The Western shores of Ghana are combating a seaweed inflow Prosper Amihere
Sargassum is a genus of brown seaweed. Over 300 species are distributed internationally in each temperate and tropical climates. The species fluitans and natans are distinctive as a result of they spend their life cycle floating on the ocean, by no means attaching to the ocean flooring. Other seaweed species reproduce and start life on the ocean flooring .
Pelagic (open sea) sargassum has been described because the “golden rainforest of the ocean” due to the floating ecosystem it helps within the Sargasso Sea, within the western Atlantic Ocean. Pelagic sargassum additionally happens naturally within the Gulf of Mexico and the Caribbean.
Floating sargassum first started arriving en masse on shores throughout the tropical Atlantic in 2011. Up to 10,000 tonnes arrived day by day throughout a very extreme peak season. Severe years since then embrace 2015, 2018 and 2022 – however yearly there’s a important inflow. In the Caribbean, there was good progress in understanding the pelagic sargassum seaweed. We now have a greater concept of the place it’s coming from: doubtless a brand new southern space of progress.
In 2009 the primary stories emerged of pelagic sargassum sightings off the coast of Ghana. Densities have elevated yearly ever since. In early March 2023, giant portions have once more arrived on the shores of the Western Region of the nation.
Pelagic sargassum is useful in a number of methods. Marine species akin to eels, white marlin and dolphin fish rely on it for spawning grounds within the Sargasso Sea. Commercial fish species together with tuna rely on it for meals.
But issues come up when giant portions are skilled close to and on the shorelines of coastal communities. Algal and seaweed blooms have gotten extra frequent in seas and oceans worldwide, each far offshore and nearshore. There is simply restricted proof of a hyperlink between pelagic sargassum blooms and local weather change, however warming oceans do appear to be one explanation for the rise in different dangerous algal blooms in coastal areas.
The pelagic sargassum off Ghana’s coast is affecting communities’ skill to fish and use their seashores.
Importance of fishing in Ghana
More than 60% of Ghana’s residents stay inside 200km of the coast and 42% inside 100km. The artisanal or small-scale fisheries sector employs an estimated 80% of the nation’s fishers.
Around 2.4 million individuals, about 10% of the inhabitants, work within the fisheries sector. Small-scale fisheries contribute about 4.5% to Ghana’s gross home product (GDP). The coastal areas of the nation are notably depending on fisheries for his or her livelihoods.
Marine fisheries are the first supply of earnings for greater than 200 coastal villages, together with about 200,000 fishers with roughly 2 million dependants .
Impacts of pelagic sargassum on fishing communities
In a current examine we assessed the impression of pelagic sargassum on the livelihoods of fishers on Ghana’s coast. Through group discussions, surveys, area observations and images, we documented the experiences of fishers. Most (70%) of these we spoke to throughout three websites within the area – Sanzule, Beyin and Newtown – trusted fishing for his or her sustenance and livelihood.
The seaweed had considerably affected the livelihoods of fishing dependent communities within the western area. Pelagic sargassum had decreased their fish catch by getting tangled in nets. It made up many of the catch as a substitute of fish.
Pelagic sargassum additionally inhibits fishing by:
breaking nets and filling nets
clogging outboard motors on boats
creating seaweed mats which are inconceivable to navigate boats by
inflicting pores and skin irritations
inflicting insufferable discomfort from the scent.
These preliminary outcomes spotlight the urgency of discovering methods to handle pelagic sargassum in western Africa. But to attain this, we additionally want extra information and an improved understanding of what’s occurring.
Solutions
To establish options, it is very important know what varieties of seaweed are arriving, their origins, makes use of and how one can monitor them. It is feasible that the solutions are the identical for west Africa as within the Caribbean. But that is an assumption. Very little is understood about pelagic sargassum in West Africa.
What we do know, as scientists, is that answering a few of these questions for locations like Ghana is likely to be even trickier than it was for the Caribbean.
Take forecasting and early warning, for instance. These processes depend on adequate cloud-free satellite tv for pc imagery together with an understanding of ocean processes and climate programs. That means detecting the place the pelagic sargassum is at any given second, together with ocean course of fashions, to forecast the place will probably be later.
But west African coasts are likely to have important cloud cowl. Methods that labored properly within the Caribbean could not work in Ghana.
Recently, a workforce from universities in Ghana, the UK and Jamaica got here collectively to discover how ground-based images may create a helpful dataset to raised perceive the seasonality and volumes of pelagic sargassum arriving in Ghana, utilizing citizen science strategies.
Citizen science recognises the vital position that the general public can play in analysis, and invitations non-researchers to be a part of information assortment and evaluation.
Citizen science is now utilized worldwide for coastal monitoring however focuses virtually solely on coastal erosion. Coastal erosion work, such because the CoastSnap platform, paperwork how the bodily construction of coastlines modifications throughout days, months and years. The citizen science monitoring is achieved by putting in a easy metallic pole and a few signage requesting {that a} passersby take a fast picture with their cell phone and share it on-line or by way of an app.
In our work, we’ve got come along with faculties and group members from Beyin, Esiama and Sanzule within the western area of Ghana to use CoastSnap to review pelagic sargassum. Together, we’ve got put in three of those metallic monitoring posts. Teachers and group members are actually photographing the impacts that the seaweed has on individuals’s lives when it arrives.
Gradually, we are going to be taught extra about pelagic sargassum impacts and adaptation choices in west Africa.
Dr Sien van der Plank was a part of the SARTRAC mission that obtained funding from UKRI ESRC GCRF ES/T002964/1 and the University of Southampton UKRI ESRC IAA.
Kwasi Addo Appeaning was a part of the SARTRAC mission that obtained funding from UKRI ESRC GCRF ES/T002964/1 and the University of Southampton UKRI ESRC IAA.
Philip-Neri Jayson-Quashigah was a part of the SARTRAC mission that obtained funding from UKRI ESRC GCRF ES/T002964/1 and the University of Southampton UKRI ESRC IAA.
Dr. Winnie N. A. Sowah was a part of the SARTRAC mission that obtained funding from UKRI ESRC GCRF ES/T002964/1 and the University of Southampton UKRI ESRC IAA.
