Fisheries browsing by category


All About That Base…Pairs: Using DNA Barcoding to Identify Fish Gut Contents

Tuesday, November 10th, 2015

by Heather Soulen

Rob Aguilar takes photos of all DNA barcoding reference specimens collected in the Chesapeake Bay

Rob Aguilar takes photos of all DNA barcoding reference specimens they collect in the Chesapeake Bay

Rob Aguilar of SERC’s Fish and Invertebrate Ecology Lab co-authored a DNA barcoding paper this past September in the journal Environmental Biology of Fishes. Rob spoke with us about his paper and the DNA barcoding work going on in the Fish and Invertebrate Lab. While the term DNA barcoding may seem difficult to understand, it’s easiest to think about it as a uniquely identifiable species level code.

Click the sound file below to listen to the interview.

Additional barcoding details are available in the full podcast transcript.

Click to continue »

What Does Life in the Ocean Sound Like?

Wednesday, November 4th, 2015

Erica Staaterman in the [X] with baby [X].

Erica Staaterman selfie with a baby larval snapper. (Erica Staaterman)

by Kristen Minogue

Dr. Erica Staaterman listens to the ocean for a living. Often seen as a silent landscape broken only by whale or dolphin songs, Staaterman is helping uncover a wealth of noise from the ocean’s hidden creatures, first in California and now in the Chesapeake as a postdoc for the Smithsonian Environmental Research Center. Learn more in the edited Q&A below, and click the sound files to hear some of the secret sounds of the sea.

How did you get into acoustic ecology?

My first research job out of my undergrad was working for Sheila Patek at UC Berkeley….She had a bunch of recordings of these [California spiny] lobsters making sound, and nobody really understood why they make sound. So we did an experiment where we tried to understand the function of the sounds made by these lobsters. So anyway, that was sort of my first foray into acoustics, and from there I just thought it was really fascinating.

In California, you described researching a chorus of mantis shrimp. What did that sound like?

We called them rumble groups. Sometimes they would have two rumbles per group, sometimes three rumbles per group, sometimes four or five….At dawn and dusk you would hear so many different rumble groups occurring at the same time that they would all be sort of overlapping, and it seems to indicate that there are many individuals making sound at the same time, just the way birds all sing out at once in air.

Listen below: Mantis Shrimp “Rumble Groups” Click to continue »

The Dark Side of Taxonomy: Part Two

Friday, October 30th, 2015

by Heather Soulen

Darker Still

Delving deeper into the dark side of taxonomy, we forge forth into the ether to uncover obscure and wickedly inspired scientific names. What’s in a scientific name? As described in The Dark Side of Taxonomy: Part One, some scientific names for organisms have dark and twisted origins. In part two of this three-part series, we peek behind the thin gauze-like veil, fearlessly sifting through time and lore to deliver a new collection of gruesome scientific names. Here we share ancient tales of Greek mythology, an Italian literary genius from the Middle Ages and the unforgiving Underworld.

Click to continue »

DNA Detects Two Hidden Oysters in Panama

Thursday, May 21st, 2015

by Monaca Noble and Katrina Lohan

Image: Oysters and other life grow on dock pilings at the Smithsonian Tropical Research Institute (Credit: Kristina Hill-Spanik)

Oysters and other life grow on dock pilings at the Smithsonian Tropical Research Institute in Panama
(Kristina Hill-Spanik)

A robin is a robin. It isn’t often confused with other birds. But some marine organisms are very difficult to identify because they look similar, too similar even for taxonomists trained to detect differences. Oysters are like this.

Oyster shells come in all shapes and sizes. As oysters fight for space and battle to survive in tough environments, their shells can change appearance based on conditions where they live. This makes it very hard to distinguish similar-looking species. Using DNA, we can identify these difficult species and provide new insights into their distribution, ecology, and ranges—insights not possible using shell morphology alone. In Panama, this DNA detective work led to two surprising discoveries.

Click to continue »

Oyster Disease Thrives in Nightly Dead Zones

Wednesday, February 11th, 2015

by Kristen Minogue

Image: Slides of oysters suffering different Dermo intensities as the parasite multiplies, from healthy (left) to severely infected (right). (Credit: SERC Marine Ecology Lab)

Slides of oysters suffering different Dermo intensities as the parasite multiplies, from healthy (left) to severely infected (right). (SERC Marine Ecology Lab)

In shallow waters around the world, where nutrient pollution runs high, oxygen levels can plummet to nearly zero at night. Oysters living in these zones are far more likely to pick up the lethal Dermo disease, a team of scientists from the Smithsonian Environmental Research Center discovered in a new study published Wednesday.

Oxygen loss in the shallows is a global phenomenon, but it is not nearly as well known as the dead zones of the deep. Unlike deep-water dead zones, which can persist for months, oxygen in shallow waters swings in day-night cycles, called diel-cycling hypoxia. In nature it works like this: When algae photosynthesize during the day, they release oxygen into the water. But at night, when photosynthesis stops, plants and animals continue to respire and take oxygen from the water, causing dissolved oxygen to drop. Nutrient pollution, because it fuels massive algal blooms, can make the cycle even more drastic. The resulting lack of oxygen can cripple the oysters’ ability to fight off the parasite Perkinsus marinus that causes Dermo and slowly takes over their bodies.

Click to continue »

Not Your Everyday Martha Stewart Glue Sticks

Friday, December 19th, 2014

by Heather Soulen, research technician

When I mention that we use “glue sticks” at the Smithsonian Environmental Research Center to help answer research questions about wetland ecology, I get looks of confusion and amusement. People often think I am using:

Glue Sticks (Credit: Heather Soulen/SERC) or GlueGun (Credit: Heather Soulen/SERC)

But, what I really mean is that I use these:

+ +

Click to continue »

Saving the River Herring: Don’t Let the Good Die Young

Wednesday, November 26th, 2014

by Kristen Minogue

Image: Alewives, a species of River Herring. (Credit: Geoffrey Gilmour-Taylor)

Alewives, one of two species of River Herring in Chesapeake Bay. (Geoffrey Gilmour-Taylor)

It’s no secret that River Herring are in trouble. There was a time, back in the 1950s, when Maryland fishermen regularly pulled in 4 million pounds or more a year of the silver fish. Then something mysterious happened. Herring harvests generally fluctuate from year to year. But in the 1970s, they fell and never came back up. For the last four decades, commercial fishermen in Maryland have been lucky to catch a few hundred thousand a year. Now they catch none.

Click to continue »

Oysters and the Chesapeake’s Jellyfish Wars

Tuesday, September 30th, 2014

Image: Jellyfish Chrysaora quinquecirrha (Credit: Lori Davias)

Jellyfish Chrysaora quinquecirrha (Lori Davias)

by Kristen Minogue

Every summer, the food web in Chesapeake Bay gets jostled around as two plankton-eating predators jockey for power: comb jellies and jellyfish. Most smaller species don’t have a stake in the battle—both predators eat zooplankton and fish eggs, after all. But for young oyster larvae, the victor could make the difference between being protected civilians or collateral damage.

Click to continue »

Banishing the Ghosts on the Bay Floor

Tuesday, August 12th, 2014

by Kristen Minogue

Image: A ghost pot pulled out of Chesapeake Bay. (Credit: Michael Reid/Southern Maryland Newspapers)

A ghost pot pulled out of Chesapeake Bay. (Michael Reid/Southern Maryland Newspapers)

Every year, thousands of crab pots disappear, their lines snapped by violent storms or severed by the propellers of passing boats. Cut off from the buoys that once marked their presence, they become “ghost pots,” lost at the bottom of the Chesapeake.

But ghost pots aren’t dead pots. They’re still quite capable of trapping crabs, including mature females undergoing their spawning migration. And with no one to retrieve them, crabs too large to escape are condemned to a slow death by starvation. This often has the eerie effect of luring even more animals to their demise, says Laura Patrick, aquatic ecologist at the Smithsonian Environmental Research Center (SERC).

“The crabs are just going in and they’re dying,” Patrick says. “And one of the problems is that the dead animals that are in there can be bait for new crabs to come in. So it’s kind of a self-baiting pot.”

Click to continue »

Virtual crabs could help real recovery

Friday, August 8th, 2014

by Sarah Hansen

Image: Julie Sepanik holds up a large male blue crab caught in the Rhode River. (Credit: SERC)

Julie Sepanik holds up a large male blue crab caught in the Rhode River. (SERC)

No one disputes that blue crab numbers in Chesapeake Bay are low.  There is much discussion, however, about what to do to fix the problem.  Smithsonian Environmental Research Center intern Julie Sepanik is working with SERC postdoctoral fellow Matt Ogburn to develop a computer model that will help improve our understanding of blue crab population dynamics in the Bay. The model works to identify where female crabs mature in the Bay and track their migration to lower Bay spawning areas. Ultimately, they hope the model will help inform decisions about preserving habitat and restoring the population.

Click to continue »