Blog 2: Marine Habitats

Part of our community awareness program for the “Our Ocean” project, funded by the Waitt Foundation, is to further the information to communities on the different marine habitats that are located in Vava’u. This awareness need was also highlighted for critical importance through the "Rapid Assessment of Biodiversity of the Vava'u Archipelago" (SPREP, 2014)

The following is an overview of each habitat, our next blog post will cover the importance of “ecosystem connectivity” and why we have to think big when looking at marine resource management and protected areas!

Mangroves are shrubs or small trees that grow on mudflat areas close to the shore. Mangrove shrubs are a salt tolerant that are able to live in harsh coastal conditions.

Mangroves habitats provide shelter for juvenile marine species to be safe from large predators through using it’s aerial root system and provide suitable habitat for oysters and other mollusks.

Mangrove areas also help reduce land based pollutants from entering the coastal waters by absorbing quantities of nitrates and phosphates through their roots as well as absorbing trace metals into the sediments.

They are also important for coastal communities as they protect our shores from large storms and waves by reducing their potential energy.  

Seagrass are a type of plant that have roots below the sandy bottom, they are commonly found in shallow, clear coastal waters. Seagrass provide shelter for a wide variety of marine species within the ocean and are a favoured food by Green sea turtles. It also helps protect and stabilise the ocean floor sediments from being eroded by wave actions and is a large carbon storage area.  

Intertidal zones, are mudflat areas exposed at low tide, this is  where communities usually do their gleaning activities for invertebrates such as the sea cucumbers, clams and other species. Clams and other seashell organisms help the ocean by cleaning the water through filter feeding.

Coral reefs are formed by tiny sea creatures named polyps that are identical to the families of jellyfish. Polyps release calcium carbonate to it’s base that form up layer by layer for so many years before it creates the hard coral reef system. 

Coral reefs are very significant as they provide shelter and food for various marine organisms and are home to some of the greatest biodiversity in the planet. 

They also safeguard our shores from large wave actions and storm. Coral reefs attract tourists from around the world and are also a very important habitat contributing to beach formation. 

Pelagic seas, are found off the coral reefs and coastal areas where waters may reach thousand of meters in depth. The pelagic seas are home to a multitude of species at varying stages in the lifecycle, as well as being critical for migratory species such as marine mammals, predatory species such as tunas and sharks.

All marine habitats are of great importance to ecological, social and economic benefits, they suffer grave threats from habitat destruction, over fishing and harvesting,  as well as land based activities such as the use of fertilisers and climate change impacts.

Coral Bleaching event in the Vava'u Group.....

A rapid survey team assessing the reefs on Tonga reports observations of the first stages of mass coral bleaching.  The SPREP (South Pacific Regional Environmental Programme) BioRAP (Biodiversity Rapid Assessment Programme) working in the northern Tonga group of islands called “Vava’u” reports about 1-3% of corals are bleached.  Some corals are white; others partly white, and others are neon colors like light blue or yellow. 

Due to increasing water temperatures, the NOAA Coral Watch program previously announced a bleaching watch for Tonga (February 2014).  The team, recorded seawater temperatures rising in the last week to about 30.5^o C, as well as the appearance of bleached corals.  Most of the bleaching observed was between 10 meters and the surface, however individually bleached coral colonies were observed up to depths of 30 meters in some places. A range of coral species was recorded as bleaching.

Corals bleach when increased seawater temperatures occur over a period of time; the corals, which are made up of skeletons, animals and single-cell plants, are placed under stress. When the algae (zooxanthellae or plant living within the animal), which give corals not only its color but also the ability to photosynthesize and feed, are released by the coral colony, the coral becomes bright white. As the coral has lost the plant component it loses them as a food source and is under extreme stress to survive.  Corals may recover from bleaching events if seawater temperatures decrease to within the limits of coral development. Bleaching events effect many different areas of the marine ecosystem including the reef fish as well as weakened coral reefs provide little protection for shorelines.

Area of bleaching coral within the Vava'u archipelago.

Most days have been sunny, with very light winds and small waves, but February 28th was cloudy and rainy when the team departed Vava’u.  The SPREP BioRAP team was surveying reefs and terrestrial ecosystems in the Vava’u group in support of conservation planning in Tonga.  The Kingdom of Tonga is located north and slightly east of New Zealand, and east of Fiji in the Pacific, and the Vava’u group of islands is at about 18.6500^o S.

The coral reef areas identified as bleaching sites will continue to be monitored and recorded for further analysis.

The marine team was based on the Waitt Institute Scientific Platform to conduct the marine surveys of Vava’u as part of the BioRAP programme with SPREP, Ministry of Lands, Environment, Climate Change,  and Natural Resources, Waitt Foundation and VEPA.

BIORAP Survey of the Vava'u archipelago

This is a vital and important survey initiated by Ministry of Lands, Environment, Climate Change and Natural Resources, SPREP, Waitt Foundation and VEPA, to explore the habitats of both land and sea for species diversity, species habitat and to collaborate resources for the improved ecosystem health of coral reefs, sea birds, reptiles, marine mammals and not forgetting plants.

As part of the marine team, we have 10 researchers involved in identifying, counting and monitoring the health of one of the most important ecosystems for Pacific Island nations, coral reefs. Coral reefs provide valuable protection and ecosystem services to both cultural and commercial avenues in Tonga.

Our studies include
Coral Taxonomy - species identification
Coral Health monitoring - percentage of coral cover, disease and invasive species impacts.
Reef Fish Biodiversity - species list and abundance.
Commercial Fish - fish used both culturally and commercially and there abundance for sustainability.
Invertebrates -  crustaceans, molluscs, nudibranch and other small yet vitally important organisms that clean, provide nutrients and food to other marine life.

Our team consists of 4 Tongan partners, 2 from Ministry of Agriculture, Fisheries, Forests and Foods and 2 from Ministry of Lands, Environment, Climate Change and Natural Resources, as well as overseas scientists residing in American Samoa, Hawaii, Singapore, Australia and oh little ole me!

So what does BIORAP mean - its a rapid assessment of the biodiversity of the islands and marine life in Vava'u. There are many areas that have data deficient statistics and though this survey is short, so much valuable data will be collected and passed on to the government and communities to fill gaps and to exchange with local knowledge on the status of the ecosystems.

None of this would of happened without a lot of input from varying parties striving towards the same goal, to improve and protect the ecosystem health and species habitat of Vava'u for a sustainable future.

For the marine team, we are currently based on the Waitt Institute Scientific Research Platform, with a crew working above and beyond to enable us to carry out and conduct these surveys of the outer coral reefs. We have spanned far and wide including Fonualei, Toku, Maninita and many other far reaching islands.

Lutjanus kasmira - Blue lined snapper.

Acropora sp. - healthy coral.

Monitoring of introduced species Trochus niloticus.

We have 7 more days to go as I write this, at present we have conducted over 30 hours of studying the reefs and their dynamics underwater and other hours are left to compile the data we collect as we blow bubbles.

This is a fantastic project, one VEPA holds very dear to its heart, but without all the hard work from all the partners, scientists and funders, this would not be happening. We have a long road ahead and a lot more data to collect in the next week, but we will keep you updated as we can.

Malo
Karen