Physiological and ecological implications of ocean deoxygenation for vision in marine organisms

Abstract

Climate change has induced ocean deoxygenation and exacerbated eutrophication-driven hypoxia in recent decades, affecting the physiology, behaviour and ecology of marine organisms. The high oxygen demand of visual tissues and the known inhibitory effects of hypoxia on human vision raise the questions if and how ocean deoxygenation alters vision in marine organisms. This is particularly important given the rapid loss of oxygen and strong vertical gradients in oxygen concentration in many areas of the ocean. This review evaluates the potential effects of low oxygen (hypoxia) on visual function in marine animals and their implications for marine biota under current and future ocean deoxygenation based on evidence from terrestrial and a few marine organisms. Evolutionary history shows radiation of eye designs during a period of increasing ocean oxygenation. Physiological effects of hypoxia on photoreceptor function and light sensitivity, in combination with morphological changes that may occur throughout ontogeny, have the potential to alter visual behaviour and, subsequently, the ecology of marine organisms, particularly for fish, cephalopods and arthropods with 'fast' vision. Visual responses to hypoxia, including greater light requirements, offer an alternative hypothesis for observed habitat compression and shoaling vertical distributions in visual marine species subject to ocean deoxygenation, which merits further investigation.This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'.

Ocean ventilation and deoxygenation in a warming world: introduction and overview

“…The biogeochemical and ecological consequences of reduced oxygen in compressing habitats are already significant in some areas and are likely to become farreaching [15,18]. Some subtle, surprising and hitherto largely unexplored consequences on predator-prey relationships may even be expected due to impaired vision at low oxygen levels [10]. In addition, the production of biogenic greenhouse gases such as nitrous oxide (N 2 O) in oxygen minimum zones is inadequately represented in current (CMIP5) models [17] and may be climatically significant.…”

“…Levin [10] reported some Physiological and ecological implications of ocean deoxygenation for vision in marine organisms: continental margins play fundamental roles in ocean biogeochemical cycling and are increasingly valued as a source of fisheries, energy, biodiversity and potentially mineral resources. Margin settings are highly sensitive to climate-induced changes in winds, upwelling, stratification, circulation, nutrient supply and freshwater input, all of which can affect oxygenation.…”

“…Twelve papers were presented at the meeting, and the final versions of 10 of these are included in this volume [9][10][11][12][13][14][15][16][17][18]. Ralph Keeling (paper not included in this volume) reviewed what we know about recent oxygen trends based on results from oceanic and atmospheric O 2 measurements.…”

Declining oxygen in the global ocean and coastal waters

“…Movement to avoid low oxygen can result in lost feeding opportunities on low-oxygen-tolerant prey and can increase energy expended in swimming (19,70). Hypoxia effects on vision, a function that is highly oxygen intensive, may contribute to these constraints, in part through changing light requirements (72).…”

Vision is highly sensitive to oxygen availability in marine invertebrate larvae

“…In the marine environment, large gradients of irradiance and oxygen exist with depth, and changes in the partial pressure of oxygen (P O2 ) with water depth in the ocean can be up to 10-fold greater than the changes in atmospheric P O2 over terrestrial altitude (McCormick and Levin, 2017). For example, oxygen content with depth can decline by as much as 35% between 7 and 17 m depth off the coast of California (Frieder et al, 2012), and varies over time with diurnal/diel cycling, seasonal hypoxia and El Niño-Southern Oscillation cycles .…”