The discourse and attention surrounding ecosystem conservation often focuses upon coral reefs and rainforests. Now this is with good reason, both are vital to the health of our planet, and are in decline for a multitude of reasons. The importance of these two however, does not detract from the value of other, perhaps less aesthetically pleasing, ecosystems. Wetlands (e.g. swamps, salt marshes and mangroves, among others) are often shunned for their stagnant smell and association with bugs, yet they have countless valuable ecosystem services. Ecosystem services are the direct and indirect benefits an ecosystem provides to humans. While ecosystem disservices are the real or perceived negative impacts of an ecosystem upon humans. Here in Bimini we are surrounded by coastal wetlands, in the form of mangroves and seagrass meadows. Every day at the lab we come into contact with these plants; from docking our boats amidst the mangroves, to swimming with the sharks that feed in the seagrass meadows. The management and conservation of these habitats is of great global importance, it does, however, require a multifaceted approach in order to maximize success for both the habitat and the people who live around it.
Through the mangrove maze. Photo by Wyatt Albert © Bimini Biological Field Station
If you have followed the work of The Shark Lab for a while, you will know we often talk of mangroves for their importance as a nursery site for young lemon sharks (Negaprion brevirostris), but their value comes from so much more than just this. Mangroves offer many ecosystem services; commonly categorized into provisioning, regulating and cultural services. Provisioning services refer to the physical resources gained from mangroves, e.g. fish and timber, these tend to be the easiest to assign a monetary value to. Regulating services indicate ways in which mangroves sustain healthy environmental functions; for example, providing safety to countless fish species, since their dense network of roots is inaccessible to larger predators. This root network also acts as a large net, catching sediment carried with the current before it’s lost to the ocean, limiting coastal erosion. Mangroves are also a natural coastal defence, the trees creating friction for the waves, forcing the energy to dissipate, buffering the coastline. Finally, cultural services encompass recreation, tourism, religious importance, and educational values - these can be the trickiest to assign value, but are often deemed some of the most valuable by stakeholders (Moore et al., 2022). Here in Bimini, tourism is the primary economic driver, with marine ecotourism increasingly popular and providing jobs to many locals. Shark dive tourism contributes a huge $117 million per year! Without healthy mangroves, the incredible diversity of life in our waters would plummet, as would the associated industry.
Juvenile lemon shark (Negaprion brevirostris) passing a red mangrove tree. Photo by Wyatt Albert © Bimini Biological Field Station
While highlighting, and studying, the benefits of mangroves can be vital in encouraging conservation, it is important to also consider negative impacts and perceptions. In the case of mangroves, these disservices often refer to odour, danger, the presence of pests and subsequent vectors of disease (Friess et al., 2020). Here in Bimini, a prominent negative perception is that mangroves are an eye-sore, blocking beautiful condos from their sea views. It is understandable for homeowners and holiday makers to want to see our iconic blue waters, but solutions, such as designing raised buildings, can accommodate both the mangrove health and the homeowners’ wishes. Historically, mangroves have been viewed as dark and gloomy, and as a harbouring danger. While in many cases these fears are unfounded nowadays, they can still impact public perception of mangroves. Increasing education about the habitat, for those who live around mangroves, can be incredibly beneficial in reducing generational fears and improving perceptions. In areas of poor water quality mangroves can produce an awful smell, with the degradation of trapped marine debris and sargassum only adding to it. Whilst a bad smell is not the end of the world, the quality of life for those who live around it is definitely impacted. Development is the primary cause of mangrove loss, through direct land reclamation and removal of mosquito habitat surrounding development. Mangrove-dwelling mosquitoes can cause general irritation at their best and disease transmission/death at their worst. And while mosquito associated mortality rates have fallen massively over the last few decades, there remains a negative perception of areas that harbour them.
Lemon shark (Negaprion brevirostris) swimming through a seagrass meadow. Photo by Wyatt Albert © Bimini Biological Field Station
Seagrass meadows are perhaps less misunderstood than mangroves, but this might be in part because they are less thought about in general. Seagrass are flowering plants that create underwater meadows and sustain a multitude of marine life. Just like terrestrial plants, their leaves contain chlorophyll that needs sunlight to produce energy, seagrass meadows must therefore be in waters shallow enough for the sun to reach them. Seagrass meadows provide a home and food resource for a huge diversity of marine species, supporting thirty times more fish than sandy habitats. This is both a provisioning and a regulatory service, since the sustained biodiversity provides more fish for catching. 400 million people in the third world get ~50% of their animal protein from fishing grounds supported by seagrass. Despite covering 0.1% of the seafloor, seagrass are responsible for up to 18% of the organic carbon buried in the ocean (Cullen-Unsworth and Unsworth, 2018). Seagrass leaves also act as a filter, cleaning pathogens, bacteria, and pollution from the seawater - improving the habitat for all who use it. This process also cycles nutrients into the sediment, preventing excessive nutrients in the water column that can lead to damaging algal blooms. Many coastal communities rely upon seagrass for various cultural practices, studies of Pacific Island peoples described seagrass meadows as ‘fish gardens’. People of the Solomon Islands knot and braid seagrass leaves for good luck spells, shouting to seagrass spirits for a good catch (McKenzie et al., 2021).
The presence of seagrass meadows in shallower, intertidal waters means humans often come into contact with them; through coastal swimming, anchoring boats or walking beaches strewn with washed up leaves. While it is illegal to remove seagrass, some seaside holiday spots request special permits in order to ‘clean’ their beaches for the sake of tourists, at the detriment of the ecosystem. Traditional boat anchoring systems also tear up seagrass, fragmenting habitats, and despite protective legislation many boat-users continue the damaging practice. Protective rules, regarding beach cleaning and anchoring, are poorly upheld and often deemed overly restrictive by those involved - a viewpoint stemming from a lack of understanding of the importance of seagrass. While these are not technically ecosystem disservices, these negative perceptions can heavily impact management - since rules are no use without compliance.
Drone shot of a seagrass meadow with visible anchor scarring. Photo by Wyatt Albert © Bimini Biological Field Station
In many cases, factors can modulate seasonally between being perceived as a service or a disservice, often being subjective and based upon which stakeholders are in question. Creating management strategies that account for the full array of services/disservices can be a bit of a juggling act, but the results are likely to have greater success rates than those that simply ignore negative perceptions. Understanding the perceptions of those who interact with mangroves and seagrass is the first step in conservation. Education is often one of the best solutions initially, but actions can’t end there.
Bimini’s mangrove-covered coastline. Photo by Wyatt Albert © Bimini Biological Field Station
Cullen-Unsworth, L. and Unsworth, R., 2013. Seagrass meadows, ecosystem services, and sustainability. Environment: Science and policy for sustainable development, 55(3), pp.14-28.
Friess, D.A., Yando, E.S., Alemu, J.B., Wong, L.W., Soto, S.D. and Bhatia, N., 2020. Ecosystem services and disservices of mangrove forests and salt marshes. Oceanography and marine biology.
Ho, Y.S. and Mukul, S.A., 2021. Publication performance and trends in mangrove forests: a bibliometric analysis. Sustainability, 13(22), p.12532.
McKenzie, L.J., Yoshida, R.L., Aini, J.W., Andréfouet, S., Colin, P.L., Cullen-Unsworth, L.C., Hughes, A.T., Payri, C.E., Rota, M., Shaw, C. and Tsuda, R.T., 2021. Seagrass ecosystem contributions to people's quality of life in the Pacific Island Countries and Territories. Marine Pollution Bulletin, 167, p.112307.
Moore, A.C., Hierro, L., Mir, N. and Stewart, T., 2022. Mangrove cultural services and values: Current status and knowledge gaps. People and Nature, 4(5), pp.1083-1097.