Featured Scientists: Robert "Bob" Arnone and the OWX Lab!

Before we return back to our corresponding labs, and start to process our samples, we have one more post from one of our collaborators! Dr. Bob Arnone was part of the land-support team which guided our survey with satellite updates and oceanographic analyses of daily conditions. The GOM is a very large and dynamic ecosystem and we can use all the help we can get! Bob and two post-doctoral researchers (Brooke Jones and Inia Soto) prepared a blog post to share some of their work at the University of Southern Mississippi. I hope you enjoy it and next year, we encourage our collaborators to do joint posts like this one to share their land based work as well!

Robert Arnone and Brooke Jones in the OWX showing the cruise track
of the Nancy Foster in the Gulf of Mexico and the daily ocean conditions

"We are Prof. Robert Arnone, Dr. Brooke Jones, and Dr. Inia Soto from the University of Southern Mississippi, Division of Marine Science, Stennis Space Center. Our Ocean Weather Laboratory (OWX) was able to work with the researchers aboard the Nancy Foster during the RESTORE Bluefin tuna survey (NF1704) this past May and early June 2017. We provided daily updates on relevant ocean conditions while we followed the ship's cruise track as well as abnormal conditions that might affect the research results. Many of the ocean products we provided are new, and working with the Foster cruise allowed us to compare the observations from our lab with ship observations. Our goal is to demonstrate that our daily ocean products can provide the Foster a better understanding of sampling for Bluefin tuna. We want to continue to work with the research group to optimize our products and the packages we provide.

"The OWX Laboratory was established to characterize the daily ocean conditions and abnormal events in the Gulf of Mexico. Our focus is to assemble products from satellite remote sensing ocean color data, sea surface temperature, and several physical ocean circulation models to define ongoing ocean activity. Our daily products include the ocean bio-optical properties of chlorophyll-a, turbidity, water clarity, phytoplankton absorption, and particle back-scattering and physical oceanographic conditions (temperature, salinity, currents, mixed layer depth). The OWX Laboratory research is focused on the understanding of the interactions between the oceanographic conditions and the ecosystem. New OWX products also include weekly dynamic "anomalies" which can help us identify abnormal physical or biological conditions that are occurring so possible bio-physical oceanographic events can be identified in the Gulf of Mexico.

The Ocean Weather Laboratory at USM with various screens visually monitoring ocean conditions using Google Earth

"The daily OWX Laboratory products provided locations to the Foster for adaptive sampling to help support optimum data collection and understand how Bluefin tuna are responding to changing bio-physical conditions, as well as identify events such as harmful algal blooms, flooding events, coral reef mortality, and others that may be occurring in the Gulf of Mexico.

"The OWX Laboratory visually displays animated ocean properties in several monitors using Google Earth. These tools provide capability to integrate ship tracks and observed data with satellite and model data so we can coordinate with ship operations.

"The videos below show Google Earth animations of the OWX Lab's animated daily products of the nowcast bio-physical processes (Chlorophyll, currents, and salinity) and the dynamic abnormal ocean conditions with the ship track for the Nancy Foster Bluefin tuna survey for the week (May 22-27, 2017)."

We love to share our collaborators' research, especially when the OWX Lab's main focus is to provide new capabilities for ship sampling so that optimum data can be collected and related to the changing ocean conditions. We hope that the daily OWX products can be used for fisheries applications very soon!

Featured Scientist: Karen Selph

Karen in the lab-van whispering to the flow cytometer!

Hello blog, today Dr. Karen Selph from the University of Hawaii at Manoa shares some of her expert insight into the nutrient-limited world! Karen shared with the blog just a few of the multiple experiments she carried out while on board the NOAA Ship Nancy Foster during NF1704 as part of our NOAA RESTORE project. Karen’s main focus was collecting phytoplankton to analyze with a “flow cytometer” – a machine that tells us how many phytoplankton are out there and gives us a rough idea of their types.

In addition, she measured water column light levels used for photosynthesis by phytoplankton with a photosynthetically-active radiation (PAR) sensor that was attached to the CTD rosette. Karen shared with the blog: "The 6 casts that we performed will yield invaluable information on the light regime during the cruise." 

"The nutrient limiting phytoplankton growth in the Gulf of Mexico is nitrogen.  Nitrogen has many forms, and most phytoplankton can only use reduced inorganic forms (e.g., nitrate (NO₃), ammonium (NH₄)).  However, some phytoplankton can use nitrogen gas (N₂), which is in abundant supply.  This is quite a trick, as the chemistry involved is anaerobic (no or low oxygen) and phytoplankton produce oxygen! 

Karen and Lucy carry out one of the PAR casts

On this cruise, we collected many samples to figure out which of the larger nitrogen-fixing organisms that might be present – in particular, Trichodesmium (usually a bane to those who study zooplankton, as it can clog their nets!!).   Additionally, to assess the base line N-isotopic value for Trichodesmium, we collected samples for stable nitrogen isotope analyses.  We even analyzed a sample of Sargassum to figure out its isotopic signature with respect to the other nitrogen-fixing players in the GOM.  Once we get back to the lab, we will also examine our samples under the microscope looking for the presence of other nitrogen-fixers – some diatoms and other species harbor symbionts capable of this remarkable feat!"

The dynamic duo, Tom and Karen processed hundreds of samples during the survey

Shaun, Karen's travel companion, makes some new friends

Finding the Features

A Battle on Many Fronts

Where is the best place to catch fish? Alas, a question that plagues not only the fisherman, but the fisheries oceanographer as well. Ocean conditions and transport mechanisms play a vital role in the lives of the fish (and other creatures) that dwell there. Hours after spawning, ocean currents are sweeping fertilized fish eggs away from their spawning location. If the temperature is just right, the eggs hatch into larval fish where ocean features such as eddies will ultimately determine if the fish will find its favorite food and grow into an adult.

How do we find these ever-changing phenomena so we can study the effect they have on larval fish? Well...we have some tools.

Satellites

You may find it strange that we use satellites orbiting hundreds of miles above the Earth to find habitat for larval fish that can only be examined under a microscope, but it’s true! From the deck of a ship, one patch of blue water often looks like the next, which is why we call on instruments such as the Advanced Very High Resolution Radiometer (AVHRR) to do our sensing. A radiometer is a high-tech piece of equipment mounted on an orbiting satellite that detects radiation which can be used for remotely determining cloud cover, or, in our case, sea surface temperatures. Our collaborators at Roffer’s Ocean Fishing Forecasting Services, Inc. (ROFFS^TM) analyze the satellite data to provide us with a picture of where the boundaries between distinct water masses (“fronts”) are. The color image below makes it easy to see the fronts differentiated by surface temperature. 

Satellite image and analysis analysis from ROFFS showing sea surface temperature (SST), currents (blue arrows), completed/planned stations (pink Xs) and future possible sampling locations (red Xs)

We know certain species such as Atlantic bluefin tuna often spawn near fronts, so this helps us in determining where the best areas to sample for larvae are. But satellites have their limitations. Despite the Caribbean’s reputation for sunny beaches, the clouds do occasionally roll in and prevent the satellites from “seeing” the ocean surface.

Circulation Models

While satellites provide accurate, near-real time information, sometimes it is useful to get an estimate of what the future holds. Ocean general circulation models such as the Hybrid Coordinate Ocean Model (HYCOM) use environmental inputs and complex mathematical formulas to produce predictions of ocean parameters such as Sea Surface Temperature (SST) and the speed and direction of ocean currents. 

HYCOM model output for sea surface temperature (degrees Celsius)

HYCOM model output for ocean currents (arrows show direction, colors show speed in cm/second)

While the model is not a perfect predictor, it proves useful on cloudy days or when you want to do some advance planning which is almost always necessary on a ship that has a maximum speed of 10.5 knots (~12 mph).

Ship Data

Having the support of satellites endlessly gathering data and computers constantly running models are great assets to what we do…but so is having access to a high-tech research vessel! Flow through sensors show real-time sea surface temperature and salinity as the ship is sailing and echo sounders are pinging the bottom and displaying a precise depth. But perhaps the most important tool aboard to detect frontal zones is the Acoustic Doppler Current Profiler, also known as the ADCP.  

ADCP output from the 2015 survey across the Yucatan Channel. The ship's track is in black with the direction and size of the arrows showing the direction and speed of the current. Color indicates SST.

The ADCP uses sound waves and the Doppler Effect to measure how fast water is moving in the water column. What does all this jargon mean? It means that we can detect the speed and direction of the current directly below the ship…while the ship is moving! So once we consult the satellite images and model outputs, the ADCP confirms that we have arrived at the right spot. Then it is time to tow some nets…