Ontogenetic and environmental responses in metabolic enzyme activity of Pacific
Arctic larval gadids
#MMPMID41384235
Slesinger E
; Thuesen EV
; Hurst TP
Conserv Physiol
2025[]; 13
(1
): coaf083
PMID41384235
show ga
Warming in high-latitude marine ecosystems is leading to the borealization of
Arctic communities. Species-specific responses to temperature provide insight
into potential co-occurrence or competitive advantage between Arctic and boreal
species. Ocean acidification may also lead to unique species-specific responses.
At the Pacific-Arctic interface, larval distributions of the boreal Pacific cod
(Gadus macrocephalus) are increasingly overlapping with those of Arctic cod
(Boreogadus saida). We assessed larval metabolic capacities by measuring
metabolic enzyme activities of citrate synthase (CS; aerobic metabolism), lactate
dehydrogenase (LDH; anaerobic metabolism), and ?-hydroxyacyl CoA dehydrogenase
(HOAD; fatty acid metabolism). Throughout early development, Pacific cod enzyme
activities, including glycolytic capacity, were higher, and fatty acid metabolism
lower than Arctic cod enzyme activities. These responses may reflect a more
active larval lifestyle of Pacific cod. Separately, larvae were reared in
multiple temperatures (Pacific cod: 3, 6, 10°C; Arctic cod 1.8, 5, 7.3°C) and
pCO(2) levels (ambient?=?~350 ?atm; high?=?~1500 ?atm). At the cold temperature,
Pacific cod enzyme activities were higher than at the control temperature,
indicating they were acclimating but less cold adapted than Arctic cod. Arctic
cod HOAD activity and LDH:CS ratio were elevated under warmer temperatures
suggesting increased energy demand. Elevated pCO(2) levels only affected larvae
at their control temperature and resulted in decreased Pacific cod HOAD activity
and increased Arctic cod CS and HOAD activities. This indicates differing
sensitivities to ocean acidification between the species. Overall, Pacific cod
may continue to be constrained in their northern habitat by cold temperatures,
but under slight warming to optimal growing temperatures, Pacific cod will have
competitive advantage over Arctic cod.
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