Nature Blog Network

Wednesday, October 28, 2009

Work with an Invert! - Amphipod Pop Gen

From EvolDir:

M.Sc. position: Marine invertebrate population genetics.

I seek a highly motivated and enthusiastic candidate to fill a fully funded MSc position in the Department of Biology at University of New Brunswick (Fredericton). The project will use DNA sequence variation to assess the level of genetic subdivision and patterns of gene flow among populations of the abundant marine amphipod Corophium volutator. The successful candidate will join a multi-disciplinary collaboration between researchers at UNB, Carleton University, and Mount Allison University. Our aim is to model the environmental interactions between climate driven processes and the population dynamics of C. volutator throughout the mudflats in the Bay of Fundy, Canada.

For more information about the Biology Department, see:
http://www.unb.ca/fredericton/science/biology/

For information about Graduate Studies at UNB, see:
http://www.unb.ca/gradschl/

For enquires, or to apply, email a CV or resume, a letter of interest, unofficial transcripts and contact information for 3 references to Jason Addison (jaddison at unb dot ca). The review of applications will begin immediately and will remain open until the position is filled. Work could potentially begin anytime, but admittance to the Graduate Studies program is expected in January, May, or September of 2010.

Monday, October 26, 2009

An Awesome Ocean Community

Just a quick note, a note of thanks!

The ocean blogging and ocean twitter communities really came through in a huge way today for Donors Choose. HP had an offer to put $2000 into the Oceans in the Classroom Initiative but only if the community could raise $2000 by midnight on Sunday the 25th. As late as 11pm it seemed a long shot with over $500 left to go. But it happened. With matching $$$ and swag from Kevin and Rick, it happened. Thanks to HP, the $2019 you all have contributed will now be doubled.

But...

There are still many more ocean themed projects out there to fund, so if you haven't yet donated, please do. We do so want to give some of these hundreds of kids the opportunity to get hooked on science and the ocean with all it marvels.

So now I still owe 2 more cards. Pick a card any card...

Sunday, October 25, 2009

Crepidula Fornicata

We've got two new Ocean Inspired Donors Choose projects that have been funded in the Oceans in the Classroom Challenge! The first one that was funded on Thursday was the awesome Invertebrates in my Tank project that will provide lots of kids with the opportunity to explore one of our favorite subjects: marine inverts!

The Inverts in my Tank card is the 6 of Spades — The Slipper Snail, Crepidula fornicata.

Classification for the Atlantic Slippersnail


Kingdom
Animalia

Phylum
Mollusca

Class
Gastropoda

Order
Littorinimorpha

Family
Calyptraeidae

Genus
Crepidula

Species
C. fornicata

I pulled this card for several reasons. First it has the cutest little veliger larvae. Second, it is all over the place here in Long Island Sound. And lastly, it is a prime example of a reproduction strategy that is comparatively rare in the animal world in general, but much less so in molluscs: protandrous sequential hermaphroditism. You may recall Dr. M's recent post, "Who likes protandric hermaphrodites?", in which he described the strategy, while reporting new findings about Idas washingtonia, a deep-sea clam.

Like I. washingtonia, the Atlantic Slippersnail (Crepidula fornicata), is a protandric sequential hermaphrodite. While they strongly resemble limpets externally, and are often called slipper limpets, they are indeed gastropods that are common inhabitants of the sub– to intertidal area of New England rocky coasts where they are often found in stacks, like the one pictured, from 3 to 20 individuals. Unfortunately, they are also an invasive species becoming all too common in areas outside its native range, where their filter feeding capabilities may negatively affect native and aquacultured filter feeding molluscs.

As Dr. M described in his post, many protandrous sequential hermaphrodites change sex based on size. A prevailing theory (the size-advantage hypothesis) predicts that a species will change its sex at a particular size that allows the individual higher reproductive success. Generally, this means smaller Atlantic Slippersnails are males and larger ones are females. It is energetically expensive for females to produce large, energy–rich eggs. It is very common in the marine realm that older, larger females produce more eggs of larger size and higher quality with resultant higher success rates. For guys to produce sperm is a comparatively inexpensive expenditure of energy. Even a wee lad can produce enough sperm of suitable quality to reproduce successfully. (Whether or not a female will have him, of if his sperm can out compete a larger male's sperm, is a different issue.)

C. fornicata follows this trait — for the most part. When the planktonic veliger larvae metamorphose and settle to the bottom, they are attracted to chemical cues produced by the adults. This guides most settling juveniles to land on, or very near, existing individuals or stacks. They then make their way (ever slowly) to the top of the stack and mature into young males. In paternity studies the oldest, largest males (sometimes the same size as females) are responsible for the majority of the viable larvae from females in the stack (upwards of 83% of larvae coming from one father). Younger males further up the stack do have some successes, though, and the more males (and more larger males) in a stack the more sperm competition appears to play a significant role in each individual's success and the less dominant the dominant male becomes. At a certain point these large dominant males may be better off as females sharing the reproductive success among a few females instead of many highly competitive males.

If a settling juvenile misses the chemical cues or for some other reason does not stack onto an existing individual or group, it will mature through a very brief male phase then become female, hopefully attracting juveniles from the next batch to settle on to it. Given that there are solitary (small) post settlement females and that some older males in a stack are as big as their female stackmates, size is clearly not the sole cue for sex change in C. fornicata. There is some plasticity in the change and social interaction appears to play a strong role on the size of the individual undergoing sex change.

You can probably see why sequential hermaphroditism is such an interesting area of study. There are several general hypotheses, but there are also so many individual variations on those general themes, that it seems we will never run out of study material!

And now a word for our Challenge this month


If you have contributed to the Oceans in the Classroom Challenge - Thank you so much!! These posts and previews are for you! You have helped the Ocean Bloggers make a difference in at least 300 kids' lives. (More considering many projects have reusable multi-year assets!)

If you have not yet given to the Donors Choose Oceans in the Classroom Challenge, please consider giving today. I know times are tough. I am a grad student with a family to feed. Believe me, I get how tough it is. Still every amount is welcome and appreciated. For my family's donation it means I have to brown bag it for two weeks. But you know, that's a small price to pay in exchange for knowing that we are exposing hundreds of kids to the science of the ocean. There is even a kindergarten class project in there - Commotion in the Ocean. Talk about a great time to open a kid's mind to the ocean and science!! If 25 readers give just $10 each, we'll help a dedicated young teacher expose 18 high poverty area kindergarten kids to science and the ocean.

There is a chance, still, to get an additional $2,000 dollars of matching funds donated by HP, but it will only happen if we can get to $2,000 donated from the Ocean Bloggers readers today. It won't be easy, but it's a great chance to really increase our impact! Please give to the Challenge!


References


Proestou DA, Goldsmith MR, & Twombly S (2008). Patterns of male reproductive success in Crepidula fornicata provide new insight for sex allocation and optimal sex change. The Biological bulletin, 214 (2), 194-202 PMID: 18401001


Richard, J., Huet, M., Thouzeau, G., & Paulet, Y. (2006). Reproduction of the invasive slipper limpet, Crepidula fornicata, in the Bay of Brest, France Marine Biology, 149 (4), 789-801 DOI: 10.1007/s00227-005-0157-4

Saturday, October 17, 2009

Wading in with Urosalpinx cinerea

As we pull into NYC on the Amtrack for a science filled weekend, Mrs. S's class in Rhode Island have gotten fully funded for their new waders as part of the Oceans in the Classroom Challenge. Hopefully they are thinking about getting in some clamming very soon! While they are out there wading in the beautiful coastal waters of Rhode Isalnd, they will no doubt see many Atlantic Oyster Drills as well since Urosalpinx cinerea is a pretty common sight around here (here being eastern Connecticut and Rhode Island). Unfortunately it is also becoming more common on the west coast in areas like Puget Sound where it is an invasive species, as well as being a nuisance to oyster fisheries on both coasts.

Even though it is a nuisance to mollusc fisheries and aquaculture, I can't help but like this particular carnivorous gastropod. It lives in the harsh intertidal zone, an area where it may well probably the most effective hunter. It "smells" out it's prey in the water: young oysters, young clams, or the thinner shelled blue mussels. Once located the one inch predator climbs onto its prey and grabs it firmly with its foot. Then the drilling begins.

Using its radula, a ribbon like organ with rows of tiny teeth on it, the oyster drill rasps away at the shell, scraping bits of the calcium shell. After rasping for a time the oyster drill brings out its secret weapon, the accessory boring organ (ABO). The oyster drills use of the ABO was described originally by Mel Carriker while he was a graduate student in the late 1930's early 1940's, we have featured his video and explanation of the drilling before (highly recommended!). Between 1 minute raspings with the radula the drill presses the ABO against the drilling site for 30 minutes, releasing calcium dissolving acid to soften the next layer of shell and make the drilling easier. Depending on the thickness of the preys shell, the process may take upwards of a day to complete. Yes the oyster drill is persistent!

video

Once through the shell the oyster drill inserts its proboscis through the hole and releases digestive enzymes into the prey shell ans slurps the resulting liquefied meat back up through the hole via its proboscis.



Another cool detail about the oyster drill is that unlike most other gastropods, the oyster drill does not have a planktonic larval stage. The oyster drill lays its eggs that each have up to 12 young in them under rocks and shells. The young snails eat their way out of the eggs and look like miniature adults.

Thursday, October 15, 2009

Iceland Scallop

Time to celebrate the funding of Mrs. M.'s project, Coral Reef Flip Books, part of the Ocean Bloggers Oceans in the Classroom Initiative. Yesterday I asked for input on which card to feature, and the results are in: with 33.33% of the "vote" the Scallop of Hearts gets the next preview here. I should note that the picture on this card is likely to change before the final version, when we hopefully will get an image of a live animal without too many epibionts (organisms that live on the surface of another living organism, generally a commensal relationship) on the valves.

Classification for the Icelandic Scallop

Kingdom
Animalia

Phylum
Mollusca

Class
Bivalvia

Order
Ostreoida

Family
Pectinidae

Genus
Chlamys

Species
C. islandica

Range


It is thought that the Chlamys genus originated in the Pacific and expanded into the Atlantic. Fossil Chlamys shells have been found dating to the Miocene in California. In the Atlantic ocean fossilized shells of the Icelandic scallop (Chlamys islandica) have been found from the late Pliestocene, when it ranged as far south as Long Island in the west Atlantic and to the Mediterranean in the east. Today it is found from Hudson Bay to Cape Cod in the western Atlantic and along the coast of Norway in the eastern Atlantic. It is also found in the fjords and waters of western Greenland and Iceland.

The Iceland Scallop (C. islandica) is the northernmost occurring of the major commercial species in the Pectinidae family, occurring in sub-arctic waters of the Atlantic. Several similar species, once thought to be subspecies of C. islandica, are found in similar areas of the sub-polar Pacific. In many areas of C. islandica's range, it is, or has been, a major fishery species. In recent years however in much of its range the fisheries have collapsed.

Fisheries


In most of Norway the fishery for the Icelandic scallop suffered complete collapse in just three seasons and has only recovered in one location. In Iceland the stock is (as of 2008) only at 13% or less of its size just one decade earlier. The causes of the rapid decline in Iceland have been investigated by several researchers. They have determined that overfishing has had a strong impact on the stocks, but the effect has been magnified because of two environmental factors. A protozoan parasite is affecting large numbers of adults, causing increased adult mortality. Sea bottom water temperatures have increased more than 2°C, possibly contributing to both adult mortality and very poor juvenile recruiting years for the past four years, take a moment to think of the implications of climate change for this species. Because of all this, the fishery was recommended for closure in the 2009 and 2010 seasons.

North American stocks have not fared much better in recent years, with strong declines in stocks. The sharp stock declines worldwide coupled with the fact that they are only wild-fished using dredges, which extensively alter the hard bottom habitats where they live, have caused organizations, such as the Blue Ocean Institute, to recommend avoiding this particular species when possible.

Biology


Icelandic scallops have separate sexes (gonochoristic) from birth, whereas most scallop species are hermaphrodites. Reproduction is by broadcast spawning, which is cued by rising ocean temperatures in June and July. After 6-10 weeks of floating as planktonic life, the larvae settle to hard sand and gravel surfaces. When settling they preferentially attach to dead hydroids, live hydroids, and algae using byssus threads.

Growth rate varies seasonally, by age, and across the species range, but the scallops generally reach maturity at 5 or 6 years old and can live in excess of 23 years.
Icelandic scallops are largely sedentary, often with large and dense coatings of epibionts, such as sponges and tube worms.

One thing that interests me right now about the Icelandic scallop, mainly because I'm spending my days doing a lot of GIS work now, is that the species is extremely temperature sensitive, with both high and low temperature limits. As the sea surface and bottom temperatures change, the stock densities and distribution of the scallop change as well. Similarly, it has known constraints in salinity, current flow velocities, depth and sediment types. This makes the Iceland scallop a good choice for a GIS-based habitat suitability modeling, using the range of potential climate change parameters to predict future range contractions or expansions and areas where stock recovery efforts or aquaculture are most likely to succeed over the long term.

Of course I also love scallops for their beautiful eyes, and yes... their taste!
I think this is one of my favorite recipes. I don't recall where it comes from originally or I'd credit it. Just make sure to use farmed or wild caught Bay scallops (Argopecten irradians) or Giant scallops (Placopecten magellanicus), not Icelandic scallops.

12 scallops
Sea Salt
2-3 tbsp olive oil (virgin)
4 tbsp chopped onion
1-2 tbsp chopped garlic (we go 3, we love garlic!)
1 dry bird pepper (or use dried thai pepper)
3 tbsp parsley
3 tbsp diced prosciutto
Saffron
Sherry
Fish Broth (splash)
12 clams

Sprinkle pinch of sea salt over scallops and let sit 5 minutes. In preheated pan on medium heat, add oil, onions, garlic and thai pepper. Cook until onions are wilted. Add scallops and pinch of saffron. Continue to cook on medium 3 more minutes. Add splash of fish broth, splash of sherry, clams and prosciutto. Cook additional 30 seconds to 1 minute. Serve with rustic bread.

References


Arsenault, D., Giasson, M., & Himmelman, J. (2000). Field examination of dispersion patterns of juvenile Iceland scallops (Chlamys islandica) in the northern Gulf of St Lawrence Journal of the Marine Biological Association of the UK, 80 (3), 501-508 DOI: 10.1017/S0025315400002198

GARCIA, E. (2006). The Fishery for Iceland Scallop (Chlamys islandica) in the Northeast Atlantic Advances in Marine Biology, 51, 1-55 DOI: 10.1016/S0065-2881(06)51001-6

Jonasson, J., Thorarinsdottir, G., Eiriksson, H., Solmundsson, J., & Marteinsdottir, G. (2006). Collapse of the fishery for Iceland scallop (Chlamys islandica) in Breidafjordur, West Iceland ICES Journal of Marine Science, 64 (2), 298-308 DOI: 10.1093/icesjms/fsl028

WROBLEWSKI, J., BELL, T., COPELAND, A., EDINGER, E., FENG, C., SAXBY, J., SCHNEIDER, D., & SIMMS, J. (2009). Toward a sustainable Iceland scallop fishery in Gilbert Bay, a marine protected area in the eastern Canada coastal zone Journal of Cleaner Production, 17 (3), 424-430 DOI: 10.1016/j.jclepro.2008.08.004

Tuesday, October 13, 2009

Pick a Card, Any Card

Another of the Ocean Challenge in the Classroom projects has been fully funded! So...
Pick a card any card, leave your pick in a comment or as a tweet to @eclecticechoes. The card with the most choices (or in a tie a random choice among the tied) will be featured here tomorrow.

Friday, October 9, 2009

Nautilus Night - Cephalopod of Diamonds

Ok. I said for each of the Ocean in the Classroom projects fully funded I would put up a post about one invert from the deck of cards I have been working on, along with a sneak peak at a card. So, since the Making Waves, Oceans and Landforms got fully funded, and in honor of Nautilus Night I bring you the Cephalopod of Diamonds - The Chambered Nautilus.


Classification for the Chambered Nautilus

Kingdom
Animalia

Phylum
Mollusca

Class
Cephalopoda

Order
Nautilida

Family
Nautilidae

Genus
Nautilus

Species
N. belauensis

ResearchBlogging.orgSome interesting facts about the chambered nautilus (and other extant nautiloids):

The 6-7 (there is still debate on the status of one species) extant species of nautilus come from two genera, the 4-5 smooth nautilus'(genus Nautilus) and the 2 species of hairy nautilus (genus Allonautilus - literally "other nautilus").

They are the only remaining cephalopods that retain an external shell, which they use for defense and as a buoyancy control system. The shell, with buoyancy control, was a significant weapon evolutionarily, as it afforded the early cephalopods the protection of a thick shell yet the advanced buoyancy control unchained them from the sea floor as most of the periods marine arthropods were.

Modern nautilus are generally found on steep coral reef slopes at a depth of 200-400m during the day. They rise at night to feed near or at the surface, using the adjustable buoyancy of their gas filled shells to good effect during the vertical migration.

Unlike other cephalopods, the nautilus do not have a lensed eye. The nautilus eye is more like a pinhole camera, leading to the hypothesis that it uses olfaction to find it's prey (mostly shrimp and other crustaceans along with some small fish.)

Nautiloids also have upwards of 90 tentacles (compare with 8 arms of octopods and 8 arms an two tentacles of squid and cuttlefish.)

Last bit for this post is their lifespan and reproduction. Most cephalopods are short lived with overall lifespans of even the Giant Pacific Octopus being around 2-3 years. For most studied cephalopods natural death from old age occurs after mating, (and for females egg guarding), which is only done once (called semelparity). Nautilus can live in 15-20 years and mate year after year (iteroparity).

The nautilus are the ancient lineage of the cephalopods, descendants of and most like the orthocerids and other nautiloids that were a major predator of the seas in the Ordovician period. Modern nautiloids are the only cephalopods that retain their external shell and are often considered to be "living fossils" as they are very similar in appearance to the ammonites and nautiloids that emerged half a billion years ago in the Cambrian. However recent molecular studies are casting some doubt on the appropriateness of the "living fossil" moniker. Studies published in the past couple years have revealed that the 6-7 extant species of nautilus evolved much more recently, around 2 million years ago, in the seas around New Guinea. They then


Sinclair, B., Briskey, L., Aspden, W., & Pegg, G. (2006). Genetic diversity of isolated populations of Nautilus pompilius (Mollusca, Cephalopoda) in the Great Barrier Reef and Coral Sea Reviews in Fish Biology and Fisheries, 17 (2-3), 223-235 DOI: 10.1007/s11160-006-9030-x

Thursday, October 8, 2009

Ocean in the Classroom Challenge

Today's a big outreach day!

First up, an outreach project I that has been part of my life for the past year is finally coming to be. This afternoon I will finally see the professionally printed version of my deck of cards that will be used to help teach molluscan diversity. They are still prototypes so I can't show them here just yet. Hopefully soon I can highlight a few of the cards along with some discussion about the animals on them and the process of making them. I am looking forward to hearing from the COSEE particpants at Avery Point who will be getting a sneak peak at them today through Saturday.

On a much larger scale Dr. M and Kevin have gathered together many of the top ocean bloggers to support some serious K-12 education outreach: Ocean in the Classroom Challenge. I just looked through the challenge and there are seven great projects in there, including several that are aquatic invertebrate centered. Personally I love the Invertebrates in my Tank, Waders and Coral Flip Book projects because they touch close to home, so to speak.

I would take the website hostage like the DSN boys are doing, but that won't work so well here where it has been so quiet lately. However, maybe the opposite will work, for each project that gets fully funded I'll put up a post on recent research about one of animals featured in the card decks.