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thank everyone for the warm welcome
now i work in the ocean in the ocean is an alien world task
we sit on the shoreline
or sit on a boat and really get only a brief glimpses of what's really happening
so in my work I use and develop sonars that allow us to see beneath the surface of
the waves to explore the ocean using pulses of sound
when we do that we find that there's not a whole lot of food in the ocean on
average even the coastal ocean which we think of as a really
rich habitat
contains an extremely small fraction
of that which is really food
let me put that in terms that you might understand a little better
in the volume of this entire theater there would be one jumbo movie theater
of popcorn worth of food available to be eaten
of course it wouldn't be neatly collected in this bucket instead you
have to swim through the entire theater and pick off individual kernels of
popcorn or maybe if you were lucky you might get a few clumps
an additional challenge is that the popcorn wouldn't be sitting there
waiting for you to eat it of course, it would try to be avoid becoming your
dinner
and so this is the environment in which animals have to make their living
so I want to introduce you to some animals in the northern most part of the Pacific Ocean
the Bering Sea where we've been
working on one of the most important prey species there - krill
these half inch long
animals are about the
heavily buttered popcorn kernel equivalent in calories for these animals
but are food for everything from whales which take them in huge mouthfuls, to
sea birds and seals that have to pick these off one kernel of popcorn at a time
we went into this with an understanding of how we thought the world worked
and we did exactly what
people have been doing there for quite a long time
and mapped how many prey were in the ocean - how many krill and that's what you see here
the red colors represent lots of krill and the purple essentially none
Now, what you see is that around those northern two colonies where these animals
are breeding the two white circles it looks like a pretty fantastic place to
be
but the populations of predators on these islands are declining despite
decades of protection while
at the southernmost island at the bottom of the screen that little white dot
those populations are doing great while it looks like there's nothing to eat
so we had a dilemma
our way of understanding the world did not explain our observations
and so we started thinking about this a little differently and created a
different map of this habitat and instead of asking how many krill,
this map says how closely together are they, how densely packed are they
how many aggregations are they
and this gives you an extremely different picture of the habitat
and when we combine this with other things like how deep were those prey
it starts to explain our population observations
at a smaller scale however
we can ask the animals what's important to them about their prey by
putting tracking tags on individuals and looking at their behavior, looking at the
distributions of these animals at sea
and what they tell us is
the abundance of prey doesn't matter that the way we've always look at things
isn't right for them they see the world differently
it is really about how aggregated the prey are that determine their success
so patches, these aggregations are critical to how these animals are able
to make a living
in addition we're now learning that aggregations can shape entire ecosystems
We'll take you to a little bit of a warmer climate here for some work we get over
the slopes of the Hawaiian islands
physics and nutrients so the fertilizer in the ocean sometimes sets up these
really dense layers in the phytoplankton, the small floating plants in the ocean,
and when that happens the predators of these small plants aggregate just
beneath them and form dense themselves
which in turn affects the
behavior and distribution of their predators, these small two or three
inches long
fish, shrimp, and squid
and ultimately that has impacts on how spinner dolphins use the habitat and what
behaviors we observe in them
so these aggregations that set up in the plants affect what's happening three
steps away the food chain, and we can actually make some pretty strong predictions
about what we see in the dolphins just by measuring the plant life
which turns out to be about the easiest problem in oceanography
of course anytime we work in the ocean or with animals in general they have
something left to teach us, and
we've learned that spinner dolphins don't just interact with the prey as they find
it , they instead find the densest patch that they can
and then they work together to make it better.
And that's what you're going to see in this visualization. We have a group of about
twenty dolphins
that are basically bulldozing prey forward so that it accumulates on itself
and once that patch that they've worked together to
aggregate has become sufficiently dense, they start circling around it to
maintain that patch for about five minutes
then you will begin to see individual pairs of dolphins break off from the circle
move into it to forage before moving back to help maintain the patch for the
rest of dolphins in the group
and so not only can prey affect predators but
the predators can affect the shape of what we see in the prey field
so we started to ask
about by asking this question how do we animals go about making a living in what
seems like an incredibly challenging environment
and they've helped us to see that aggregations are really critical they've
given us a whole new way of seeing their world
when we look more deeply at the ocean we are given new insights and how we
interact with that ocean
and what we can do to effectively protect it. Thank you.