Tips and Tricks for Error-free Classification!
Hi! My name is Tom Bell and I am a scientist with Floating Forests. For the past 3 years, I have been working with Landsat images to estimate giant kelp biomass along the California and Baja California coasts. I have also had the opportunity to advise over 20 undergraduate analysts at the University of California, Santa Barbara to help process these images.
One of the great things about Floating Forests is that image processing has been simplified so that users need very little training before they are off and running. However, this does not mean that every image will present a straightforward classification. Today, I want to take you through some common kelp classification errors and give you some tips on how to determine if that the questionable blob is kelp.
First lets start with the natural history of giant kelp and the general characteristics of the environment where it exists. Giant kelp is a coastal marine alga that forms dense stands in the Eastern Pacific, as well as off the coasts of South Africa, Australia, and New Zealand. Giant kelp anchors itself to the sea floor using a holdfast that tightly grips onto hard bottom, like a rocky reef. Kelp fronds can grow up to 45 meters long, but the maximum depth for an individual is about 30 meters, this is due to the limited sunlight where the newly settled microscopic kelp begin to grow. Waves are a major destructive force to kelp forests and can set its nearshore limit along rocky coastlines.
So now that we know the environment where kelp exists, we can use this information to better inform our kelp classification decisions. Let’s go through a few examples!
See these white (sometime blue) blobs along the coast? These are breaking waves. We know that breaking waves can be a major destructive force on a kelp forest, so you usually don’t see kelp where you see breaking waves. Remember, kelp forests will show up as green blobs. You can clearly see this large kelp forest growing just outside of the breaking waves.
This sure does look like a dense kelp forest, bright green blobs right off the coast, but in fact these are tidal mudflats. This can be one of the most difficult issues you may face. Algae or seagrass growing on these mudflats is going to show a similar green color as kelp, but we know that giant kelp only grows on hard seafloor, like rocks and boulders.
One way to make sure this is the right type of habitat for giant kelp is to use Google Maps or Google Earth. You can click on the coordinates above each image to automatically take you to a new page showing the approximate area of that image. Then, I like to copy just the coordinate numbers and paste them into the Google Maps search bar like, ‘38.557, -123.300’, this will place a pin on that exact location and show you a satellite image of the area with better spatial resolution.
Small islands off the coast can sometimes appear to be dense kelp forests. Again, if you are unsure, I recommend using the Google Maps trick I explained above. You should then be able to confirm whether or not the green blob is kelp or a small rock/island.
Giant kelp will never be growing in inland lakes or water bodies. This is a coastal marine species. If you see a green blob in a lake or some kind of inland river/delta/estuary/bay, it is probably something cool, but it is definitely not giant kelp. Again, if you are unsure, use the Google Maps link to see if the body of water you are looking at is coastal ocean or a lake/river/canal.
That is all for today! I am having a great time interacting with everyone on Zooniverse Talk, please keep the questions coming!
Out of Images? Not so Fast…
A number of you have been getting this message – either on login or when clicking through images.
Are we really done?
In short, no.
Basically, you all have been too amazing, and have gone through images far faster than we anticipated. We started with a number of Landsat scenes from California and Tasmania from 2012-2014 last Thursday. We thought it would take at least until Wednesday to get through that, and in that time, we’d have the rest of the California and Tasmania images chopped up and ready to go.
How wrong we were.
By Friday, the Zooniverse folk were scrambling to get the rest of the California and Tassie images into the system. And now you all are blowing through those, too! We had a beautiful artful roll-out plan for the entire globe that would stretch out over the course of the year. Clearly, we were wrong.
So, via Twitter we reached out to the NASA Landsat folk who put us in contact with the USGS Landsat folk who maintain the data, and we’re trying to see if we can fast track data acquisition. We’ll keep you posted.
But, now, we do have new data that the Zooniverse folk have put into the system (faster than anticipated because you all are awesome), and more on the way, so fear not! If you get the above message, it’s just a minor glitch that should go away shortly. Hit reload once or twice, and you should be all good!
Welcome to Floating Forests!
Welcome to the blog for Floating Forests! We’re totally excited to bring you into our kelpy world! What do I mean? Well, we’re a team of scientists (more on that later) who are trying to discover whether the amount of Giant Kelp in the world is changing. And we need *you* to help us.
Yes, Giant Kelp! I’m talking about Macrocystis – a HUGE brown alga that can grow over 100 feet (that’s 33m) with its fronds laying across the surface of the ocean. It’s found in close to shore in colder waters – California, Chile, Tasmania, and more. Divers love it. Diving in a mature forest is like being in the Redwoods. All kinds of sea life love it, too, as it grows incredibly fast and sloughs off a lot of material for grazers to munch on every day. Kelp forests are a huge providers of services and benefits for oceans wherever they occur.
So if the amount of kelp and kelp forests in the world was changing, there could be all sorts of consequences for the services our coastal oceans can provide.
Why might it be changing?
There are a lot of reasons the amount of Giant Kelp in the world might have shrunk or grown over the past few decades: Climate change, coastal urbanization, changes in kelp-munching urchins, to name just a few. But we just don’t know.
While some awesome research programs have gone out and measured change in kelp over time at a small handfull of places, Giant Kelp is found throughout the world – often in places researchers seldom can get in the water, such as the sub-Antarctic Islands.
So, why don’t you know if the amount of Giant Kelp in the world is changing already?
Well, scientists have been monitoring Giant Kelp in some places for years. But only a few places where they can get constant good access to dive sites. And even in many of those places, by ‘years’ I mean ten, or twenty. So, something like long-term records of kelp abundances on the sub-Antarctic Islands? Nope. We’ve got nada. Heck, there are even areas in California or Chile where people have been working for decades, but are too difficult to access, so we don’t have any data.
But we have a solution. We can see Giant Kelp from space.
Kelp from space?
Kelp! From! Space! We’re very excited.
I’ll post the origin story for this project next week, but in short, Kyle Cavanaugh, while a PhD student at UC Santa Barbara figured out how to see kelp using the Landsat family of satellites. These images provide global coverage back into the early 1980s! We potentially have over 30 years of data, waiting to be pulled out!
Yeah, sure, can’t computers just do this?
Nope. Things like clouds, the crests of waves, sun glint, and more can confuse image recognition algorithms. But people. People can get the job done. And so, we want to take you on a tour of the Giant Kelp forests of the world, and have you help us hunt down when and where kelp exists! Fortunately, the good folk at Zooniverse thought this was as cool of a project as we do, and so they built this amazing platform to help us bring the kelp to you!
OK, I’m interested. But who is this we you keep talking about?
The Science team at the Floating Forests project is a group of researchers who have been working in kelp forests all of their lives. We’re divers, remote sensors, stats monkies, and all around passionate kelp enthusiasts. We’re part of the global Kelp Ecosystem Ecology Network – a network of over 60 scientists working in a wide variety of kelp ecosystems.
This project represents a dream of ours – to look at a wonderful global dataset, but to bring citizen scientists and folk just interested in looking at how their coastlines have been changing into the process with us. We hope you enjoy, and we’re really excited to tell you more about kelp forests and the amazing science that goes on there as this project moves forward!
And thanks again to the amazing team at Zooniverse for making this happen!
Stay tuned to this spot as we launch later today!