Dataset: SR2114 Fish larvae abundances
Deployment: SR2114

SR2114 Fish larvae abundances by development stages

View Data: For data, See Dataset Metadata Page: https://osprey.bco-dmo.org/dataset/930172

Principal Investigator:

Juan Gerardo Gutiérrez-Bravo (University of Massachusetts Dartmouth SMAST, UMASSD-SMAST)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

Collaborative Research: Multiyear autonomous measurement of N-loss in the ETNP ODZ (N-loss in the ETNP ODZ)

Version:

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Description

Methods & Sampling

Dataset acquisition description

Data were collected on R/V Sally Ride cruise SR2114 in the Eastern Tropical North Pacific from December 2021 to January 2022.

The MOCNESS was equipped with 10 nets of 1 square meter (m^2) mouth opening and 333 micrometer (µm) mesh size, a SeaBird SBE9+ CTD, a SeaBird SBE 43 dissolved oxygen (DO) sensor, and flow meter and angle sensors. The MOCNESS tows were performed at 1.5-2 knots net speed and at a 40-50° net angle. A horizontal net tow strategy was followed to sample selected DO concentrations (oxypleths) in five sampling levels: 1) the oxic level (~200 micromoles per kilogram (μmol/kg), near surface), 2) the hypoxic (~100 μmol/kg) and 3) suboxic (~10 μmol/kg) levels in the upper core boundary, 4) the anoxic core level (<1 μmol/kg, at the center of the anoxic core), and 5) the deep level (~10 μmol/kg in the lower boundary below the anoxic core). The remaining 5 MONCESS nets were opened during transitions between target depths and were not used for this study. This horizontal sampling protocol allows for discrete, punctual sampling events, but cannot provide continuous, vertically-integrated abundances as oblique tows would (Wiebe et al. 2015).

Fish larvae and juveniles were separated and counted under a stereoscope using metal tweezers. Fish larvae were identified to the most specific taxonomic level possible using a specialized bibliography. The larval stages (preflexion, flexion, postflexion, and transformation) were defined according to Moser (1996). Preflexion and flexion larvae were considered "early larval stages" as they both lack fully-developed fins. Larval abundances were standardized to larvae per 1000 cubic meters and were considered absolute abundances. Juveniles and adults were separated, counted, and identified to family level, except for the Gonostomatidae, that were represented entirely by the genus Cyclothone. Adult abundances were standardized to fish per 1000 cubic meters. Because the increased swimming ability of adult fish could affect fishing efficiency, abundances were considered relative, and should not be compared with the absolute abundances of fish larvae.

Data Processing Description

Dataset Processing Description

Using manufacturer software (SBE Data Processing), CTD data were filtered and aligned. CTD-rosette data were binned to 1 meter depth and MOCNESS data were binned to 10 seconds. Conservative Temperature and Absolute Salinity were calculated. CTD-rosette data were used to construct hydrographic sections, while MOCNESS sensor data was used to describe the environmental conditions of zooplankton samples.

Zooplankton biovolume was measured by the displacement method (Steedman 1976) and standardized to milliliters per 1000 cubic meters (mL/1000 m^3) by dividing the zooplankton displacement volume (mL) by the volume of water filtered by the net (m^3).

Larval abundances were standardized to larvae per 1000 cubic meters (larvae/1000 m^3) and were considered absolute abundances.

Adult abundances were standardized to fish per 1000 cubic meters (fish/1000 m^3). Because the increased swimming ability of adult fish could affect fishing efficiency, abundances were considered relative, and should not be compared with the absolute abundances of fish larvae.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-1851361	NSF Division of Ocean Sciences

Instruments

CTD MOCNESS

Supplied Name: MOCNESS, SeaBird SBE9+ CTD

Supplied Description:

The MOCNESS was equipped with 10 nets of 1 m^2 mouth opening and 333 µm mesh size, a SeaBird SBE9+ CTD, a SeaBird SBE 43 DO sensor, and flow meter and angle sensors.

Instrument Type

Generic Name: CTD MOCNESS

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/131/

Generic 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)

Flow Meter

Supplied Name: flow meter

Supplied Description:

Instrument Type

Generic Name: Flow Meter

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/388/

Generic Description:

General term for a sensor that quantifies the rate at which fluids (e.g. water or air) pass through sensor packages, instruments, or sampling devices. A flow meter may be mechanical, optical, electromagnetic, etc.

Manual Biota Sampler

Supplied Name: metal tweezers

Supplied Description:

Instrument Type

Generic Name: Manual Biota Sampler

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/90/

Generic Description:

"Manual Biota Sampler" indicates that a sample was collected in situ by a person, possibly using a hand-held collection device such as a jar, a net, or their hands. This term could also refer to a simple tool like a hammer, saw, or other hand-held tool.

Microscope - Optical

Supplied Name: stereoscopic microscope

Supplied Description:

Instrument Type

Generic Name: Microscope - Optical

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB05/

Generic Description:

Instruments that generate enlarged images of samples using the phenomena of reflection and absorption of visible light. Includes conventional and inverted instruments. Also called a "light microscope".

Sea-Bird SBE 43 Dissolved Oxygen Sensor

Supplied Name: SeaBird SBE 43 DO sensor

Supplied Description:

Instrument Type

Generic Name: Sea-Bird SBE 43 Dissolved Oxygen Sensor

Acronym: SBE-43 DO

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0036/

Generic Description:

The Sea-Bird SBE 43 dissolved oxygen sensor is a redesign of the Clark polarographic membrane type of dissolved oxygen sensors. more information from Sea-Bird Electronics

Parameters

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Database

Contribute Data

Dataset: SR2114 Fish larvae abundances
Deployment: SR2114

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: SR2114 Fish larvae abundancesDeployment: SR2114

Dataset acquisition description

Dataset Processing Description

Dataset: SR2114 Fish larvae abundances
Deployment: SR2114