(water sloshing) (gentle music)
- My name is Alex Moore, and I am a NSF postdoctoral fellow.
I do research looking at coastal wetland ecosystems
and community dynamics within those ecosystems
to help inform restoration and conservation.
I think that people often think about natural space
as being separate and very different
from the spaces where we live in urban centers
and so people often themselves think of themselves
as being very removed from these natural spaces
and things that are less built by humans.
And so I think, at least in my work,
I try to think about the value
that both of these spaces hold separately and then, also,
the ways that we can have these spaces
be integrated together.
Historically, restoration has focused on the science.
We go out, we see the space, we see what it needs,
and we just decided to fix it
in the ways that we deem best.
That often excludes the people who live in those spaces
and are impacted
by the availability and access to those resources.
And so what I'm trying to do is make sure, in my work,
that I'm paying attention to the science
and my approaches to it,
but also making sure that I'm talking to people,
thinking about what matters to you,
how have you historically used this land,
what are the ways that we can take all of that knowledge
and combine it together so that we restore it
in a way that's healthy and sustainable.
Also, not only for the landscape,
but then also for the people who live across that system.
Since roughly the 1800s,
we've lost about half of the world's global wetlands
and so, we've lost them for a number of different reasons.
We usually see lots of land conversion,
so something that was a wetland
is typically converted into something like agriculture
or an urban space, like a city.
We also have lost them due to climate change
and the associated sea level rise.
So as those sea levels do increase
the extent of the wetland decreases over time
because it can't maintain itself
along those coastal regions.
And we've also lost them
just due to taking out really important species
that you find within them.
Wetlands are incredibly important ecosystems.
They have a number of values associated with them,
both in terms of what people get from them
and also the services that they provide to people
just by their existence.
When coastal storms occur,
having wetlands there can help buffer the damage
that communities that live in those spaces might influence.
They're also really important recreationally,
people love to go fishing and wetland spaces.
They're also important as nursery habitats for other species
or things that might be important economically,
so shellfish and other different areas of economic sector
also rely quite heavily on wetland ecosystem.
So the uses of them are quite broad
and those are just a handful of things
that people get from them.
So one of the general ideas around restoration
that has been quite strong
in a lot of different ecological spaces
is this idea that if you build a habitat,
so if you make sure the soil is there,
if you plant some trees, if you plant some grass,
if you build it, species will come back to that space.
With this if we build it, they will come idea
we're really focusing on the bottom.
We're building this habitat,
we're building physical structures
and we're saying the top-down elements,
or the species that interact with each other,
will come all on its own over time.
That bottom-up approach gives us certain level of recovery
and then we kind of flatten out over time.
And so the average here is that restored wetland ecosystem,
where you're really focusing
mostly on recovering these physical components,
tend to function roughly 30% less well
than a natural ecosystem
that hasn't been degraded or damaged in any kind of way.
So, we are seeing this gap
in terms of what level of function we see
in a restored wetland versus a natural, healthy wetland.
My interest lies in filling that gap, essentially,
as thinking about
we have this gap in terms of the restored wetland,
what its level of function is,
a healthy wetland, its level of function.
We know that they're different and so my research
is really trying to fill that gap a little bit
and thinking about,
well, maybe the reason that we're not seeing
the kind of recovery that we're hoping for
is because we're not thinking about other elements
that are also important within that ecosystem.
So thinking about these top-down elements,
thinking about these different species
that play specific roles,
maybe we should be incorporating them into the restoration
to get better recovery of ecosystem functions.
For me, when I talk about ecosystem functions
within wetland systems, I'm thinking about nutrient cycling.
So, nitrogen within the soil,
how is it moving from one form to another
so that plants can use it for their growth?
I'm interested in the rates of decomposition,
so if you've got organic dead tissue within the soil,
how is that being broken down
to make more nutrients available for other species?
I'm also interested in growth of vegetation,
so how much biomass are we seeing produced
over a period of time?
So, these are all functions that indicate levels of health
that you can compare to other historical points in time
or other areas that are known to be healthy.
And so, these are the functions that I'm most interested in
when I think about and work in these coastal systems.
So, I just want to give you a brief example
of how that might actually go within a coastal system.
Here is a very simplified schematic
of a salt marsh food web.
And so at the top, we've got a predator,
so this might be a blue crab, for example,
and then beneath it we've got potential prey.
So here, this is a Fiddler crab
or a herbivorous purple marsh crab,
and then beneath that
we can see the vegetation and the soil within the system.
So, in a situation where we remove this top predator,
so this might be because of recreational removal
or economic incentives to remove this species,
this then frees up its prey.
So it means that these prey species
are no longer concerned about being consumed by predators
and so they're able to eat their food and then reproduce
because they don't really have to worry about this control
coming from the top down
with this predator influencing their population size.
And once that happens, that means that they are now able
to consume their vegetation and so, in this situation,
what happens is you have all of these crabs,
they're now eating all of the vegetation
and it's being removed entirely from the system.
And depending on how intense this is, what this can lead to
is these species will now move to other places
because now there's no more vegetation.
They've now also consumed it to the point
where it's very difficult for it to grow back
and what you end up with is a degraded, lost ecosystem
where nothing's really productive
and it's not functioning very well.
So in my research, what I do
in terms of evaluating the impact
that consumers have on ecosystem function
is I manipulate the presence and absence of certain species.
And so for me,
that looks like going into these wetlands systems,
identifying certain locations, and then building these cages
that either allow me to remove certain species
or put certain species within those cages
and then measure the effects.
And so I'll know
certain cages have one combination of species.
Another set of cages
has a separate combination of those species,
and then comparing between
in terms of measuring soil quality,
looking at carbon storage,
looking at nutrients between those two different setups
can allow us to better understand
how different kinds of communities
might be influencing different levels of function
within those spaces.
The cage setups have been pretty simple.
So, the idea is that I typically have
three or four different experimental treatments
within each of the cages.
And so one of them might be
a situation where the predator is present
and the herbivores are present along with the vegetation.
One of the other cages
might just be that the predator is absent
and so, within that cage, you only see the herbivores
and their vegetation.
And then in other cages
we might only just see the vegetation
just to get a sense of looking at
if we remove certain species
and we measure the same functions
across each of these different cages,
what are the outcomes going to be
and what does this tell us
about the importance of those species?
And what we found
is that the removal of the predator from that ecosystem
had impacts on both vegetation growth over time,
and then also nitrogen availability in the soil.
So, having that nutrient available there
is important for vegetation growth.
And so what we found was that that species,
that predator, if you take it out of that system,
it has these cascading impacts on these functions
that are quite important for the health of that system.
And so we also saw that the species
that that predator was eating,
so the purple marsh crab and the Fiddler crab,
their presence also impacted both vegetation growth
and also soil nutrient availability over time.
So we know from these experiments
that these are really important species
and they play a role in levels of function
that might be really important
when we're thinking about
how to conserve and restore these spaces.
What we also saw was that the changes were not consistent
across all of the different locations.
So at one field site, we saw one change,
at another field site, we saw different changes.
And so what this means
is that the impacts that consumers are having
is not just if you do this one thing,
you will see this one thing everywhere
and so that's really dependent on the context, the area,
what's the history of the space,
what it's being used as right now?
So there's lots of variation there but the overall takeaway
is that the consumers are playing a role,
just that role looks very different across different sites
because historically ecologists have led with the idea
that bottom-up control is what's most important
within salt marsh systems.
So any measure of health and function
is being driven predominantly by the bottom up,
so by these soil factors, by nutrients,
by abiotic features like the tides
or other physical factors within that system.
It turns out, over time we've recognized more and more
that top-down factors, so thinking about these interactions
between different species
are also quite important for the health and function
of these ecosystems.
So, it's really not driven just from the bottom-up,
like we have historically been told
but rather we're seeing
a lot more top-down control happening
within these ecosystems,
which indicates that the both of them are important.
So a combination and bottom-up and top-down control
are really what is driving function
within wetland ecosystems.
When you are considering restoration work
within these certain spaces.
So in this case, in New England coastal salt marshes,
and you're trying to get
as much recovery as you can over time,
it could be really important to not only focus
on making sure that physical habitat is present and healthy,
but also incorporating species like the purple marsh crab,
like the Fiddler crab and also their predators
to help jumpstart additional recovery
and hopefully
you'll see that increase the level of function over time
once you add these top-down features back into the system.
Most research studies
looking at consumer impacts within wetlands
focus on salt marsh ecosystems.
And so that means
that we don't really have a good understanding
of how consumers might impact mangrove ecosystems
or seagrass bed system, so these other coastal ecosystems
that we also know are quite important.
And so in my work, what that means
is I put a pause on work within salt marshes
to really move into these spaces
where we haven't seen as much research done,
so that we can get a better understanding
about how these systems function.
So, I work now in mangrove ecosystems
and that's partially because of this gap
that I recognized from the literature review.
So, I recognized that we don't really understand
how mangrove systems are influenced
by consumer interactions.
And so for me, that really meant going out
and thinking about ways that I can expand my research
from these salt marsh spaces into these mangrove ecosystems.
And so now in my position,
what I do is I work within the Pacific Islands,
which are known for their mangrove habitats
and working in American Samoa
I do similar experimental studies
to see what impacts are being had
and how can we get a better understanding
of larger scale coastal ecosystem,
understanding of how consumers impact the function
by adding in the mangrove knowledge
into what we already know about salt marshes.
And so I'm doing these same experimental designs
where I have these cages, I remove certain species
or I include certain species
and then measure various similar functions.
So, thinking about soil dynamics,
thinking about growth of the vegetation,
so the trees themselves and how they function over time.
So trying to make sure
that my measurements are quite consistent
so that when we think about
adding these things all together,
we can compare across ecosystems
using very similar metrics.
So, whenever I'm thinking about the work that I do,
I'm also very aware of my identity and the roles that I play
within the different spaces that I enter.
And so right now, working in American Samoa,
I think that that stands out in a very unique way for me,
in terms of being a Black American citizen
working in this space that is an American territory
but the residents themselves are not US citizens.
And so the access and the privilege
and the resources that are available to me
are not available in similar ways
to most residents in American Samoa.
And so when I enter that space
I am very aware of the power and privilege that I have
because of my background and because of my identity.
So I find that it's really important for scientists
to be aware of their identity as they enter these spaces
and think about the ways that you influence the work
and how that, in turn,
can influence how you think about things
and walk through those spaces.
I'm always really interested
in thinking about the ways that we can help educate people
in terms of not only the science,
but also recognizing that science is influenced by people
and people are influenced by science.
And so whenever I give these kinds of talks,
I'm really interested in making sure that people recognize
that we do have the scientific information.
We have all of this background,
we have all of this research,
but all of it matters in the context of the people
who are being influenced by that work
and who have an ability to influence that work themselves.
And so I try to make sure
that science is given this more social component to it
so that we recognize that all of these other elements
are just as important.