Navigation
Twitter and News feeds
about 8 years ago
Manta Ray hot lunch Marianas Variety (Press Release) — The Manta Ray Band will be having a hot lunch this Saturday, Feb. 6, 2016, to raise funds for their trip to the Tumon Bay Music Festival on Guam next month. The lunches are $5 each and include fried chicken, lumpia (fried spring roll ...
about 8 years ago
gulfnews.com Whale shark sightings along UAE coast not alarming: experts gulfnews.com Dr. Elsayed Ahmad Mohammed, Regional Director, Middle East and North Africa, of International Fund for Animal Welfare (IFAW), told Gulf News that the recent appearances of the fish make sense given the whale shark feeds close to the surface and often ... and more »
about 8 years ago
KHON2 Whale shark surprises tour group off Haleiwa KHON2 A group led by North Shore Shark Adventures was visited by a whale shark Friday morning, the intimate experience captured on video. They were about three miles off Haleiwa when the shark slowly emerged. “It swam right up to the boat, really slow ... and more »
about 8 years ago
Thanh Nien Daily Carcass of beached whale shark to be preserved by Vietnamese scientists Thanh Nien Daily The Nha Trang Oceanography Institute in central Vietnam has decided to preserve the carcass of a whale shark that died after it got caught in a fishing net last week. Fishermen and local authorities on Thursday handed over the dead fish to the institute. Giant whale shark to be embalmed for scientific researchVietNamNet Bridge all 2 news articles ...
about 8 years ago
National Geographic Manta Rays Get Crittercams for First Time Ever National Geographic We didn't think suction cups would work because manta ray skin is really rough like sand paper. We knew suction cups worked well on the smooth skin of whales. The cups were originally designed to move pieces of glass. But we gave it a try, and with a ... Scripps Grad Student Receives Prestigious Environmental FellowshipScripps Oceanography News all 4 news articles » ...
about 8 years ago
Video From a Whale Shark's Point of View National Geographic Their goal was to deploy Crittercams on whale sharks to get a glimpse of the sharks' underwater world and to better understand their behavior along the reef. Like most people, Wilhelm had never seen a whale shark. He worked on the Crittercams for about ... and more »
about 8 years ago
Zap2It Dominic Monaghan on meeting the Whale Shark: 'I had this sort of out of body experience' Zap2It “Wild Things With Dominic Monaghan” returned to Travel Channel with its third season on Wednesday (Jan. 27). The premiere, aptly titled, “Majestic Mozambique,” finds our host on the hunt for the elusive — and quite massive — Whale Shark. Early on in ... Monaghan knows where the 'Wild Things' areVirgin Islands Daily News all 9 news articles ...
about 8 years ago
CBC.ca Brian Keating swims alongside La Paz's mysterious whale sharks CBC.ca They're such huge animals," said Keating, who saw his first whale shark less than 15 minutes out of the bay. By the day's end, Keating had met at least a dozen whale sharks. He even managed to snap a few underwater photos from their tail end as proof.
about 8 years ago
FIS Fishing ban for giant manta ray FIS The Ministry of Production (Produce) has banned the capture of the giant manta ray (Manta birostris) in the Peruvian marine waters, in order to preserve this species on the coast of the country. The measure, established by a ministerial decree, is in ... and more »
about 8 years ago
The National Whale shark seen swimming in Abu Dhabi marina The National ABU DHABI // A whale shark between three and four metres long has been seen swimming in the marina at the InterContinental Abu Dhabi. Employees at the hotel first noticed the fish at 1.45pm on Friday and quickly took a video and photos to capture the ...
Search this site
Networked Blogs

Entries in CTD (1)

Tuesday
Jan252011

Good old-fashioned home-grown oceanography!

If oceanography had a classic bread-and-butter technique, CTD casts would have to be it.  The C stands for conductivity (basically salinity), the T for temperature and the D for depth.  The “cast” refers to the fact that you measure these three properties as the instruments descend to - and return from - the sea floor.  CTD casts tell scientists about the structure of the water column beneath them.  How can water have structure?  Well, differences in temperature and salinity can lead to layers in the water and these can tell you about how the water is or isnt moving and also have implications for animal life living there.  If you’ve ever swum in a lake where your body was warm but your legs were cold, then you’ve experienced a structured water column, or water layers.  (Strong structure like that often happens in summer when surface waters are warmed by the sun, which makes them less dense, so that they are even more buoyant.  When winter comes, the surface layer cools until it is denser than the underlying water, at which point the surface water sinks and the water column “turns over”)

In a world of side-scan sonar, ADCP and satellite sensing, CTD casts still play a really important role in understanding the water column, so they are still a core part of any oceanographer’s toolkit.  Let’s take a look at one.  This CTD/rosette sampler is part of an instrument package belonging to the Rosenstiel School of Marine Science at the University of Miami:

 

This rather expensive bit of kit stands about 6 feet high and consist of 24 sample bottles arranged in a ring, with the actual CTD instrument package underneath.  Together, this equipment can make accurate measurements of not only salinity, temperature and depth, but also dissolved oxygen and chlorophyll concentration, AND it can take a 10L sample at any depth using the “rosette” of bottles.  In the following video, U. Miami oceanographers deploy the CTD, then I discuss the acquisition of data with Cepemar oceanographer Carlos Fonseca, and finally graduate student Nelson Alves collects water samples from the sample bottles for a study on bacteria and virus diversity

 

So far here in Brazil we’ve seen a typical “surface mixed layer”, where the temperature and salinity is the same throughout the top 10-20m.  Below that, temperature drops sharply 4-5 degrees C to a colder underlying layer; this transition is called a thermocline (thermo = temperature, cline = a gradient) and is a standard feature of that well-layered water column.  Below that, temperature drops more gradually, but with some jagged steps that result from “salt fingers”.  These are small-scale turbulence features that tell oceanographers (like Carlos in the video) about mixing processes taking place in the water column.

The CTD - long time friend of oceanographers the world over!