Vertical Distribution Patterns of Cephalopods in the Northern Gulf of Mexico

Heather Judkins,Michael Vecchione

doi:10.3389/fmars.2020.00047

Abstract

Cephalopods are important in midwater ecosystems of the Gulf of Mexico (GOM) as both predator and prey. Vertical distribution and migration patterns (both diel and ontogenic) are not known for the majority of deep-water cephalopods. These varying patterns are of interest as they have the potential to contribute to the movement of large amounts of nutrients and contaminants through the water column during diel migrations. This can be of particular importance if the migration traverses a discrete layer with particular properties, as happened with the deep-water oil plume located between 1000-1400 m during the Deepwater Horizon oil spill. Two recent studies focusing on the deep water column of the GOM (2011 Offshore Nekton Sampling and Analysis Program (ONSAP) and 2015-2018 Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND) program, produced a combined dataset of over 12,500 midwater-cephalopod records for the northern GOM region. We summarize vertical distribution patterns of cephalopods from the cruises that utilized a 10 m2 Multiple Opening/Closing Net and Environmental Sensing System (MOC10). About 95% of the cephalopods analyzed here either move through or live within 1000-1400 m zone. Species accounts include those with synchronous (e.g. Pterygioteuthis sp.) and asynchronous (e.g. Stigmatoteuthis arcturi) vertical migration. Non-migration patterns of some midwater cephalopods (e.g. Vampyroteuthis infernalis) are also highlighted. Ontogenic shifts are noted for some species examined.

Highlights

The Deepwater Horizon (DWH) oil spill generated one of the largest oil spill responses to date, including millions of dollars allocated to scientific research to examine the impacts of this devastating event (i.e., Gulf of Mexico Research Initiative, NAS Gulf Research Program)
In light of the need to know which cephalopods may have been exposed to the deep oil plume, as well as a need for comprehensive accounts on deep-sea species, this study reports on 39 cephalopod species from the northern Gulf of Mexico (GOM), examining the following questions: (1) How many species move through or are found within the deep oil plume located between 1000 and 1400 m? (2) What are the vertical distribution patterns of deep-sea cephalopods in water column of the northern GOM and how does this relate to past accounts of these species? (3) Are there developmental shifts in vertical distribution of these cephalopods?
Cephalopods are widely distributed throughout the water column down to 1500 m with the mesopelagic zone containing the largest number of individuals

Summary

Introduction

The Deepwater Horizon (DWH) oil spill generated one of the largest oil spill responses to date, including millions of dollars allocated to scientific research to examine the impacts of this devastating event (i.e., Gulf of Mexico Research Initiative, NAS Gulf Research Program). Passow and Hetland (2016) determined that a deep plume of trapped oil formed between 1000 and 1400 m depth (Socolofsky et al, 2011) due to the petrocarbons that became neutrally buoyant in seawater at that depth This contaminated layer dispersed from the site via subsurface. The Offshore Nekton Sampling and Analysis Program (ONSAP) and the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND) consortium have compiled an immense dataset for midwater fauna over a period of 8 years (2011–2018) examining biodiversity and contaminant questions about multiple deepwater pelagic faunal groups (Judkins et al, 2016; Burdett et al, 2017; Richards et al, 2018; Romero et al, 2018)

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