Four Aquarium staff members and one volunteer recently traveled to Neah Bay on Washington’s coast to survey rockfish populations. We visit the same sites each year, where divers swim a 50-meter transect line in both directions, counting and catching on video each rockfish that crosses their path. Why swim a transect? It’s a proven method for studying the abundance of sessile species like rockfish. A rockfish may spend its whole life on one single pile of rocks. Why study rockfish? We’ve exhibited them since the Aquarium opened, they are commercially important, and 32 species of rockfish live in Washington waters. Thirteen are listed as species of concern. Seattle Aquarium Curator of Conservation Research Shawn Larson, shared these photos from the trip and answered our questions.
Seattle Aquarium rockfish research team.
Q: How long have we been studying rockfish at Neah Bay and what trends have we found?
A: Eleven years. Adult rockfish have been stable over time; young-of-the-year rockfish (this year’s babies) have been variable and we have been able to document significant recruitment events in 2006, 2012 and 2013. Overall fish abundance has been slightly increasing over the years.
Q: Did you have any expectations before you started this research about what you would find?
A: We didn’t have any expectations. Our goal was to document a baseline and any significant changes, and we achieved it.
Q: You visit the same site every year. Is each trip quite similar or do some stand out?
A: We do visit the same sites annually, but each trip is different based on the people, the water conditions, the dives and the animals that we see. This year the water conditions were great (good visibility and minimal current), we saw lots of cool animals (whales, sea otters, porpoises, octopuses, rockfish, wolf eels and a halibut!), and the divers were amazing.
Interested in learning more about rockfish? Read our fact sheet!
In our last post, Aquarium Aquarist Steven Yong gave us a brief tour of the world of coral reproduction—in preparation for this post, describing his recent trip to Curaçao with the SECORE (SExual COral REproduction) Foundation:
The elkhorn coral, Acropora palmata, is one of the most important reef-building coral species in the Atlantic and was once one of the most abundant in the Florida Keys and Caribbean. Unfortunately, an estimated 90–95 percent of the population has been lost since the 1980s due to disease, bleaching, climate change and human influence. This led the species to be listed as Threatened under the Endangered Species Act (ESA) and Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species™.
The SECORE (SExual COral REproduction) Foundation has been organizing field and lab workshops for 10 years. They take techniques developed by aquarists and scientists for reproducing corals and teach and apply them for coral conservation and research. Workshops have been held in Curaçao, Puerto Rico, Guam, Singapore, Mexico and the Philippines. I’ve been involved with SECORE since 2010, when I was able to attend a lab workshop hosted by the Henry Doorly Zoo and Aquarium in Omaha, NE. I was fortunate enough to be invited to attend a coral reproduction and reef restoration workshop in Puerto Morelos, Mexico in August 2014. There, for the first time, I was able to gain hands-on experience working with elkhorn coral and grooved brain coral, Diploria labyrinthiformis. This year, I was invited to work in Curaçao for the mass spawning of the same two species.
I arrived in Willemstad, the capital of Curaçao, on July 31. I would be working with three other aquarists from the Pittsburgh Zoo and PPG Aquarium, Omaha’s Henry Doorly Zoo and Aquarium and Columbus Zoo and Aquarium, as well as scientists at the Caribbean Research & Management of Biodiversity (CARMABI) biological research station. We would be diving every night for two weeks: first for the elkhorn coral spawn, which typically takes place three to eight nights after the full moon from nine to ten o’clock at night; and second for the grooved brain coral spawn, which takes place nine to twelve nights after the full moon from five to six o’clock in the evening.
During the day, we would be preparing to care for the coral larvae by setting up special nurseries and cleaning the special tiles on which the baby corals will eventually settle. At night we monitored all the coral colonies for signs of “setting,” when gamete bundles are visible in the coral polyps before they are released into the water.
Arrow crab, reef octopus and sleeping parrotfish
Coming from our local Puget Sound waters, which are usually around 53°F in August, the 78° Curaçao reefs felt almost like a soothing bath. The locals found this temperature unseasonably cool, about five degrees below average for this time of year. The elkhorn coral must have felt the same, as none of the colonies spawned. Though we missed our main objective, we did still enjoy several nights of night diving with calm ocean conditions and saw some neat animals such as arrow crabs, reef octopuses and sleeping parrotfish.
Brain coral and butterfly fish
Fortunately, some corals are a bit more forgiving when it comes to spawning cues. The grooved brain coral actually spawns twice a year: once in the late spring as again in late summer. We hoped that this flexibility would allow the corals to still spawn, even with the cooler temperatures. Since this species spawns just before sunset, it releases its bundles very quickly with little to no setting. In order to know which corals will spawn, we actually rely on fish behavior. Two local butterflyfish species; the foureye butterfly (Chaetodon capistratus) and banded butterfly (Chaetodon striatus); are able to sense the impending spawn and frantically pick at the coral in anticipation of the highly nutritious gametes. When we saw groups of two to three dozen fish all crowding a particular coral, we knew to tent it with a net. Soon after, the coral released its bundles and they floated up the net and into our collection vial.
Over three nights we collected about 20mL of gametes from five different coral colonies. This amounts to about 153,000 eggs. With a lab fertilization rate of approximately 80 percent, that means we ended up with 123,000 coral larvae!
During this this time, the larvae are very delicate. They are very sensitive to water quality and will die or develop improperly if handled too roughly. So we spent the following days very carefully removing any dead and dying larvae, performing water changes on their holding containers, and tracking cellular development under the microscope.
Lab, nursery and dividing cells from under a microscope
Once the larvae fully developed to planula and began to swim around looking for a place to settle, we placed our prepared tiles into their holding containers. We also conducted an experiment and exposed the planula to different species of bacteria to see if we could identify specific ones that would stimulate settlement.
Once settled into a primary polyp, the settlement tiles will be moved to flow-through tanks in the CARMABI wet lab, into ocean nurseries for grow out, or shipped to participating institutions for exhibit purposes. Hopefully I’ll get to see the juvenile brain corals if I’m able to participate in the workshop next year!
Interested in coral? Read our coral fact sheet, then come learn more at the Seattle Aquarium, where you can view tropical corals as well as species that make their homes in our local waters!
To lay the groundwork for our upcoming blog post about the involvement of one of our staff aquarists with the SECORE (SExual COral REproduction) Foundation, we present a brief tutorial on the basics of coral reproduction. Aquarist Steven Yong, take it away!
Corals can reproduce sexually and asexually. In asexual reproduction, new polyps bud off the parent and grow into a separate colony which is a clone of the original animal. Asexual reproduction also happens with a branch of a stony coral colony breaks off and reattaches somewhere else in a process called fragmentation or “fragging.” This happens naturally in the wild during storms or when animals such as parrotfish break off pieces to eat. Most reproduction in aquariums occurs when aquarists trim coral that’s gotten too big or needs to be moved.
Though budding and fragging can produce large numbers of baby corals, these offspring are all clones of the original colony and lack genetic diversity, which is critical to species survival. This isn’t as important for maintaining our exhibits at the Aquarium—but it’s extremely important for corals in the wild.
Some coral species have reproduced sexually in our exhibits. Most of the pink and green cauliflower corals, Pocillopora damicornis, in our largest live coral exhibit and Only in Hawaii exhibit as well as the orange cup corals, Tubaestrea spp., in our non-photosynthetic coral exhibit are a result of spawning. These two species are brooders: male coral polyps release sperm into the water column, where it disperses and sinks. Female coral polyps contain egg cells, which are fertilized by the sperm and begin to develop inside the polyp. Once the egg develops into a larval form known as a planula, the polyp releases it into the water, where it swims until it finds a place to settle and metamorphose into a primary polyp and eventually divide and grow into a full colony. Because brooded planulae settle within a couple of days from being released, most of these offspring don’t travel far from the parent colony.
The majority of stony coral species are not brooders. About three quarters of them are broadcast spawners, producing male and/or female gametes and releasing them into the water in huge numbers. This allows the coral to distribute their offspring over a large area via ocean currents. Once released, the gametes float to the surface where they fertilize and develop into planula. These planulae also begin to seek settlement sites once they form. The time from spawning to larval settlement can span from a few days to a few weeks depending on the coral species. This allows broadcast spawning corals to distribute their offspring much farther than brooders can.
With so many coral species inhabiting a reef, how do corals make sure that the right gametes meet to make fertilization possible? On many reefs, spawning occurs as a synchronized event, with the male and female polyps of the same species releasing their gametes around the same time every year. This is very important because corals cannot move to mate and they may be quite far from one another. These mass spawnings occur in response to environmental cues such as temperature, lunar cycle and day length. Scientists have studied these spawning events and are able to predict with good accuracy when certain species will spawn. For instance, the critically endangered Caribbean elkhorn coral, Acropora palmata, spawns three to six nights after the full moon in late summer (August and September), two hours after sunset.
Thank you, Steven! Stay tuned for our next post, dedicated to his trip to Curaçao for a SECORE Foundation workshop dedicated to the mass spawning of elkhorn and grooved brain coral. Interested in coral? Read our coral fact sheet, then come learn more at the Seattle Aquarium, where you can view tropical corals as well as species that make their homes in our local waters!
That was the question asked by a recent Aquarium visitor after noticing the long hooked nose on a sockeye salmon.
Our male sockeye salmon, especially those in our Window on Washington Waters exhibit, are getting a lot of attention due to the morphological changes they undergo as they get closer to the spawning phase of their life. They have developed long hooked noses, red coloration and humped backs. These changes are useful for attracting females and competing with other males.
On November 3, Washington voters will have a chance to vote yes on Initiative 1401, a Washington State ballot measure that is designed to help save animals threatened with extinction.
Sea turtles, sharks and manta rays are the marine species that would be protected by the passage of the initiative. Their populations are in serious decline worldwide; they are being hunted to death. If passed, I-1401 will prohibit the trade of these animals (and/or their parts) in Washington State and reduce our state’s contribution to the illegal poaching and animal trafficking that are dramatically reducing their populations in the wild. The initiative would also protect land-based animals including elephants, lions, tigers, rhinos, leopards, cheetahs and pangolins.
A few facts about the marine animals that would receive protection under I-1401:
Sea turtles: All seven sea turtle species are endangered, three of them critically so. Hunting and illegal egg collection are a major factor in the decline of these beautiful aquatic creatures; it is estimated that more than 80,000 are killed each year.
Sharks: According to the International Union for Conservation of Nature (IUCN), a quarter of the world’s shark species are threatened with extinction due to overfishing—every year, over 100 million sharks are slaughtered. Many are killed by the cruel practice of finning, where sharks have their fins sliced off while they’re alive and are then thrown back into the water where, unable to swim, they slowly die.
Manta rays: Over the last decade, a spike in demand for the gills of rays has led to a massive decline in population; up to 50 percent in some areas. Because the gills fetch a high price in certain markets, the killing continues unabated.
Why is it important for the Seattle Aquarium support the passage of this measure? Says President & CEO Robert W. Davidson, “Our mission of Inspiring Conservation of Our Marine Environment compels us to strongly support Initiative 1401. By strengthening protections against trafficking in products from these increasingly endangered animals, we can help to save sharks, manta rays and sea turtles, and protect our ocean life.”
–Robert W. Davidson, president and CEO, Seattle Aquarium
Washington voters, click here to learn more—and please support this important measure. The turtles, sharks and rays thank you!