Changement climatique

Imagine a Florida where the coral reefs have dissolved, droughts are the norm, exotic species outnumber native ones, daily high tides flood the streets of coastal cities, and people are abandoning multi-million dollar coastal homes and retreating inland. Climate change has made this hypothetical a reality for the Sunshine State, with impacts already being observed.

Florida is a highly developed state, with more than 70% of the population living or working along the state’s 1,197 miles of coastline. These coastal areas have always been threatened by hurricanes and flooding, but in recent years, a much more serious and long-term threat to the coasts has been identified: climate change.

How Will Manatees Be Affected?

A flotation device is positioned under a manatee suffering from red tide and awaiting rescue. Red tide acts as a neurotoxin in manatees, giving them seizures that can result in drowning. Manatees are mammals and must surface to breathe.

While some have suggested that increased ocean surface temperatures associated with climate change may benefit manatees, this view fails to recognize how the species may be affected by countless other consequences associated with climate change, including sea level rise, changes in seagrass abundance and location, and loss of funding as agencies shift resources away from individual species in an attempt to confront climate change. Manatees are part of an interconnected aquatic ecosystem and are affected by the health of the plants and animals that share this and the surrounding terrestrial ecosystems. As humans adapt to climate change, it is likely that other species, including manatees, will be adversely affected.

Manatees, as herbivores, rely on seagrass as a primary food source. Seagrass grows in shallow, relatively clear water. However, as sea level rises and is accompanied by increased turbidity and other impacts to water quality, seagrasses will likely be negatively impacted. Over time, seagrass beds may become reestablished, but major shifts in seagrass distribution and abundance could threaten Florida’s manatees, along with the many species of fish and invertebrates that also inhabit seagrass beds. With sea level rise, coastal habitats will also be threatened by “armoring,” as coastal towns and cities build seawalls and levees to deflect rising waters. Such human-made structures can be detrimental to benthic (water-body floor) habitats, including seagrass beds.

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Thousands of acres of seagrass in Florida have died because of nutrient pollution that has caused algae blooms and left manatees without an adequate food source.

As coastal habitats shift, manatees and boats may find themselves traversing new travel corridors that are not protected by manatee speed zones. Additionally, with a changing climate, manatees may extend their range farther north along the Atlantic Coast and west along the Gulf Coast. These adjacent states currently lack well defined manatee speed zones, and residents are not accustomed to sharing the waterways with manatees. Manatees will face increased risk if they inhabit waters that lack safeguards for their protection.

Residents rescue a manatee stranded by the storm surge after Hurricane Charley swept through Florida in 2004.

The frequency, intensity, and even composition of storms, such as hurricanes, will change with increasing land and ocean temperatures. Manatees may be killed, displaced, or suffer delayed effects to health and reproduction due to ecosystem changes resulting from intense storms. The magnitude of impact varies with the destructiveness of the storm, the density of manatees in the area, the number of storms within a season, or concurrence with other mortality factors. Storm surge, in addition to rising sea levels, may cause saltwater intrusion in certain freshwater aquifers and other coastal waters that currently provide sources of freshwater vegetation and drinking for manatees. Manatees will need to adapt to such changes in order to survive. More intense rainfall and inundation events may result in more frequent red tide events, which are fueled by fertilizer runoff into coastal waters. Red tide is caused by a population explosion, or bloom, of a single-celled marine organism called a dinoflagellate, which produces a neurotoxin that can be fatal to manatees and other marine life. Such events can be fatal to large numbers of manatees.

Perhaps the most challenging obstacle that manatees will face with a changing climate is a lack of financial resources dedicated to the protection of this species. As human priorities shift to disaster reduction, concern for wildlife may decrease, and agency funding may shift away from individual species.

What Can Be Done?

In order to protect manatees and Florida’s future, we must restrain our GHG emissions, stop building and rebuilding in Florida’s coastal high-hazard area, and educate ourselves about the potential impact of climate change on both our generation and future generations. Forests and wetlands must be protected because they act as carbon sinks, removing carbon dioxide from the atmosphere and helping to diminish greenhouse gas emissions. Healthy wetlands also help prevent coastal flooding, filter pollutants, and protect our shorelines from erosion. We need to invest in the health of our ecosystems because healthier systems will be more resilient against a changing climate. Every proactive step we take will help safeguard the future for manatees and ourselves.

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What do manatees do during and after hurricanes? Patrick Rose, Save the Manatee Club’s Executive Director, explains in this short video.