Abstract:

This dataset contains seasonal and interannual discrete chlorophyll data collected from the northeastern Gulf of Mexico and the west Florida shelf. The contents of the dataset are an assessment of the seasonal and interannual changes in distributions of chlorophyll after the Deepwater Horizon oil spill.

Suggested Citation:

Daly, Kendra. 2016. Discrete chlorophyll data for the northeastern Gulf of Mexico and west Florida shelf: June 2012 – August 2014. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7M043B7

Publications:

Daly, K. L., Remsen, A., Outram, D. M., Broadbent, H., Kramer, K., & Dubickas, K. (2021). Resilience of the zooplankton community in the northeast Gulf of Mexico during and after the Deepwater Horizon oil spill. Marine Pollution Bulletin, 163, 111882. doi:10.1016/j.marpolbul.2020.111882

Quigg, A., Parsons, M., Bargu, S., Ozhan, K., Daly, K. L., Chakraborty, S., … Buskey, E. J. (2021). Marine phytoplankton responses to oil and dispersant exposures: Knowledge gained since the Deepwater Horizon oil spill. Marine Pollution Bulletin, 164, 112074. doi:10.1016/j.marpolbul.2021.112074

Purpose:

To assess the seasonal and interannual changes in distributions of chlorophyll after the Deepwater Horizon oil spill.

Data Parameters and Units:

Average (Avg) and standard deviation (std dev) of chlorophyll and phaeopigment concentrations (µg/L) and phaeopigment/chlorophyll ratios. Chlorophyll and phaeopigment size fractions (>3 µm and whole minus >3 µm) are provided for some cruises. Date (local and GMT), Time (local and GMT), Latitude (N), Longitude (W), station, depth (m).

Methods:

Environmental data were collected aboard the R/V Weatherbird II and the R/V Bellows. A CTD-rosette was deployed between the surface (2 m) and up to a maximum depth ranging from 5 m to about 1,450 m, depending on the bottom depth of the station. On the downcast, the depths of the fluorescence maxima, top of the thermocline, base of the thermocline, and other features of interest were noted on the CTD log sheet. Niskin bottles were fired at these depths and other pre-determined depths on the upcast. Water samples were collected during more than one CTD cast at some stations where water demand was high or the depth was >200 m. The Weatherbird II rosette held 12-12 L Niskin bottles, and the Bellows rosette held 12-5 L Niskin bottles. Chlorophyll: Chlorophyll samples were collected in 2 L amber bottles using tygon tubing without mesh for depths between 2 to 500 m. Gloves were worn for sample collection and bottles and caps rinsed three times before sample collection. The sample bottles were immediately processed after collection. The collection bottle was gently swirled and 500 mL to 2 L was filtered under low vacuum onto a 25 mm GF/F filter. The filter was then placed in a foil packet and labeled, and frozen at -20 C. Some field samples were size-fractionated. In the lab, the filter was placed in a 13 x 100 mm borosilicate tube and then 7 mL of 90% acetone was added. The tube was covered with parafilm and placed in a dark box in a -20 C freezer for 24 hours. After the 24 hr extraction, samples were allowed to come to room temperature (10-15 min) in the dark. Chlorophyll a concentrations were determined using a Turner fluorometer 10-A before and after acidification following the methods described in Holm-Hansen et al. (1965). The fluorometer was calibrated every six months using a Sigma-Aldrich chlorophyll a standard. Reference: Holm-Hansen, O., C.J. Lorenzen, R.W. Holmes, and J.D. Strickland. 1965. Fluorometric determination of chlorophyll. J. Cons. Cons. Int. Explor. Mer 30: 3-15. Chlorophyll data are provided in excel files, with each cruise in a separate excel file. Files are named by cruise/date, where BE: RV Bellows; WB: RV Weatherbird II.

Individual Files: