Life on Kachemak Bay: an everyday appreciation for one of Alaska's most diverse estuaries
Spring is around the corner, and snowmelt will soon be rushing into Kachemak Bay and Cook Inlet from streams and rivers along the Kenai Peninsula. The mixing of fresh and saltwater makes Kachemak Bay one of the most diverse estuaries in Alaska, stretching along 320 miles of shoreline.
KBBI’s Sean McDermott spoke with Kris Holderied, director of the Kasitsna Bay Laboratory, a marine research and teaching facility near Seldovia, to learn more about how the marine ecosystems of Kachemak Bay and Cook Inlet support the plants, animals and people who call this place home.
This interview has been edited for length and clarity.
MCDERMOTT: There was a recent social media campaign to celebrate estuaries nationwide. But here in Homer, it seems like something we should probably be thinking about every day. So I was hoping to start, could you help listeners understand the essentials of what estuaries are, and what that means for the Kenai Peninsula?
HOLDERIED: So estuaries are, in its simplest description, it's a place where salt and freshwater are meeting. And we care a lot about them because that mixing of salt and fresh — and they have kind of a usually a bit complicated shorelines and things like that, particularly here in Kachemak Bay and Cook Inlet are places that also make lots of locations for life.
Estuaries have very complex habitats, both for the water and along the shore that are great for a lot of life to grow. And so whether you're talking about the microscopic life in the water — the plants that fuel everything else in the marine food web — or you're going all the way up to whales and otters and birds, and you know, the fish that we like harvesting, estuaries are great places for all that life to get started and to grow.
MCDERMOTT: How does Kachemak Bay and Cook Inlet being estuaries, how does that shape what life looks like here? Both for people and wildlife?
HOLDERIED: We are lucky enough to be in a part of the Gulf of Alaska that is a very rich marine area. It's very productive. That happens because you have a lot of phytoplankton. So the microscopic plants of the water, that is the beginning of the marine foodweb, which then a little larger, microscopic animals eat, and then slightly larger ones, and then fish and then birds and whales. And some of the whales, of course, eat the plankton too.
Because this mixing of different waters, and this bringing of nutrients in the places where there's light, and where things are pulled together oceanographically —- between the runoff of the freshwater from the land and the bringing in of saltwater in the ocean — it just creates places where there's a lot of growth, and a lot of gathering of food.
That makes it a place where we, as humans, like to come, and like to live and play and recreate and harvest. So it also becomes the place where we humans have liked to be for a long time.
MCDERMOTT: One of the things that I was struck by, learning a little bit more about estuaries, is how they can both be vulnerable and resilient to climate change. And I was wondering if you could walk me through some of the challenges estuaries might face here, and some of the hope that they can offer?
HOLDERIED: Estuaries are the place where the watershed is intersecting with the ocean. And so part of that means that they are going to get input of water from the rivers and you know, run-off. And people add things to the water, right, we add pollution, we put fertilizer on, which then runs off and into the waters. And that can cause problems.
But so there's a lot of processes in the salt marsh and in the mudflats, and that can actually help degrade some of these pollutants. So estuaries have the ability to be resilient to certain additions. And then if you remove the habitats that do that, if you remove the marshes and those things, then you lose kind of that filtering effect.
With respect to climate change, estuaries are places animals and plants are adapted to a wide range of conditions. So if you think about Kachemak Bay, the plants in the intertidal have to deal with being exposed to air — in the wintertime, being exposed to air below freezing temperatures — into being underwater, being exposed to this big range of both temperature and salinity conditions. And so they've had to be pretty hardy to be able to be in that environment at all. So with climate change, they have a certain, I'll say built in resilience, because they're already in an environment that sees a lot of change naturally.
But like anything, there's limitations to that. And so one of the things that we look for in research is are the thresholds above which it's going to be too much — that's a fairly big area of research, to understand variability. So what are these ranges? What are they kind of naturally adapted to? And what are the thresholds over which things just won't survive?
You can learn more about estuaries and ongoing research around the Bay through the Kachemak Bay National Estuarine Research Reserve, or about the Kasitsna Bay Lab through National Centers for Coastal Ocean Science.