FSO Safer: Environmental risks (Coastal wetlands)

Coastal wetlands play an important function as habitats. An Oil spill will endanger that.

L Brown

Oct 18, 2022

[NOTE: Many of the findings related to the environmental risks described below are derived from the Greenpeace briefing paper “FSO Safer: A Shipwreck In Slow Motion”, which in turn draws a lot on an article in Nature by Benjamin Q. Huynh et al called “Public health impacts of an imminent Red Sea oil spill.”]

Guardians of the Coast

The Red Sea is home to 100 kilometres of the world’s northernmost mangrove forests. Sometimes referred to as “Guardians of the Coast”, this is a phrase that could also be applied to its Seagrass Beds; the two combined make up the region’s Coastal Wetlands.

Mangroves

These are tough, tropical trees which can grow in environs many other plants cannot. Able to withstand less ideal conditions such as salty water and ever shifting tides, they are an important habitat for nascent fish, various flora and fauna, regulate carbon dioxide and salinity, filter out water contaminants, provide shelter and food for a lot of other species, and protect the coast from storms.

Seagrass Beds

Not to be confused with seaweed, these plants play a fairly similar role to their above-water counterparts, the mangroves. Providing food and shelter to an array of creatures in the water, they produce flowers and seeds, and have roots, veins and leaves like other plants.

Risks from an Oil Spill

As described in the Greenpeace briefing paper:

In addition to the general positive characteristics described above, the Red Sea’s coastal wetlands also provide an important habitat for mammals such as dugongs and marine birds.
Bucking global trends, the mangroves in the southern region of the Red Sea along the coasts of Saudi Arabia and Yemen, have actually increased in size and scope since 1972, currently covering an area of around 120 square kilometres.
Out of the 60 species of seagrass found globally, 12 appear in the Red Sea and provide that important habitat function for dugongs, turtles and fish. But they are already at risk from the march of coastal development, ever present pollution and climate change. An oil spill would be “highly destructive”.

Particular key risks posed by an oil spill to coastal wetlands, as detailed by the invaluable online resources of the National Oceanic and Atmospheric Administration’s Office of Response and Restoration, are:

Mangroves are highly susceptible to oil exposure; oiling may kill them within a few weeks to several months.
Lighter oils are more acutely toxic to mangroves than are heavier oils. Increased weathering generally lowers oil toxicity. However, heavier oils can result in substantial physical smothering and coating impacts.
Oil-impacted mangroves may suffer yellowed leaves, defoliation, and tree death.
More subtle responses include branching of pneumatophores, germination failure, decreased canopy cover, increased rate of mutation, and increased sensitivity to other stresses.
Response techniques that reduce oil contact with mangroves, such as offshore use of chemical dispersants, reduce the resultant effects as well. Tradeoffs include potential increased toxicity to adjacent communities, and increased penetration of dispersed oil to mangrove sediments.
The amount of oil reaching the mangroves and the length of time spilled oil remains near the mangroves are key variables in determining the severity of effect.
Mangrove-associated invertebrates and plants recover more quickly from oiling than do the mangroves themselves, because of the longer time for mangroves to reach maturity.
Under severe oiling conditions, mangrove impacts may continue for years to decades, resulting in permanent habitat loss.

In the next, and final, post on the environmental risks posed by the Safer, we will examine Ecosystem-wide risks.