Interspecies variation in hypoxia tolerance, swimming performance and plasticity in cyprinids that prefer different habitats

Abstract

This study quantified and compared hypoxia tolerance and swim performance among cyprinid fish species from rapid-, slow-and intermediate-flow habitats (four species per habitat) in China. In addition, we explored the effects of short-term acclimation on swim performance, maximum metabolic rate (Ṁ O2,max ) and gill remodelling to detect habitat-associated patterns of plastic response to hypoxia. Indices of hypoxia tolerance included oxygen threshold for loss of equilibrium (LOE 50 ) and aquatic surface respiration (ASR 50 ), and critical oxygen tension for routine metabolic rate (P crit ). Critical swimming speed (U crit ) and Ṁ O2,max were measured under normoxic and hypoxic conditions after 48 h acclimation to normoxia and hypoxia, and gill remodelling was estimated after 48 h of hypoxia exposure. Both traditional ANCOVA and phylogenetically independent contrast (PDANOVA) analyses showed that fish species from rapidflow habitats exhibited lower LOE 50 compared with fish from intermediate-and slow-flow habitats. Habitat-specific differences in P crit and U crit were detected using PDANOVA but not traditional ANCOVA analyses, with fish species from rapid-flow habitats exhibiting lower P crit but higher U crit values compared with fish from intermediate-and slow-flow habitats. Fish species from rapid-flow habitats were also characterized by less plasticity in swim performance and gill morphology in response to hypoxia acclimation compared with species from slow-flow habitats, but a greater drop in swim performance in response to acute hypoxia exposure. The study detected a habitat-specific difference in hypoxia tolerance, swimming performance and its plasticity among fish from habitats with different flow conditions, possibly because of the long-term adaptation to the habitat caused by selection stress. The PDANOVA analyses were more powerful than traditional statistical analyses according to the habitat effects in both hypoxia tolerance and swimming performance in this study.

Ecological Influences and Morphological Correlates of Resting and Maximal Metabolic Rates across Teleost Fish Species

“…These results not only support recent experimental work suggesting that adaptation for high activity may trade-off with hypoxia tolerance in fishes (Crans et al 2015;Fu et al 2014;Stoffels 2015), but also suggest that this phenomenon may generate interspecific diversity in metabolic and performance traits across a broad range of teleost lineages.…”

“…When faced with hypoxic and hypercapnic conditions, several fish species increase oxygen extraction and transport efficiency by modulating gill surface area, oxygen affinity of haemoglobin and muscle mitochondrial density (Dhillon et al 2013;Fu et al 2014;Nilsson and Renshaw 2004). Additionally, at least three cyprinid species (Carassius carassius, C.…”

“…In our dataset, species belonging to the genera Carassius, Rhodeus, Cyprinus, Hypophthalmichthys and Aristichthys, which are known to tolerate very high levels of hypoxia (Dhillon et al 2013;Fu et al 2014), exhibit very low levels of adjusted RMR (range:…”

Physiological tradeoffs may underlie the evolution of hypoxia tolerance and exercise performance in sunfish (Centrarchidae)

“…Our current findings in fish from the family Centrarchidae, along with recent observations in other taxa (Fu et al, 2014), suggest that this tradeoff may exist among closely related species. We also identified a variety of respiratory and metabolic traits from across the O 2 cascade that vary in association with hypoxia tolerance and/or aerobic exercise capacity.…”

“…For example, it has been found that cyprinid fish species from habitats with high water flows (wild-caught but acclimated to laboratory conditions) tend to have a higher capacity for sustained swimming but a lesser hypoxia tolerance than species from slow flowing habitats, suggesting that there is a mechanistic tradeoff between hypoxia tolerance and performance among closely related species, even after phylogenetic relationships are taken into account (Fu et al, 2014). An increase in hypoxia tolerance coincident with a decrease in sustained swimming performance has been observed during development in coral reef damselfish .…”