Abstract:

Two research cruises, one in 2012 one in 2013, were conducted to continue to monitor the microbial and planktonic communities and to assess rates of particle flux and the rates of removal of PAHs from the system via this process and accumulation of PAHs in bottom sediments. Size-fractionated chlorophyll samples were collected from full water column CDT casts and microzooplankton grazing experiment samples at various stations in the Gulf of Mexico during April 2012 and April 2013. Chlorophyll concentrations were calculated according to EPA Method 445.0. Grazing experiments were carried out according to now-standard dilution method protocols first used by Landry and Hassett (1982).

Suggested Citation:

Sutor, Malinda. 2015. Size-fractionated chlorophyll concentrations, Mississippi Canyon, Gulf of Mexico, spring 2012 and 2013.. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7H99352

Purpose:

Chlorophyll-a concentrations serve as a proxy for phytoplankton density. The change in phytoplankton density over time is used to estimate the apparent phytoplankton growth rate, and this rate at each dilution is used to calculate the bulk microzooplankton grazing rate.

Data Parameters and Units:

Year (YYYY) Sample ID (WS1206cruise, Station, CTD cast ID) Station ID (numeric) CTD cast ID (numeric) Latitude (decimal degrees) Longitude (decimal degrees) Depth (meters) Filter Size (mg m-3) Sample Date (MM/DD/YYYY) Chl S,C concentration (µg/L) Dilution (%) Initial/Final Sample Incubation Temperature (°C) Notes

Methods:

Chlorophyll concentration calculated according to EPA Method 445.0, and is expressed in micrograms of chlorophyll-a per liter. Note that values do not represent bulk chlorophyll-a concentrations. Rather, sample water was filtered through a stacked cup filtering apparatus, with water flowing first through the 20um filter cup, then through the 8um filter cup, and finally through the GFF filter cup. Microzooplankton grazing experiments carried out according to the now-standard dilution method, first used by Landry (1982). Landry, M. R. and R. P. Hassett, 1982. Estimating the grazing impact of marine micro-zooplankton. Marine Biology 67: 283-288.

Instruments:

Chlorophyll-a extracts measured with Turner Designs Model 10AU Fluorometer.

Individual Files: