USGS Field Activities 11BHM01 and 11BHM02 on the West Florida Shelf, Gulf of Mexico, in May and June 2011
By Lisa L. Robbins,1 Paul O. Knorr,1 Kendra Daly,2 Carl Taylor,3 and Kira E. Barrera1
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Project Summary
As part of the USGS Climate Change project “Monitoring and modeling of 
Florida Shelf carbonate saturation state and calcification rates: setting 
a baseline for response of ocean acidification on marine habitats” and the USGS 
Coastal and Marine Geology Program project "Response of Florida Shelf 
Ecosystems to Climate Change" (PI: Dr. Lisa Robbins), data on surface 
seawater (SW) carbonate chemistry were collected along transects on the shallow 
inner west Florida shelf. The data collected will allow the USGS, National Oceanic Atmoshperic Administration, 
and USF to map variations in ocean chemistry including carbonate 
saturation states along designated tracks. The USGS is also partnering 
with NOAA and the National Aeronautics and Space Administration for the modeling of saturation state data.

During May and June 2011 the (USGS), in cooperation with (USF), conducted geochemical surveys on the west Florida Shelf to investigate the effects of climate change on ocean acidification within the northern Gulf of Mexico, specifically, the effect of ocean acidification on marine organisms and habitats. The first cruise was conducted from May 3 to 9 (11BHM01) and the second was from June 25 to 30 (11BHM02). To view each cruise's survey lines, please see the Trackline page. Each cruise took place aboard the Research Vessel (R/V) Weatherbird II, a ship of opportunity led by Dr. Kendra Daly (USF), which departed from and returned to Saint Petersburg, Florida.

Data collection included sampling of the surface and water column with lab analysis of pH, dissolved inorganic carbon (DIC) or total carbon dioxide (TCO2), and total alkalinity (TA). lLb analysis was augmented with a continuous flow-through system (referred to as sonde data) with a conductivity-temperature-depth (CTD) sensor, which also recorded salinity and pH. Corroborating the USGS data are the vertical CTD profiles (referred to as station samples) collected by USF. The CTD casts measured continuous vertical profiles of oxygen, chlorophyll fluorescence and optical backscatter. Discrete samples for nutrients, chlorophyll, and particulate organic carbon/nitrogen were also collected during the CTD casts. Two autonomous flow-through (AFT) instruments recorded pH and CO2 every 3-5 minutes on each cruise (referred to as AFT data).