Miriam Hlawatsch, August 3, 2007

NOAA Teacher at Sea
Miriam Hlawatsch
Onboard NOAA Ship Nancy Foster
July 29 – August 10, 2007

Mission: Lionfish Survey
Geographical Area: Atlantic Ocean, off the coast of North Carolina
Date: August 3, 2007

NOAA Teacher at Sea Miriam Hlawatsch recording weather data on the Bridge of the NANCY FOSTER.
NOAA Teacher at Sea Miriam Hlawatsch recording weather data on the Bridge of the NANCY FOSTER.

Weather Data from Bridge
Visibility: 10 miles
Wind Direction: 186º
Wind Speed: 11 knots
Sea Wave Height: 1-2 ft.
Swell Wave Height: 2 ft.
Seawater Temperature: 28.6ºC
Sea Level pressure: 1017.3 mb (millibars)
Cloud Cover: 8 oktas, cumulous, cumulonimbus

Personal Log

I’ve been recording weather data for the last two days and spent three hours on the Bridge learning the responsibilities of the watch crew. When NANCY FOSTER began hydrographic multi-beaming at 1500 hours, there were several ships (tankers and small craft) in the area. The NOAA Officers on watch had to keep a careful eye on those vessels and, at times, let them know survey work was going on … so move over, please! Also, I’ve been able to watch as our dive locations were plotted on the nautical chart of Onslow Bay. Ensign Lecia Salerno explained that, as Navigation Officer, one of her duties is to update the nautical charts when NOAA informs her of changes. She must record these updates by hand as new charts are only printed every few years.

NOAA Teacher at Sea Miriam Hlawatsch attempting to read sea swells and sea wave height from the Bridge.
NOAA Teacher at Sea Miriam Hlawatsch attempting to read sea swells and sea wave height from the Bridge.

Science Log

Objective #3: Conduct cryptic/prey fish sampling using a special enclosure quadrat net. 

In order to collect cryptic (small) prey fish, NOAA scientist Dr. Roldan Muñoz sets up a special enclosure net during his dive rotation. Divers in the next rotation retrieve the net with captured specimens. Dr. Muñoz examines the catch to determine the type and number of prey fishes (what lionfish may be eating) within a square meter. Such data provides a better understanding of the habitat community.

Objective #4: Characterize and quantify habitat and macroalgae with digital still photography and specimen collections. 

Currently, not much is known about off shore Hard Bottom habitats where lionfish appear to be thriving. In order to understand the impact an outside force (i.e. lionfish) has upon a marine community, scientists must first examine the community in its original state. In other words, a baseline must be established. When Marine Phycologist Dr. D. Wilson Freshwater dives, his goal is to identify habitat characteristics and existing macroalgae. This is done via still photographs and specimen collections gathered every five meters along the transect line.

Dr. Freshwater’s photo showing seven types of algae.
Dr. Freshwater’s photo showing seven types of algae.

Back in the lab, Dr. Freshwater processes his samples for species identification and DNA analysis. He reviews the photos, creates a list of everything he sees, then uses the computer to establish the percentage of cover and frequency of occurrence for each species. A comparison of the different sites is made and, from this empirical data, an overall picture of the community structure begins to emerge.

Note: I learned the term Hard Bottom refers the rocky outcrops that cover much of the continental shelf along the southeastern US from Cape Hatteras, NC to Cape Canaveral, FL. Fish are drawn to the hard bottom outcroppings; here, they find a source of food and shelter on what is otherwise a vast sandy sea floor. It explains why recreational fishermen often seek out hard bottom areas.

Dr. D. Wilson Freshwater processing algae specimens in the lab aboard NOAA ship NANCY FOSTER.
Dr. D. Wilson Freshwater processing algae specimens in the lab aboard NOAA ship NANCY FOSTER.
NOAA scientist Dr. Roldan Muñoz counting cryptic fish collected.
NOAA scientist Dr. Roldan Muñoz counting cryptic fish collected.
Hard Bottom habitat with lionfish invader.
Hard Bottom habitat with lionfish invader.

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