Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

The MOCNESS Plankton Net was deployed over the aft to horizontally sample three discrete depth strata in the water column: (1) Under Chla maximum layer above bottom, (2) within the Chla maximum layer, (3) Above Chla maximum layer underneath the surface. Ship speed was 1.5-2.0 knots and was adjusted according to online flowmeter readings.

One net per sampled stratum was analyzed for ichthyoplankton (net # 1, 5, 7). Nets were rinsed and processed on board and samples were preserved in 200 proof Ethanol (ETOH) according to NOAA SEAMAP Operations Manual upon retrieval of nets. After 24 hours, ETOH was exchanged with fresh ETOH. Plankton samples were stored in 1000ml plastic jars until processing in the Geist Early Life History Research Laboratory at Texas A&M University Corpus Christi during 2017 and 2020. Total Zooplankton Displacement Volume was determined using a calibrated 1000ml measuring cylinder by subtracting the volume of ethanol without sample from the volume of ethanol with sample. The plankton sample was separated from ethanol using a concentrator sieve with a mesh size < than the net mesh size. Then the plankton sample was resuspended in Ethanol. Larval fish were picked under dissecting microscopes using feather steel tweezers. Every sample was looked through twice for quality check purposes.

Data Processing:
Filtered Volume was calculated automatically by MOCNESS software. Total Plankton Displacement Volume and Total Larval Fish Density was standardized per 100m³ filtered water volume.

Problems/Issues:
On the RAPID Plankton 1 cruise (PS1813), at shallow bottom depths, deployment time was shortened, which resulted in less than 3 nets available for analyses.
On the RAPID Plankton 2 cruise (PE18-18), rough weather did not allow deployment at station 1. At other shallow bottom depth stations, deployment time was shortened, which resulted in less than 3 nets available for analyses.
On the RAPID Plankton 3 cruise (PE18-21), MOCNESS was not deployed at station 1. At other shallow bottom depth stations, deployment time was shortened, which resulted in less than 3 nets available for analyses.

BCO-DMO Processing:
- concatenated separate files into one dataset;
- converted date format to YYYY-MM-DD;
- added ISO date-time fields;
- added Cruise_ID numbers.

NSF Award Abstract:
This project will examine how plankton in the northwestern Gulf of Mexico respond to large floodwater plumes generated by extreme weather events like Hurricane Harvey at time scales relevant to its development and evolution (days to months). The goal is to understand how the timing, magnitude, and constituent loads of a massive pulse of freshwater to the Louisiana-Texas shelf are: (1) driving changes in phytoplankton, zooplankton, and larval fish communities and distributions over monthly, seasonal, and annual time scales and, (2) what the consequences of those changes are to food web interactions within the plankton. The timing of Hurricane Harvey flood water disturbance coincides with the summer-fall spawning seasons for economically important Gulf of Mexico fisheries (e.g. red drum, sea trouts, snappers), raising additional questions of longer term effects of food web disruptions on recruitment. This project will train two undergraduate students and four PhD-level graduate students across three institutions, as well as support three early-career investigators. Pre- and post-floodwater plume data and samples will be shared with the broader scientific community within one year of collection to facilitate their immediate use by scientists beyond the research team. The team will give coordinated public talks at established regional science communication series and through other existing regional outreach partnerships to extend the educational scope of the project. Finally, results from this research will be incorporated in course curriculum and shared through scientific presentations and publications in peer-reviewed journals.

Record-breaking rain delivered by Hurricane Harvey to Southeast Texas in late August 2017 has resulted in a massive floodwater plume being delivered to coastal waters in the northern Gulf of Mexico (GOM). This project will investigate the short- and mid-term effects of that plume on planktonic (from pico- to ichthyoplankton) community composition and trophic interactions in that system. Building on data collected in July 2017 during a GOM Ecosystems and Carbon Cycle (GOMECC-3) cruise, and from historical datasets in the region, plankton assemblages, abundance, and food web interactions will assessed during three research cruises 2, 4, and 8 months after the event. Oceanographic data and samples will be collected and processed using standard and state of the art gear, including ZooScan, FlowCAM, flow cytometry, and next generation sequencing. Onboard micro- and mesozooplankton grazing experiments will be conducted to understand the trophodynamic interactions and relationships between different plankton groups under changing environmental conditions. Diet and growth rate analyses of larval fish will be undertaken and related to phyto- and zooplankton (i.e. prey) abundance and community composition data. Application of the same gear types and methods during the three project cruises will ensure comparability of these new data to existing samples and datasets. These post-Harvey data will be compared to immediately-preceding and long-term data collected in the area by NOAA's Southeast Area Monitoring and Assessment Program (SEAMAP), allowing for investigation of the temporal evolution of planktonic assemblages and interpretation of plankton regime shifts in seasonal, multiyear, and decadal contexts.