Cocktail Week: Dark n’ Stormy Effects on Kelps

It is cocktail week over at Deep Sea News. And it has been glorious, with marine biology themed cocktails galore. As a cocktilian myself, I felt that I had to kick in, well, a real classic. I classic that, I daresay, may lay at the root of kelp forest ecology itself. And yet may be under threat.

“Wait, what?” I hear you saying. Let me explain.

Kelps are incredible. I mean, this is a clade of algae with members who can grow a foot per day, that form giant forests that rival the redwoods in beauty, that embrace diversity looking like everything from a mini-palm-tree to a majestic pair of antlers 60 feet high, to a lasagna noodle.

The awesomeness of kelps knows no bounds.

What is truly incredible about kelps is the way they feed the whole frackin’ shorline. Not only do they get nibbled on by all manner of snail, amphipod, urchin, and fish, but they also shed off prodigious amounts of sea-snot (a highly technical term) that can nourish rich productive bacterial communities. But they don’t stop there. This delicious mucilage and bits of kelp ripped off and churned up in the surf into tiny little bits can get recirculated by all manner of filter feeders hanging around on the sea floor. So, they feed grazers and filter feeders and bacteria, all at once, without breaking a… well, ok, maybe you can consider their mucous ‘kelp-sweat’, but, you get what I’m saying.

Would that only be the way they feed the world around them, it would have been enough. But kelps don’t stop there.

Rather, the lose a ton of their prodigious productivity all the time. They’re constantly sloughing off ends of blades, whole fronds, and in storms often whole individuals come loose and fly out into the ocean only to settle down and get eaten by all manner of scavengers. Heck, kelps are so awesome, that they turn many hungry grazer into passive little detritivores who sit and wait for kelpy manna to rain down on them. And not just in the ocean, but up on beaches, too! They feed the ocean, *and* the land.

Wooo!  Kelp in flow!  Food for all! From

Wooo! Kelp in flow! Food for all! From

(FYI, for a lot of the references on this, see excellent work by folk like Kira Krumhansl, Dan Reed and the good folk at the SBC LTER, Dave Duggins, and many more)

That storms are a major driver of kelp detritus getting shunted out in to the vasty deeps and sunny sands is a major paradigm in kelp forest research. We see correlations between wave heights and kelp loss in many systems, and the major kelp die-back of the year in many systems is often correlated with the biggest storm events of the year.

So the threat? A fascinating piece this week in Limnology & Oceanography by Bettignies et al. that details kelps in Australia eroding into detritus not because of storms, but rather potentially as a tradeoff for reproduction. As they reproduce, tissues become weaker and slough off. However, once sloughed, the smaller more svelte kelps are actually more resisitant to the high wave action that comes right afterwards. So, while a broad-brush look might make it look like kelp loss happens around the same time as big storms, a close look at timing, physiology, and kelp adaptations shows that the story is far more interesting.

Will this hold elsewhere? Time will tell. But in the meantime, let’s drink a glass to big intense storms and their kelp-removing powers. I speak, of course, of the Dark N’ Stormy.


I do not know the shrouded origins of this fine beverage, nor how it made its way into marine science. All I know is that at any marine lab I have visited, you will find passionate devotees. Long day in the field? Lab equipment break down on you? Stuck debugging R code while everyone else is in the fun and sun? Time for a Dark n’ Stormy evening. And if you have a favorite ginger beer? Be ready for some arguments.

And so, the Dark n’ Stormy (as taught to me maaaany years ago at a field station)

Dark n’ Stormy
2 oz. Gosling’s Black Seal rum
1/2 a lime
Ginger beer (I go with Reed’s and typically use 1/2 of a 12 oz. bottle)

Fill tall glass with ice. Pour over rum, juice of lime, and fill with ginger beer. Huck in your lime husk, stir, and sip. Contemplate the role of disturbance versus reproductive timing in kelp removal across the globe.