TY - JOUR
T1 - Behavioural, physiological and biochemical responses to aquatic hypoxia in the freshwater crayfish, Paranephrops zealandicus
AU - Broughton, Rebecca J.
AU - Marsden, Islay D.
AU - Hill, Jonathan V.
AU - Glover, Chris N.
N1 - Publisher Copyright:
© 2017 Elsevier Inc.
PY - 2017/10
Y1 - 2017/10
N2 - Hypoxia resulting from aquatic eutrophication threatens the population health of the New Zealand freshwater crayfish (koura), Paranephrops zealandicus. An integrated study, combining behavioural, physiological and biochemical approaches, was therefore conducted to characterise the tolerance of this species to hypoxia. When provided with a choice between water flows of high or low dissolved oxygen in short-term laboratory assays, crayfish did not preferentially inhabit waters of higher PO2. However, when an aerial refuge was provided and dissolved oxygen was progressively decreased, crayfish emersed at a PO2 of 0.56 ± 0.03 kPa, suggesting a relatively high tolerance to hypoxia. Closed-box respirometry delineated a Pcrit, the point at which crayfish transition from oxyregulating to oxyconforming, of 6.0 kPa. Simultaneous measurement of heart rate showed no changes across the PO2 range. In response to 6-h exposures to fixed dissolved oxygen levels (normoxia, 19.3 kPa; moderate hypoxia, 3.5 kPa; and severe hypoxia, 1.7 kPa), P. zealandicus showed a haemolymph PO2 that declined with the magnitude of hypoxia, and while plasma pH declined in severe hypoxia, there were no changes in plasma PCO2. Plasma glucose concentrations fell, and plasma lactate increased in both hypoxic groups. There were no changes in tissue glucose or lactate concentrations. These data indicate that P. zealandicus is relatively tolerant of hypoxia, and possesses biochemical and physiological mechanisms that facilitate survival during short-term exposures to acute hypoxia. If hypoxia is severe and/or prolonged, then this species is capable of escaping to aerial refugia.
AB - Hypoxia resulting from aquatic eutrophication threatens the population health of the New Zealand freshwater crayfish (koura), Paranephrops zealandicus. An integrated study, combining behavioural, physiological and biochemical approaches, was therefore conducted to characterise the tolerance of this species to hypoxia. When provided with a choice between water flows of high or low dissolved oxygen in short-term laboratory assays, crayfish did not preferentially inhabit waters of higher PO2. However, when an aerial refuge was provided and dissolved oxygen was progressively decreased, crayfish emersed at a PO2 of 0.56 ± 0.03 kPa, suggesting a relatively high tolerance to hypoxia. Closed-box respirometry delineated a Pcrit, the point at which crayfish transition from oxyregulating to oxyconforming, of 6.0 kPa. Simultaneous measurement of heart rate showed no changes across the PO2 range. In response to 6-h exposures to fixed dissolved oxygen levels (normoxia, 19.3 kPa; moderate hypoxia, 3.5 kPa; and severe hypoxia, 1.7 kPa), P. zealandicus showed a haemolymph PO2 that declined with the magnitude of hypoxia, and while plasma pH declined in severe hypoxia, there were no changes in plasma PCO2. Plasma glucose concentrations fell, and plasma lactate increased in both hypoxic groups. There were no changes in tissue glucose or lactate concentrations. These data indicate that P. zealandicus is relatively tolerant of hypoxia, and possesses biochemical and physiological mechanisms that facilitate survival during short-term exposures to acute hypoxia. If hypoxia is severe and/or prolonged, then this species is capable of escaping to aerial refugia.
KW - Acid-base regulation
KW - Anaerobic metabolism
KW - Crustacean
KW - Decapod
KW - Emersion
KW - Eutrophication
KW - Freshwater crayfish
KW - Hypoxia
KW - Metabolic rate
KW - Respirometry
UR - http://www.scopus.com/inward/record.url?scp=85026451599&partnerID=8YFLogxK
U2 - 10.1016/j.cbpa.2017.07.013
DO - 10.1016/j.cbpa.2017.07.013
M3 - Journal Article
C2 - 28756185
AN - SCOPUS:85026451599
SN - 1095-6433
VL - 212
SP - 72
EP - 80
JO - Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology
JF - Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology
ER -