|Roman, Michael R.||University of Maryland Center for Environmental Science (UMCES/HPL)||Principal Investigator|
|Pierson, James J.||University of Maryland Center for Environmental Science (UMCES/HPL)||Co-Principal Investigator, Contact|
|Fitzgerald, Catherine||University of Maryland Center for Environmental Science (UMCES/HPL)||Contact|
|Ake, Hannah||Woods Hole Oceanographic Institution (WHOI BCO-DMO)||BCO-DMO Data Manager|
Species composition via MOCNESS and associated CTD information
This abundance data was obtained from two week-long cruises (1301 in August and 1302 in September) during which MOCNESS samples were taken from the mid-bay of the Chesapeake from 9 stations in a box formation; 3 stations in a northern transect across the bay (N1-N3), 3 in a midline transect (M1-M3), and 3 in a southern transect (S1-S3).
The MOCNESS had a 0.5 meter square opening for each of 5 nets, which were 200um mesh. It was deployed from the aft A-frame of the RV Sharp, along with an array of sensors connected to the MOCNESS frame, including Sea-Bird temperature, salinity, and dissolved oxygen (SBE 43) sensors, a WetLabs FLNTU to measure chlorophyll a fluorescence and turbidity, and a LiCor 4π PAR sensor.
A CTD cast was done at each station prior to sampling with the MOCNESS. Sampling depths were determined based on the location of the pycnocline; the aim was to capture zooplankton below, within, and above the pycnocline. A drogue net (net 0) without a codend was used to deploy the MOCNESS to within 3m of the bottom. On the upcast, nets were triggered to close electronically from the wet lab so that they captured a depth range representing one of the three areas of interest.
Once brought on board, the nets were rinsed down with filtered seawater (provided by the Hugh R. Sharp) to collect plankton in the codend. Codends were filtered onto 64um sieves, then the samples were transferred to glass jars labeled on the inside and outside with the cast number, date, time, net number, and depth sampled. Sieves with 64um mesh were selected to catch all life stages of the copepod Acartia tonsa since Acartia tonsa eggs are about 75um in diameter and all subsequent life stages are larger. Buffered formalin was added to preserve the sample in a 4% solution, and then the jars were stores in labeled boxes.
After returning from the cruises, samples were stored indoors in climate-controlled laboratory space. To process the samples, the contents of the jars were filtered onto 64um mesh (to avoid loss of organisms), resuspended, and a subsample taken with a stemple pipette was transferred to a counting wheel where it was checked for density and diluted if necessary, the goal being at least 200 individuals of Acartia tonsa present but less than 300.
The sample was then examined for species composition under dissecting microscope with darkfield illumination. All organisms were identified to lowest possible taxonomic level. When species composition analysis was complete, the processed aliquot was photographed for size measurements and stored in 4% buffered formalin solution in a glass vial. The unused portion of the sample was returned to the original glass jar and returned to storage.
Abundance data were entered into Excel spreadsheets and checked for transcription errors, then imported into MatLab for data analysis.
MOCNESS electronic data was post processed using a series of MATLAB scripts to read the raw and processed data, and to calculate summary statistics for each net. These are usually generated from the MOCNESS software in a “.TAB” file for each cruise, but the MOCNESS program does not use the incoming GPS data for calculation of time and instead used computer time. The MOCNESS scripts calculate time and location using GPS and also include the time from the computer.
Zooplankton samples were sorted under a stereo dissecting microscope within two years of collection. Sub samples were taken with a stempel pipet such that a minimum of 200 individuals were counted from each sample. Zooplankton were identified to lowest possible taxonomic level, to species where possible for copepods, and copepod adults were sexed.
BCO-DMO Data Processing Notes:
- replaced blank cells with nd
- reformatted column names to comply with BCO-DMO standards
- reformated dates to YYYY/MM/DD
|cruise||Designation cruise 1301 or 1302; a week-long plankton survey in August and September respectively.||unitless|
|MOC||Number ID of each MOCNESS cast as recorded by the MOCNESS software||unitless|
|NET||Number ID of each net used during a MOCNESS cast as recorded by the MOCNESS software||unitless|
|year||Year as recorded by the MOCNESS software; YYYY||unitless|
|month_GMT||GMT month as recorded by MOCNESS software; MM||unitless|
|day_GMT||GMT day as recorded by MOCNESS software; DD||unitless|
|DOY_day_GMT||Numeric day of year calculated from year, month, and day as recorded by MOCNESS software||decimal day|
|hour_GMT||GMT hour as recorded by MOCNESS software||hours|
|minute_GMT||GMT minute as recorded by MOCNESS software||minutes|
|second_GMT||GMT second as recorded by MOCNESS software||seconds|
|DOY_GMT||Day of year calculation using MOCNESS recorded GMT time||decimal day|
|lat||Average latitude traveled during collection for each net||decimal degrees|
|lon||Average longitude traveled during collection for each net||decimal degrees|
|vol||Volume filtered by each net during each cast, as recorded by MOCNESS software||cubic meters|
|temp||Water temperature recorded by MOCNESS sensors during each cast||degrees Celsius|
|salt||Salinity recorded by MOCNESS sensors during each cast||Practical Salinity Units (PSU)|
|Ox||Oxygen level recorded by MOCNESS sensors during each cast||milligrams per liter|
|fluor||Fluorescence recorded by MOCNESS sensors during each cast||milligrams per meter cubed|
|turb||Turbidity recorded by MOCNESS sensors during each cast||Nephelometric Turbidity Units (NTU)|
|PAR||Photosynthetically active radiation recorded by MOCNESS sensors during each cast||Watts/meters squared|
|startLat||Latitude at the time the net opened||decimal degrees|
|endLat||Latitude at the time the same net closed||decimal degrees|
|startLon||Longitude at the time the net opened||decimal degrees|
|endLon||Longitude at the time the net closed||decimal degrees|
|upDepth||Upper limit of depth traversed while the net was open||meters|
|lowDepth1||Lower limit of the depth traversed while the net was open||meters|
|angle||The angle of the tow line for the MOCNESS, with vertical being 0 and horizontal being 90||degrees|
|distance||Horizontal distance the ship traveled while the net was open||meters|
|openArea||The open area of the net face- calculated from the size of the net opening when held vertically and the angle of the tow line||meters squared|
|idx||Unique numeric ID for each row of data||unitless|
|cruise2||Designation cruise 1301 or 1302; a week-long plankton survey in August and September respectively||unitless|
|date_EDT||Gergorian claendar date as recorded in the cruise log; YYYY/MM/DD||unitless|
|station||Station ID as recorded in the cruise log||unitless|
|time_EDT||Time in EDT as recorded in the cruise log; HH:MM||unitless|
|DOY_EDT||Day of year calculation using cruise log EDT time||decimal day|
|gear||Description of collection gear used. For this data set, only the MOCNESS was used||unitless|
|mesh_size||Size of pores in mesh of MOCENSS nets||microns|
|cast_num||Number ID of each MOCNESS cast as recorded in cruise log||unitless|
|net||Number ID of each net used during a MOCNESS cast as recorded in cruise log||unitless|
|lowDepth2||Lower limit of the depth traversed by a single net as recorded in cruise log||meters|
|high_depth||Upper limit of the depth traversed by a single net as recorded in cruise log||meters|
|splits||Number of times the sample gathered by the specific cast and net was split into two equal portions via plankton splitter||count|
|dilution||Amount of water added to sample to reach the desired concentration of >= 200 Acartia/subsample||milliliters|
|subsample_size||Amount of sample (in diluted state, if applicable) examined for species composition||milliliters|
|genus||Genus or least specific identifier of organism in sample||unitless|
|species||Species or most specific identifier of organism in sample||unitless|
|stage||Life stage of organism in sample||unitless|
|count||Total number of organism found in subsample||number of organism/subsample|
|num_per_m3||Concentration of organism per cubic meter calculated from dilutions, splits, and Volume_Filtered data||number of organism/cubic meter|
|volume_filtered||Volume filtered by each net during each cast, as recorded by MOCNESS software, augmented by record in operator log where necessary||cubic meters|
|abundM3||Concentration of organism per cubic meter calculated from dilutions, splits, and Vol data||number of organism/cubic meter|
|abundM2||Abundance of organism per meter squared calculated from AbundM3 and total depth traversed by net||number of organism/ meter squared|
|CTD_number||Number ID of each CTD cast corresponding to each MOCNESS tow||unitless|
|CTD_DOY_GMT||Numeric day of year calculated from year, month, and day as recorded by CTD||decimal day|
|CTD_temperature||Water temperature recorded by CTD sensors during each cast; binned into 0.5m depths and then averaged over the depth range of the MOCNESS net||degrees Celsius|
|CTD_salinity||Salinity recorded by CTD sensors during each cast; binned into 0.5m depths and then averaged over the depth range of the MOCNESS net||PSU|
|CTD_sigma_t||Density recorded by CTD sensors during each cast; binned into 0.5m depths and then averaged over the depth range of the MOCNESS net||milligrams per liter|
|CTD_Ox__mgperL||Dissolved oxygen recorded by CTD sensors during each cast; binned into 0.5m depths and then averaged over the depth range of the MOCNESS net||milligrams per liter|
|CTD_fluorescence||Fluorescence recorded by CTD sensors during each cast; binned into 0.5m depths and then averaged over the depth range of the MOCNESS net||milligrams per meter cubed|
|CTD_depth||Depth recorded by CTD sensors during each cast; binned into 0.5m depths and then averaged over the depth range of the MOCNESS net||meters|
|comments||Comments from sample counter regarding sample processing||unitless|
|Dataset-specific Instrument Name|| |
|Generic Instrument Name|| |
|Dataset-specific Description|| |
Used for water sampling
|Generic Instrument Description|| |
The CTD part of the MOCNESS includes 1) a pressure (depth) sensor which is a thermally isolated titanium strain gauge with a standard range of 0-5000 decibars full scale, 2) A Sea Bird temperature sensor whose frequency output is measured and sent to the surface for logging and conversion to temperature by the software in the MOCNESS computer (The system allows better than 1 milli-degree resolution at 10 Hz sampling rate), and 3) A Sea Bird conductivity sensor whose output frequency is measured and sent to the surface for logging and conversion to conductivity by the software in the computer (The system allows better than 1 micro mho/cm at 10 Hz sampling rate). The data rate depends on the speed of the computer and the quality of the cable. With a good cable, the system can operate at 2400 baud, sampling all variables at 2 times per second. One sample every 4 seconds is the default, although the hardware can operate much faster. (From The MOCNESS Manual)
R/V Hugh R. Sharp
|Start Date|| |
|End Date|| |
R/V Hugh R Sharp 1316. Mid-bay of Chesapeake Bay, 38°N 76°W.
R/V Hugh R. Sharp
|Start Date|| |
|End Date|| |
R/V Hugh R Sharp 1317. Mid-bay of Chesapeake Bay, 38°N 76°W.
Description from NSF award abstract:
The PIs will develop a mechanistic understanding of how circulation interacts with hypoxia-induced behavioral and physiological changes to affect the population dynamics of coastal zooplankton. They will do this by assessing two potentially contrasting mechanisms influencing the dynamics of the copepod Acartia tonsa in the hypoxic zone of Chesapeake Bay. The first hypothesis is that maintenance of copepod populations in the hypoxic region requires replenishment by advection (immigration) of animals through wind-driven lateral transport processes. The second, counteractive, hypothesis is that bottom water hypoxia alters the vertical distribution of A. tonsa, thereby making them more susceptible to advective losses from the region (emigration) via surface water transport in the estuarine circulation. They will take advantage of a current NSF-funded physical oceanography research program in Chesapeake Bay that will comprehensively measure and model axial and lateral water exchanges in the mid-Bay region.
The present study will use the physical oceanography study site as a Controlled Volume (CV) in which the oceanographic exchanges of water and the driving mechanisms for those exchanges will be well defined. The PIs will conduct high-resolution spatial and temporal sampling of zooplankton and combine the data with measurements of copepod behavior, mortality and egg production in the hypoxic region. They will use an improved Individual-Based Model of the life history of A. tonsa coupled with the circulation to explore the combined effects of advection, behavior, egg production, and mortality on population dynamics. In addition to increasing our knowledge of the impacts of bottom water hypoxia on copepod populations in Chesapeake Bay, the study will improve our general understanding of the regulation of zooplankton populations by physical and biological processes and the impacts of hypoxia on secondary production and food webs in coastal waters.