A Sea Lion Story

By now it's probably come across your computer screen at least once. The story may have even shown up in your physical paper. More than 1,800 California sea lion (Zalophus californianus) pups have shown up emaciated on the beaches of California since January. Unusual mortality events like this are most troubling to us because it's adorable baby animals that are suffering, so it's a good opportunity to draw awareness to ecosystem scale issues.

D'aww who's a good vector for a better understanding

 of ecology!? You are, yes you are!

Courtesy: Jaina via Flickr

So what do baby sea lions have to do with the ecosystem as a whole? Well ecosystems are all the living and non-living things in an area that interact with one another. This means that every piece in an ecosystem is significant to the others in some way. For example small fish are important to large predators, currents are important to plankton, and temperature is important to everyone. Each piece has direct effects on the others and those effects themselves interact.

On the surface (pun intended) starving sea lion pups seems to have a pretty straightforward cause. You would assume it's because there isn't enough of whatever it is sea lions eat. That's part of the story, but there's more to it. When baby seals and sea lions are first born they lack the thick blubber of their parents. Pups have to drink extremely rich milk to bulk up enough to survive on their own. California sea lion milk averages about 35% fat, that's about the same fat content as whipping cream, and about ten times the fat content of whole milk. Not only does the thick layer of blubber the pups develop help keep them warm it's important as an energy reserve when they first strike out on their own.

Despite what this sea lion seems to be telling you, Cronuts are not 

a viable source of energy reserves.

Courtesy: Makitani via Flickr

The most important prey for lactating mothers are anchovy, sardine, and hake. These fish live in large schools, so they're usually plentiful and they have extremely oily flesh; perfect producing rich milk. In the past there were very large fisheries for these species off of California. Think Cannery Row on Monterey Bay. However, we aren't taking too much of the sea lions' food away anymore because canned, oily fish have declined in popularity.

I can't imagine why...
Courtesy: dr.coop via Flickr

 What's happened is that for the last few years the waters around the Channel Islands, where the sea lions give birth, have been abnormally warm. Each of the fish the sea lions rely on are cold water species, in fact North Pacific anchovy won't go into water warmer than 62 degrees F. Since California's seas have been so warm the food fish have shifted themselves to colder waters. Sardines have been spawning farther offshore and other fish schools have moved north. These migrations have forced mother sea lions to hunt farther afield, and when their moms don't come back for extended periods of time, the pups set out on their own too early.

So where are the dad's in all this? Why don't we see adult males stranding in California? Well they're not there. Male and female sea lions both take on long migrations from British Columbia to California and back every year, but they have different schedules. Females head down to the breeding grounds first to give birth. Then males head down to meet up with the females once they're ready to mate again; about three weeks later. Being further north for longer has actually lead to boom times for male sea lions. At the mouth of the Columbia river between Washington State and Oregon more than ten times the usual number of males have been hanging out. They came in for this year's copious smelt run and are fattening up to make the trip south to the rookeries. Males need a lot of mass and energy reserves to defend territories on beaches which they won't leave and thus don't eat for several weeks.

   "I'll calm when I haven't gone twelve days without food!"
Courtesy: Bridget Samuels via Flickr

So that's the story. Warm water pooling at the surface has pushed forage fish away from the Channel Islands. This means that female California sea lions have to travel farther to find food that makes rich enough milk for their babies. These longer trips mean that many young are leaving the rookeries too early, and are washing up along the shore. All the while, farther north, males are enjoying a greater supply of food than ever. The biological needs of its inhabitants, and the physical characteristics of the ocean come together to tell the complex story of an ecosystem as long as a continent. We're able to discover the changes happening in the environment thanks to this single species.

Scientists aren't sure if the warming is caused by the changes happening to the global climate system, or if this is part of natural variations of the Pacific. Either way marine mammal stranding networks will need support in the near future. If you want to help one of the best things you can do is to remain informed about who's best prepared to help hungry or sick sea lion pups. There's a good list of organizations to contact and a lot of information here.

References:

"California Sea Lion (Zalophus Californianus)", NOAA Fisheries: Office of Protected Resources. Accessed via: http://www.nmfs.noaa.gov/pr/species/mammals/pinnipeds/californiasealion.htm

Bernton, Hal, "Boom Times on the Columbia for California Sea Lions", The Seattle Times, March 27th, 2015, Accessed via: http://www.seattletimes.com/seattle-news/boom-times-on-the-columbia-for-california-sea-lions/

"2013-2015 California Sea Lion Unusual Mortality Event in California", National Marine Fisheries Service Health and Stranding Reports,
Accessed via: http://www.nmfs.noaa.gov/pr/health/mmume/californiasealions2013.htm

Redman, Marianne, "The Pinnipeds: Seals, Sea Lions, and Walruses", pg 282, University of California Press, 1990.

Orr et al., 2011, "Intraspecific Comparison of Diet of California Sea Lions (Zalophus californianus) Assessed Using Fecal and Stable Isotope Analyses", Canadian Journal of Zoology, 89:109-122. 

What is a Seahawk Anyway?

You may or may not have seen that Chris Evans (Captain America) and Chris Pratt (Star Lord) got into a discussion on twitter over who would win the NFL championship today (I can't legally say the name of the event due to copyrights, yay!). Depending on which team wins the big game; one of their superhero personas will show up at non-profit for children with cancer in the other's hometown. Chris Pratt is from North of Seattle, and Chris Evans is from Boston. During the exchange Chris Evans asked a question that's actually pretty common even here in the land of the 12th Man. #whatisaseahawkanyway? Good question Chris, I think this week we'll answer that.

Seahawk (Superbowli repetensis)

It's not always the case with sports emblems, but the seahawk is actually surprisingly accurate to it's namesake.

 You were expecting it to be blue weren't you?

Courtesy: vladeb via Flickr

That bird is an osprey (Pandion haliaetus) and some of its alternative common names are: fish hawk, fishing eagle, and sea hawk. Now don't me started on the hilarious missed opportunity when we didn't call the team the fishawks, but otherwise this bird of prey is a powerful emblem for my home team.

If you feel like you've seen this bird before you probably have. Osprey are distributed world wide, from North to South America, and from Europe across Asia to Australia. The only place where these birds don't winter or breed is in Antarctica. There's only one requirement for these raptors to survive somewhere; fish. 

Osprey are almost exclusively piscivorous (piss-i-vore-us), not unlike that guy everyone knows who claims to be vegetarian, but doesn't count fish for some reason. Fish approaches 100% of their diet with occasional hors d'oeuvres of reptiles, rodents, and small mammals. The grace and power with which osprey catch their prey is astonishing. Their adaptations for hunting would make them pretty great football players as well.

Ugh this guy's Endzone celebration is really weird...

Courtesy: David Mills via Flickr

Osprey begin their hunts by circling above the water searching for the right place to strike. Not unlike Russell Wilson in the pocket, an osprey's eyes are perfectly adapted to find their target in all sorts of weather. The dark bars around their eyes help reduce glare (the charcoal football players use does the same thing) so they can see into the water. Once they've spotted a fish they have a couple ways they can catch it. There's the Richard Sherman style snag where they swoop down and snatch up their prey without getting touched by the water. You may have seen bald eagles do the same type of catch. Or they can go Beast Mode and crash directly into the water, talons outstretched in front of them, penetrating the surface to about 3 feet. This type of hunting is unique to osprey because most birds of prey can't scramble back to flight after getting wet. You can see both styles of hunting in this great video from Wildscreen.

They are so good at holding on to struggling fish because their talons are covered in minute hooks. These dig into the fish and make sure the osprey never fumbles. They also have another unique adaptation that allows them to get back to the air; wrists. They can bend their wings at a joint most other birds can't and that allows them to get lift straight out of the water from a dead stop.

Oh, Wilson's lost in the scrum at the line of scrimmage.

Courtesy: Jeff Bosco via Flickr

But wait he's managed to scramble out for a five yard gain!

Courtesy: Michael Utin via Flickr

So what are seahawks anyway? They're a unique and well adapted predator with all the skills necessary to dominate in almost any environment. Also they're a bird.

References:

Flemming, Stephen, & Smith, Peter, "Environmental Influences on Osprey Foraging in Northeastern Nova Scotia", Journal of Raptor Research, 24(3):64-67, 1990

Accessed via: https://sora.unm.edu/sites/default/files/journals/jrr/v024n03/p00064-p00067.pdf

"Pandion haliaetus, Osprey"

The Encyclopedia of Life

Accessed via: http://eol.org/pages/1049145/details

"Pandion haliaetus"

US Forest Service

Accessed via: http://www.fs.fed.us/database/feis/animals/bird/paha/all.html

Getting Ston(ey)ed with Coral

We're Back! The new Depth and Taxa headquarters (AKA my apartment) is all set up with a fancy desk and everything. Thanks everyone for your patience during my moving process. So without further ado let's get back in the swing of things.

There was some great news that came out of the US National Oceanographic and Atmospheric Administration (NOAA) last month. Twenty coral species have been listed under the Endangered Species Act. "What? That's horrible, more corals are at risk of extinction!" you might be saying, but listing as endangered actually benefits many animals that are at the brink. When organisms are imperiled by extinction listing them serves to provide legal protections for, not only them, but also their ecosystems. It's kind of like a silent alarm going off. When someone breaks in, property is at risk, but once the alarm goes off; the police can come and take steps to keep you from being burgled. It's about time we got serious about protecting coral too. Whole reefs are in danger of disappearing. One study suggests that coral cover in the region between Asia, Australia and Hawaii has decreased by 20% since just the early eighties.

So why do we care? Coral is certainly very pretty, but it's also a fascinating and essential organism.

Seen here being all three at once.

Courtesy Ian Robertson via Flickr

Coral is a massive and incredibly old group of animals. In fact just about anything you think of as ancient, corals were there for its beginning: Megalodon? Coral bemoans its short time on the planet. Dinosaurs? Yeah coral thought they were cool for a while. Coelocanths? They're just trying to steal coral's old-timey charm. What I'm getting at is that coral shows up very early in the fossil record, something like 480 million years ago!

So what's the secret to coral's success? Well diversity is a big part of it. There are something like 2,500 coral species on earth today. They can be hard, soft, individual, colonial, small, large, tropical, temperate, shallow, and deep.  The corals we're most familiar with, and all of those recently added to the endangered species list, are the shallow-living stony corals we like to brag about snorkeling among when we take a trip to the tropics.

All corals are a part of the cnidarian phylum which you may remember from the earlier post about jellyfish.You might also remember that the scyphozoa, hydrozoa, and cubozoa have two life stages: the free-living medusa and the stuck-on polyp. Corals are part of the anthozoa which are all the animals that have no medusa stage.

Perseus can get behind an animal that removes the medusa. (I will not apologize for this terrible joke)
Courtesy Wally Gobetz via Flickr

What stands stony corals out from other members of their phylum is their structure. Unlike sea anemones or jellies; stony corals actually secrete a skeleton. Coral that you might find at a jeweler's, or on the beach, is in fact the skeletal remains of a stony coral. So your beach house may have skeletons in its closet as well as on its coffee table. These skeletons, made of the same molecules as eggshells, are what allow for the gigantic reefs seen in tropical waters throughout the world. And amazingly every reef starts out as a single teeny-tiny coral polyp.

See when a coral mommy-daddy and daddy-mommy (many stony corals are hermaphroditic) love each other very much, and the season and tidal phase are right, they pour floating packets of sperm and eggs out of their bodies and into the water. It's all very romantic as thousands of other animals circle the waters around them devouring their genetic material before it even has a chance to mix. But luckily there are so many of these gamete (reproductive cells) balloons that some do make a new baby coral. At this point in their life baby corals are called a planula, they're microscopic, and they're covered in little cellular oars that allow them to move and find a place to settle. As they settle, baby coral metamorphoses into its adult form, but its still incredibly tiny and all alone. So our intrepid hero begins making itself some friends, by cloning.

"I'm pleased...we're pleased...it's nice to meet you"
Courtesy Nhobgood via Wikimedia Commons

Each of those little anemone looking things up there is a clone of a single polyp that settled on a hard surface. If the entire colony is very large, then the original polyp probably settled decades ago. Some head's of coral have been estimated to be over a thousand years old! This slow growth rate is one of the reasons many coral reefs are at risk of extinction.

 Amazingly, although the clones are separate individuals from the other polyps they all share body tissues with one another. As the polyps catch prey with their stinging tentacles and eat it; the nutrients from that food are actually spread across the shared tissue so that the whole colony benefits. These shared tissues are also what secrete the hard skeleton of stony corals. And it's inside the corals' shared tissues that we can find the reason for their stony skeleton.

Just beneath the skin of stony corals lives one of a number of different algae. These single-celled seaweeds, called zooxanthellae, (pronounced zo-zan-thell-ee) are taken in by the coral deliberately because they can benefit one another greatly. The algae is protected from the thousands of mouths out in the plankton and the corals' wastes make great fertilizer. The coral also benefits because the algae's photosynthesis provides oxygen and nutrients both of which the coral can use. So the coral creates this elaborate skeleton in part to reach for the sun. The skeleton acts like the trunk and branches of a tree pushing the coral and its algae buddies towards the light. The constant competition for sun is what has driven the evolution of so many amazing forms and shapes of different corals.

Enough sun salutes to make a yogi weep for joy
Courtesy US Fish and Wildlife via Flickr

 This mutual symbiosis has been going on for so long and is so beneficial that some coral species can't feed themselves without their zooxanthellae. When people talk about coral bleaching this is what they mean. Something has gone wrong in the ecosystem, so the algae have either gone elsewhere or died. Leaving only skeletons behind. Luckily you can easily help prevent bleaching if you visit tropical areas. Danovaro et. al discovered that synthetic sunscreens actually encourage the growth of viruses that infect and kill zooxanthellae. So when you take that snorkeling trip make sure to use non-synthetics like titanium dioxide or zinc oxide. Often times these sunscreens are labeled as "coral safe" or "sensitive skin" so they're easily found.

References:

http://www.fws.gov/endangered/laws-policies/

http://www.noaanews.noaa.gov/stories2014/20140827_corallisting.html

http://www.ucmp.berkeley.edu/cnidaria/anthozoafr.html

https://marine.rutgers.edu/pubs/private/Mass%20et%20al_Immunolocalization_PNAS2014.full.pdf

Danovaro et. al, "Sunscreens Cause Coral Bleaching by Promoting Viral Infections", Environmental Heatlth Perspectives Apr. 2008: 116(14): 441-447. Accessed via http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2291018/

Hoover, John P. "Hawai'i's Sea Creatures: A Guide to Hawai'i's Marine Invertebrates", pg 46-49, Mutual Publishing, 1999