Impact of hypoxia on the metabolism of Greenland halibut (Reinhardtius hippoglossoides)

Abstract

Greenland halibut (Reinhardtius hippoglossoides), especially juveniles, are frequently found in severely hypoxic areas (18%–25% saturation) of the St. Lawrence Estuary. We investigated the tolerance of this species to hypoxia and evaluated the consequences of low oxygen levels on metabolic capacity. At 5 °C, juveniles had a higher critical oxygen threshold than adults (15% versus 11% saturation), indicating that they were less tolerant to hypoxia. Severe hypoxia (19% saturation) did not affect the juveniles' standard metabolic rate but significantly reduced (by 55%) their maximum metabolic rate compared with normoxia. Consequently, the aerobic scope was reduced by 72% in hypoxia compared with normoxia. In juveniles, severe hypoxia increased the duration of digestive processes. The decrease in aerobic scope in hypoxia and the determination of critical oxygen threshold at a saturation level close to actual field dissolved oxygen values strongly suggest that juveniles from the St. Lawrence Estuary are living at the edge of their metabolic capacity. Consequently, the growth and distribution of Greenland halibut could be affected if there are further declines in dissolved oxygen availability.

Outside influences on the water column of Cumberland Sound, Baffin Island

“…Therefore, deep water renewal must occur often enough to prevent hypoxia. As hypoxia threshold definitions vary [ Hofmann et al ., ], here a midvalue of 20% dissolved oxygen (DO) saturation will be used, which is within the range that Greenland Halibut have been found elsewhere [ Dupont‐Prinet et al ., ]. For Cumberland Sound's bottom temperatures, 20% DO saturation corresponds to an oxygen concentration of roughly 3 mg L −1 .…”

“…Even though no oxygen measurements have been previously reported in Cumberland Sound, based on the existence of a bottom‐dwelling population of Greenland Halibut in the sound [ Peklova et al ., ], we can assume that the deepest regions are not hypoxic. However, oxygen levels may be low, as Greenland Halibut have been found in regions with 18−25% oxygen saturation and can survive down to 15% in laboratory studies [ Dupont‐Prinet et al ., ].…”

Movements of a deep‐water fish: establishing marine fisheries management boundaries in coastal Arctic waters

“…In contrast, in northwestern Greenland, whereas fish also moved to the inner section of the fjord, this occurred during the summer ice-free period, although fishing effort may have biased the observed distribution pattern (Boje 2002). While Greenland halibut and flatfish generally have a low aerobic scope when compared with pelagic fishes (Dupont-Prinet et al 2013) and are reported to occur in high abundances at low The left panels (a, c, and e) are environmental variables recorded in the southern region of Cumberland Sound, including bottom dissolved oxygen and percent ice cover data for the entire deep water southern region (see Appendix S2; both significant factors in the GLMM) and temperature readings from near the mouth of the Sound (SMOUTH, Fig. Boje et al (2014) reported Greenland halibut occupying colder waters during the winter months in the deep inner icefjord of Disko Bay, a similar trend observed in this and a previous study in Cumberland Sound (Peklova et al 2012).…”

“…In the southern deep region, fish occupied waters with oxygen concentrations of ~3.6-3.7 mg/L, similar to the values recorded during peak fish occurrence in the northern region. While Greenland halibut and flatfish generally have a low aerobic scope when compared with pelagic fishes (Dupont-Prinet et al 2013) and are reported to occur in high abundances at low Fig. 7.…”

Fisheries, low oxygen and climate change: how much do we really know?

“…Intertidal invertebrates may be more tolerant as they are adapted to fluctuating environmental conditions (Leiva et al , ). By contrast, Vaquer‐Sunyer & Duarte () found that crustaceans were the least tolerant to hypoxia of all organisms they tested and that some tolerant groups such as bivalves may benefit from hypoxia due to reduced predation and competition, in a similar way to R. hippoglossoides (Mejri et al , ; Dupont‐Prinet et al , 2013 b ). Although bivalves may be more tolerant, sessile organisms will be generally more vulnerable as they cannot usually move to localities with higher oxygen concentrations if they need to, unlike mobile species such as fin fishes.…”