Bloomin’ jellies on the rise?

Seacology
Seacology
Chain or salp jellies bloom off the coast of New Zealand. Source: Seacology.

I should preface this with the fact that my experience with jelly fish is limited. To me, they’re just an occasional nuisance that looks cool at the aquarium. I’ve only been stung once, but I did have to wear a fashionable blue unitard to go snorkeling on the Great Barrier Reef  and avoid the seasonal danger of getting stung by a tiny, (sometimes) lethal box jellyfish.

Jellyfish have been around for millions of years, and jellyfish blooms, in Australia and elsewhere, are just another facet of a healthy ocean environment.  But, blooms are becoming more and more common, and spawning the  In the Sea of Japan, a now almost yearly swarm of the gigantic Nomura’s jellyfish (Nemopilema nomurai) famously capsized a boat. Large blooms disrupt fishing industries and even shutdown nuclear power plants.

Y.Taniguchi, Niu Fisheries Cooperative
RAWR BLOBS ATTACK! An outbreak of giant Nomura jellyfish off the coast of Japan in 2003 made life difficult for local fishermen. Source: Y.Taniguchi, Niu Fisheries Cooperative

Jelly fish blooms are cyclic and seasonal — lots of factors come into play like sun exposure, temperature, nutrient levels, changes in ocean currents, and the balance between predators and prey in the ecosystem. Some scientists think human influence might be the underlying issue. Agricultural runoff can add nutrients to the system, providing more food to the zooplankton that jellies eat.

Fishing can also take competitors — small pelagic fish (fish that live in the water column, near the ocean surface) such as sardines, herrings, and anchovies — out of the ecological equation. Jellies also feed on these fishes’ eggs and larva, and sans regulation, their populations can easily explode and invade new territories. Thus, over-fishing is another suspect that some scientists and conservationists point to, and a recent paper in the Bulletin of Marine Science adds evidence to the pile.

Researchers at France’s Institut de Recherche pour le Développement (IRD) present two contrasting case studies in the Benguela ocean current, which flows north along the southeastern coast of Africa. In the first, just off the coast of Namibia in an area with lax fishing regulations, pelagic fish populations barely have time to recover before fishing stars up again, and jellies are already colonizing the area. If the current trajectory plays out, sardines and the like might one day be absent from the local food chain, with negative implications for the ecosystems other inhabitants. On the other hand, the small fish still dominate the second ecosystem, off the coast of South Africa where strict fishing regulations have been in place for nearly half a century.

These scientists aren’t the first to point to over-fishing as the problem. A 2009 review paper published in Trends in Ecology and Evolution pin-pointed over-fishing, in addition to the effects of climate change and excess nutrients from fertilizers and sewage run-off, as a compelling culprit for jellyfish population growth.

“Mounting evidence suggests that open-ocean ecosystems can flip from being dominated by fish, to being dominated by jellyfish,” Anthony Richardson, a marine ecologist and a co-author, said in a statement at the time. “This would have lasting, ecological, economic, and social consequences. We need to start managing the marine environment in a holistic and precautionary way to prevent more examples of what could be termed a ‘jellyfish joyride’.”

Other researchers suggest that jellyfish are doing the same thing in Antarctica, and out-compete local penguins species.

Though some scientists think global jellyfish populations are booming, others aren’t convinced. The data is iffy (from anecdotes and case studies), and historic jelly population data is even worse. These pesky blobs are ridiculously hard to study, especially when they rival sumo wrestlers in weight. However, one group of marine biologists is tackling the daunting task of crunching jellyfish numbers. Their results published earlier this year in PNAS, say that the evidence for a jellyfish population explosion just isn’t there (…yet). It turns out that jelly fish populations oscillate over a natural 20ish year period. They also detected a small linear uptick since the 1970s, but only further monitoring will tell if that trend is a serious problem or a minor blip.

So, if we are indeed on a ‘jellyfish joyride’, how do we get off? One solution or consequence (depending on how you look at it): eat the jellies. It fact, jellyfish ending up on dinner plates seems to be the go-to example of the hardships we’ll face with over-fishing and other global food-related crisis.

Flickr/Roland Tanglao, CC-Generic
Jellyfish strips with soy sauce and sesame oil… looks a lot like pad thai. Source: Flickr/Roland Tanglao, CC-Generic.

Upon reading this, I could not help, but google, “jellyfish edible”. It turns out that some species are harvested for food. They produce tentacle toxins that are not harmful to humans and/or their bodies are more rigid. Rhopilema esculentum is popular in China, while Cannonball jellies (Stomolophus meleagris) off the US east coast are growing in popularity, as well.

In fact, jellyfish has been a staple of Chinese cuisine (read not Panda Express) for centuries. “Jellyfish masters” (I kid you not, it’s an actual job title) soak jellyfish strips in a salty mix, dry them, and ship them off to restaurants, where chefs rehydrate the strips and serve them raw or cooked. Smithsonian describes “cold shredded jellyfish” purchased at Jackey Cafe in DC’s Chinatown as “wetly crunchy” in a seaweed salad sort of way. Yum?

Advertisements

Sea slugs with disposable penises…or is it “penes”?

For a species of sea slugs (or nudibranchs) that calls the Pacific Ocean home, penises are apparently disposable. In fact, disposable penises are a natural part of sex for them. That’s according to a paper published recently in the journal Biology Letters.

Scientists first discovered this bright pinkish orange slug — called Chormodoris reticulata for the latin speakers out there — in the 1800s. Many sea slugs are simultaneous hermaphrodites, so have both both male and female parts, so to speak. Also, in terms of the female bits, they typically have two pouches to store sperm — one of which can destroy sperm. So, they can mate with two males and pick with sperm stash to dump. In the human world, we might call this the purest form of rejection, but in animal behavior terms, it’s called “female choice”.

Lots of sea slug species mate in weird ways, so it makes them an interesting group for animal behavior scientists to study. In this case, a team of Japanese researchers went scuba diving to collect Chormodoris specimen during their mating season — in 2005, 2006, 2009, and 2010. Back in the lab, they stuck the slugs in tanks to watch what happened. They either paired two slugs that had been isolated for 24 plus hours, or stuck an isolated slug in a tank with one that had recently mated. In addition, to the observation, they took photos and tissue samples of the slugs’ reproductive layout.

So, based on their study here’s how this particularly brand of kinky sea slug sex works: the slug has a really long penis that’s curled up inside it’s body, with a little bit hanging out. When two slugs are ready to get it on, the little bit hanging out elongates and develops prickly spines on the end. After either seconds or minutes of sex, the end of the penis falls off. It takes at least 24 hours for a new “penis” to uncurl from the spiral section inside the body, but then they’re ready to go at it again. A slug can do this up to three times, and this particular species is the only organism in the world that can chuck it’s penis and mate again 24 hours later. (Other slug species drop their penises after mating season is over, but they have a much longer time to replenish).

Weird sex happens all the time in the animal world, so what makes this particular instance a big deal. Sexual selection rarely happens with hermaphrodites — they have the best of both worlds, so they’re all kind of on an equal playing field. But, because it takes 24 hours for the slug to bounce back, replenished slugs have the advantage.

Smithsonian does a nice job of summing it all up, here.

Sea cucumber gut slime may be killing the GBR

Sea Cucumbers are like the crappy vacuum cleaners (the ones that spit out half the dirt they take in) of the ocean, and I mean that in the best possible way. They trudge along the sea floor like the gigantic slugs that they are, basically eating a lovely stew of sand and rocks and leaving it up to their digestive tracts to filter out the edible stuff. These cukes then proceed to poop out the not-so-edible stuff (the hence the crappy vacuum analogy) for other organisms to use or munch on. (Yay nutrient cycles!) But, thanks to ocean chemistry getting increasingly unbalanced for a multitude of unsavory reasons, their role as ocean floor recycling bins may be dissolving coral reefs, at least according to a study published back in late December in the Journal of Geophysical Research. In the course of their digestive antics sea cukes secrete acid compounds to dissolve the carbonate-based sand, spilling a whole bunch of soluble carbonate minerals into the water. But, what the heck does that have to do with reef building…

Brief Digression on How to Build a Coral Reef: The primary component of a coral reef is calcium carbonate (CaCO3). That goes for both the coral and the surrounding sand a rubble that falls to the ocean floor and fills up the crevices and holes between rock and coral. Most organisms that live on a reef either add to or absorb CaCO3 from the surrounding environment. In a healthy reef, there’s balance between CaCO3 getting absorbed into the reef and CaCO3 getting released by orgs like sea cucumbers.

….Marine scientists use this to measure how healthy a reef is. So, when there’s not a lot of CaCO3 in the water, the reef is growing aka healthy. And vice versa – too much CaCO3 means something’s out of whack, and in this case, sea cucumbers could be contributing to reef erosion. But, it’s by no fault of their own, increased ocean acidity and warmer waters (aka thermal stress) make it harder for other organisms that live on the reef to turn soluble CaCO3 into solid CaCO3.

Brief Digression on Ocean Acidity: As with most environmental issues these days, the main culprit behind the world’s oceans getting more acidic is the ridiculous amount of excess CO2 in the atmosphere (thanks coal, oil, and gas!). All that carbon dioxide gets absorbed by the world’s oceans; combine CO2, water, and carbonate ions, and (poof!) sea water gets more acidic. Only slightly kidding. Don’t believe me, check out NOAA’s unusually informative website.

In this particular study is that they looked at a specific section of the One Tree Island Reef area of the gigantic Great Barrier Reef creatively title DK13 and collected sea cukes to study in a lab setting. Although it’s name might cause one to think otherwise, One Tree Island does in fact have more than more form of vegetation. DK13 is oddly popular among sea cucumbers, so the research team, lead by Kenneth Schneider of the Carnegie Institution, wanted to find out if they could somehow be contributing to the higher calcium carbonate levels. They collected a swath of animals (Stichopus herrmanni and Holothuria leucospilota) to study how sea cuke digestion changes sea water in the lab and found an alarming amount of CaCO3. One could argue that the reef itself is producing this excess CaCO3, but it that were the case you’d expect to see the reef getting bigger, which it’s not. The same research group previously found that the DK13 was dissolving at night, and they estimate that sea cucumbers produce about half of the carbonate released during the night.

Second cousins of starfish and sea urchins, sea cucumbers enjoy slurping up food with their 8 to 30 tentacle-like feet, ensaring their enemies with slime thread, and breeding both sexually and asexually. Ow ow. CREDIT: Carnegie Institution/Dr. Aya Schneider Mor.

Obviously, scientists at Carnegie aren’t just hating on defenseless sea cucumbers – lead author Schneider said, “Although sea cucumbers may play a part in reef dissolution, they are also an important part of an incredible marine environment.” For the non-chemically inclined, this might sound like bad science (especially since the press release makes it sound like sea cucumbers are making the water more acidic, which would be kind of hard given that CaCO3 is basic). The fact that the water is getting more basic is good because it might stave off ocean acidification in the long term, but at the moment, understanding how sea cucumbers could be damaging Australia’s Great Barrier Reef. As Mr. T would say, I pity da fool who messes with ocean chemistry.

For a more positive take on sea cucumbers: here’s a study from last February that aims to use these “over-sized slugs” to save the world, one fish farm at a time, in addition to transforming British gourmet cuisine. “Next on Jamie Oliver, how to prepare sea cucumber en flambe in the nude…” Cheerio!

Flamboyant shrimp communication

California Mantis Shrimp, water color by Erica Staaterman
Mantis Shrimp watercolor by Erica Staaterman

Mantis Shrimp #1: “Bbbbrrrnanndndndggghhhh” (MARCO!)

Mantis Shrimp #2: “Grrryyyyybbbbbghhhhhhhh” (POLO!)

Communication can be difficult even for us humans – otherwise how on earth would fashion magazines make their money off of columns like “Male Body Language Decoded – how to tell if he’s the one.” But, that’s perhaps why we spend a lot of time and effort analyzing how animals say “Heyyyy how you doin’?” This can be especially difficult in environments – like the bottom of the ocean – where it’s so dark that organisms can’t even see, let alone pick up the intricacies of body language.

In this pitch-black world, California mantis shrimp (Hemisquilla californiensis, a vibrantly colored benthic dwelling crustacean that lives in muddy holes along the ocean floor of the west coast) use sound. Or more specifically, they ‘rumble’.  A study by six scientists from the University of Miami, UMass Amherst, Cornell, and Berkeley looks at how deep sea dwelling mantis shrimp flirt, scare off rivals, escape predators, and say hey get off my porch.

The research graces the August cover of Aquatic Biology and shows that not only do mantis shrimp communicate through low frequency muscle vibrations or rumbles, they each have a unique “voice”, too. It’s hard to study this in a lab because the shrimp vary their rumbles acoustically and temporally to a much higher degree in the wild. So, in addition to recording shrimp in lab tanks, the researchers strapped on their scuba gear and placed high tech audio-visual equipment – an autonomous recording unit (audio) and a hydrophone array (visual/location calculator) – near mantis shrimp burrows on the ocean floor near Catalina Island in California.

Continue reading

Tropical Coral Strength SPF

Courtesy of the Australian Institute for Marine Science:     great barrier reef corals with ity bity fish

To quote Yoda, sunscreen good, no sunscreen bad. Well as it turns out, sunscreen from corals could be even better, according to a study out of King’s College London and the Australian Institute for Marine Science based on samples of Acropora coral collected from Australia’s Great Barrier Reef (oh what I would give to be a grad student in that lab).

When I say coral, I mean the coral animal backbone and the algae that live inside of it. The two engage in a fairly straightforward symbiotic relationship: the coral provides shelter, while the algae share their sugar, produced through photosynthesis. What the guys at Kings College found is that these algae produce natural sunscreen compounds to protect from nasty UV rays, which damage their external cells.

Although the team is still looking into how the algal cells produce these compounds, they think that the compound gets transported to the coral cells where it undergoes some sort of chemical modification to become more sunscreen-esque. And from there, fish that nibble on the corals retain some of the benefits of UV-ray protection, and so on down the food chain.

This actually isn’t all that surprising when you think about it. In order to get high photosynthetic yields – or lots of grub – corals tend to grow in shallow water, and because the UV rays have a shallower depth of water to pass through, corals, like humans, have to deal with icky sunburns.

One thing that seemed especially interesting about this study is that the team wants to try to use the compound to create UV-tolerant and thus more sustainable crops in underdeveloped countries. Granted they also want to brew up a lotion for human use, solving world hunger = clearly a big deal. If anything this is all the more reason to yell at the dumb tourists who trample coral reefs in Hawaii and along the Gold Coast. (“FLIPPERS ARE FOR SWIMMING NOT CLUMSY WALKING! DUH.”)

The King’s College London team is currently trying to replicate the compound in the lab. From there they hope to develop the lotion and eventually a pill-form to avoid awkward handprint tans, among other things.

For more details check out the BBC’s write-up.