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  • 1
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    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 47 (7). pp. 1247-1260.
    Publication Date: 2021-06-25
    Description: The oxygen consumption rates and activities of key metabolic enzymes were measured and analyzed as a function of habitat depth for several species of benthic octopod (Cephalopoda: Octopoda) including a recently described hydrothermal vent endemic species. Oxygen consumption rates and citrate synthase activity, an indicator of aerobic metabolic potential, did not vary significantly with increasing habitat depth. Anaerobic metabolic potential, as evidenced by octopine dehydrogenase activity, declined significantly with increasing habitat depth. It is suggested that burst swimming abilities, and hence glycolytic potential, are not strongly selected for in the deep-sea, where visual predator-prey interactions are reduced because of light-limitation. Oxygen consumption rates for Octopus californicus and O. bimaculoides were analyzed as a function of oxygen partial pressure as well. O. californicus, which lives in the hypoxic Santa Barbara basin at 500 m depth, was able to regulate its oxygen consumption to the limit of detectable oxygen partial pressures. O. bimaculoides, an intertidal species, had a minimum critical oxygen partial pressure of 16 mmHg. It is also shown that oxygen consumption rates and oxygen consumption regulation are strongly affected by individual experiment duration (either handling stress or food deprivation). O. californicus appears to be much more strongly affected by experiment duration than is O. bimaculoides.
    Type: Article , PeerReviewed
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  • 2
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    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 313 (2). pp. 375-387.
    Publication Date: 2021-08-23
    Description: The majority of squid families (Teuthoidea: Cephalopoda) exchange sodium for ammonium, creating a low-density fluid that imparts lift for neutral buoyancy. However, previous methods for measuring ammonium did not distinguish between NH4+ and various other amine compounds. The present study, using single column ion chromatography, reassessed the cation concentrations in several midwater cephalopod species. High NH4+ levels were confirmed for histioteuthid, cranchiid, and chiroteuthid and related squids. A strong relationship is reported between ammonium content and body mass in Histioteuthis heteropsis, suggesting a gradual accumulation of ammonium coincident with an ontogenetic migration to greater depths. The bathypelagic squids Bathyteuthis abyssicola and Bathyteuthis berryi, on the other hand, contained very little ammonium but rather contained large quantities of an as yet unidentified cation. The ecological significance of this compound is not yet known. Morphology in Bathyteuthid squids suggests that the unknown cation is contained intracellularly and so, unlike sequestered ammonia, does not diminish the space available for muscle tissue. Accordingly, protein measurements in B. berryi mantle muscle are on par with shallower-living muscular squids, and in situ submersible observations reveal strong locomotory abilities relative to other deep-water squids.
    Type: Article , PeerReviewed
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  • 3
    Publication Date: 2021-08-24
    Description: The Humboldt (or jumbo) squid, Dosidicus gigas, is an active predator endemic to the Eastern Pacific that undergoes diel vertical migrations into a pronounced oxygen minimum layer (OML). Here, we investigate the physiological mechanisms that facilitate these migrations and assess the associated costs and benefits. Exposure to hypoxic conditions equivalent to those found in the OML (∼10 μM O2 at 10 °C) led to a significant reduction in the squid’s routine metabolic rate (RMR), from 8.9 to 1.6 μmol O2 g−1 h−1 (p 〈 0.05), and a concomitant increase in mantle muscle octopine levels (from 0.50 to 5.24 μmol g−1 tissue, p 〈 0.05). Enhanced glycolitic ATP production accounted for only 7.0% and 2.8% at 10 °C and 20 °C, respectively, of the energy deficit that resulted from the decline in aerobic respiration. The observed metabolic suppression presumably extends survival time in the OML by conserving the finite stores of fermentable substrate and avoiding the accumulation of the deleterious anaerobic end products in the tissues. RMR increased significantly with temperature (p 〈 0.05), from 8.9 (at 10 °C) to 49.85 μmol O2 g−1 h−1 (at 25 °C) which yielded a Q10 of 2.0 between 10 and 20 °C and 7.9 between 20 and 25 °C (p 〈 0.05). These results suggest that 25 °C, although within the normal surface temperature range in the Gulf of California, is outside this species’ normal temperature range. By following the scattering layer into oxygen-enriched shallow water at night, D. gigas may repay any oxygen debt accumulated during the daytime. The dive to deeper water may minimize exposure to stressful surface temperatures when most prey have migrated to depth during the daytime. The physiological and ecological strategies demonstrated here may have facilitated the recent range expansion of this species into northern waters where expanding hypoxic zones prohibit competing top predators.
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2022-05-25
    Description: Author Posting. © The Oceanography Society, 2015. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 28, no. 2 (2015): 48-61, doi:10.5670/oceanog.2015.31.
    Description: Oceanic and coastal waters are acidifying due to processes dominated in the open ocean by increasing atmospheric CO2 and dominated in estuaries and some coastal waters by nutrient-fueled respiration. The patterns and severity of acidification, as well as its effects, are modified by the host of stressors related to human activities that also influence these habitats. Temperature, deoxygenation, and changes in food webs are particularly important co-stressors because they are pervasive, and both their causes and effects are often mechanistically linked to acidification. Development of a theoretical underpinning to multiple stressor research that considers physiological, ecological, and evolutionary perspectives is needed because testing all combinations of stressors and stressor intensities experimentally is impossible. Nevertheless, use of a wide variety of research approaches is a logical and promising strategy for improving understanding of acidification and its effects. Future research that focuses on spatial and temporal patterns of stressor interactions and on identifying mechanisms by which multiple stressors affect individuals, populations, and ecosystems is critical. It is also necessary to incorporate consideration of multiple stressors into management, mitigation, and adaptation to acidification and to increase public and policy recognition of the importance of addressing acidification in the context of the suite of other stressors with which it potentially interacts.
    Description: Funding for research on acidification and multiple stressors was provided by NOAACSCOR NA10NOS4780138 to DLB, NASA NNX14AL8 to JS, NSF OCE-1219948 to JMB, NSF OCE-927445 and OCE-1041062 to LAL, NSF EF-1041070 to W-JC, a Linnaeus grant from the Swedish Research Councils VR and Formas to SD, NSF EF-0424599 to SCD, NSF OCE-1041038 to UP, NSF EF-1316113 to BAS, NSF ANT-1142122 to AET, NSF OCE-1316040 to AMT, and the NOAA Ocean Acidification Program Office to BP, LMM, and WCL.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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