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2 results on '"habitat compression"'

1. Exploring connections between mesopelagic ecosystems, epipelagic predators, and a changing ocean climate in the California Current

Author

Iglesias, Ilysa

Subjects
Biological oceanography, acoustics, epipelagic-mesopelagic coupling, habitat compression, heatwave, mesopelagic, twilight zone
Abstract

The deep-pelagic ocean represents one of the largest biomes, and is home to adiverse assemblage of organisms, whose collective vertical movements represent thegreatest migration on earth. Deep-pelagic environments and denizens are oftendefined by their distance and distinctness from surface ecosystems. However, in thisdissertation, I explore how mesopelagic communities are interconnected to pelagicfood webs and impacted by changing oceanographic conditions at the surface.Focusing on the California Current, we use a combination of diet data, fisheriesacoustics, and downscaled climate projections to investigate the role of mesopelagicfishes as prey to higher trophic level predators, the effects of a large marine heatwaveon the deep scattering community, and the compression of mesopelagic habitatprojected by the end of the 21st century. Our results suggest that mesopelagiccommunities provide prey for numerous federally managed and protected species,adjust their vertical position in response to marine heatwave events, and willexperience vertical habitat compression as low oxygen conditions shoal due to globalclimate change. As anthropogenic threats to exploit and alter deep-pelagic ecosystemsrise, our work demonstrates the need to consider more carefully the role ofmesopelagic communities in supporting healthy and functioning ocean ecosystems.

Published
2024

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

Author

McCormick, Lillian R and Levin, Lisa A

Subjects
Eye Disease and Disorders of Vision, Neurosciences, Eye, Life Below Water, Animals, Aquatic Organisms, Behavior, Animal, Climate Change, Ecosystem, Oceans and Seas, Oxygen, Seawater, Temperature, Vision, Ocular, deoxygenation, ocean, hypoxia, vision, eye, habitat compression, General Science & Technology
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'.

Published
2017

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