Artificial Reefs, revisited…

Photograph by David Doubilet, National Geographic

Well I finally picked up a copy of the this month’s National Geographic with the artificial reef article in it. And by picked up I mean borrowed from a waiting room, but I have to go back on Thursday and will return it then, so I am no thief.  Anyway, I briefly blogged about this article already when I was depressed about winter weather and longing to be someplace else, preferably warm, and diving.  That’s because I love diving.  And sometimes, there’s nothing better than diving on wrecks.  Sometimes.  Don’t get me wrong, there is plenty of cool things to see on naturally occurring bottom.  But artificial reefs created by wrecks are definitely very cool (so is this video).

Image from Pangea-yep.com

But actually reading the article, in print, and seeing the pictures, made me want to blog about it all over again.  This time, though, I will concentrate a little more on artificial reefs themselves. Artificial reefs are quite simply structures artificially sunk by man to create a hard bottom in an otherwise sandy and structure-less habitat.  The idea is to mimic some of the functions of naturally occurring reefs – namely, by providing a hard, 3-dimensional structure that sits in the water column.  These reefs are intended to attract and enhance many marine species, in particular, finfish.    In fact, fisherman have been sinking things for decades (probably even centuries) to attract fish, so this is not a particularly novel idea.  However, the number and magnitude of  artificial reefs has certainly expanded greatly in recent years (Edit – as Dr Alan Dove pointed out in the comments below, there have been numerous “natural” or unintentional wrecks sunk over the years.  So the rate of sinking artificial reefs might not have increased, but I imagine the rate of intentionally sunk reefs has).  Typically, “Artificial reefs” just consisted of junk.  Now, many have expanded to be large decommissioned ships, subway cars, and oil rigs (and other cool things).  And even more recently, companies are creating artificial reefs from concrete, such as Reef Balls, which I think are pretty cool (and, if you are lucky, when you die, you can be commemorated for eternity as an artificial reef ball! Sign me up!).

It might not happen over night, but eventually these sunken structures become teeming with life.  Swirling currents around these structures can kick up and contain plankton, which attracts small planktivorous fish.  These little guys, in turn, attract larger piscivorous fish.  In addition to seeking food, many fish arrive simply to seek shelter in the many nooks and crannies that artificial reefs provide.  But its not just fish.  The artificial structures also become colonized by invertebrates and macroalgae, creating a crusty layer of living organisms growing as a living shell of sorts on the submerged structure.  This living structure offers more nooks and crannies for smaller creatures, and provides food for numerous species that inhabit the reef.  It essentially becomes just like a natural, living reef, with the only difference being that the underlying structure is man-made.  Typically, when we think of artificial reefs, we think of tropical locations.  However, they are also used in many temperate coastal waters to enhance fisheries, including Maryland,  South Carolina and New Jersey.  Here, they create ecosystem structure typically only present on the few limestone rocky outcroppings that stick out of the sand bottoms.

Despite providing food and shelter to numerous species, there are certainly detractors, and artificial reefs aren’t without certain cons.  One major concern is that some things are just tossed in the ocean as junk, but that companies/organizations/municipalities/entities use the “artificial reef” moniker as an excuse to dump crap.   Its cheaper to just toss things into the water than dispose on land, and so sometimes, things are called reefs just as an excuse.  That is bad.  Additionally, many things that are sunk have toxic substances on them, which can actually do more harm to the environment, leaking contaminants for the life of the reef.  It is for these reasons that there are now strict, stringent regulations for sinking artificial reefs.

But one of the biggest complaints against artificial reefs is the very reason they are created in the first place – they concentrate fish.  The complaint is that these concentrations make fish easier targets for fishermen, and can be potentially harmful to specific species.  According to the NatGeo article, some biologists believe that this artificial enhancement of certain fishes, can be extremely detrimental to stocks.  One such fish that is likely being negatively impacted by artificial reef structures is the red snapper, which concentrate around the structures and become easy targets for fishermen.  In other words, these artificial reefs might make fishing as easy as shooting fish in a barrel.  Obviously, acting as fish attractants with easy access can be harmful to fish populations, and some might argue that recreational fishermen are quite capable of decimating fish stocks, even in the absence of commercial fishing pressure

Clearly there are pros and cons of artificial reefs.  However, it is my opinion that the pros outweigh the cons.  And an easy way to eliminate the major negative impact of artificial reefs – the potential to overfish exploited stocks due to large congregations of target species around these structures – is to incorporate reefs into marine reserves and no-take zones.  Yes, this might defeat the purpose of the reefs, and many will argue against this.  I am not suggesting all artificial reefs become no take zones, but by leaving some as no take refuges, the reefs could serve there original purposes.  While there is some debate as to the usefulness of marine reserves on highly mobile species, it stands to reason that artificial reefs create habitat where there is otherwise none, and enhances the local ecology of the area of the reef, enhancing species abundance and diversity.  Plus, they are just awesome to dive on.

Warming Associated Range Shifts – King Crabs in Antarctica

Editor’s Selection IconThis post was chosen as an Editor's Selection for ResearchBlogging.orgWell I haven’t done a Research Blogging post in a very long time.  But I was inspired by this news release I read today about crabs spilling onto the Antarctic peninsula with warming waters.   On a recent voyage to Antarctica, marine biologists collected digital images of these deep water predators moving closer to shallow coastal waters which have been excluded from for potentially millions of years, because the shallow coastal waters, until recently, have been too cold to support these predators.  This can be devastating to the coastal shelf community in Antarctica, which has adapted no defenses in the absence of these predators – many organisms here have  thin shells or don’t burrow into sediments.

My friend and fellow Southampton College alum, Molly, recently blogged about this issue.  She is currently doing graduate work at the University of Alaska Fairbanks on snow crabs, so she loves crabs (as her blog title suggests).  The idea is that, as the above article states, these crabs are moving closer to the Antarctic shelf, and this can have devastating impacts on the local fauna there.  It was highlighted in a National Geographic article in 2008.

According to research, the Antarctic coastal shelf experienced a cooling trend starting around 40 mya, and the waters, due to the cooler temperatures, essentially became devoid of many types of predators.  The subsequent community had evolved over those millions of years in the absence of major durophagous predators – known for their shell crushing abilities.  The major predators in these bottom waters are slow moving invertebrates, and the community developed over time accordingly.  Now as surface waters are warming, crabs are able to enter these new areas from the depths, and can have potentially harmful impacts.

At first, this might seem counter-intuitive – typically bottom waters, and the deep ocean, are very cold, and the water warms as you get shallower.  This is not the case on the Antarctic shelf, where the shallow waters are actually colder than the surrounding deep waters.  This is due to the cold Antarctic circumpolar current, which runs clockwise around Antarctica, isolating its cold water and continental shelf from crabs and fish with bony jaws.

However, the absence of crushing predators was not due to geograhic isolation of the Antarctic continental shelf (although Antarctica is oceanographically isolated, the barriers of biological invasion in this case are physiological, according to Richard Aronson, professor of biology at the Florida Institute of Technology, and others in 2007).  Physiologically, the crabs are unable to process magnesium in their blood at the normal shelf water temperatures, resulting in narcotic effects.  So the crabs, for millions of years, had stayed away.  The resulting shelf community, consisting of epifaunal suspension feeders, lacked the typical defense mechanisms seen in other benthic environments where soft bottom bethos have been evolving with predators in an evolutionary arms race.  As already mentioned, the archaic communities of the Antarctic shelf, consist of animals with thin shells which don’t burrow.  So one could imagine that if these crab predators were allowed to move into these coastal waters, it could have devastating consequences on the community there.

This is not a crab you would encounter in the Antarctic, however, it is as close a figure to the "arms race" - crab claws, thick clam shell - as I could find on the interwebs.

Recent research suggests that the physiological barrier separating these durophagous predators are being lifted by a rapidly warming Southern Ocean and Antarctic shelf.  This warming is allowing predators to move closer to the shelf communities, as demonstrated by Sven Thatje, evolutionary biologist at the University of Southampton in England.  Thatje and colleagues found the shallowest lithodid crab every recorded on the Antarctic shelf (photo above) and suggested they were “reconquering” the Antarctic back in 2005.  This led to Aronson and colleagues (2009) to predict rapid changes over the coming decades in the benthic community on the Antarctic shelf.  The crab populations could reduce or eliminate suspension feeding echinoderms (starfish, sea cucumbers), and the overall impact will likely render the formerly unique Antarctic shelf benthic community to resemble other benthic communities in low latitudes.

Range expansions are something that are particularly interesting to me.  The lifting of physiological barriers due to temperature will allow biological invasions of numerous species.  How these species interact with native species is of great concern.  In particular, predator-prey relationships between novel predators and naive prey can restructure communities in warming oceans. Despite its perceived isolation, this research suggests that Antarctica will not be immune to these impacts (and it fact, polar regions are likely to experience a greater magnitude of temperature change).

And the real news here, is not only is there evidence the crabs are moving closer to these shallow shelf communities, but that it is occurring at a much more rapid rate than anticipated.

A quote by Dr. Aronson from the new article:  “If you look at the warming trends on the peninsula, you would expect that the crabs would come back in 40 or 50 years,” Aronson said from his office in Melbourne, Fla. ”But boom, they’re already here. This is the last pristine marine system on Earth and it could get destroyed”.

This is big and bad news for the Antarctic bottom communities.  Clearly, this is something that should be monitored closely.  But it is not in any means an Antarctic phenomenon.  In many regions where warming is taking place, range expansion of novel predators can occur.  This is something all benthic communities could experience in the near future.

ResearchBlogging.orgAronson, R., Thatje, S., Clarke, A., Peck, L., Blake, D., Wilga, C., & Seibel, B. (2007). Climate Change and Invasibility of the Antarctic Benthos Annual Review of Ecology, Evolution, and Systematics, 38 (1), 129-154 DOI: 10.1146/annurev.ecolsys.38.091206.095525

Aronson RB, Moody RM, Ivany LC, Blake DB, Werner JE, & Glass A (2009). Climate change and trophic response of the Antarctic bottom fauna. PloS one, 4 (2) PMID: 19194490

Thatje, S., Anger, K., Calcagno, J., Lovrich, G., Pörtner, H., & Arntz, W. (2005). CHALLENGING THE COLD: CRABS RECONQUER THE ANTARCTIC Ecology, 86 (3), 619-625 DOI: 10.1890/04-0620

Thatje, S., Hall, S., Hauton, C., Held, C., & Tyler, P. (2008). Encounter of lithodid crab Paralomis birsteini on the continental slope off Antarctica, sampled by ROV Polar Biology, 31 (9), 1143-1148 DOI: 10.1007/s00300-008-0457-5

Because I couldn't have a climate related article without citing the Church of the Flying Spaghetti Monster

 

Shark Skin Technology

Recently, CBS covered a story of researchers investigating the pattern on shark skin, and how it is able to resist fouling organisms that are common on other long lived, large marine vertebrates such as whales and turtles.  This has major implications for the boating industry, and come companies have already begun to capitalize on the unique structure of shark skin to use as coatings for boats.  This isn’t necessarily news, as shark skin coating has been investigated as an anti-fouling mechanism for the NAVY for some time.  The idea behind that research is that a) fouling organisms settle on ship hulls and grow, increasing drag forces of the hull in the water, b) this increased drag reduces the ships efficiency and adds considerable cost to powering the vessel, and c) the pre-existing anti-fouling methods are either cost and time prohibitive (hauling the ship out on dry dock) or extremely harmful to the environment (such as using copper or tin based bottom paints).  The adverse affects of the bottom paints used were extremely harmful to the environment, leading to accumulation in the sediments of ports and bioaccumulation through the food chain.  The adverse affects led to the ban of tributyl-tin , TBT, bottom paint in the US and many countries abroad.  Additionally, some states are beginning to ban copper based paints as well.

In comes the shark skin, whose scales and denticles (tiny “skin teeth” ) are arranged in a diamond shaped pattern. The pattern of sharks skin is already effective at reducing drag forces.  So by merely mimicking the pattern, drag should be reduced along a ships hull.    Add to that the lack of spores being able to settle onto this skin pattern, and you have a bottom coating that is much more efficient for boats and more safe for the environment.

But now, researchers are interesting in a different kind of biofouling – bacteria and the medical industry.  Some research, according to the CBS article, indicates that Sharklet patterned plastic had significantly reduced numbers of bacteria on it when compared against a smooth plastic sheet.  This has major implications for the health industry, as some bacteria are difficult to kill, and many places like hospitals and doctor’s offices, as well as schools and public offices, are bacterial breeding grounds (although I guess technically anywhere is a bacterial breeding ground of some sort).  This material may be important for use combating  infections, by coating commonly touched places with the shark skin patterned material.

Interesting stuff.

Functional Extinction

Recently, a few articles started appearing about the dramatic loss of oysters throughout the world, and how in many areas, they are “functionally extinct.”  The article from ScienceBlogs talks about the findings of an international research team lead by Dr. Mark Luckenbach of the Virginia Institute of Marine Science.  In over 70% of the 144 estuaries studied, current oyster levels are at 10% or less of historic levels.  They estimate that over 85% of the world’s oyster reefs have been lost.  The amount of loss exceeds any other shallow water benthic marine habitat that has been similarly studied.  Obviously, this can cause problems.

The Underwater Times article mentions the term “functionally extinct” when referring to current oyster populations – that in some areas, oyster populations are less than 1% of historic levels, mainly due to overharvesting, disease, and invasive species introductions.  But what does “functionally extinct” mean? In this sense of the term, it is when a species experienced such a reduced population that said species no longer plays a role in the functioning of an ecosystem.  Obviously, the loss of any players in an ecosystem can be devastating.  But oysters are a foundation species, providing a variety of ecosystem functions that renders them more important to their estuarine ecosystems than many of the other species. Oysters create biogenic 3-D structure in the forms of reefs, which build up from the seafloor and in many locations emerge from the water, particularly at low tide.  This structure provides a plethora of microhabitats and niches for a variety of species to live.  In addition, since oysters are filter feeders, they play an important role in nutrient cycling in estuaries, packaging things in the water column (plankton, particulates) and delivering them to the bottom where they are consumed and utilized.  During this process, oysters actively clear the water column, increasing light penetration to the bottom and potentially allowing valuable submerged macrophytes to grow, adding structure to the reef and surrounding area, creating even more habitat.  A number of species depend on this habitat for food ad shelter, as they are valued nursery and feeding grounds for numerous estuarine species.  This function is vital to fisheries, as many finfish spend a portion of their lives foraging around oyster reefs.  So when the articles suggest that oysters are becoming functionally extinct, it has serious repercussions for the ecosystem as a whole.

Understanding oyster reef ecosystem services are important as researchers and managers move forward in trying to save oysters worldwide.  Oysters have been subject to considerable research, and more recently, a variety of restoration efforts have been conducted in the Chesapeake, Delaware Bay, North Carolina, and, more recently, the Hudson River.  The Hudson River project in particular is focusing on restoration of ecological function and not for the fishery.  In fact, due to their filtration capacity, landscape architects have proposed using oysters in the Greater New York City Area to clean up some highly polluted canals.

Clearly, the loss of oyster reefs are problems both economically and ecologically.  However, some research suggests all is not lost.  Stricter harvesting laws, fewer baymen, and no-take sanctuaries have helped maintain oyster populations, albeit low populations, in some areas.  Better and more successful management is the first step towards saving oysters, and the report made the following suggestions for restoring and maintaining oyster reefs:

  • The prohibition of harvests where oyster populations constitute less than 10% of their prior abundances, unless it can be shown that dredging and other harvest methods do not substantially limit reef recovery.
  • New thinking and approaches to ensure that oyster reefs are managed not only for fisheries production but also as fundamental ecological components of bays and coasts that provide invaluable ecosystem services.
  • Steps to ensure that harvests, particularly those carried out by dredging, do not damage the remaining reefs.
  • Regular monitoring of reef conditions.

There is plenty of other relevant information out there about oyster reefs, research, and the issues facing them.  I particularly recommend the blog In the Grass On the Reef, which focuses on research underway by Florida State researchers on salt marshes and oyster reefs.  In particular, they update posts about their research in ways which are easy to understand with great visual aids including photos and videos.  Definitely check that one out.

More Lionfish, Oh My!

Lionfish from my Fiji dive trip. It was upside down under a coral ledge

So wow.  I’m not saying it has anything to do with me, but I made a post about lionfish a few months back, and had a very special guest blog by colleague Amber Stubler about her experience capturing lionfish with a spear gun and eating them.  A commenter was concerned about that post, indicating that some research is showing that lionfish may contain ciguatera poisoning, so I had already decided to do a new post about that.  But then, in the last 2 days, lionfish are making the news – first in Florida, then in the US Virgin Islands.

In Florida, dive master Randy Jordan of Emerald Dive Charters is the self-proclaimed “lion-tamer.”  He has caught 331 lionfish to date, including his most recent haul, a 16 inch (!) 2 and a half pound fish.  According to Fishbase, thats about as big as they get.  According to the article, Jordan is scheduled to give a lecture on the subject on February 26th at the Loxahatchee River District meeting to talk about his special device to catch these invaders.

Then just yesterday, an article about the invasion problem in the USVI, where the lionfish now number in the thousands.  The governing agencies there are planning meetings with divers, fishermen and businessmen to discuss the problem and how to combat it, and, in particular, to get divers and fishermen to report their kills.  The worry is that these invasive voracious predators will wreak havoc on the local reefs and hit the major tourism industry.

From American Museum of Natural History

Lionfish are getting a lot of attention currently.  And I have advocated the consumption as an eradication plan.  But as I mentioned, commenter John Rubattino from the USVI had commented his concerns about ciguatera poisoning being prevalent in fish caught there.  This would create a major problem, as ciguatera is a food poison, and when humans consume fish that contain the toxin, they often experience nausea, vomiting, diarrhea, pain, dizziness, vertigo, chills, rashes, and other symptoms.

So how does one get ciguatera poisoning?  Again, its a food poisoning which results from eating large predatory tropical fish which contain the poison.  According to the CDC, these fish include barracuda, certain snappers and groupers, jacks, king mackerel and hogfish.   But where does the toxin come from, since these fish don’t produce it themselves?  Tiny microalgae.  In particular, this toxin is produced by a harmful dinoflagellate known as Gambierdiscus toxicus.  When it grows, it often settles on reef structure and macroalgae where it is consumed by herbivores and small predators.  Then these fish are consumed, and so on and so forth up the food chain.  But the toxin is not harmful to the fish.  So the large predators listed above contuinue to accumulate (a process known as bioaccumulation, also here, one of the reasons why you shouldn’t eat too much tuna or many other fish due to mercury) the toxin.  Then, when humans eat those fish, they get extremely ill.

So I did some research on the itnerwebs about lionfish and ciguatera.  Lionfish already produce their own toxin, present in their spines, but the thought was as long as they were processed carefully, that would not be harmful to humans.  Surprisingly, there is little information about lionfish and ciguatera.  There are a few posts from the Caribbean Oceanic Restoration and Education (CORE) Foundation in the USVI about lionfish with ciguatera, and how to proceed.  Attached 5. Ciguatera is a .pdf from the Caribbean Epidemiology Centre about ciguatera cases in the Caribbean.

So its now out there and at least something to think about.  There haven’t been many reported cases, but it might be worthy of investigation in the future.  Obviously, lionfish present a considerable risk to the coral ecosystems they are invading, and so eradication must be considered.  A simple way is to encourage locals to fish and eat them, and hopefully fish them out.  However, if they might present a risk to human consumption, this idea needs to change.  Research is warranted to resolve these issues.

ASUs in the News (I’m a poet, in case you didn’t know it)

So I frequent the UnderwaterTimes almost daily.  I like to find out what’s going on in underwater related news.  So imagine my excitement at this article today:

Fake seagrass could help boost fish numbers

The premise of the article states that scientists in New Zealand are using artificial seagrass to help boost fish stocks.  Seagrass is an extremely vulnerable marine habitat, with worldwide losses.  In some places where lush underwater meadows used to exist, the grass has been replaced by barren sediments.  This can have an impact on fish stocks, as many marine species utilize seagrass as a habitat for at least some portion of their life cycle.  So it comes as no surprise that scientists want to try to replenish fish stocks by enhancing seagrass.  This is apparently what they are trying to do in a bay in New Zealand. Although, I imagine that the researchers are actually using ASUs to test affects of fragmentation on local fisheries species and not to actually be used to enhance species, it is interesting none-the-less.

I have a certain affinity for all things fake seagrass.  Why? Well, a portion of my dissertation research involves using artificial seagrass units (ASUs) to investigate the impacts of patch size and shape (perimeter, area, and P:A ratios) has on scallop recruitment, survival and growth.  As I mentioned already, seagrasses are important habitats, and bay scallops have long been known to associate with seagrass.  Scallop populations are currently undergoing varying degrees of restoration (depending on location) but with restoration comes certain issues – namely, how are these little guys going to be affected by declining seagrass.  In many areas where scallop populations crashed, seagrasses have also diminished in extent.  Since seagrass is important for scallops, a decline in seagrass cover can have implications for scallops and their restoration.  For my work, I use 2 sizes of seagrass mats, 8.5 and 17 square meters, and 2 shapes – a circle and 4 pointed star to maximize perimeter.  Just in case those numbers don’t mean much to you, the small circles are just over 3 meters in diameter, the large circles around 5 meters across.  The large star is 7 meters from tip to tip.  These ASUs have 500 shoots per meter, consisting of 4 blades of polypropelene ribbon.  It was quite the undertaking, and required many beer and pizza nights for fellow grad students, as well as help from local schools and scout troops.

I have generated some interesting, and unexpected, data.  There is a wealth of literature out there about the impacts of fragmented seagrass habitats, patch configuration, edge effects, etc, that has been accumulating over the last 15 or so years.  Going into the experiments, I had a pretty good idea about what I would expect to see – more scallop recruits along the edges of the mats, but higher predation at the edge.  Growth to be slowest in the centers of the mats, etc.  However, not everything happens the way I planned or anticipated.  In particular, I have been working up some of my recruitment data, and I did not see a “settlement shadow” or edge effects due to predation.  What is a “settlement shadow?”  Essentially, bivalve larvae can be assumed to be passive particles, moving at the mercy of the currents.  As a current comes into a seagrass meadow, the flow is attenuated.  Particles settle out along the edge, and become diminished with distance into the meadow.  Hence, recruitment is expected to be highest along the edges of seagrass meadows (and, also, the edges of my ASUs). On the opposite end of the spectrum, survival is expected to be the lowest along the edge, since predators are likely to have more access along the edges, and thus predator encounter with scallops should be higher.  However, this isn’t what I saw. The reason? The dominant predator in my particular system is a small mud crab – not likely to be impeded by seagrass structure and essentially ubiquitous throughout the ASUs.  This tells me the dominant process structuring post set scallop communities on my grass mats is predation, and the predator is apparently not impacted by fragmentation.  This could have implications for restoration.  I haven’t finished all the analysis yet, but it was pretty interesting.  I just presented some of this work at a graduate symposium last week, and plan on presenting it again at the National Shellfish Association annual meeting in March.



Today on the Interwebs!

There has been a lot of really interesting posts on the internet over the last few days, so I thought I might concentrate some here in yet another LINK DUMP!

Over at Southern Fried Science, Andrew continued in his series of gear reviews, this time talking about how important and cheap  proper sunglasses can be.  Additionally, resident shark expert David gave his thoughts on the latest “sharks eating humans” commercial by Snickers, and gave us a run-down about whether MPAs work or not.

Over at Cephalove, Mike talks about how we can build a better blogosphere.

Chuck at Ya Like Dags does a Research Blogging post about North Pacific Dogfish officially being recognized as a different species.

Dr Al Dove has just embarked on a research cruise to study the deep reef platform off of Brazil known as Abrolhos.  Check it out at Deep Type Flow.

Apparently, smaller, short-lived corals are more disease resistant and resilient.

Whale threesomes! Need I say more?

Deep Sea News had a busy couple of days.  First Dr. M highlighted his article from WIRED where he talked about a mass extinction of scientists who study species. Dr Bik followed up that sentiment with a post of her own about the issue. And Mirian just posted a couple of ocean education opportunities for students and educators.

And in the news, Dubai’s artificial islands are sinking and channels filling in (shocker, right?) and in Japan, corals are moving poleward as fast as 14km a year! Crazy!

All’s not well in Oz…

A colleague, friend, and former roommate of mine took a post doc position over in Australia around this time last year, doing harmful algal research.  He recently sent me this video:

flooding in australia

It’s pretty wild.  And to think, people here on the east coast are complaining because their streets weren’t plowed fast enough! Imagine these rapidly moving flood waters racing down your street? Absolutely nuts.  It has claimed lives and caused considerable devastation.  Obviously, due to the harsh weather we have been receiving here, we haven’t heard all that much about the flooding.  You can read about some of it here, here, here, and here.  My friend Tim even blogged about it.  Google it too, theres plenty of info about it out there.

An interesting article I came across piqued my interest – the flooding has supposedly given bull sharks access to the town streets, and a couple have been spotted swimming around.   Could you imagine? I mean wow! I find that both exciting and petrifying.  On one hand, it just speaks to the incredible adaptive ability of bull sharks.  On the other hand, they are often considered among the most aggressive sharks in the world, and you wouldn’t expect to see them wading through floodwaters in the middle of you town.  Many of you are probably thinking how impossible that must be.  But bull sharks are tolerant of fresher waters, and in some parts of the world, are found venturing up rivers!  They are extremely tolerant of wide-ranging salinities via unique osmoregulation abilities.  In fact, these sharks are often found in rivers, even in the US, like Alabama and the Potomac River.   It is also thought that a bull shark is responsible for the Matawan creek attacks in 1916, an event originally attributed to a white shark and the inspiration for the movie Jaws.

Maybe Chuck over at Ya Like Dags or David over at Southern Fried Science might have some more insight into the reasons bull sharks are so freshwater tolerant.  But I thought it was interesting and worthy of mention.

Edit- Shark biologist Lyndell Bade informed me that bull sharks can be found up the Mississippi all the way to St Louis and can live in Lake Nicaragua.  These are quite amazing fish.

Beware of the…. SQUIDWORM!!!

That sounds and looks scary! Squidworm.  It’s almost like something Tim Burton would conjure up.  Discovered by a team of scientists from Scripps  Institution of Oceanography, the squidworm is an annelid worm – similar to earthworms.  However, this creature is from the deep.  And it has up to 10 squid like tentacles, which gives this creature both its unique look and its name.  This organism hails from the depths of the Celebes Sea, between the Philippines and Indonesia.  It swims using a series of paddles along its sides and its tentacles are specialized for touching and smelling.  They feed on a rain of detritus (one of my favorite marine bio terms, and wouldn’t that make for an awesome heavy metal band name?), aka, marine snow – a rain of particles consisting of (but not limited to) sinking plankton, fecal matter, mucus, dead stuff, etc.  You can read all about this discovery here.

Breathing water, underwater…

So I frequent the UnderwaterTimes site on occasion, trying to see whats new in the world of all things underwater.  Yesterday, there was an article about diving in The Independent, something about a “diving suit that turns men into fish.“  Naturally, I was intrigued, as I love diving, and while I can’t afford most advanced SCUBA technologies, I like to read about these advances that will make diving a better experience, last longer, etc.

So I started reading the article.  Its introduction talks about all of humans accomplishments, ie, flying, tunneling, space travel, and yes diving – things that we have learned how to do successfully.  Well except for diving.  Very few people have descended to experience depths using scuba over 200 feet (the closest I ever came was 140, and typically, I stay above 70 feet).  And, according to the article, more people have walked on the moon than descended to over 700 feet.  Now you might be thinking why would you want to dive that deep? While one could make the same argument about why would you want to climb Mt Everest or travel to the Moon.  Its all about discovery.  Big things live down there.  Odd things live down there.  It is a unique world, one few have ever seen.  That’s what makes it so appealing.  It’s also kind of frightening.

But for me, its not so much about the discovery of the depths.  It is dark and scary down there.  I am intrigued by a no decompression, no danger of  “the bends” diving opportunity.  I can imagine being able to spend hours at 60 feet in Fiji, looking for shells, photographing nudibranchs, without worrying about saturation.  That is appealing to me.

So I read on.  Apparently, retired lung specialist Arnold Lande has patented a scuba suit that would allow humans to breath “liquified” oxygen.  Sound interested? I’m on the fence now.  Breathing fluid? Wouldn’t that feel like drowning?

“The first trick you would have to learn is overcoming the gag reflex,” explains Lande, a 79-year-old inventor from St Louis, Missouri. “But once that oxygenated liquid is inside your lungs it would feel just like breathing air.”

Wow.  I am sure that’s a pretty hard trick to learn.  But I guess I would be interested in finding out more.  The suit would use a specialized liquid known as highly oxygenated perfluorocarbons, a liquid which is capable of dissolving large quantities of gas.  The liquid is then contained in a helmet and replaces all the air in your lungs, nose and ears.  Again, sounds frightening.  However, hospitals use similar fluids for premature births which struggle to breath air.  Mice have been dropped in this liquid and survived after the initial “drowning” reaction.  And US Navy Seals experimented with liquid breathing in he 1980s.  So it is possible.

This would allow us to explore the depths. Send workers down to exploded deep sea oil rigs.  Collect sediment and animal samples on scientific expeditions.  Photograph angler fish.  All cool and useful things.  According to the article, using oxygen suspended in liquid would not have to worry about decompression sickness, since theoretically, there would be no bubbles in the blood stream.  This is appealing because it allows the divers to dive deeper and stay down longer.

But then I read this part: the CO2 would be scrubbed from the blood stream by attaching a “gill” to the femoral vein in the leg.  And that’s all the article says about this.  Granted, its a news article about the possibility.  But, wait, what?  Not only do I have to breath in liquid, I need to have some mechanical gill attached into my leg?  Clearly, this is not for people like me.  It is interesting to think about, though, that’s for sure.