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Rey's Masters blog - 4

Find out all about the end of Rey's second semester!

The last half of the module, "Management of Aquatic Protected Areas', looked at several different marine habitats with the final assignment asking me to 'designate' a MPA in the Ria Formosa in the southern tip of Portugal. This required using GIS for mapping (which I talked about in my last blog) and DPSIR (Drivers, Pressures, States, Impacts, Responses) analysis. This is a framework in which you can look at and analyse the important and interlinked relationship between social and environmental factors, particularly important when land use is shared.

For this blog I thought I’d go through some of the different marine habitats and stressors we went though and list some factoids, rather than delve back into the heavy world of policy and regulation.

Mangroves

Mangroves are basically forests that can grow in intertidal areas, which is special because these areas  are saline, so the trees are growing in salty water, something that needs specialised plants and tree species. There isn’t anything really comparable in our temperate climate, the closest we have is probably salt marsh (we have a tiny bit of salt marsh on Island, at Poyll Dooey in Ramsey).

Fun fact time!

Mangrove

Mangroves are viviparous (have live young). Rather than producing dormant resting seeds like most flowering plants, mangrove flowers are pollinated and then the plant produces seeds that immediately begin to germinate into seedlings. The little seedlings, called propagules (shown in the image), are then dispersed by the sea to hopefully take root and increase the mangrove. 

mangrove

Mangroves have aerial roots. This is to help with anchoring in the shifting muddy sediment but is an important feature as there isn’t much oxygen within this sediment. The areal roots are an adaptation which allows oxygen intake.

mangrove

Mangroves are a nursery ground for juvenile fish with the root systems offering protection from predators!

mangrove carbon

Mangroves hold a vast amount of sequestered carbon. They store carbon dioxide from the air  in their roots and branches, but the most impressive thing about mangrove carbon sequestration is the collection in sediment. The roots of mangroves trap and collect carbon rich sediment, building up coastal defences alongside trapping carbon. They do this so well that they can store up to 10 times more carbon than forests!

Mangroves provide a vital service in coastal protection. They reduce coastal erosion, and massively reduce the force of wave action as the wave passes through the mangrove. The way the water travels through the mangroves reduces wave height, and, unlike sea walls, allows trapped water to travel back through them. Attached is a video of how the wave action is changed. I think this is incredible, it blows my mind every time I watch it!

Mobile marine stressors

One of the topics we looked at was mobile marine stressors, in other words things like boats!

Many marine mammals have an incredible sense of hearing and this extends well beyond what we as humans hear. Humans are very visual and it can be hard to comprehend the noise something could be making when we can’t hear the higher and lower frequencies ourselves.

Marine vessel traffic is a global problem. Have a look at the map in this webpage -www.marinetraffic.com . It shows the movement of boats in real time ( only marine vessels over a certain size, small boats wont be recorded). Its incredible to see just how vast the number of vessels there are at sea, and to see them on a world map too.

It's easy to think that the ocean is big so why is noise that we can’t even hear a problem?

Lots of large marine cetaceans use noise to communicate, navigate and forage for food. Noise can travel for long distances in water which is good when you are a whale searching for food but this also means any noises we make will also travel for long distances. The increase in marine noise limits animals abilities to hunt, navigate and find mates, leading to a reduced food source and mating opportunities by confusing them with man made noise and making the ocean too 'noisy'.

By keeping to designated shipping zones and respecting the designations of MPAs (Marine Nature Reserves around the Island) we can reduce the noise impact from boats whilst still enjoying the marine environment. 

In this video the blue dot is a tracked blue whale that you can see bouncing between lanes of shipping, showing visually the impact of marine traffic on cetaceans.

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