Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

This dataset is part of a larger collaborative study called BIOSWOT-Med in the Northwestern Mediterranean Sea. The Scripps Zooglider was deployed in collaboration with a French-led team aboard the R/V L'Atalante from March to May 2023.

Data from the Zooglider mission include: CTD, Zonar, Particle counts from Zoocam images and Zooglider dive record data (see related datasets).

Data were acquired in 351 Zooglider dive profiles in the Northwestern Mediterranean, usually from approximately 420 m depth to the sea surface.  These dives are numbered 1-314 and 353-389.  The intervening numbers (315-353) refer to time periods when the Zooglider was in transit onboard R/V L’Atalante, during which time no in situ data were acquired.  CTD and Chl-a fluorometer data were recorded on all dives when Zooglider was immersed.   Zonar data were not acquired on odd-numbered dives from 47-241 (inclusive).  Zoocam (shadowgraph imaging) data were acquired on a total of 115 dives (dives 1-8, 245-314, and 353-389).  The Zoocam was powered off during intervening dives in order to conserve memory storage.

Zooglider was moving at approximately 15 cm s-1 horizontally and 10 cm s-1 vertically while sampling, at an average angle of 16-18° off the horizontal.  All sampling was done only on the Zooglider ascents.  During descents, ultraviolet LEDs were powered intermittently and wipers activated to remove any biofouling materials on the optical surfaces.

Zonar sampling was conducted by collecting a four-ping burst ensemble every 4 m on ascent. These data were averaged into 1 m vertical depth bins.  For the present study, volume backscatter was analyzed in range bins from 3-6 m from the transducer, corresponding to an ensonified volume of 1.98 m3 at 200 kHz and 0.33 m3 at 1 MHz.  NaN values indicate no volume backscatter was recorded.

Sampling details may be found in Ohman et al. (2019). The parallel BIOSWOT-Med sampling program aboard the French research vessel L’Atalante, including other autonomous instruments is described in Doglioli and Gérald. (2023) (see related publications). 

Volume backscatter (Sv) at two frequencies (1000 and 200 kHz) was calculated using the sonar equation as described in Gastauer et al. (2022).  Sv was averaged in 1 m vertical depth bins as described in Ohman et al. (2019, supplementary material).

* NA values converted to blanks
* Converted date to ISO format (yyyymmdd -> yyyy-mm-dd)
* Converted time to ISO format (hhmmss -> hh:mm:ss)
* Created an ISO_DateTime_UTC column from the original, separate date and time columns (the original two date and time columns have been removed from the data file
* Added ISO_DateTime_UTC column to dataset

NSF Award Abstract:
Ocean fronts are regions of sharp horizontal discontinuities that can alter phytoplankton growth rates and community composition, zooplankton distributions and grazing activity, and predator foraging success. This study is using Zooglider, an autonomous ocean sampler equipped with a range of sensors and capitalizing on a unique opportunity to investigate frontal gradients and plankton communities in the western Mediterranean Sea. It is timed to coincide with a rapid crossover phase of a new NASA satellite mission. The combination of satellite and field-collected data will provide high resolution of the bio-physical consequences of oceanic frontal processes. The project incorporates training for graduate and undergraduate students as well as public outreach. Results are broadly communicated by partnering with a major public aquarium that serves 450,000 visitors per year, including by exhibiting novel porcelain ‘Zooware’ meant to convey the sensory experience of exploring the ocean’s planktonic fauna.

This project focuses on advancing understanding of frontal processes in the western Mediterranean Sea, at a ‘crossover’ site where NASA’s new Surface Water Ocean Topography (SWOT) satellite is making high-frequency sea surface height measurements using a high-resolution sensor. Measurements from the SWOT satellite are resolving small changes in sea-surface height, making it possible to follow the development and temporal progression of ocean frontal systems. The investigator is assessing the consequences of these frontal systems by testing the hypotheses that 1) zooplankton, marine snow particles, and predators are altered in these ocean frontal regions with a size-dependent or trait-dependent response; 2) particle-grazing zooplankton are more closely associated with layers of marine snow than with layers of living phytoplankton; 3) vertical thin layers of zooplankton are more likely to form in frontal than non-frontal regions; and 4) higher predators such as zooplanktivorous fish and marine mammals are more detectable in frontal regions The project makes use of an autonomous ocean instrument, the Zooglider. It includes a shadowgraph imaging Zoocam for resolving zooplankton and marine snow; a dual frequency Zonar to resolve mesozooplankton and larger sources of acoustic backscatter; and a sensitive hydrophone for recording ambient sounds, especially from marine mammals and fishes. These autonomous measurements are coordinated with complementary measurements from a ship-based sampling program, other autonomous vehicles, and satellite remote sensing.