Prior to 1967, the environmental extremes of the deep were thought to limit life. The deep sea is dark (can’t-see-your-hand-in-front-of-your-face dark), cold (only-four-degrees-above-freezing cold), and under an extreme amount of pressure (one-elephant-on-each-square-inch-of-your-body pressure).  This suite of factors should make survival challenging, and thus for a century, scientists assumed the deep sea was biologically a desolate wasteland.  Even after the discoveries of animals living at extreme depths in the late 1800s, Victorian scientists expected that there could not be a diverse array of animals surviving in the deep sea.  Enter Robert Hessler and Howard Sanders who in 1967 used newly developed sampling devices to discover that the deep sea is shockingly diverse, and perhaps just as diverse as tropical shallow-water habitats. 

Scientists were completely baffled as to how high diversity could occur in such a bleak place.  They began to throw out theories, but they were limited by the little data that had been gathered from a poorly explored deep ocean.  The scientific publications of this time on deep-sea diversity read like there were a few people in a room with a whiteboard, writing everything they remember from their ecological textbooks, talking through each theory, slowly crossing off possibilities, and working their way down the list.  

Howard Sanders began by writing “Specialization” on the whiteboard with his paper introducing the Stability-Time Hypothesis in 1968.  He suggested that because the deep sea is monotonous and predictable (i.e., it is stable), populations have the evolutionary time to become newly specialized in how they feed. Over time, these populations become so specialized they evolve into totally new species, eventually driving diversity up.  Further research and explorations indicated that the premise of this argument was wrong- the deep sea is actually not that stable.

Then, Paul Dayton and Robert Hessler walked up to the board and scratched off the “Specialization” idea with their paper in 1972 entitled “The role of biological disturbance in maintaining diversity in the deep sea.”  The pair do not argue against the idea that the deep sea is predictable and stable.  In fact, they favor the idea… except for the part where they proved that deep-sea species are actually not more specialized than shallow water species.

“Specialization” got a strikethrough on the whiteboard, and Dayton and Hessler wrote “Predation” below it.   The duo introduced a specific type of predation pressure they labelled “biological cropping.”  No, biological cropping is not deep-sea animals learning agricultural techniques… but a combination of predation and deposit feeding.  Animals can eat other animals either intentionally (e.g. hunting down prey) or unintentionally (e.g. stuffing everything you come across into your mouth and it just so happens that you get a live one).  This “cropping,” whether accidental or not, reduces competition by preventing one or a few abundant species from monopolizing the resource.  These species get knocked out, allowing far more species to get a piece of the proverbial pie. Nobody gets sent into extinction by competition.  Dayton and Hessler’s idea is not necessarily that diversity is driven to be high in the deep sea, just that it is not limited.

Dayton and Hessler’s “Predation” idea never got fully scratched off the list, but the difficulty of testing the idea and conflicting results have led many to write large question marks next to it.   Many other ideas now are situated below “Predation,” including: “Disturbance,” “Patchiness,” and “Successional Dynamics.”

Ultimately, those of us in the deep-sea scientific community are still today standing around the dry erase board bouncing many of these same ideas off each other.  Sometimes we manage to cross one off the list, or add one, or at least add to our understanding of the ideas.  One thing is clear though, we still haven’t gotten it all figured out.  So… anyone have a dry erase marker?

The post How is the deep sea so diverse? The struggle is real for late 1900s ecologists first appeared on Deep Sea News.

I was lucky enough to attend an all-day workshop today, just down the road at Georgia Tech, where Prof. Mark Hay organised the Teasley Symposium on the interactions between corals and seaweeds on reefs.   Like many, I was aware that coral reefs can become “algae reefs” if they become too denuded of live coral cover, but I never appreciated the complexity and subtleties of how reef-forming corals interact with their more strictly plant-like photosynthetic neighbours.  Speakers included Peter Mumby from my Alma, the University of Queensland, Bob Steneck from U. Maine and Nancy Knowlton from Smithsonian, to name but three.  Common themes included (1) the diversity of chemical defences that algae use to kill corals with which they come into contact, (2) that algae, especially turf algae, produce large amounts of dissolved organic carbon (like sugars) that promote localised bacterial blooms and lethal (to corals) hypoxia along the margins of contact with corals, (3) that the greater resilience of Pacific reefs to disturbance by diseases, cyclones and bleaching events may stem from a greater herbivorous fish diversity that can keep algae at bay long enough for corals to recover, (4) conversely, that the effective decimation of many Caribbean reefs may stem from a species poor assemblage of grazers that is, certainly in the case of the sea urchin Diadema, not doing so well itself.

The stand-out for me was an elegant set of experiments by Doug Rasher, a newly-minted PhD from Hay’s lab, showing that Chlorodesmis, a rich green hairy algae sometimes called turtle weed, is a veritable black belt in allelopathy (antagonistic competition mediated by secreted chemicals).  In some instances, just a single minute of contact between Chlorodesmis and a coral was enough to produce partial loss of photosynthetic ability in the coral that lasted days, and longer exposures often rapidly lead to visible bleaching and coral tissue death.  Other work from that group showed that the chemicals responsible are bound to the algae surface and not released into the water.  Take home message: don’t mess with Chlorodesmis, its endogenous terpenes will mess. you. up.  Given their relative wussiness in the face of such ninja-like chemical defences, what’s a coral to do?  In many cases, the answer seems to be get yourself a body guard: any number of mutualistic herbivorous critters (crabs, shrimp, blennies etc.) that live among the coral branches and vigorously attack any Chlorodesmis filaments that might drift too close to the scleractinian shangri-la.

It’s no surprise that inter-species interactions between corals and seaweeds should be ubiquitous; these sorts of intimate relationships are a hallmark of life on all coral reefs.  What has been really interesting to think about is how the elegant case studies described today might scale up to define patterns of reef ecology at the landscape and regional scales.  And all of it is set against a fascinating backdrop of a rapidly shifting climate system that is a profound driver of reef function.  Some of the predictions about the future of reefs are enough to make you want to open a vein or two and we certainly weren’t going to solve any of those problems in a one day symposium about corals and seaweeds, but that doesn’t diminish the importance of science well done and the significance of the work to our understanding of how reefs function (or not), for now at least.

The post Turf wars first appeared on Deep Sea News.

Hagfish can produce copious amounts of slime from 90 to 200 slime pores that run the length of their body. With these dedicated sliming glands, a single hagfish can produce over a gallon of mucus in single sliming event. The video below should convince you that the hagfish’s superpower is to produce a slimepocalypse. What should a hagfish use this power for? Create a slip and slide for friends at parties? Lubricate the chassis of a fleet of 18-wheelers hauling bourbon out of Kentucky? Defeat the forces of evil?

Hagfish choose not to get eaten by predators because with great power comes great responsibility—like not getting eaten.

Recent work by Vincent Zintzen and others video documents for the first time hagfishes choking would-be predators with gill-clogging slime. When a hagfish finds itself in the mouth of the would-be predator, the slime glands of the hagfish inside the predator’s mouth fire off. Within as little as 4 seconds, 14 different predators in Zintzen’s recorded footage (embedded below) fell victim to the slimepocalypse. Each predator, be shark or fish, “convulsed their gill arches dramatically in a gagging-type effort to clear the slime from their gill chambers.” Whether the predator was a biter like sharks and conger eels or a sucker like wreckfishes and scorpionfishes, hagfish slime prevailed.

In addition, hagfish can also use their super slime power to deter competitors. In the words of the author, “when multiple hagfish were present at the bait, the bait bag would become draped in slime, deterring other fishes from approaching the food source.”

But predators and competitors are not the only ones to feel the slimepocalypse. Hagfish are typically viewed as scavengers but Zintzen and colleagues observe hagfish preying on red bandfish (video embedded below). Upon locating a burrow, the hagfish enters and tangles with the prey using its retracting dental plates to begin swallowing the unlucky victim. At this point the hagfish waits for the victim to die and may suffocate its prey with slime, similar to the hagfish’s predators. To retract the bandfish from the burrow the hagfish knots the part of its body outside the burrow to provide leverage to both remove itself and the victim.

Unfortunately, Zintzen and friends do not document increased attraction of lady hagfish to males who produce slime. But why wouldn’t the ladies love it? During The Operation I might have faired better with other males if I was hagfish, but more research will be required to determine if I would have attracted or repelled my Tall Blond.

Zintzen V., Roberts, C.D., Anderson M.J., Stewart A.L., Struthers C.D. & Harvey E.S. (2011) Hagfish predatory behaviour and slime defence mechanism. Scientific Reports 1, 131

http://www.nature.com/srep/2011/111027/srep00131/full/srep00131.html

The post If I Was A Hagfish Could I Get With Tall Blonds? first appeared on Deep Sea News.

First there is sperm rivalry. Feel free to borrow the phrase sperm rivalry for your next party as well. A sperm that is longer and larger will swim faster, fertilizing the egg first. The environment also plays a big role. Whether the sperm and egg pair up out in the open for the whole world to see or within the hot love nest of a female can determine sperm size. In frogs sperm size can vary depending on whether the sexual rendezvous occurs on land or in the water. In the Bleeker’s squid it is both rivalry and the environment that shapes the sperm.

Female Bleeker’s squids can recieve sperm either in a seminal receptacle (location marked by blue arrow above), a specialized sac for holding sperm near her mouth (yes you read that right) or an internal oviduct (red arrow), the tube by which the egg passes from an ovary, behind her head. If you’re a big male and fight off the all other big males, you’re crowned the consort male! As a consort male you slide along side the female, put on some Marvin Gaye, and place your packets of sperm directly into her oviduct. At this point you guard her. She may interpret this as snuggling. This is a win for both of you. You’re ensuring no other males can mate with her until she spawns.

But maybe you’re not a consort male and have your small squid ass handed to you on platter all day long. Never despair! You are the sneaker male! A sneaker male rushes to the female and her consort then mates with the female head to head. Yeah baby stare into my alluring squid eyes. F you big consort squid and F your Marvin Gaye. During this tryst, the sneaker male places his sperm packets near the seminal receptacle.

During the actual spawning event both the consort and sneaker male’s sperms can fertilize egg.

Due to the process of egg laying in L.bleekeri, insemination and fertilization can occur in two sites … a string of eggs is extruded from the oviduct (inside the mantle cavity) where it is exposed to consort sperm inside the oviduct (i.e. internal fertilization conditions), and the female pulls the egg string through her siphon and into position within her arm crown around mouth, where it is exposed to sneaker sperm (i.e. external fertilization conditions), before she deposits the egg string onto the sea bed.

An obvious advantage goes to the consort because of the proximity of his sperm to the eggs. But sneaker males up the ante for the game by producing huge sperm over 30% larger than consort males (above photo). Why? You might guess this is because brawny sperm could outcompete their scrawny competitors. But no difference in sperm velocity is seen between sneaker and consort males. For you information, their sperm swims at about 1/3 a mile per hour. The larger sperm size of sneaker males is likely related to the environment of the external fertilization conditions. A larger sperm may be better able to swim in viscous environment or may need to be larger to hold more mitochondria (the power generator for cells) because it needs to cover more swimming distance to eventually reach the egg.

So the moral of the story is to…well you’ve got it by now.

Iwata, Y., Shaw, P., Fujiwara, E., Shiba, K., Kakiuchi, Y., & Hirohashi, N. (2011). Why small males have big sperm: dimorphic squid sperm linked to alternative mating behaviours BMC Evolutionary Biology, 11 (1) DOI: 10.1186/1471-2148-11-236

All figures from Iwata et al. (2011)

The post There Is More Than One Way To Impregnate A Squid first appeared on Deep Sea News.

In January 2009, a reserve was set up in South Africa to benefit the endemic black-footed penguin*. While a reserve may be set up with a specific goal or species in mind,  they are static boundaries that encapsulate everything that lives in or passes through it. It was unclear how the penguins would respond to the reserve as they are a highly mobile top predator and their prey (sardines and anchovy) are even more mobile and migratory. Additionally, their prey are also fished by humans, directly in competition with the penguins.

The authors collected data in Spring 2008 prior to the reserve’s establishment and approximately a year later during Spring 2009 after the reserve was closed to purse seine fishing for 4-6 months. Data were collected in the reserve site (St. Croix Colony) and at a nearby site that was open to fishing the entire time (Bird Island). Purse seine vessels were monitored via satellite for compliance.

What was interesting is that none of the diving metrics differed between years or colonies, such as dive time and depth and penguin body mass. What did change was trip behavior. The figure at left shows the density of foraging dives pre (top) and post (bottom) reserve establishment. Trip length, trip duration, and maximum distance from colony were significantly less between years and between colonies.

What does this mean for the penguins? Penguins are expending less energy traveling for food after their breeding season, saving up to 43% of the daily energy expenditure! This is presumably because there are more fish in vicinity since purse seiners are not competing for resources with the penguins, evidenced from data between colonies post-MPA.

It will be interesting to follow these colonies to see if the MPA ends up recruiting more penguins into St. Croix colony due to the foraging success of its current inhabitants. With prey not as limiting a resource, density dependent effects, i.e. overcrowding, might be a concern in the future. There could also be spillover effects from the MPA. More fish in the MPA might mean more fish overall in the region and nearby unprotected colonies and fishermen may both reap the rewards.

*Disclaimer: I used to take of black-footed penguins at Monterey Bay Aquarium and am immensely biased in this report. Go Penguins!! :)

Pichegru, L., Gremillet, D., Crawford, R., & Ryan, P. (2010). Marine no-take zone rapidly benefits endangered penguin Biology Letters, 6 (4), 498-501 DOI: 10.1098/rsbl.2009.0913

The post Penguins Immediately Benefit From MPA first appeared on Deep Sea News.

I am very excited today!  My new paper in the journal Ecology will be coming out in April on the regulation of biodiversity in the deep sea.  NESCent is issuing a press release (below) written by our very talented, Communications Director Robin Smith.  Above is a high-definition Youtube video we put together for the occasion.

Durham, NC – Surplus food can be a double-edged sword for bottom-feeders in the ocean deep, according to a new study in the April issue of Ecology. While extra nutrients give a boost to large animals on the deep sea floor, the feeding frenzy that results wreaks havoc on smaller animals in the seafloor sediment, researchers say.

Descend thousands of feet under the ocean to the deep sea floor, and you’ll find a blue-black world of cold and darkness, blanketed in muddy ooze. In this world without sunlight, food is often in short supply.

Animals in the deep sea survive on dead and decaying matter drifting down from above, said marine biologist Craig McClain of the National Evolutionary Synthesis Center. Only about 3-5% of the remains of microscopic plants and animals that feed life at shallower depths actually makes it to the deep sea floor, he explained. “If the ocean’s primary production were a 5-pound bag of sugar, that would be the equivalent of a sugar packet.”

Collaborating with James Barry of the Monterey Bay Aquarium Research Institute (MBARI), McClain traveled to the deep waters off the coast of California to an area of the ocean floor that receives an additional source of food. In a steep, winding, underwater gorge known as Monterey Canyon —similar in size to the Grand Canyon —bottom-feeders get a boost from nutrient-rich sediments that slough off the canyon walls and collect on the canyon floor.

“There’s typically more food available in the canyon than you would see outside the canyon,” Barry explained. “The stuff that rains down from above and accumulates at the base of the cliffs isn’t just mud – it’s food,” McClain added. “There are tiny food particles and bacteria in the sediment.”

The researchers wanted to understand how the surplus food affected deep sea life on the canyon floor. Buried in the sediment and hidden from view, a diverse world of tiny marine animals – snails, worms, crustaceans, clams, and other creatures no bigger than a pencil eraser – live and feed in the canyon mud.

To find out how these animals are affected by the boost of food, the researchers sent a Remotely Operated Vehicle (ROV) equipped with video and sampling equipment to the base of the canyon. Piloted from a control room onboard a ship at the ocean surface, the ROV dove more than a mile to the canyon floor. As the ROV crept across the seafloor sediment, it video recorded everything in its path and pushed plastic tubes into the mud, pulling up cores of and animals and silt.

When they brought the samples back to the surface, they found nearly 200 species in the sediment. But as they sampled closer to the canyon walls, they were surprised to find that despite the extra food and nutrients, the small sediment-dwellers (0.25 to 25 mm in size) became even smaller and less diverse. Why might this be?

A closer look at the video footage suggests the answer lies not in the sediment, but just above. As the ROV approached the canyon walls, the researchers noticed swarms of bigger, mobile animals – crabs, starfish, urchins, sea cucumbers and other seafloor scavengers – crawling on the sediment surface. Normally few and far between, these animals sense that food has arrived and converge at the base of the cliffs, the researchers explained. “The cliff face becomes a smorgasbord for larger animals,” said McClain.

Ironically, more food for big, mobile animals on the sediment surface is bad news for smaller sediment-dwellers buried below. The larger animals devour all the food in their path as they plow across the canyon floor, wrecking habitat and leaving little for other animals to feed on. “Larger organisms come in and they churn up the sediment and eat all the food. That has big consequences for smaller animals that live there,” McClain explained.

“The number of species near the cliff face was reduced by half compared to the middle of the canyon,” said McClain. “More food isn’t always better,” he added.

The team’s findings will be published online in the April 2010 issue of Ecology.

The post When the dinner bell rings for seafloor scavengers, larger animals get first dibs first appeared on Deep Sea News.

The Marine Advanced Technology Education (MATE) Center’s International Student ROV Competition just occurred in Buzzard’s Bay, Mass.  This is the competition for those who already won in 16 regional competitions.  The competition featured 54 student teams representing middle schools, high schools, home schools, community colleges, universities, after-school clubs, outreach programs, and 4-H and Scout clubs, from five countries.

This year MATE worked with OceanWorks International and the Deep Submergence Systems Office at Portsmouth Naval Shipyard to develop the missions focusing on real submarine rescue training exercise. Student teams were required to build and pilot ROV’s to inspect a simulated submarine for damage, deliver emergency supplies, and replenish the onboard air supply, among other tasks.

The winners of the Explorer Class were Long Beach City College of Long Beach, Calif who took first and are vetrans of the competition earning top ranks in engineering, presentation, and performance as well as being the only team to complete all the pool missions.  Second place went to Flower Mound Robotics of Flower Mound, Texas and third when to Sea-Tech 4-H Club of Skagit County, Washington.  The team also won the “Sharkpedo” award for innovation and originality, and was recognized for being the most safety-conscious team.

The Ranger Class was taken by the Canadians with Dalbrae Academy of Mabou, Nova Scotia taking first place aand Heritage Collegiate of Lethbridge, Newfoundland taking second.  But my hold stomping grounds took third place.  Monterey Academy of Oceanographic Sciences of Monterey, Calif. earned overall third place. Team member James Caress received one of three Ranger class “Engineering MVP” awards.

The post MATE Center’s International Student ROV Competition first appeared on Deep Sea News.

Post by Matt Hoch. Dr. J. Matt Hoch is newly minted PhD from SUNY Stony Brook who is interested in the reproductive ecology and life history evolution of barnacles. We have reported on Matt’s research previously here at DSN.
“Does your mother know what you’re doing?” The question was asked from the back of the room and I responded with what I thought was a truthful answer: “Yes.  She is proud of me.”  This was one of the only questions that anyone asked me.  I had just finished presenting my first talk on my own original work at a national scientific meeting, “A preliminary study of variation in penis characteristics in barnacles.”  My mother was at least proud that I was successfully carrying out research in a good PhD program.  I don’t actually know if she was proud of my project of choice.  I imagine that when telling her co-workers about my project, she might blush or tiptoe around it, but she at least tried to explain it to my grandmother.  “Why don’t you try to figure out a way to keep barnacles off my boat?”  That’s what my dad asked when I described my dissertation topic to him; “You’ll make us rich!”

It turns out the functional morphology of the barnacle’s…ahem…naughty bit… has important implications for evolutionary theory.  Barnacles are familiar as the small rock-like crustaceans growing on almost any hard surface that spends a significant amount of time in salt water.  Probably their most famous feature is the glue that they use to anchor themselves.  Living this permanently glued lifestyle imparts a few challenges on their ability to mate.  Unlike most sessile organisms, which broadcast spawn, barnacles reproduce by copulation.  They have to physically couple.  Since they can’t get up and walk, the only way to do this is with a penis that is capable of searching for partners and then mating with them.  The penis of the barnacle can stretch to about ten times the length of its body during attempts at mating.  It’s covered with chemosensory setae, bristles that are capable of detecting chemical signals; basically a series of noses that it uses to smell out receptive mates.  Once it locates a receptive partner, it might have to compete with many other barnacles attempting to fertilize the same eggs.  Once fertilized those eggs are brooded inside their mother’s shell for several weeks until they are released as larvae.

All of the barnacles involved may act as either a male or female at any given time.  They are simultaneous hermaphrodites.  An important decision that each barnacle must make is how much effort to put into acting as a male and how much to put into acting as a female.  Theory developed by scientific superstars W.D. Hamilton (1967) and Eric Charnov (1980) suggests that competition between barnacles acting as males should drive this decision making process.  As more and more barnacles compete to fertilize eggs, they need to produce more sperm to remain competitive.  They essentially try to produce enough sperm to overflow the functional female’s mantle cavity and displace the sperm of their competitors.  Large quantities of sperm can be deposited in these competitions.  So much so that functionally female barnacles have been reported as having so much sperm stuck to their cirri that they are unable to feed.

My work, on variation in penis characteristics, aims to determine how competition between barnacles acting as males changes in different physical environments.  For example, in wavy sites, barnacles are unable to reach mates as far away as barnacles in calm bays.  When they try, their penises probably get knocked around like crazy.  They deal with this by growing thicker penises, which may be more resistant to interference by waves, but lose the ability to stretch as far as the thinner penises grown by barnacles in calm water (Hoch 2008, 2009).  Since none of the barnacles in wavy sites can stretch as far, each barnacle acting as a male will have fewer others able to compete with it.  They are freed from intense competition, and following Eric Charnov’s predictions, should have larger clutches of eggs.

I recently explained this to my parents.  They seemed to understand it, but my dad asked the follow up question that I should have expected. “Can’t you figure out how to manufacture their glue?  We could get rich off of that.”

Further Reading
Charnov, E. 1980. Sex Allocation and local mate competition in barnacles. Marine Biology Letters 1:269-272.
Hamilton, W. D. 1967. Extraordinary sex ratios. Science 156:477-488.
Hoch, J. 2008. Variation in penis morphology and mating ability in the barnacle, Semibalanus balanoides. Journal of Experimental Marine Biology and Ecology 359:126-130.
Hoch, J. 2009. Adaptive plasticity of the penis in a simultaneous hermaphrodite. Evolution in press.

The post On the study of crustaceous genitalia first appeared on Deep Sea News.

This unique technology based competition challenged students to design and operate a remotely operated vehicle (ROV) in a pool-based exercise that simulates a descent to 2500 m depth to survey and sample a hydrothermal vent. Each robotic device in the regional competition was required to collect three “lava” samples, free a buried instrument, and take the temperature of a simulated hydrothermal vent (a pvc pipe with hot water running out).

What’s the day rate on these ROVs, I wonder? And how many of these kids could we squeeze in a double berth? I have a cruise at the end of the summer that could use some back-up support!

Seriously, DSN sends heartfelt congratulations to all the contest participants and organizers of the ROV Competition, and a very special sense of admiration for the good folks at MATE. This is a valuable project and an exciting competition that helps foster growth in the our generation of ocean explorers. You go, kids!

To learn more read the story in the June 2008 issue Marine Technology Reporter

The post Score one for home schoolers! first appeared on Deep Sea News.