Oxygen consumption during and post-hypoxia exposure in bearded fireworms (Annelida: Amphinomidae)
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ORIGINAL PAPER
Oxygen consumption during and post‑hypoxia exposure in bearded fireworms (Annelida: Amphinomidae) Candace J. Grimes1 · Crystal Capps1 · Lene H. Petersen1 · Anja Schulze1 Received: 8 May 2020 / Revised: 10 August 2020 / Accepted: 9 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Oxygen is necessary for all marine animals to support metabolic functions. When chronic low dissolved oxygen (DO) conditions occur, organisms must adjust to overcome this stressor’s effect on metabolic rates. The bearded fireworm, Hermodice carunculata, is a widespread species frequently exposed to hypoxic conditions in areas within its broad distribution which may impact metabolism, wound healing, and regeneration. To study the impact of hypoxia on their metabolic rates, we exposed fireworms to two levels of lower than normal DO conditions (low 2.5 ± 0.25 mg O 2 L−1 and mid 4.5 ± 0.25 mg O2 −1 L ) for 7 days by pumping nitrogen into their holding tanks. During a chronic hypoxia trial, we quantified oxygen consumption in each experimental group and subsequently determined post-hypoxia oxygen consumption of individuals from the lowest oxygen level. During the hypoxic exposure, the oxygen uptake rates declined in low and mid DO conditions, while remaining relatively constant for the normoxic (7.0 ± 0.25 mg O2 L−1) control. We then compared the oxygen consumption rates from the lowest DO condition to fireworms likely never exposed to hypoxia and fireworms from a location likely to be exposed to hypoxia. We found higher oxygen consumption rates in the experimentally hypoxia-exposed worms. These results suggest prolonged negative impacts of hypoxic exposure, leading to a lasting elevation of metabolic rates of these marine invertebrates. The increase in metabolic rates may lead to increased predation on their prey of choice, economically and commercially important coral, causing increased degradation of already threatened coral reef ecosystems. Keywords Annelida · Metabolism · Stress response · Oxygen deficiency
Introduction Oxygen is a crucial factor for sustaining animal life. Even though atmospheric oxygen levels have varied significantly over geological time frames, air breathers generally live under relatively stable oxygen conditions throughout their lifetime. Aquatic animals, on the other hand, not only Communicated by G. Heldmaier. * Candace J. Grimes [email protected] Crystal Capps [email protected] Lene H. Petersen [email protected] Anja Schulze [email protected] 1
Texas A&M University at Galveston, Galveston, TX 77554, USA
encounter less oxygen per volume medium and a fraction of the diffusion rates in air, but many are also exposed to extreme shorter-term fluctuations in dissolved oxygen (DO) levels (Abele et al. 2007). Water breathers are therefore at higher risk for oxygen deficiency and damaging effects of fluctuating DO levels compared to air breathers. Hypoxic zones, or areas of low (
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