As divers, I’m guessing most of us love diving on coral reefs; if those reefs are pristine and full of life, even better! Coral reefs are incredible and diverse ecosystems, but they are strongly linked and interdependent on three other ecosystems: seagrasses, mangroves and rivers. Here I’m going to discuss mangroves, and why they are one of the most important ecosystems to conserve in order to have beautiful, healthy coral reefs. Hopefully I can convince every diver to love them as much as I do and to explore our options in protecting these habitats. Though historically, mangroves were viewed as insect filled, tangled and muddy swamps and shrub forests, we have become increasingly aware of how diverse and special this amazing habitat is for both wildlife and protecting our shorelines from extreme weather events.
So, what is a mangrove?
Mangroves are trees and shrubs that love very warm, wet conditions and grow in saline coastal habitats in tropics and subtropics. You have probably seen them fringing islands and coastlines when diving on coral reefs. They can often be recognised by their dense tangle of prop root that make the trees look like they are on stilts. Mangroves are unique because they can live in areas with low oxygen soil and where the water has a variable salt content. As they live in the coastal intertidal zone, the roots can cope with being flooded twice a day. They are flowering plants, where the upper trunk, branches and leaves live above the water line and the lower trunk and roots can live below.
There are over 80 different species of mangrove tree and several more species associated with mangroves for their ability to tolerate the coastal intertidal zone, such as buttonwoods. The Asia-Pacific region has the most diversity and the largest mangrove region in the world is The Great Sundarbans in Bangladesh (a UNESCO World Heritage Site). Having said this, there are three main dominant types of mangroves in a mangrove forest; red, black and white.
Red mangroves are evergreen trees that can grow to 25m, often less. They live closest to the water and elaborate arching prop roots and red bark colour make it very easy to identify. They are salt excluders; the roots contain a waxy substance that helps keep the salt out. If any salt does get through, it is deposited in older leaves and the tree sheds them. They produce propagules (seeds) that grow from the tree, then detach and stick into the mud or float away somewhere new.
Black mangroves live between red and white mangroves. The easily identifiable roots (pneumatophores) stick up vertically from sediment and are specially designed to take in oxygen, acting like snorkels in the water. Black mangroves have longer pointed leaves which are often covered in salt crystals and dark scaly bark. They produce seeds which germinate while still connected to the parent tree, so trees are often grouped together.
White mangroves live closest to the land in the back portion of the mangrove swamps, where they are unaffected by tidal inundation, except on spring tides. With no visible aerial roots, they may seem harder to identify, but the leaves have two glands at the base which excrete the salt taken in by the roots, so the leaves are often coated with white salt crystals. The salt crystals give this species its common name and the bark is lighter in colour.
Why should we love them?
Mangroves are ecosystem engineers, meaning they form their own ecosystem and provide habitats for other species, but they also have lots of benefits to us:
- Trapping sediments
Mangrove forests have huge root systems that slow the movement of tidal waters, making the sediment settle out of the water, the roots then trap this soft sediment and build up the muddy bottom. In dense forests, mangroves have created entire islands.
- Reducing wave action
The network of sediment-trapping roots stabilize the coastline, reducing erosion from wave and tidal action and providing a buffer, an important defence for costal ecosystems and communities from tropical storms and their storm surges.
- Important nursery grounds
Mangroves provide an intricate network of nursery habitat for many fish and invertebrate species, which move out to coral reefs and other ecosystems when they mature. The mangroves provide a safe haven for juvenile fish, including commercially important fisheries species, which seek food and shelter from predators. Many shark species, including lemon sharks, bull sharks and blacktip sharks, spend their juvenile years in mangrove forests.
- Rich biodiverse ecosystems
In addition to being a great habitat for the young of reef and pelagic species, mangroves are a primary habitat for mature individuals of many species of marine animal, amphibians, reptiles, seabirds and waterfowl. Mangroves are always teeming with life!
For anyone who enjoys diving on coral reefs, it is important to be aware that coral reefs and mangroves have a symbiotic relationship – the reefs protect the coast from being eroded by the sea, blocking the power of the open ocean and the mangroves trap the sediment washed from the land that would smother and kill the reef. Species depend on both ecosystems for different life stages and both ecosystems provide coastal protection and commercial value through fish stocks and tourism for us. Mangroves are one of the most valuable ecosystems in the world.
Unfortunately, like coral reefs, mangrove forests are under threat and are being lost at a very rapid rate. Clear cutting for aquaculture, mainly shrimp farming and coastal developments, such as marinas, housing and hotels is a major issue, as is harvesting for wood.
It is estimated that at least one third of all mangrove forests have been lost in the last few decades. Without protection, they may disappear in areas that cannot afford the ecological or economic loss. This in turn negatively effects our beloved coral reefs, which are already struggling with pollution, sedimentation, climate change, ocean acidification, overfishing and destructive commercial practices. After that thoroughly depressing paragraph, lets move onto the positive bit…
What can we do to help?
- Help support and encourage more protected areas. If you are travelling in an area with a protected area, donate or take a guided tour from rangers.
- Make sustainable choices; shrimp farming is a leading cause of mangrove habitat loss, know where your food is coming from and whether you should be making that choice. If you don’t want to give up a food, there is usually a sustainable option – it may cost a little extra, but it will be completely worth it!
- Spread the word! As ever, education is always important and particularly in countries with mangrove forests; many NGO’s work in schools to educate the next generation, which we can support through donations. However it isn’t just about spreading the word in other countries, the more people everywhere learn about the value of mangrove forests, the more drive there will be to protect this amazing habitat!
Visiting the mangroves
So, if you are now totally hooked on marvellous mangroves and want to go and see the wildlife for yourself, there are now many places that will take you snorkelling or on kayak tours. By picking an organisation that donates to mangrove protection or does educational programmes you get to help out while having a great time!
The BiG Scuba Podcast… with Julianne Zielfle
Ian and Gemma chat about what they have been up to and we hear from a caller on The BiG Scuba Bat Phone. Our guest is Julianne Zielfle. Julianne became a certified diver in 1985 and she is an award-winning speaker, photographer and media professional. She first appeared in dive magazines in the late 1980s when she met Stephen Frink. She worked on Cousteau’s Campaign on Rights of Future Generations in 1994. She co-chaired the Hans Hass Film Festival and was co-creator of the Dive Industry Awards Gala in 2000. She has been helping schools in the South Pacific since 1992 and teaches in her local school district. In 1999, she was recognized by D.A.N. with the Outstanding Volunteer of the Year Award.
You can follow Julianne Zielfle on Facebook here.
Find more podcast episodes and information at www.thebigscuba.com and on most social platforms @thebigscuba
Jeff chats to… Marine Biologist and Underwater Videographer Jake Davies (Watch Video)
In this exclusive Zoom interview, Jeff Goodman, Scubaverse Editor-at-Large, chats to Jake Davies, Marine Biologist, HSE Professional scuba diver, underwater videographer (using videos and 360 clips for VR) and CAA licensed drone pilot.
Jake grew up on Pen Llŷn, North Wales and coming from a maritime family meant that from a young age the underwater world and marine life have played a major role in his life. His interest in marine life and the sea led to him studying Marine Biology at Bangor University where he was successful in obtaining a year in industry with the Intertidal & Coastal team at Natural Resources Wales.
In 2017 Jake was successfully awarded a Sea-Changers Grant to run ‘Dive Into Monitoring: Seagrass’ surveys with SeaSearch North Wales. The surveys aimed to gather updated information on the Seagrass bed in Porthdinllaen with volunteer divers and local dive clubs.
As a media diver, Jake has worked as part of the dive team (Marine Ecosol) filming for BBC Wales Hidden Wales with Will Millard (Lazerbeam Productions & Folk Films).
Footage which Jake has filmed off the Welsh Coast, as well as the Canary Islands, has been featured for a variety of BBC programmes including an episode of Countryfile where he was interviewed about the Seagrass in Porthdinllaen, Wales along with the rest of the Project Seagrass team. He is also a blogger and contributor to Scubaverse @JDScuba, and a co-director of Under Water Wales @dandwrcymru.
As well as being a HSE Scuba Diver Jake is also employed as the Project Coordinator for Angel Shark Project: Wales. He is also a Project Leader on a Save Our Seas Foundation Project.
Through sharing underwater videos and photos of amazing and unique wildlife/habitats that are found beneath the waves along the Welsh Coast as well as abroad Jake hopes to inspire people to go beneath the waves and making the underwater world more accessible for all.
Find out more about Jake and his work at: https://jakeddavies1996.wixsite.com/jdscuba
Rather listen to a podcast? Listen to the audio HERE on the new Scubaverse podcast channel at Anchor FM.
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Explore the amazing triangle of Red Sea Reefs - The Brothers, Daedalus and Elphinstone on board the brand new liveaboard Big Blue. With an option to add on a week at Roots Red Sea before or after.
Strong currents and deep blue water are the catalysts that bring the pelagic species flocking to these reefs. The reefs themselves provide exquisite homes for a multitude of marine life. The wafting soft corals are adorned with thousands of colourful fish. The gorgonian fans and hard corals provide magnificent back drops, all being patrolled by the reef’s predatory species.
£1475 per person based on double occupancy. Soft all inclusive board basis, buffet meals with snacks, tea and coffee always available. Add a week on at Roots Red Sea Resort before or after the liveaboard for just £725pp. Flights and transfers are included. See our brochure linked above for the full itinerary.
This trip will be hosted by The Scuba Place. Come Dive with Us!
Call 020 3515 9955 or email email@example.com
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