Sue Zupko: 12 What’s in the Water?

NOAA Teacher at Sea: Sue Zupko
NOAA Ship: Pisces
Mission: Extreme Corals 2011; Study deep water coral and its habitat off the east coast of FL
Geographical Area of Cruise: SE United States from off Mayport, FL to St. Lucie, FL
Date: June 8, 2011
Time: 1900

Weather Data from the Bridge
Position: 25.3°N  79.6°W
Present weather: 3/8 Alto Cumulus
Visibility: 10 n.m.
Wind Direction: 065°true
Wind Speed: 10 kts
Surface Wave Height: 3 ft
Swell Wave Direction: 110°
Swell Wave Height: 3 ft
Surface Water Temperature: 28.4°
Barometric Pressure: 1013.2 mb
Water Depth: 363 m
Salinity: 36.28 PSU
Wet/Dry Bulb: 27.7/24.8

This blog runs in chronological order.  If you haven’t been following, scroll down to “1 Introduction to my Voyage on the Pisces” and work your way back.

Take this quiz before reading this post.

Dr. Diego Figueroa and I went fishing over the side of the ship this evening with a straining bucket to try to catch zooplankton (animals which cannot swim against the current–free floating).  We had no plankton net so we had to improvise.

Diego, a zooplankton expert, got a plastic container like you’d use to store food in the fridge, and we headed to the lab with what we hoped would be a good catch.  He got a cup of salt water from the special faucet in the ship’s science lab and poured it into the bottom of the bucket.  As he poured the water, he had the plastic container at the top of the it to retrieve our catch.

We  then examined the container to see what the naked eye could find.

Wow!  Our first specimen was a shrimp.  It’s huge.  Well, huge in comparison to the other zooplankton.  We still saw it best under the microscope.  He left that in to container to pull out later and caught some copepods with an eye dropper.

Eureka!  There were at least six Calanus copepods.  Cope– is Greek for oar or handle and pod–  means foot or limb.  These are very common off the coast of Florida and about 80% of all the zooplankton on the planet are some type of copepod.  He explained that the Calanus has five rows of legs that flap downward (like the doggie paddle that most of of use when learning to swim) in order to move around.  The Calanus eats phytoplankton (algae), making it a primary consumer.  It has five pairs of mouth parts.  The hairy seta (the plural is called setae)  act like a sieve when it eats.  This is so interesting.  The Calanus opens its mouth parts and gathers water molecules toward its body.  Then, it pulls its mouth parts in and squeezes the water out. What’s left is a scrumptious meal of diatoms.  The grazing copepod we watched was a female.  Her tail is shaped differently than the male’s tail.

The shrimp is at least 20 times bigger than the Calanus.  Diego hasn’t studied the shrimp like he has the copepods.  That’s because the shrimp are one of the bigger zooplankton and large ones make up only about 5% of all zooplankton.  He says that there are more copepods in the world than all the insects combined.  That makes sense since the earth’s surface is  71% water.

When the ROV was flying through the ocean, we always saw snow in the water.  I used to scuba dive a lot and I never really noticed the snow.  If it was deep, they weren’t there.  Andy David explained that we see them so well since we’re shining light on them.  These are mostly zooplankton in the water.  In addition, there is a bunch of decaying organic matter called detritus flying along.

Further examination of the water yielded a Microsetella rosea, a hyperiid, and a Chaetognath (arrow worm). The Microsetella is a detritis-eating filter feeder, but it is only about 1/5 the size of the Calanus.   Well, with micro in its name, small had to figure into it somehow.  Since it’s small, it eats smaller things.

The arrow worm is like something from a horror movie because it attacks its prey viciously (it’s a carnivore and is a voracious predator).  I asked what all the other floating bits were in the water.  Detritus.  It’s the snow we kept seeing.

Diego has a special camera which attaches to the microscope.  We would examine the zooplankton in the petri dish and then he would take off the microscope eyepiece and insert his camera.  Then, through the viewfinder, he would try to find the zooplankton resting somewhere.  Apparently, they don’t rest much, but he still got photographs.

I really enjoyed this mini lab.  Diego taught me things about plankton in general and I now better understand this amazing  world of particulates in the ocean a bit better.  Jana and I had gone on deck last night to see what it was like in the pitch black.  We discovered it isn’t totally dark, though your eyes do have to adjust.  The moon kept peeking from between clouds off the starboard (right) side and lights shone from portholes below deck.  These lights reflected off the waves and were so fascinating to watch.  I’ve only had a beachside view of the ocean at night so this was a real treat.  Jana and I watched for bioluminescence in the water, a sign of some plankton.  We found little sparkles of green in the wave and hypothesized these were zooplankton.  After explaining what we had seen to Diego, he confirmed that these were zooplankton rather than phytoplankton.  Zooplankton have little sparkles in turning water while phytoplankton will cover a large area and just glow.  Too interesting.

Special thanks to Diego for sharing his knowledge with me after a long day and to Jana for helping get some pictures of this.

And the answer to the quiz above….Copepods.  They are so small you don’t notice them, but there are almost as many copepods as there are grains of sand on the beach.  It’s hard to fathom that many creatures swimming around.  Diego said that they eat the phytoplankton so fast that often there are more zooplankton than phytoplankton.