Dataset: SR2114 Fish larvae abundances

Name: Fish larvae abundances across the Eastern Tropical North Pacific Oxygen Minimum Zone determined from MOCNESS sampling conducted on R/V Sally Ride cruise SR2114 from December 2021 to January 2022
Published: 2024-09-25
Keywords: fish larvae, myctophidae, oxygen minimum zone, oceans

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Spatial Extent: N:11.14 E:-93.98 S:8.587 W:-102.43

Eastern Tropical North Pacific

Temporal Extent: 2021-12-26 - 2022-01-17

Project:

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

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)

Version:

Version Date:

2024-09-25

Restricted:

Validated:

Current State:

Data not available

Fish larvae abundances across the Eastern Tropical North Pacific Oxygen Minimum Zone determined from MOCNESS sampling conducted on R/V Sally Ride cruise SR2114 from December 2021 to January 2022

Abstract:

This dataset includes the environmental variables and the abundance of fish larvae by species and by develoment stage from eight MOCNESS samples taken during the SR2114 expedition to the Eastern Tropical North Pacific Oxygen Minimum Zone (OMZ), onboard the R/V Sally Ride from December 2021 to January 2022. The MOCNESS tows were performed at locations of particular biological interest, such as the CRTD (M1), San Jose submarine canyon (M2), the center (M3, M5) and borders (M4, M6) of two anticyclonic eddies (abbreviated ACE-1 and ACE-2), and across the northern portion of the OMZ (M7 and M8). The MOCNESS tows were performed at 1.5-2 knots net speed and at 40-50° net angle. A horizontal net tow strategy was followed. Fish larvae and juveniles were separated and counted under a stereoscope. 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). Larval abundances were standardized and were considered absolute abundances. Adult abundances were standardized and are considered relative.

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Methods & Sampling

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.

Problems/Issues

Abrupt vertical oxygen gradients and the lagged depth control of the MOCNESS tow caused DO values to be less than half or more than double the desired values in 7 out of 40 nets (M1-Oxic, M1-Hypoxic, M6-Hypoxic, M3-Suboxic, M6-Suboxic, M7-Suboxic, and M8-Anoxic).

Data 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.

BCO-DMO Processing

- Imported original file "SR2114_FishLarvae__dev stages.xlsx" into the BCO-DMO system.

- Loaded sheets containing the standard data (sheet numbers 2,4,7,9,11,13) (named with "std"; omitted the combined pre+flex sheet as instructed by the data submitter).

- Concatenated all sheets into one dataset.

- Renamed fields to comply with BCO-DMO naming conventions.

- Converted Date column to YYYY-MM-DD format.

- Replaced the following in the Gpo_Dom column to remove special characters:
-- Copépodos with Copepods
-- Anfípodos with Amphipods
-- Eufáusidos with Euphausiids

-Renamed the following species names that contained typos, identified using WoRMS taxa match tool:
-- Acanthocybium solandrii changed to Acanthocybium solandri
-- Ceratoscopelus townsendii changed to Ceratoscopelus townsendi
-- Citarichthys platophrys changed to Citharichthys platophrys
-- Evermanella ahlstromi changed to Evermannella ahlstromi
-- Lampadaena urophaos changed to Lampadena urophaos
-- Lepidocybium flavobrunnei changed to Lepidocybium flavobrunneum
-- Muraenida sp2 changed to Muraenidae sp2
-- Ophichthus cf zophochyr changed to Ophichthus cf zophochir
-- Unnamed column "zzz" changed to Myctophidae
-- Ophichthus sp1 (zophochir?) changed to to Ophichthus cf zophochir
-- Scopelogados buspinnosus changed to Scopelogadus bispinosus
-- Scopelogadus buspinosus changed to Scopelogadus bispinosus

- Saved the final file as "930172_v1_s2r114_fish_larvae_abundances.csv".

More Information about this dataset

Funding Sources

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

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
SR2114		2021-12-23	R/V Sally Ride	Mark A. Altabet (Chief Scientist)	data info

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

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Dataset: SR2114 Fish larvae abundances