Our 10th DEEPEND cruise, 10 years after the program began

The DP10 science team during the pre-cruise safety briefing. Photo from H. Judkins.

We are just back from our 10th research cruise of the DEEPEND and DEEPEND|RESTORE research programs aboard the R/V Point Sur. The DEEPEND program (2015 - 2019) followed an extensive NOAA NRDA survey in 2011 (the Offshore Nekton Sampling and Analysis Program; ONSAP) and was originally established in 2015 to examine the trends and drivers of oceanic and deep-living micronekton (animals c. 2 - 20cm in length). DEEPEND|RESTORE (2019 - 2024) and DEEPEND|RESTORE II (2024 - 2029) extends that work with NOAA RESTORE funding, and brings a new focus towards integrating our science with management applications for the offshore space. We are currently a 47-member, 11-institution research program, with focus on myriad research topics from taxonomic and biodiversity studies, species distribution analyses, genomic analyses, to acoustic surveys and more. At the Seascape Ecology lab at NSU, we play a central role in conducting and integrating the faunal analyses across the consortium and developing research products with management applicability. We have several new papers in the works on these topics, so stay tuned for updates!

The DEEPEND team sorting one of our net catches

Sorting the DEEPEND catch

A viperfish (Chauliodus sloani): this predatory fish is a common occurrence in our deep catches.

This last cruise continues our time-series work in the offshore Gulf (beyond the 1000 m isobath) using the 10-m2 Multiple Opening-Closing Net and Environmental Sensing System (MOCNESS) that has become the workhorse of our program. Using these nets, we can capture micronektonic animals from specific, known depth ranges, to examine their vertical distribution patterns and examine changes in biodiversity and composition, abundances, and biomass patterns across the northern Gulf and through time. This ability to capture animals from known depths is especially important since so many of the species we study conduct Diel Vertical Migration (DVM), which means that they spend the daylight hours in the relative darkness of the mesopelagic zone (or twilight zone; usually defined as 200 - 1000 m depth) where they can hide from surface-dwelling visual predators, and then migrate upwards to the epipelagic zone (usually defined as 0 - 200 m depth) to feed in the food-rich upper waters under the cover of darkness. This typical pattern is surprisingly variable, with individual migration patterns varying by species, the age (size) of the animal, and local abiotic conditions. Disentangling the different patterns of DVM is a major part of our current research since these patterns will affect the vertical distributions of the animals (i.e., what depths they inhabit), and in turn influence the ecological services they provide within open ocean ecosystems and the extent to which they create connections with other ecosystem types (e.g., at the seafloor and ocean surface, and even with coastal and terrestrial ecosystems, depending on who eats them and where).

Echogram showing DVM of the deep-scattering layer. Image from: https://oceanexplorer.noaa.gov/facts/vertical-migration.html

Every research cruise we conduct provides new insight into the status of the offshore Gulf fauna, and brings us another step closer to understanding the offshore ecosystems and their variability, patterns of connectivity, and potential vulnerability to current and future human impacts - all of which helps us develop strategies to inform current and future management of the oceanic Gulf ecosystems. We've learned an enormous amount in the past ten years of DEEPEND, and built a globally unmatched dataset of oceanic micronekton. Here's hoping for another 10 years of this!

For more cruise blogs from this latest cruise, check out the official DEEPEND|RESTORE cruise blog.