An inside look into our closest friends

A few weeks ago, we had the opportunity to dissect a few creatures in our marine invertebrates lab. The results were surprising...and for some refined palettes, very tasty!

The stomach of a sea star extends down each of the legs.

The orange globs are urchin gonads, also known as roe and is a popular Asian dish.

Having some fun while cutting open the tough calcium carbonate test.

We fished out the beak of our squid, which is found in the mouth.

Does size really matter?

The intertidal zone is one of the most unforgiving marine ecosystems. Waves constantly crash on you, and when the tides are low you are likely to get eaten by voracious predators, stomped on by curious scientists, or fried sunny-side up.

Rocky intertidal shores are also rich in their abundance of invertebrates and seaweeds. If you aren’t out-competed, then you are likely to die from the harsh elements, unless of course you evolved to not only survive but thrive.

Survival and success are dominated by factors including nourishment acquisition, mobility, reproduction, flexibility, and, of course, SIZE!

As I said before, the intertidal is a rough place to live, but many are adapted and thrive in this ecosystem. An organism’s response to wave strength with respect to its size will almost always result in smaller organisms outliving the larger. Not the result you expected, right?

The size of an organism is important in many other ways. Smaller organisms respond to viscous forces more readily than inertial forces, they can create their own feeding currents (barnacles and copepods), and they are less likely to get ripped off a rock by waves. (Don’t forget that the smallest organisms are basal food sources for marine consumers and therefore are very important to the biological success of the ocean).

Big WIN for the little guy!

Barnacles are one of the smallest invertebrate organisms on rocky shores and are still the most efficient at staying on the rocks.

(They can also attach themselves to ships, wharves, and other marine animals)

This graph shows, on a logarithmic scale, how easy it is to remove an object from a rock with respect to the height of a breaking wave.

So, the next time you step on a barnacle, squishing its little crustacean head into the rock, think about how if it could laugh at you when you get swept off the rock by a wave, it probably would.

Marine inverts and climate change

It is almost Thanksgiving and everyone is really excited to see family and friends, eat lots of food that is not ramen or mac and cheese, and sleep. We also are getting closer to the end of the semester and that means two things: finals and projects. For Marine Invertebrate Zoology, we have to do a presentation and short paper on an invert of our choice and how climate change is affecting it. I have an unreasonable fascination with venomous and "dangerous" animals and so my invert of choice is Acanthaster planci, the "crown-of-thorns" sea star.

A little background information: Acanthaster planci is a nocturnal sea star that bears between 8 and 21 arms and can range up to ~70 cm in diameter making it the second largest species of sea star. Acanthaster comes in a variety of colors depending on diet and region. These sea stars have a calcium carbonate skeleton and possess large, venomous spines in contrast to the short, blunt spines usually present on sea stars. They are found throughout the Indo-Pacific region, though they are most common on the Great Barrier Reef. Their average life span is about 16 years. Juvenile A. planci eat plankton, but adults are opportunistic carnivores, consuming scleractinian corals, encrusting sessile invertebrates, and dead animals. Individuals crawl at the rate of up to 35 cm per minute and feed by everting their stomachs through their mouths onto their prey and digesting the tissues. While A. planci is generally protected by its venomous spines, predators of A. planci include the giant triton shell Charonia tritonis and various fishes. An average sized adult (40 cm) can consume up to 478 square cm of live coral per day.

So why study the impacts of climate change on this animal? It seems that it has a negative impact on their ecosystem and humans, so why should we care if it is negatively impacted by climate change? I thought it would be interesting to see whether this sea star is being negatively affected by climate change or thriving. Since we got the assignment two days ago, I do not have all the answers yet. But from what we have studied so far, I would expect ocean acidification to negatively affect these animals. Ocean acidification is caused by carbon dioxide mixing with ocean water, creating hydrogen ions (i.e., acid) that attach to carbonate and form bicarbonate. This also inhibits formation of calcium carbonate because the hydrogen ions attach to the carbonate, inhibiting calcium. Sea stars have a calcium carbonate skeleton and are dependent on the ability of calcium carbonate to form in the ocean. This process also affects coral calcification, so there is a double negative impact. From what I have read so far, the increase in temperature is likely to be extremely bad for coral reefs but beneficial for A. planci. More research has to be done but regardless, I think it will prove to be an interesting project.

Mystery bone

A few weeks ago, we had the first Nor'easter and snow of the year. While the land was relatively unaffected here in Nahant, the marine system was another story.

A few days after the storm, we went diving in one of our well-known and well-loved sites and found the benthos completely changed. The storm brought in all sorts of algae and treasures from some far off place, and rocks had been moved to form new topographic conditions.
However, coming back I found the greatest find: a mystery bone.

Photos of the mystery bone

After consulting with faculty and consulting online sources, I believe it is the shoulder blade of a seal. While seals are not necessarily common in Nahant, there are some that live in the general area. This find - and the other treasures from the storm - shows how connected marine ecosystems are.

skeleton of a seal with the shoulder bone highlighted

The seal tonking begins

For all you lovers of charismatic megafauna:

You know when you've been Tango'd.

Marine Botany

Seaweeds just can't win sometimes. When one thinks of the ocean, generally the big poster children like whales and dolphins come to mind, and to a lesser extent, fish and other small animals. Even massive kelp forests are praised, not for the kelp itself, but for all the animals that live there. When visiting the beach, its common to hear a shriek as someone's leg becomes the unwitting, entangled victim of a slimy rope of kelp. Heck, even their name has negative connotations, they're not sea "plants", they're "weeds". According to dictionary.com, a weed is "any undesirable or troublesome plant, especially one that grows profusely where it is not wanted".

Well, in one of our classes, Marine Botany, we're beginning to learn to appreciate all that seaweeds do, and how they should be valued much more than they are. Marine Botany initially terrified me. So many species of algae, and I had to know the names of all of them! They're just algae, who cares? However, as the class progressed and I stopped panicking and started examining, I found that algae were a lot more interesting than I initially had thought. Sure, its not a perfect relationship. I still occasionally find myself struggling to pay attention when Don explains the difference between two nearly identical red algae, but the algae tend to get me back in the form of slippery surfaces resulting in painful intertidal falls. However, we've learned how different algae define different ecosystems, and how they provide important habitats that allow all the animals we appreciate so much to thrive and grow.

Kelp forests, mangroves, sea grasses, and intertidal algae all play host to fascinating arrays of creatures. Even the algae we can't see, like diatoms and dinoflagellates, have huge global impacts, producing 50% of the world's oxygen. In this last week, I realized just how much I rely on something I formerly dismissed. My yogurt has Chondrus crispus in it, as does my toothpaste. Sushi, my favorite food, obviously relies on seaweed, Porphyra umbilicalis, commonly known as Nori. The ingredients on my shampoo bottle used to seem like a confusing jumble of chemicals, but upon further examination, I recognized that 4 species of algae I can easily find back home and here in Nahant helped my hair stay smooth. This semester, I've had to change my opinion on algae, from summer beach nuisance to humble, but mighty, ecosystem driver.

Diving After DRM

Even though our Diving Research Methods course has come to an end, many of us are putting our AAUS certification to good use and are continuing to do more "scientific dives". A lot of us have been going on dives outside the class just to simply be in the water, and some of us have been using our dive time to collect algae for either our herbariums or botany project experiments. Yesterday, a few of us went on an afternoon dive to Canoe Beach and it was possibly one of the best dives we've ever been on since the start of our program. The seas were calm and according to my dive computer, the air temperature was a unusually comfortable 72 degrees. The water, however, wasn't quite as warm but was still bearable nonetheless. The visibility was extremely good, which made our diving objective (testing out camera/video skills) quite enjoyable. As you will be able to tell, my video skills need a fair amount of work...

Where's the kelp?

We have officially concluded our Diving Research Methods class. This means that we have successfully completed a scientific diving training program, this in conjunction with the 12+ scientific training dives means that we are recognized by the American Academy of Underwater Sciences as certified scientific divers up to 30 ft!

This certification allows us to conduct scientific research on dives up to 30 ft and take other open water certified, non-scientific divers on scientific dives up to 30 ft. The journey leading us to this new title was certainly very exciting. We conducted many underwater projects including mobile benthic invertebrate surveys, topographic complexity surveys, and everyone's favorite, kelp blade length measurements. Along with these fun dives we also received training in first aid, CPR, AED, and oxygen administration as part of the program.

We are all very excited to move forward in this new stage of our diving careers and try out our skills on Panama's coral reefs soon!

Mangroves as foundation species

John Bruno, East West VI alum and Associate Professor at UNC Chapel Hill, posted this awesome video highlighting the role of mangroves as foundation species:

Murderers, cartoons, and costumes: the MSC Halloween party

Although the Three Seas program can be a lot of work, we as college kids have not forgotten how to party. Every year the students in the program throw a Halloween party with themes for each individual lab or house. This year the party was thrown at the Pleasant Street house, an old Victorian with a "Clue" theme. The members of the house dressed up to match this secret theme, and members from the Vernon Street house dressed up as Pixar movie characters. Family and friends also joined in on the fun and it turned out to be a very fun night away from homework and school.

The Vernon Street house in their outfits. Each person dressed up as a character from a Pixar movie.

The hosts of the party, the Pleasant Street house. They all dressed as their favorite member from the popular game "Clue."

The Bracken Lab had the same idea and also donned costumes from "Clue."

Just one of the many decorations at the Pleasant Street house.

Each room had a name and matching decorations. This was the entrance to the "Billiard Room."