Sharks Unknown with Jasmin Graham

This summer, an unprecedented ocean heat wave swept the U.S. coast in July, a possible record breaking 101 degree Fahrenheit temperature was recorded off the coast of south Florida.

That's more than 15 degrees higher than average.

And basically the temperature of a Jacuzzi warming water can have major impacts on marine ecosystems, ranging from events such as coral bleaching to the stressing of cold blooded marine animals who are sensitive to changes in temperature.

So I went to Jupiter, Florida, to see how this extreme weather event is impacting sharks.

I went out into the Gulf Stream, Atlantic Ocean, with a few experts.

Meyer, the host of PBS's Taras Weathered, which explores climate systems.

Hanna, the founder of the American Shark Conservancy, an organization created on the premise of collecting scientific data with the help of community members.

And my friend Deb, a scientist who's been working for several years with Hanna to track shark populations off the coast of Jupiter.

Before we set out, Meyer broke down the Gulf Stream.

The Gulf Stream is an ocean current that acts as the primary heat pump for the North Atlantic Ocean.

That's because the Gulf Stream is a part of a system of currents in the Atlantic Ocean known as the Atlantic Meridional, overturning circulation or AMOC.

This system cycles water between the surface and the ocean floor.

The amount transports warm tropical water to the North Atlantic Ocean, where it eventually cools and becomes denser, leaving cooler saltier water, which sinks due to its increased density and travels down towards the ocean floor.

That water then flows back to the south, where it will eventually warm up again as this cycle continues.

And it's this process that makes the Gulf Stream what we call a productive area for sharks.

We're actually sitting in the Gulf Stream right now, which is a place where a lot of sharks gather.

There is colder nutrient rich water coming up in what we call upwelling to the surface.

And so there's a lot of plankton that are feeding on that nutrients and then fish feeding on the plankton and sharks feeding on the fish.

So ocean temperatures change all the time and certain parts of the ocean are naturally warmer like the Gulf Stream.

So how is an ocean heat wave different?

A marine heat wave is a distinct phenomenon characterized by unusually high ocean temperatures in a particular region, particularly including areas affected by the Gulf Stream.

It's defined by when the ocean temperatures are warmer than 90% of the previous observations for a given time of year.

And according to the National Oceanic and Atmospheric Administration, this heat wave would have likely still occurred without climate change, but is warmer and more intense because of climate change.

My main concern is how sharks are going to be able to cope with these extreme temperatures as they become more prevalent.

What is the work that you're doing out here on the ocean?

So we're going to be getting in the water snorkeling.

We're going to count what species are present.

We're going to use the six laser beam system to be able to measure the sharks from a distance.

But we also take account of like what the temperature is when we're doing the surveys, what the dissolved oxygen is, what the salinity is.

And those factors are important because over time, you can pull them up and see if any of that has any effect on what charts we've seen.

And we can tell also on the behavior of the sharks as well.

Our plan is to compare today's outing with outings that Hanna and Deb have conducted in previous years to see if there's a difference in the number of shark species present as a result of this ocean.

Heat Wave.

Water temperature 86.04 degrees Fahrenheit.

Persuading for some sharks to come up and it is really high.

I've been doing these surveys specifically this summer.

I did overall like four different surveys last few months.

And this is the first time that we've had a reset.

Like three times have been really hard for us to grab sharks.

Of course, there's different factors involved in It's the ocean, so you never know what you're going to get.

But I do think this excessive heat wave is playing a part into the sharks, go into maybe deeper water.

Haven't gotten sharks up yet, but it is hot.

I wonder how the sharks must feel because the water is also warm too.

Yeah.

I would hate to be a cold blooded critter right now.

That's probably why they're not coming up right now.

Yeah, yeah.

They're probably somewhere Culver, which is where I would be too.

Sharks and almost all fishes are active burns.

If the water is too warm, it can negatively impact the enzymes they use for digestion and other organ systems, which in turn can affect growth and reproduction in addition.

Warm water contains less dissolved oxygen than colder water, which also stresses the fish out in this unprecedented ocean heat wave.

We're likely going to see the pelagic shark species, those living off the coast, going into that deeper, colder water in order to maintain their internal body temperature.

So they won't be spending as much time at the surface because the surface water will be slightly warmer than the deeper water, which isn't getting as much exposure to sunlight.

So we working on it.

Three Being in the water.

I'm not sure you guys have fun.

We saw a silky shark that had a fishing line wrapped around its tail and it was more than 50 feet.

And Hannah, one of the divers, are in the water with us, was able to snag it off for seeing these fishing lines getting wrapped up in them.

That's just like another way that we can tell with our surveys how we can keep track of information of like how these sharks are getting impacted by humans.

Some of the sharks, we see hooks already in their mouth.

Some sharks, we see propeller cuts in their tails.

Doing these studies.

In these surveys that we have, we can look at real life physical evidence of impacts that humans are having.

We were out pretty deep today and we were seeing some temperature differences from normal.

Yeah.

I'm wondering how extreme those temperatures are in the shallower mangrove coastline environments.

Are there are there mangroves around here?

Yes.

So a lot of our Intercoastal Waterway has really good mangrove habitat and it's definitely a great nursery area for different species of fish, including different species of sharks.

Oh, so maybe we could go check that out.

Yeah, I'm down.

Let's go do it.

Mangrove forests are important.

Shoreline habitats.

They're made up of different species of mangrove trees which have roots that lead into the water.

These roots are often used as hiding places for small juvenile fish and sharks.

The trees also serve as a barrier against storms and help prevent erosion.

Wow.

This spot's really cool.

It's really neat to be.

Held over here and checked out of potential baby shark nursery with my own little baby shark in my belly.

While hopefully not a baby shark, hopefully a baby human.

I wonder with my ears, he's collared mangrove habitats.

I mean, it is a perfect place to raise a baby human for nine months.

I love the mangroves.

I get to spend a lot of time in the mangrove shorelines because a lot of our starfish nurseries are in mangroves.

It is a perfect location for a baby shark, lemon shark, bull sharks, tiger sharks.

So yesterday when we did the survey, we were able to look at human impacts there from the heat wave that's occurring right now.

That's like the one factor that I realized know from our survey yesterday that this excessive heat wave is causing a change in behavior in the sharks.

And then today, I took Jasmine to a potential shark nursery, some mangrove habitat where baby sharks like to hangout in.

And we were able to take the dissolved oxygen, the temperature and salinity of that mangrove habitat temperature.

30.7.

Ms..

Pretty warm.

So we can kind of correlate to how is the water in the mangroves where baby sharks are born and they like to grow up in and mature versus how warm the water is in the ocean.

Just looking at the different impacts of humans in a nursery and compared to the open ocean.

For our surveys yesterday, I am doing my two and a half months and there's no other place I'd rather be than the ocean.

It's really cool being able to do this as a woman as well and just showing people that like, it doesn't matter if you're female, it doesn't matter if you're pregnant.

Like if you want to do something, you can do it.

I started working and doing stuff in marine conservation and that's kind of like what jump started everything.

Getting involved in an organization who have like women and shark science and minorities just like me.

I was like, This is amazing because for so long you think you're alone.

You think you're just the only one who wants to do this.

And you know, if anyone wants that in marine biology, they can.

It doesn't matter where you're from.

And hopefully one day my daughter will, you know, watch these videos and just see how awesome that women can be.

And if she wants to do anything, she really can.

So nice to be out here.

This sharks are millions of years old, meaning that they've had millions of years to evolve and to adapt to change.

But with change happening on the ocean so quickly in a matter of decades versus millions of years, it's unfortunate that they may not be able to adapt that quickly.

It's still too early to tell how climate events like this ocean heat wave will impact marine life long term.

But Deb Hannah and their team will be studying shark populations off the coast of Jupiter for years to come and advocate on their behalf as the climate changes.

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