than 100,000 local residents, most of whom depend on the fish in these waters for their diets and livelihoods.

There are  incredible tourism opportunities  that locals can also benefit from, but the first priority is a sustainable and well-managed fishery, which includes designated sanctuaries called Marine Protected Areas (MPAs) and zoned fishing areas.

This is  goal 14  of the  UN's Sustainable Development Goals  (SDGs): to conserve and sustainable use the oceans seas and marine resources for sustainable development.

Let me briefly explain how this works in practice:

Marine Protected Areas: Explained with a WWF Infographic.

An area of open water and/or coastline is designated as protected. In this area fishing is not allowed at certain times of the year, allowing the habitats to be restored and fish populations to grow again - not only in number but also size, density, biomass and diversity.

Larger fish produce disproportionally more eggs and larvae, so there is a positive feedback. With greater numbers the fish swim into non-protected areas and replenish fishing grounds.

In some places, like the Philippines, fishers have doubled their catch rate in just 18 years, so they go out less, saving fuel and time - and get to catch more.

To know where to create, and manage these zones effectively, we need really good spatial data and maps. Let's find out how it's done.


Welcome to the beautiful Quirimbas National Park on the Indian Ocean.

Its one of the places in which  satellite remote sensing  expert Aurélie Shapiro is leading an international team, (comprised mostly of women) to find out more about the coastal habitats below the water.

They are using apps, boats, depth finders and drones to collect data on corals, seagrasses and mangroves in order to create the first complete seascape map of the Quirimbas Archipelago.

The low tide was often too shallow for the boats, so Aurélie's team would find a pristine sand bank or paradise island to wait for the tide to turn. (What a tough job!)

That's when it was time to take out the drones and safely fly reconnaissance missions over the open water.

From Left to right we have:

Aurélie Shapiro (WWF-Germany)  Senior Remote sensing specialist , leading this female all-star marine science team.

Next to her we have Lara Muaves (WWF-Mozambique), Senior Marine Officer and an  Ocean Witness 

In the middle are Helena Motta (Mozambique) whose long-term ambition was fulfilled with the Quirimbas Park, and Inger Näslund (WWF-Sweden) Senior Advisor Marine & Fisheries.

Second from the right is another brilliant marine scientist and  Coral Reef Adventure film star Maria Joao Rodrigues  (Mozambique).

Lastly but certainly not leastly, our freelance remote sensing specialist, Luisa Teixeira (Portugal) is on the far right (not politically).

Supported well by local WWF staff and partners, here we see our guys in action.

Everyone was trained and equipped with a mobile app to record marine information digitally and update it to the cloud without the need for pen and paper.

Aurélie's team is here because Mozambique has some of the most climate-resilient coral ecosystems in the world -  one of the world's most important 50 reefs .

These include the so called  Super Corals  that flourish in warmer, acidic, low-oxygen water " effectively being pre-conditioned to future climate conditions". 

These may be the last hope for safeguarding these thriving underwater forests in a warmer world.

Corals sequester carbon - taking CO2 out of the atmosphere and holding onto it, which mitigates climate change, while protecting coastlines from sea level rise and storm events and feeding over one billion people.

Let me repeat that: these corals actually counteract climate change by absorbing CO2 from the atmosphere, whilst protecting the coastline and feeding everybody at the same time!

Occupying less than one percent of the ocean floor,  coral reefs are home to more than twenty-five percent of marine life. 

A square kilometer of healthy, well-managed coral reef can yield a catch of over 15 tons of  fish and other seafood every year .

The corals are essential nurseries for extremely diverse aquatic life, supporting thousands of fish species and crabs, and associated with mangroves, seagrasses, sponges, even endangered dugongs, turtles and whales.

Yes, that's a dugong (known to some as a sea cow)!

Safeguarding corals is an essential conservation opportunity - but to protect something we need to know where it is first.

So this is the high tech/low tech way to see what's below the surface from the boat:

Luisa bought a bucket at the hardware store, painted it black so it's nice and dark on the inside, put a plexiglass window in the bottom and stuck a camera inside.

Look at those corals, seagrasses and urchins!

Helena's job was to record depth - she is holding the "Lucky Fishfinder" depth sounder.

She cleverly attached it to the side of the boat to avoid repeatedly bringing it and letting it down again.

That worked perfectly until she "caught" seaweed.

ummm delicious.

(maybe not such a "Lucky Fishfinder" after all)

And do you see those little yellow fins?

That's our prize diver Inger. She's the one who'll grab the GoPro and jump into the water at a moment's notice to record what's down there.

This effort has mapped over 100,000 Hectares of shallow water habitat in this protected area - the first map of its kind to help park managers know where everything is and where to zone different activities like fisheries or tourism.

So how did they map all that? Did Inger swim it all? Did Luisa scan the entire seafloor with a glass-bottomed bucket?

Not exactly. These observations are really important to validate our maps - but Quirimbas has over 100 km of coastline, and tons of reefs - it's vast!

The answer is in the stars... well, that general direction anyway.

The European Space Agency's Copernicus Program

 This ESA infographic highlights facts and achievements of the mission after its first five years of operations.

Above us right now are a fleet of satellites, all with different tasks, accurately monitoring the earth. Sentinel 2 is actually a pair of satellites, on the same orbit 180 degrees apart, covering the entire planet every 5 days.

Using  Google Earth Engine  (a free, cloud-based service with insane computing power), Aurélie, Luisa, and two Greek seagrass experts,  Dimos  at  DLR  and Dimitris from  FORTH , accessed data from Sentinel-2 to get multispectral satellite images of the Mozambican coastline.

With some clever tweaking of the data (clearing up sunshine reflected by the water, for example) we can actually see through the water column to observe what is, and isn't growing on the sea floor. Nearby are lots and lots of green mangroves. Corals and mangroves are like the two slices of bread in a biodiversity sandwich (seagrass is like the lettuce, I suppose). Combined they make more complex and more abundant fish communities than they do individually. Evidence suggests  super corals like mangroves  too.

Can you trust a satellite? Sentinel 2 is watching... so I'm going to say YES

Back on Earth the Russian proverb says Доверяй, но проверяй or in English "Trust, but verify", so when we're dealing with gigabytes, sorry petabytes (that's 15 zeros: 000000000000000) of information from 800km above the Blue Planet, it's worth checking that we're barking up the right reef...

In order to train the machine learning algorithms, Aurélie and the team went to  this corner of paradise . Aurélie brought 3 different drones (one of which she might have lost in the water - don't tell her Panda boss) and, working with locals, some of which the team has known for years, used apps, smart phones, hand-held depth finders, glass bottomed buckets and GoPros to learn what was really going on.

The first and most necessary thing is a baseline study, so we can see where we're starting. ie. check the location and health of these "Benthic Habitats" (Benthos is Greek for Depth of the Sea).

Here's what the results look like: an interactive digital map with satellite-derived water depth on the left and the benthic habitats (showing Deep Water, Corals, Sea Grass, Soft Substrate and Mangroves) on the right. You can swipe between them to see what happening at depth.

On the left, a satellite basemap with satellite bathymetry, on the right, the mapped mangroves and benthic habitats (corals in pink, seagrass in green, sand in yellow)

And even cooler/geekier - we can create change maps to see how the benthic habitats are changing over time - are the protective actions we're taking actually working? Or is climate change ruining it all? What happened with all those cyclones? And the pandemic?

Here's an example of the potential change in coral cover observed between 2018 and 2020

Unfortunately, no one can travel there to check at the moment... but we have done the ground work, so using methods and data that are consistent and stable over time (like our trusty Sentinel-2 sensor) we can start assessing what's going over time.


A GLOBIL perspective

The  Space+Science  team manages an online database called  GLOBIL  - WWF's Global Observation and Biodiversity Information Portal.

GLOBIL, which is based on a geographical information system called  ArcGIS Online,  is used by hundreds of scientists, including governments, agencies, universities and private citizens, to host geo-spatial data and web maps that can be shared, viewed and used by millions of people around the world (how do you think I made this story map, with my hands?)

This is the Live GLOBIL site. WWF's Global Observation and Biodiversity Information Portal

At the moment the Space and Science team is building an  East African Data Hub on GLOBIL . Sadly, it can't physically bring you there, (its not that kind of portal) but it does allow you to investigate this valuable ecosystem from you own home.

Here is overview poster I made showing the satellite imagery, bathymetry and benthic habitats...

Quirimbas Archipelago Seascape poster.

...And now the East African Seascapes data, where you can explore the data yourself in the web application, access the data for offline use.

East African Seascapes Data: click and open

Understanding and looking after those carbon-sequesting corals is a great start for dealing with climate change whilst also supporting the livelihoods of coastal communities, which is the primary goal of the Quirimbas Protected Area.

With good information and proper planning we can sustainably support local fisheries by  managing the protected area  - this means setting aside safe sanctuaries and no fishing zones, or  temporary closures, for local favourites, like octopus .

BIG octopus = happy residents ©WWF-Mozambique

So long, and thanks for all the fish.

That's all folks - thanks for joining us on this journey and Sea you soon with more in-depth information! (uuuh, don't worry, its over now).

Citation: Poursanidis, D., Traganos, D., Teixeira, L., & Shapiro, A. 2020. Cloud-native Seascape Mapping of Mozambique’s Quirimbas National Park with Sentinel-2. Remote Sensing in Ecology and Conservation.

Project Resources:


WWF's  Space+ Science  supports conservation efforts around the world

Would you like to know even more? Below are some of our  other projects :

Space+Science - WWF Germany

Bookmark our site: https://space-science.wwf.de

and thanks to our project supporters and partners:

Dimos Traganos

Story Map Master

Espin Bowder

BMZ Bengo

Project Funding

Consevation X Labs, WWF Oceans Practice

Innovation Funding

Loading... The green line surrounds the Quirimbas National Park, a recently designated UNESCO Biosphere Reserve.

Another tough day on the water for a local Quirimbas Fisherman. To feed his family in the long term, local resources must be managed sustainably. ©WWF-Mozambique

Marine Protected Areas: Explained with a WWF Infographic.

 This ESA infographic highlights facts and achievements of the mission after its first five years of operations.

Can you trust a satellite? Sentinel 2 is watching... so I'm going to say YES

Here's an example of the potential change in coral cover observed between 2018 and 2020

Quirimbas Archipelago Seascape poster.

BIG octopus = happy residents ©WWF-Mozambique

So long, and thanks for all the fish.