Friday, October 31, 2014

Fish Aggravating or Fish Aggregating Houses in the Sea


2nd FAD houseboat
Houseboat/FAD off Ontong Java Atoll.  SOI/Mark Heckman
One of my last posts from the Ontong Java Plateau was our discovery of some floating "houses" hundreds of miles from anywhere. You can see the post here: It's a Houseboat FAD.

Non-fishing oriented conservationists sometimes joke about the FADs, most of which in Hawaii are buoy's but can be a variety of devices. The question is often put, when a vessel is sunk to provide more "fish habitat" or a floating FAD is put in - are these devices actually producing more fish by creating fish habitat, or just creating ways for fishers to harvest dwindling and hard to find fish by creating an attractive space that lures them in. Hence the title, "Fish aggravation or aggregation." The answer depends on the level of use of the FAD and the type. PEWTrusts has a very interesting read on effects of FADs on tuna, see: Fish Aggregation Devices and Tuna, and Hawaii always seems to have some current research on FADs as a matter of course, of which HIMB's Holland lab is often involved through their HIMB Pelagic Fisheries Research unit. They do, as always, excellent work.

FAD houseboat above Ontong Java Plateau
Houseboat FAD 2. SOI/Tomer Ketter
It is unlikely that FADs will go away, so it is important that management based research continues on these devices.  As is common in fishing issues, research will give us the facts upon which to base opinions and action. So have a read through some of the resources given above. Interesting stuff!

Aloha,

Mark

Friday, October 24, 2014

Blogs from the R/V Falkor off Ontong Java

CTD array headed down. SOI/ Mark Heckman
Have you been following along? It is 4 a.m. here on the R/V Falkor off of Ontong Java Atoll. I am midway through my midnight to 8 a.m. seafloor mapping shift. Mostly I just watch while my shift partners (who actually know what they are doing), make sure all is well. The other night, a sharp rise on the port side of the seafloor map prompted my night shift partner Tomer Ketter, to call up to the bridge and turn the boat around. We reversed course, mapped a new seamount and then went back on track.

There are new blog posts every day, either by myself or the Chief Scientist, or whomever in the science crew I can convince to write. I will also be on the radio with Carlie on the 28th.

Some topics so far:
10/15 Converging on a Point (Getting everyone in to Pohnpei from around the world)
10/15-Present Mapping with Mike - Cruise accounts from the Chief Scientist
10/18 Using the CTD to Calibrate the Multibeam Sonar (less technical than it sounds and great images taken by putting my camera on a very long stick off the back of the ship)
10/19 Amelia Earhart and Nukumanu Atoll (yup, we are off the last confirmed position for Amelia Earhart)
10/20 The Meaning of Life or at Least a Multibeam Acquisition Screen (a look at the coloful screens we watch 24-7)
10/23 Flying in Darkness - Charting Unknown Reefs at Night
and our most current:
10/24 Colored Lines - Decyphering the CTD Code (again, less technical than it sounds. I am also aiming some of these for HS students studying sea floor mapping)

Next up will be an entry on the barracuda that ended up on deck and the results thereof. 

Aloha!

Mark
Section of atoll we have been mapping. SOI/Tomer Ketter

Wednesday, October 8, 2014

Mysteries of Ontong Java

Next week and I will be off to Pohnpei, Micronesia via a 10+hr flight to board the state of the art research ship Falkor - from there, on to the Ontong Java plateau.

Schmidt Ocean Institute R/V Falkor

The plan is that I will be working for my colleague Carlie Wiener, handling the outreach on a research/exploration cruise.  The ship is run by the Schmidt Ocean Institute (SOI), a private non-profit organization dedicated to ocean exploration. I like the quote from Wendy Schmidt (March 6, 2012), "The purpose of this ship, as she leaves on her various missions, is to communicate about the science of the oceans to people so that they can care about it.  We can't take care of something that we don't understand and we can't care if we don't know."

http://www.schmidtocean.org/story/show/2253

I will be posting daily  to the SOI blog, Facebook, Google+, and Twitter accounts. Better yet, the scientists on the cruise who actually know something will do some of the postings too. So follow along and learn about multibeam sonar scanning, multipurpose landers, and a mystery - an undersea plateau almost as large as Alaska that was probably the largest known volcanic eruption in Earth's history. Join me as I accompany Chief Scientist Mike Coffin from Tasmania with a group of scientists from around the world and the ship's crew of the Falkor, to explore "The Mysteries of Ontong Java."

The name of the area alone makes it worth checking out. I will link back to this blog, or you can follow directly via the SOI site.

For the University of Tasmania Press Release on the cruise see: Tsunami risk estimates will improve with Pacific voyage study
Aloha,

Mark

Friday, September 19, 2014

UXO - Finding Unexploded Ordinace on the Reef or On Your Way to Work

 Image - S. Pagliaro
Sal was walking in to work today when he noticed an encrusted mortar shell lying by the side of the path. Being obviously more aware of his surroundings than I am in the morning, he pulled up short. "How in the heck did that get there?" was his first thought, followed by, "That should NOT be there."

He did not touch it or move it. He called Jim, our facilities manager, the police came, followed by an EOD (Explosive Ordinance Disposal) team. When I walked up, there was a 50 meter perimeter already set up.

Now most of us in Hawaii have some experience with unexploded or old shells, casings and so on. Perhaps most dramatic for me was off of Kaho'olawe (image below), but - most all of us know not to pick these things up. Even if it looks harmless, you never know. As the EOD officer told me, a piece can be lying there for years, someone collects it, folks hand it around and around and then one day it just goes off. Bummer for the one holding it at that point.
Snorkeling above UXO off of Kaho'olawe.  Image M. Heckman

So this seems like a good time to reinforce the guidelines for finding shells, bombs, bullets (some of which may be explosive) on the reef, at the beach, in the forest, wherever. The rules are simple:
1. Recognize, 2. Retreat and 3. Report. Do not take it home as a souvenir

I went to the DoD site on UXO and enjoyed reading through the material, although it was rather disturbing at points. Such as the comment that munitions are hard to recognize and can resemble a "baseball, soda can, or muffler." Hmm, that is clear as mud. I also like the warning on marking the location,
"mark the general area, not the munition, in some manner (e.g., with a hat, piece of cloth, or tying a piece of plastic to a tree branch)" (bold added).  
You can easily imagine some yahoo saying, "I'll just put my hat on this bomb so we can find it again."

So resist the treasure hunter urge, mark the location and call it in. Don't we all have enough junk in our houses and lives anyway? Who needs a nice old munition that might unexpectedly explode. I don't know about you, but my life has enough randomly occurring drama as it is.

By the by, the ordinance Sal noted was apparently quite empty, which was a good thing.
Mortar round. Image S. Pagliaro

From the Department of Defense Site:

RECOGNIZE:

Recognize when you may have encountered a munition.


RETREAT:

Do not touch, move or disturb it, but carefully leave the area the way you entered.


REPORT:

Call 911! Immediately notify local law enforcement of what you saw and where you saw it.


For more info, check out their site at: Explosives Safety

Aloha,

Mark




Friday, September 12, 2014

Coral-eating Sea Slug, Phestilla lugubris, Bane of a Coral Keeper's Tank

View of the Porites compressa on Monday morning. Photo - M. Heckman 
Time for an update on one of our less desirable community tank inhabitants!

Trying to recreate nature in an aquarium is always a tough thing to do. We strive to keep a relatively harmonious mix of creatures in our touch/observation table. But with raw seawater coming in and clumps of new sponge continuously being added for the tiger cowries to eat, it is inevitable that some less desirable characters will appear.

Such was the case again recently - we have been having an infestation, which seems to happen to us at least once a year. When I leave on Friday for the weekend, I always check the tank and typically the corals look good. But about once or twice a year when I come in Monday morning, pieces of the finger coral (Porites compressa) have gone from healthy to compromised. They have big white blanched areas down near their base. 

Phestilla lugubris: on black
Phystilla sea slug, C. Pittman photo
The culprit is easy to guess, the white sickly looking area is living tissue devoured by the coral eating sea slug Phestilla lugubris. This is an animal feared by those that try and raise Porites (finger and lobe) corals in captivity. Outbreaks can be devastating if not checked. A quick examination of any coral in question typically reveals a large (well fed) specimen of Phestilla settled between two of the coral's branches.


Note sea slug at top, areas that the sea slug has eaten and the 
various egg masses that it has laid - all in one weekend.
Closer view - M. Heckman Photo
Phestilla tend to hide under corals or rocks during the day and come out at night to feed on living corals.  In the wild, they are rarely a major issue for coral health since many predators will feed on them. A study by Dr. Aeby (from HIMB) and colleagues found that the threadfin butterflyfish (Chaetodon auriga would eat small specimens and the old woman wrasse (Thalassoma ballieui)  would eat any large Phestilla slugs that made the mistake of wandering up in the open during the day. 
Old woman wrasse
Threadfin butterflyfish
As to those hidden during the day, they would be sharing their habitat with various crabs and mantis shrimp that Dr. Aeby and group has found would also feed on the slugs. 
Gonodactylaceua falcatus
Gonodactylaceus mantis shrimp from
Introduced Marine Species of Hawaii
Areolated xanthid crab
The slugs are not without their own defenses. Although they are not able to transfer the coral's stinging cells to their skin (like some of their relatives) they do exude a slightly noxious substance when disturbed.

These are very interesting animals. They are one of the few sea slugs that scientist have figured out their entire life history - think egg to adult in less than 40 days, adults live only a few months, laying thousands of egg a day, then die a couple of weeks later. Contrast this to an adult sea cucumber that might live decades. Some invertebrates move slow and live slow, some move slow and live fast. Phestilla  may take down 10 square inches of coral a day, lay thousands of eggs and pass away, leaving their progeny to continue on.  

Crawl slow, eat large, live fast. 

For some great sites on these animals (and some of my references for this article), see:

Bill Rudman photo
The Phestilla lugubris page at the Sea Slug Forum - a great site, bits of info, questions with pictures from readers and answers to those questions. See: http://www.seaslugforum.net/showall/pheslugu
Phestilla lugubris: mottled
Pauline Fiene photo
Sea Slugs of Hawaii by Cory Pittman and Pauline Fiene - excellent site - simple, straightforward information with life history and more. A good place to go to learn about our local sea slugs (also, Cory was one of the first marine biologists I encountered as an undergraduate - ask me about the meeting sometime). See: http://seaslugsofhawaii.com/species/Phestilla-lugubris-a.html
Dana Riddle Photo
A recent article (this month) in Advanced Aquarist by Dana Riddle on coral eating sea slugs. Broad coverage, information for those who keep corals in captivity and the most up to date information. See: //www.advancedaquarist.com/2012/6/inverts

Other references
Control of populations of the coral-feeding nudibranch Phestilla sibogae by fish and crustacean predators. D.J. Gochfeld and G.S. Aeby. MARINE BIOLOGY, Vol. 130, Number 1 (1997)


Friday, August 15, 2014

Blue Swallowtail Slugs

Chelidonura hirundinina. image by L. Weaver
Observing the "No Touch Table" with the green zoanthids, it appears that there has been an inadvertent recruitment of a variety of new volunteer organisms.  While we are quite fond of our human volunteers, the invertebrate volunteers are not always appreciated.  The overwhelming majority of the new additions are sea anemones, which can, unfortunately, sting the corals in the tank as they compete for space.

Stylocheilus striatus. image by L. Weaver
Another new inhabitant I noticed was the lined sea hare, Stylocheilus striatus (Quoy & Gaimard, 1832), whose prevalence coincides with the appearance of patches of Lyngbya algae floating around the Bay during the second half of summer.

The last of the new inhabitants was the blue swallowtail slug, Chelidonura hirundinina (Quoy & Gaimard 1832), which almost went unnoticed, despite its dramatic coloration of pitch black, offset by lines of bright neon blue, green and orange.  These tiny slugs are known flatworm predators.  As in my previous observations of the blue swallowtail slugs, there were two individuals present.  Which is good, because this is the minimum number necessary for sperm trading!

Chelidonura hirundinina. image by L. Weaver
"What?!" you say?

Like most sea slugs, the blue swallowtail slugs are hermaphrodites, possessing both male and female reproductive organs. During mating, each slug is simultaneously playing the role of male and female, both giving and receiving.  The ocean is a very big place and it isn't easy for these less common animals to find a partner.  So, when they do encounter another slug of the same species, possessing both female and male anatomy tremendously increases the likelihood of successful mating and egg-laying.

Even among slugs, there is a level of  behavioral recriprocation during the act of reproduction.  In the article titled, "Gender Trading in a Hermaphrodite," researchers ran an experiment to see if mating behavior would change if one of the partners was basically neutered and could not fully reciprocate in the mating process by giving sperm. They found that, although these slugs will normally copulate multiple times in row, a slug which doesn't inseminate its partner will soon be abandoned. After all, it isn't sperm trading if only one slug goes away "pregnant."

Chelidonura hirundinina. image by L. Weaver
It gets more interesting. What if a slug's partner does produce sperm for trade, but isn't "father" material? Since the receiving slug has invested a lot of energy creating its own eggs and sperm, instead of ejecting a partner's "useless" sperm, the recipient ingests it, presumably recouping some of its energetic losses. Not a great trade, but better than nothing.

The next time you are walking by the No Touch Tables, lift the cover and take a close look.  You might find something new and unexpected.

Leon Weaver

Sources:
Anthes, Nils, Annika Putz, and Nico Michiels. "Gender Trading in a Hermaphrodite." Current Biology. Cell Press, 11 Oct. 2005. Web. 14 Aug. 2014. .

Mating Behaviour of the Sperm Trading Sea Slug Chelidonura hirundinina: Repeated Sex Role Alternation Balances Reciprocity: http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0310.2007.01440.x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false



Friday, July 25, 2014

Tiger Cowry

CEP image

Tiger Cowry

These may just look like any cool shell that you find on a reef or on the beach, but they are actually home to the one and only tiger cowry (Cypraea tigris Linnaeus 1758). The cowry is actually a type of ocean snail. They are found throughout the Indo-Pacific, although Hawaii produces the largest tiger cowries worldwide. Like all snails, the shell is actually an external skeleton, they have muscle and skin attached directly to the shell and a special layer of skin lays down new shell as they grow.

 The cowrie's shell starts out looking like a typical shell, growing in a spiral out from small to large, with a wide opening at the end. When the cowry nears adulthood, shell growth changes dramatically. Instead of continuing to add shell to the outer edges of the spiral, the outside of the shell curls in and almost encloses, leaving a tiny slit for the living cowry. Once the shell folds over, the shell starts to harden and begins growing into the shells that are so appealing to the eye.



Image from http://www.divegallery.com/shellfish4.jpgre
You may be wondering what keeps these shells so shiny and in such a nice condition. The snail’s mantle actually comes up over the outside of the shell when they are adults - adding thickness and coincidentally keeping it polished nicely. As you can see in the photo to the right, the mantle of the cowry has folded up and over the outside of the shell. The purpose of the small, white tipped papillae on the mantle are still unclear, but it’s been thought that they aid with absorption of oxygen in the water.
              
 

         

   
Image by Z. Boone
One interesting thing about the Tiger Cowry is that they consume what is believed to be Mycale Spp. as a tasty treat. This is a good thing because this particular sponge is invasive to Hawaii, meaning that is not a natural inhabitant to the area. To the right is a photo I took during a snorkel session of a large Tiger Cowry sitting on a patch of sponge in between a colony of Finger Coral.  

Another interesting piece of information is that because of the beauty of these shells, they have been and still are used as different jewelry pieces. Also, a long time ago, they have been used as currency in some parts of the world.

-Zach


Sources:
http://www.waikikiaquarium.org/experience/animal-guide/invertebrates/molluscs/tiger-cowry/
Hoover, John P. Hawai’i’s Sea Creatures. Revised Edition ed. Honolulu, HI: Mutual Publishing, 1999. 108-21. Print.