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ReefDoctor becomes an official partner to SeagrassNet, the world wide monitoring body for Seagrass
Apr 20, 2009
The Bay of Ranobe supports extensive seagrass meadows which are valuable contributors of coastal water productivity and act as an important habitat for a large number of organisms. They provide nurseries, shelter and food for a variety of ecologically and commercially important species such as reef fish, turtles and crustaceans. Additionally, seagrass beds stabilize bottom sediments, act as hydrodynamic barriers to reduce wave energy and filter coastal waters of nutrients, contaminants and sediments.
As they exist at the interface of terrestrial margins and the world’s oceans, seagrasses are threatened by numerous anthropogenic impacts such as eutrophication, changes in water chemistry/sedimentation, human development and like coral reefs, are also under threat from global climate change. It is therefore important to study and monitor, over time the health of these valuable yet threatened habitats.
The main impacts to these meadows in the Bay, is the use of a fishing technique called Beach Seine fishing. This is a process whereby the fishermen (usually those whom have limited fishing experiences as they used to be farmers but drawn to the coast for a better way of life due to the heavily impacted terrestrial environment), place a net (and mostly made of very fine meshed nets, such as mosquito nets, so it catches everything) up to 1km in length attached to people on the shore out over the meadows and then back again forming a large loop. Fishermen then stay inside the net carolling fish to stay within the net as the people on the beach pull the net in, and is usually a family affair with kids and adults participating.
This technique causes physical damage to the meadows but at present the biggest impact is it removes the juvenile reef fish species which inhabit the meadows as part of their life cycle, being born on the reef, move to meadows and then back to the reef once they are larger in size. This removal of juvenile species causes huge problems for the regeneration of the reef itself where other reef fishermen are already having problems with reduced availability of their main fish and reduction in sizes.
ReefDoctor understood there was a need to first monitor the impact of this fishing on the meadows and also try and stop the beach seine technique.
Through ReefDoctors head science officer Mr. Brice Remy-Zephir we contacted SeagrassNet the world monitoring body for the worlds seagrasses to see if they could come and train our staff to undertake proper internationally recoganised protocols and also have this data contribute to the global knowledge of seagrasses.
In late August 2007 Dr. Fred Short and his colleagues (phd student Aaren Freeman and Ms. Nikki Sarrette) came and visited us and undertook a week long training season for ReefDoctor staff and also those of Blue Ventures who came down to be trained so that they can implement a surveying post in Andavadoaka and thus becoming the first sampling stations for SeagrassNet in Madagascar.
By October 2007, ReefDoctor became an active participant of the global seagrass monitoring network, ‘SeagrassNet’ and by the end of 2008 had successfully completed its first year of seasonal surveys in two of the Bay of Ranobe’s seagrass meadows.
By becoming a member of SeagrassNet ReefDoctor and Blue Ventures adopted a global monitoring protocol and along with other SeagrassNet teams worldwide (covering over 23 countries) agreed to conduct synchronous quarterly sampling of the Bay of Ranobe’s seagrass meadows and those in Andavadoaka.
There is a lack of information on the status and health of seagrasses worldwide, particularly in less developed regions. The results collected by ReefDoctor are fed directly into SeagrassNet’s web-based data reporting system in order to document the status of the seagrass resources in this region and forming the important first steps in understanding and preserving these productive habitats.
The seagrass surveys occur during a two day period, when the tide is at its lowest (during a spring tide) in the months of January, April, July and October and require a concerted effort from the ReefDoctor team to ensure all sampling is conducted in a narrow time frame. Volunteers play an important role in the successful completion of each seagrass survey event so the science team also run seagrass workshops to teach sampling techniques, plant identification, and environmental monitoring. The Seagrassnet monitoring protocol consists of a comprehensive set of surveying and sampling procedures (such as the deployment of temperature/light sensors, specimen collection and processing, quadrat samples, canopy height measurements, photographic analysis, sediment coring, water samples and GPS mapping) which take place across permanently established transects in the seagrass bed, both on foot and by scuba.
Naturally, tropical seagrass beds change over time showing important seasonal variations, it is therefore important to develop a clear picture of the status of a seagrass bed in any one season to take into account seasonal variability. The surveys conducted throughout 2007-2008 have provided essential baseline data of the bay’s seagrass beds for each season allowing it to be accurately compared over time with deviations from recorded natural cycles being more easily interpreted. The data will be used to establish the current extent and health of the meadows and, over time will enable the assessment of the impacts of sedimentation, pollution and the local fishing practice of beach seining which is considered to be destructive to these seagrass beds.
