Category: Natural World

Seining in the Sound

Setting up the seine.

After surface sampling with the dip nets, and subsurface sampling with the little corers, we tried sampling the water column using a small seine.

Seining requires teamwork, and I was pleased to see everyone working well together, focused on the job at hand.

Working together to bring in the catch.

Hauling on the nets, with the smell of salt in the air, resurrected long neglected memories of fishermen at work on tropical, Atlantic beaches. Back then they were going after fish for the market, here, with our much finer meshed net, we were looking for anything interesting in the water column.

Examining the catch.

Everyone got touch a ctenophore (comb jelly), which I will note is not a jellyfish, and is also not poisonous.

If you look carefully you can just make out a comb jelly in the jar.

Students also had a chance to hold a croaker (a fish of the family Sciaenidae), and feel it croak.

Feeling the croak.

Our guide was great. She was quite knowledgeable about the fauna we ran into, and very good at sharing information.

Stephanie T. pointing out the finer points of piscine morphology.

Interestingly, we were not the only ones out seining that morning. There was a small group from the research lab looking for skates for a research project. I think they said that this was their third time out looking, but like us, they did not find any elasmobranchs (not counting the one dead specimen we ran into while dip netting).

Remains of a skate, lying in the grass at the edge of the beach.

Dip Nets in the Estuary

Dip nets in action.
Sampling in the estuary.

Doing the “sting ray shuffle” through the shallow waters of the estuary of a small stream and the Mississippi Sound, we used dip nets to collect organisms from the sediment-water interface.

We found mostly invertebrates. There were lots of small white crabs. Most, but not all, were too small to pinch.

We also grabbed quite a number of translucent shrimp.

You can very clearly see the entire gastro-intestinal system of this small shrimp.

And there were a lot of hermit crabs.

An understandably shy hermit crab.

A couple students also picked up some small snakes, but they quickly slipped through the dip net’s mesh and escaped.

Simple and effective, dip netting was a nice way to start the Coastal Sciences Camp.

Coastal Science Camp at the Gulf Coast Research Lab

Dip netting in a small estuary.

As you may have guessed from the previous posts about waterspouts and the dolphin, we’ve been on the Gulf coast for the last few days. Specifically, we were visiting the Gulf Coast Research Lab‘s Marine Education Center for two days for our end-of-year trip.

It was excellent. The weather was perfect; sunny with lots of cumuliform clouds for shade but little rain. However, the what really made the trip work was that we had a good, interesting, and varied program, directed by an excellent instructor, Stephanie T..

Stephanie T. pointing out the finer points of piscine morphology.

For reference (to link all posts about the Coastal Science Camp):


View Coastal Sciences Camp, Gulf Coast Research Lab in a larger map

Dolphin

Dolphin in the boat's wake.

We weren’t looking for them at the time, and later when we were looking for them we didn’t find them, but on our trip back to the GCRL-MEC a dolphin decided it wanted to play in our boat’s wake.

It would jump through the face of the bow wave. Usually horizontally, but vertically once or twice.

Playing.

Dolphins usually travel in pods of up to a dozen or so individuals. This one, however, was alone. We’d seen it earlier, while we were walking on the beach and picking up trash. The dolphin may have been playing or eating, but it was certainly scaring the small fish. A couple birds took advantage of this to make their own catches, with near vertical dives into the gently rolling waters of the sound.

It was wonderful to observe.

Bird caught in the middle of a dive, just before it splashed into the water.

Waterspouts

Two waterspouts seen over Ocean Springs.

As we waded through the Mississippi Sound, doing the Sting Ray Shuffle, sampling for benthic fauna, we came across these two waterspouts. Our guide, Stephanie, from the Gulf Coast Research Lab’s Marine Education Center, said they’re not that common.

Subtly sinuous.

They’re quite elegant.

In the distance.

Fortunately, they were very far away.

Fascinating.

Alpha Magnetic Spectrometer

The BBC has an excellent article on the Alpha Magnetic Spectrometer (AMS) launched on the second to last shuttle flight to investigate the origins of the universe. NASA’s page is giving regular updates.

What’s nice is that the basic physics of magnetic spectrometers, where magnets are used to deflect the motion of charged particles, should be accessible to middle school students once they get into electricity and magnetism.

How the AMS works. Image from CERN via the BBC.

Transition Radiation Detector determines highest-energy particle velocities
Silicon Trackers follow particle paths; how they bend reveals their charge
Permanent Magnet is core component of AMS and makes particles curve
Time-of-flight Counters determine lowest-energy particle velocities
Star Trackers scan star fields to establish AMS’s orientation in space
Cerenkov Detector makes accurate velocity measurements of fast particles
Electromagnetic Calorimeter measures energy of impacting particles
Anti-coincidence Counter filters signal from unwanted side particles

— Amos (2011): Alpha Magnetic Spectrometer to go on Endeavour shuttle on the BBC.

For additional information, that really gets into the nuts and bolts, you can go CERN’s technical site or get more general info at their public site, which has a wonderful set of videos and animations.

Breaching the Morganza Spillway

Flooded mobile home park in Memphis on May 10, 2011. © 2011 Google, GeoEye

The worst of this spring’s flood has passed Memphis, but they’re still dealing with the water downstream on the Mississippi.

PBS has before and after pictures of the opening of the Morganza Spillway, which is intended to stave off flooding in Baton Rouge and New Orleans.

The Coastlines Project blog is also aggregating a lot of information about the effect of the flooding. I found the post on the effect of the flooding on New Orleans) to be particularly provocative. It’s probably a good candidate for a Socratic dialogue, because it points out the tradeoff between the ecology of the Mississippi delta and the health and utility of New Orleans. The Corps of Engineers have been regulating the Mississippi along its present course for the last half a century, but this has prevented the river from avulsing and flowing down the Atchafalaya river instead of its current course. This would leave New Orleans high and dry (but not for long) but be a great boon for the Atchafalaya part of the delta.

The current Mississippi River is in blue, while the Atchufalaya River is in green. The Atchufalaya takes a much more direct route to the Gulf of Mexico, and that is the route the Mississippi would take if it were not for the levees. This map also shows the different deltas built up by the Mississippi River as it has changed its course over the last 10,000 years (the Holocene). Image adapted from Aslan et al. (2005; pdf).

Coastlines Project also deals with other issues, such as how the lingering effects of the BP oil spill, affecting the Gulf coast. It’s an interesting blog to follow, especially since we’ll be on that coast next week for our end-of-year trip.