Back it up. Back it up.
Florida’s Crystal River is a hot spot for
manatees and for researchers trying to capture
a better understanding of these massive marine
mammals.
Drop that net. Drop that net. So if you’re
on the left side of that manatee you’ve
gotta get on the other side of the stretcher
here.
Manatees are vulnerable to environmental changes,
human behavior, and low reproductive rates.
Since their listing as an endangered species
in 1967, federal laws have helped the population
rebound from a few hundred in the 1960s to
an estimated 6,000 today.
That comeback spawned proposals to cut the
manatee’s status from “endangered” species
to “threatened.” But with this apparent
success come questions.
What biological criteria define a healthy
manatee population today? And will Florida’s
habitats and food sources be enough to sustain
the growing population in the future?
In steady pursuit of the answers, researchers
are using everything they’ve learned up
to today to predict what manatees will do
tomorrow.
Major funding for this program was provided
by the Batchelor Foundation, encouraging people
to preserve and protect America’s underwater
resources. And by Divers Direct/Emocean Sports
inspiring the pursuit of adventure and water
sports. And by the following In Memory of
Harriet Fagan, the Do Unto Others Trust, and
the Friends of Changing Seas.
Sailors of olden days thought they were the
mythical sirens of the sea… while others
dubbed them sea-cows because of their gentle,
slow-moving nature. Manatees and their cousins,
the dugongs, live in shallow tropical and
subtropical waterways from North and South
America… to West Africa… and the Indo-Pacific
region.
Paleontologists tell us that sixty million
years ago, the ancestors of manatees were
part of a super-order of mammals called Afrotheria,
which later became today’s manatees, elephants
and aardvarks.
Manatees and their closer relatives make
up the order Sirenia. Nearly fifty million
years ago, a sirenian called Pezosiren portelli
evolved, the animal scientists believe to
be an evolutionary link between land-based
creatures and ocean-going sea cows.
Ten million years later, the family tree branched
into the predecessors of today’s sirenians…
the Trichechidae, the manatees, and the Dugongidae,
the dugongs… and the Steller’s sea cow,
a species hunted to extinction in the 1700s.
Evidence of ancient manatees and dugongs is
preserved at the Florida Museum of Natural
History. Paleontologist Richard Hulbert catalogs
the fossil record
The skull and jaws of Metaxytherium, one of
the most common dugongs found in Florida.
It’s from a skeleton that’s about nine
million years old found here in Gainesville.
These bones and teeth are about a million
and a half years old. They come from just
a short distance south of Tampa on Florida’s
Gulf coast, some of the oldest manatee fossils
from North America.
Here is a skeleton of a modern individual
found dead in Florida about twenty years ago.
Modern-day manatees are branched into three
groups: the West African Manatee, the Amazonian
Manatee, and the West Indian Manatee, a group
that includes the Antillean Manatee, ranging
from the Caribbean to Brazil, and the Florida
Manatee.
During cool winter months, a group of Florida
manatees return to a favorite gathering place
warmed by the natural springs of Crystal River
National Wildlife Refuge on the state’s
west coast. Crystal River is a “resting
zone” for manatees, and a place with fond
memories for biologist Dr. James “Buddy”
Powell.
I grew up in Crystal River. And I probably spent as
much time under the water as I did over the water, growing up. So I’ve always been intrigued by marine
biology, and so forth. The water was gin clear
through the entire bay and it was a magical
place to grow up as a kid.
Powell was also intrigued by aviation, which
made him a perfect fit for the early manatee
aerial surveys.
In the early 70s, when we didn’t
know really where manatees were or how many, we conducted
aerial surveys in a little J3 cub airplane
flying from the pan handle of Florida up every
river, creek, bay along the entire coast,
all the way around to Savannah, Georgia.
It was always very exciting when we had a
manatee sighting because they were so few
and far between.
When we first started our work in Crystal
River, there were only about fifty, or so
manatees that would use that area. But as
time went on, that population has slowly increased.
Today, the Crystal River National Wildlife
Refuge counts an estimated population of 750
manatees thanks to its abundant food source,
low human habitation and long-term protection.
Crystal River is almost a mecca, for not only
manatees but manatee biologists because
all the conditions are right. You’ve
got lots of manatees that use this area, the
water is very clear. It’s like a giant laboratory.
We want to welcome you to this capture. I
think this is the one that’s going to give…
The number of people, it’s evident it’s
going to be the highest capture we’ve ever
had.
Research biologist Dr. Bob Bonde is part of
a group of scientists that began the Sirenia
Project in the mid-1970s, a program for long-term
study of the life history, population dynamics,
and ecological requirements of the manatee,
and for outreach to other countries with Sirenian
populations. Bonde is the director and leader
of the program’s capture and assessment
teams at Crystal River.
We realized there was this opportunity to
learn about what’s going on with the health
of the manatees in the population, and so
the initial thrust of this was to determine
what constituted a healthy manatee in Crystal
River.
Back it up, back it up.
Researchers, like Michelle Davis, collect
biological samples to study the health of
individual manatees.
The health assessments at Crystal River are
a big event. We go out and we net the manatees
and we bring them up on shore.
The most exciting part is when that first
manatee comes up.
You think about it, you’re taking a 1000
to 2000 pound animal out of its environment,
and so we have to restrain them and it gets
physically difficult, and if you’re in the
wrong place at the wrong time you could be
injured.
Drop that net, drop that net. Alright come
down. Reverse it. 1,2,3 up. Turn. Little steps
guys, little steps. Keep going. Keep going.
Turn the head. Stop.
1,2,3…Spin the head. Almost there.
We want to try and work quickly and not keep
them out of the water for a long period of
time.
331
We do lengths and girths…
71. Can you call out breaths if you see them, please?
...and weight.
1012. Help him down.
We take all sorts of biological samples.
We draw blood from the animals, we pit tag
them, we take biopsies… we look at the skin…
we evaluate the world and the microcosm that
lives on the skin of the manatee because the
manatee is a floating island, it’s full
of all kinds of really interesting things. You
can see the barnacles on their bodies, which
is an indicator that they’ve been out in
the marine environment, and now they come
into the freshwater to take advantage of the
warmth.
Over the last decade, more than two hundred
manatees have been captured and examined at
Crystal River in a quest to evaluate the fitness
of the population and determine normal health
ranges and reproductive rates for the species.
That’s better. Much better.
During one examination, a developing fetus
is discovered.
Manatees, as far as we’ve studied, have
really good immune systems. They’ve been
around for millions of years and I think that
they’re pretty hardy.
The clear water and large number of manatees
at Crystal River make it easy to capture and
examine the marine mammals. But in other parts
of the world, murky waters and elusive animals
make manatee sightings a difficult task.
…but everything is being spun though? One
of the greens is not being spun.
Dr. Margaret Hunter, research geneticist with
the US Geological Survey, is pioneering the
adaptation of environmental DNA, or e-DNA,
for manatee detection.
This is really the epicenter of manatee genetics.
We’ve worked not only in Florida to a large
degree but also looking at genetic samples
from Puerto Rico, Belize, Brazil, all across
the range in Africa, the Amazon manatee. We
work with the cousin of the manatees, the dugong,
looking at population structure and helping
with the conservation of these species.
Environmental DNA is a method that we use
to detect wild animals without having to visually
identify them in nature.
It’s a unique tool, it’s evolved, that’s
allowed us to, in a forensic way, look into
their biology with even more intensity than
we can do with our eyes.
Environmental DNA is found in water, soil
and air. Manatees shed DNA into the environment
through excrement, saliva and loss of skin
cells. Small fragments of manatee DNA can
be found in water samples collected from the
animal’s habitat. It’s a tool that can
identify specific waterways for more intensive
monitoring.
We did this in Cuba, they actually went to
the Guantanamo Bay and there’s the Guantanamo
River and the first detection of DNA that
we had for manatees in the Guantanamo River
were fragments of the DNA that came up positive.
A large part of it is a great challenge. We
have to collect a lot of samples, and a large
enough volume of water to be able to detect
the DNA within the water. Our current protocol
is to collect 1 liter of water, and we collect
replicates so that we can increase our confidence
and our statistical information.
We’ll take a water sample and add preservative
to be able to preserve the DNA that’s within
this water sample. Then we will chill these
bottles down on ice and take them back to
the lab for processing.
The US Geological Survey Wetlands and Aquatic
Research Center in Gainesville, Florida is
leading the study of manatee habitats by analyzing
water samples for manatee DNA.
The water is poured through a filter to collect
the DNA, then chemically treated to purify
the DNA from proteins and other substances.
The DNA is concentrated in a centrifuge, then
chemically treated to purify the DNA from proteins and other substances.
Digital Polymerase Chain Reaction, or digital
PCR, is a process that amplifies environmental
DNA to visualize or quantify it within the
sample.
DNA is very small, it’s molecularly tiny
and so we have to replicate it or copy it
many times to be able to see it.
This is similar to a photocopier. It’s an
exponential amplification. So if you have
a single copy and then you put it into a photocopier,
you’ll have two. And then you can put that
back in and you’ll have four. And so this
continues over and over and gives us a large
enough amount of DNA to be able to visualize
it on our equipment.
DNA analysis has revealed troubling issues
about the genetic diversity of the species.
Manatees have been shown to have extremely
low diversity on par with other critically endangered
species. You don’t have the genes and the
diversity needed to battle diseases. It can
possibly lead to an extinction vortex, which
is continuation of loss of individuals which
leads to smaller population sizes and that
leads to more inbreeding which then repeats
itself and can potentially severely harm a
population.
Researcher Michelle Davis focuses on genetic
projects that analyze manatee relatedness,
inbreeding and parentage.
There was a founder effect in Florida, where only
a few manatees came and founded all of Florida.
It created this large population and then
there was a population bottleneck where the
population was really big, it came down to
a smaller population and then it expanded
from there. And so there is low genetic diversity.
So everybody looks like they’re related
based on the diversity, but they’re not
actually like brothers and sisters. They’re
averagely related at the level of first cousins.
If you go out and sample, usually about one
in five would be related at the level of half
siblings.
While running one genetic analysis, researchers
made a discovery. The first documented case
of what appear to be identical twins found
in the wild.
And so we reran them to make sure that we
had analyzed it properly and hadn’t made any
mistakes in the laboratory, and found that
they came back as being identical again. And
so we went and looked at their sample names
and matched it to our photo identification
information and found that they were two different
animals with different scar patterns, but
they had the same exact genotype and the same
genes.
Scar patterns are the physical evidence that
help wildlife biologist Cathy Beck track the
life story of individual manatees.
Some of the manatees that we were seeing at
Crystal River had marks on them that were
distinguishing, unique features that we could
use for identification. So initially, we were
just going out and taking photographs and
we had a shoebox. Literally, a shoebox of
photographs on a bulletin board.
We outgrew our shoebox real fast and our bulletin
board and had to come up with some sort of
computerized database and it 's evolved to
what is now the Manatee Photo Identification
System, MIPS for short.
Half a million images are cataloged in the
database. Each photo documents the history
of an individual, gives information on the
status of the species and helps estimate adult
manatee survival over time. Although they
are a protected species, the majority of Florida
manatees suffer from trauma caused by boat
propellers, rope or fishing line entanglement,
and cold-water exposure.
Usually, by the time a manatee is an adult,
we find some kind of mark on it. I’m hard
pressed to find an animal that doesn’t have
some kind of feature that we can use for identification.
Most of the features are a result of an encounter
with a boat, but not all.
This animal in particular had a pretty severe
boat wound and you can see an actual deformity
here where the bone underneath is trying to
heal and it’s cauliflowering out. This wound
healed to have a feature now that is still
identifiable. It’s survived and it’s still
out there. This is our catalog of survivors.
Looking at pictures of scarred animals day
after day after day and especially calves
with fresh hits is hard. You have to remove
yourself from what you’re actually seeing
and what the animal is no doubt suffering
Is that affecting their long-term survival?
Does that shorten their life span? Does it
affect their reproduction? Right now manatees
in Florida seem to be doing well and it doesn’t
seem like that’s the case but long-term
trends, we are still gathering that data.
The Manatee Photo ID System can help identify
manatees that venture far from Florida’s
waters like one from Miami that showed up
in Cape Cod, and a female from Crystal River
that ended up on the north shore of Cuba.
Recent studies have documented an expansion
of the population into north Florida… and
along the Gulf coast to Alabama and Louisiana.
eDNA is really important in this study to
potentially identify where manatees are in
this migration and where we can find them.
We believe it’s based on the population
expansion and that there are now enough manatees,
that they're seeking additional food resources
in the summer. And then as it gets cooler,
in the winter, they return to Florida, to
overwinter in our natural springs, which hold
a constant temperature, and allow them to
survive the colder temperatures.
Sustained water temperatures below sixty-eight
degrees can cause life-threatening hypothermia
in manatees. And as creatures of habit, they
return to the same warm water sources year
after year.
But scientists believe as many as seventy
per cent of Florida’s manatee population
is dependent on artificial sources of warm
water produced by coastal power plants. It
is thought that these warm water “stepping-stones”
around the state have helped the manatee population
expand its numbers and range. But now, power
companies are gradually converting their plants
from oil to natural gas, a cleaner fuel, but
a process that cuts the warm water flow.
They’ve got to tear down the plant for about
three years to rebuild it as they shift to natural gas.
Well during that time, the warm water disappears.
And so one of our projects has been to tag
manatees that come into these plants to find
out what they do when there’s no warm water.
What Florida Power and Light has done is actually
installed giant heaters that if temperatures
really drop, they’ll turn these heaters
on just for manatees, to keep them warm…
to ensure that this…species that has largely
become dependent on the warm water from the
power plants has sanctuary even as they’re
making this change and this transition.
If you flip a switch at a power plant
and it’s not strategically done and it goes off, you’re
going to have a lot of dead manatees if they
don’t have any other options.
With the potential reduction of artificial
warm water sites in the future, spring-fed
habitats like Crystal River could become even
more important for long-term manatee survival.
If you have a thousand manatees now and in
ten or twenty years you have two thousand
or four thousand, is there enough vegetation
out there? Is there enough carrying capacity
and habitat for those manatees to live comfortably?
Those are the kinds of fundamental questions
that we’re anticipating that we’re going
to be able to answer in the future.
As researchers continue to document the biological
data that characterize a healthy manatee today,
scientists from around the world are adopting
the techniques developed at Crystal River
to evaluate and conserve their own manatee
populations.
Wherever we work we try to work with the agencies
that have responsibility for this species,
as well as trying to recruit students and
biologists that we can help train and mentor
because they’re the ones who are going to
leave a legacy behind when we’re no longer
working there.
The common denominator is right behind me,
and that’s the animal that brings us all
here, and we’re all trying to do something
for that animal.
The more that can be done for the manatee
today, in understanding its health and habitat
needs, the more realistic are the possibilities
for the future success of the entire species.
1,2,3 slide. Hand it off. 1,2,3 slide. 1,2,3
slide. Okay, hold the stretcher, and we’re
good.
Major funding for this program was provided
by the Batchelor Foundation, encouraging people
to preserve and protect America’s underwater
resources. And by Divers Direct/Emocean Sports
inspiring the pursuit of adventure and water
sports. And by the following In Memory of
Harriet Fagan, the Do Unto Others Trust, and
the Friends of Changing Seas.
