Thursday, December 9, 2021

Will Marine Life Struggle in Warmer Water?

Stepping Stones

Photo by Bob McConville


It’s no secret that we live on an unstable planet. The Earth is continually undergoing transitions from warmer to cooler temperatures and then back again. Even George Washington experienced a “little ice age” and, because of his outdoor knowledge as a surveyor, he used this weather to escape capture from the British.  

Now, the planet is warming and also spinning faster. It is adjusting and will continue to do so long after we are gone. For the short term, though, warmer is the word, and it’s not just the air temp, it’s also the water. A change from cooler to warmer water, and vice versa, means a change has to be made by the plants and animals living in it. 

Ecosystems around the globe will be affected and species that rely on their prospective environments will need to adjust their biological processes… or perish. Many animals are “ectotherms” and must match their body temperatures to the environmental conditions. 

A great example locally would be alligators. You see them in the water when they need to cool down, and on land when they need to warm up. They need a body temperature of about eighty to eighty-two degrees to be able to do all that is necessary for their survival. 

Also, sea turtles depend on temperatures to have both males and females hatch. The warmer the sand becomes, there will be more females and less males. That could lead to a reproduction issue in the future. 

Some shark species along the Great Barrier Reef can tolerate climate changes very well, but the warming waters may take a toll on those plants and animals that don’t adjust as fast. One of the shark varieties on this Reef is the Epaulette shark, which has adjusted well with minor temperature changes. 

It is estimated that ocean waters could have an increase in temps of four degrees by the end of this century. In a lab setting with warmer waters, the Epaulette embryos hatched earlier, were born smaller, lacked energy but needed to feed immediately. The young emerged from the egg cases in one hundred days in the lab, while the current incubation time is one hundred twenty-five days. 

There are a few scenarios for the future of these sharks. First, they could find colder water, but the habitat would need to be right for them. Second, they might genetically adapt to the change in climate but that might be unlikely because they reproduce at low rates and do not grow quickly. Last, they could become extinct; disappear from the Earth, like so many species are currently doing. 

Why is this important? When sharks, which are apex predators, change their behavior it affects an entire ecosystem. If they are not around to feed on the next level of prey below them, then that level has a population explosion that will deplete the next level of prey below them. There is a balance to Nature and if it becomes unbalanced then the entire spectrum of predators and prey becomes unstable and drastic change is inevitable. 

It may not seem important to us, since the Great Barrier Reef is in Australia, but this is just an example. Closer to home, Florida’s reef system is the third largest coral reef in the world. Think about that. Do you feel that changes will take place in our own state? It already has, but that’s a story for another time!!! 

Bob is a Naturalist for the 10,000 Island Dolphin Study Project on board the Dolphin Explorer. He is also an owner of Wild Florida Ecotours which gives guests a chance to explore the western Everglades’ ecosystems from Port of the Islands. Bob loves his wife very much! 


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