Source: NZ Department of Conservation
By Brian Vayndell
Welcome to spooky season, e hoa! This year, instead of the fiction you’d expect around Halloween, we’ve decided to bring you some real-life scares from the biosecurity world.
Sometimes, after all, reality is way scarier than the imagination…
Frightful Fish – Koi carp
When you think about the zombie hordes, you probably imagine people. Well, try fish.
A wall of flesh, seething ever onward, destroying all in its path and leaving devastation in its wake. No, it’s not Night of the Living Dead. It’s koi carp.
Maybe you think I’m being dramatic, so let’s get this straight; I’m definitely being dramatic. But also, look at this:
Is that dramatic enough? This is the aftermath of an operation to remove some of these invasive fish from our waterways. And that’s only a fraction of these invasive pests, which have now spread across the country.
Koi carp are an ornamental strain of the common carp (Cyprinus rubrofuscus) native to Eastern Asia. This species probably first arrived in New Zealand in the 1960s as a stowaway in a goldfish consignment.
Now I’m sure you’re thinking “Yeah that’s a lot of fish, but it’s still just fish right? They’re not that scary, you handsome devil.” Well, dear reader, you’re half right. But while a few thousand fish aren’t scary for many of us, they represent an existential threat to much of our freshwater ecosystem. Koi carp feed like fishy little Roombas; they stir up sediment and splash around in shallow water to get their food, filling the water with silt and literally choking our native (and yes, endangered) species.
That’s bad enough but for me, the real horror is that a huge part of their spread was intentional. Yup; a bunch of people thought coarse fishing was more important than preserving our country’s unique native biodiversity.
You can help fight this fishy foe by joining DOC’s Always Be Naturing movement…
The Blob from Beyond – Didymo
It’s big, it’s slimy, and it’s damn near impossible to get rid of. Yes, it’s didymo.
Honestly, I’m here to convince you that didymo is a nasty little nightmare. Looking at the picture, and the hundreds like it in the DOC vaults, this really shouldn’t be that hard.
Didymo is gross, guys. Like really gross.
Sometimes invasive species look nice or cute. Hedgehogs are cute little guys, despite all the damage they do to our native invertebrates, and even koi carp have their place (elsewhere) as ornamental fish. But no such luck with didymo, which looks as bad as it is for the environment.
Didymo is a triple threat invader. Not only are the massive algal blooms it forms dangerous to swimmers and waders, it also messes with the insects our native fish rely on for food. It can also clog water filters and hydroelectric generators, by gunking everything up with its slimy-looking… well, the scientific term probably is just gunk.
Didymo is found in many lakes and rivers. Frankly, that’s already too many places, and it’s already past the point of eradication being an option. Following the Check, Clean, Dry protocol before leaving a known didymo area is the way to keep it contained. And, actually, Check, Clean, Dry prevents the spread of all freshwater pests, not just didymo. So, you know, do that. If I can manage to do it, anyone can!
Creepy Clams – Corbicula
Ok, you think, he must be joking now. There’s no way a clam can be considered horrifying, unless it’s insanely huge or something. Well, think again; the Corbicula clams are one of the world’s most invasive species, and they’re an ecological nightmare.
The clams grow up to the size of a two dollar coin. Oooh, spoooooky, physical currency! They also breed constantly, and form carpets of shells up to two metres deep, and simply can’t be removed once they’ve taken hold, without destroying everything else in the water too.
Yeah. Now they’re scarier, right? $2 coins don’t do that, or else I’d be a millionaire and not writing edu-tainment blogs for DOC.
We’re actually quite lucky here in Aotearoa that the clams aren’t more of a problem. At least, not yet. Look at Ireland, where a 2011 report found a maximum of over 9000 clams per square metre. Not a typo, by the way. Nine. Thousand. That’s no longer an itty-bitty shellfish committee. That’s a… well it’s a township, I guess.
It’s certainly not something we want here, so Check Clean Dry, unless you want all our rivers choked with clams. Honestly, it’s only through community efforts and Check, Clean, Dry that these things aren’t everywhere already.
If you see any of these around, let DOC or MPI know. But don’t remove them yourself, as they can get mixed up with our natives; the last thing we want is some kind of clam witch hunt!
Clouds of Doom – Toxic Algae
Do… Do you really need me to explain why something called ‘toxic algae’ is nightmarish? It’s not called super-fun-happy algae for a reason.
OK, so this isn’t TECHNICALLY biosecurity, and DOC doesn’t manage it. But I decided to include it for humanitarian reasons, since it’s dangerous and pretty scary.
Also commonly called ‘harmful algal blooms’ (which, c’mon, isn’t nearly as catchy), these aren’t even really algae. It’s a form of cyanobacteria which, during warm, dry weather, explode in population, clouding rivers and other waterways with their blooms of babies. Except instead of nice fluffy clouds, these ones can kill you if you accidentally eat it. And, while you’re obviously not going to try and munch on some bacterial blooms, you’ve definitely swallowed water while swimming before, so think how easy it’d be to get a couple of grams of this into you.
Adults are able to handle this better, but children and especially dogs are really vulnerable, since they do like a thirsty drink after a swim. It can also cause skin irritation: ever see ‘Cabin Fever’? That’s a (barely) exaggerated version of this. You don’t want it.
Land Air Water Aotearoa (LAWA) have a great resource for water health, which you can find here. If you see soupy water or excessive slime on rocks, and it’s not showing as a risk, reach out to LAWA.
The Things from the Waterways– Aquatic Weeds
Look, I couldn’t pick just one. And I won’t apologise for that; I’m sorry, it’s just the way I am.
It’s pretty irritating when something is terrible for the environment but also has a very funny name. For example, hornwort is ranked New Zealand’s worst submerged weed, and smothers all other aquatic plant beds, including native and exotic. But it also sounds hilariously innocuous. Same with Elodia densa, or Brazilian pondweed, and everyone’s favourite curly waterweed, Lagarosiphon major.
This could be any of us if these weeds continue to spread… Or if you’re diving to collect Elodia densa. I just think it’s a great picture.
But let’s take hornwort. Native to the USA but first found in Napier in 1961, this plant has now spread to much of the North Island. Once used in the aquarium trade for its fast-growing capabilities, that same strength is now why it’s an absolute mission to deal with. It also got its name from the little ‘horns’ it seems to have; oooh, spooooooky!
The South Island is largely free of hornwort, except for Christchurch, where it was recently re-discovered. And we would like to keep it this way; we don’t want to see it spread further, and we’d even like to eradicate it where possible.
Here’s some Lagarosiphon major. Look at it there, lurking. Smothering everything else. Bloody ominous, that is. Watch out for this floating around. If it gets stuck to any of your gear (especially propellors), get rid of it and Check, Clean, Dry to make sure it’s gone for good.
So this spooky season and beyond, make sure you:
Check Clean Dry when moving between waterways
Look at the LAWA website before going swimming outdoors
Consider joining your local conservation group to help locally
Make a donation to conservation, which also helps
Watch out for other threats; there are WAY more than just these.
And, you know, Always Be Naturing.
