Accumulation of 210Po by spiny dogfish (Squalus acanthias), elephant fish (Callorhinchus milii) and red gurnard (Chelodonichthys kumu) in New Zealand shelf waters

1997 ◽  
Vol 48 (3) ◽  
pp. 229 ◽  
Author(s):  
Peter Bellamy ◽  
Keith A. Hunter
Keyword(s):  
New Zealand ◽  
Fish Species ◽  
Sea Water ◽  
Radioactive Decay ◽  
Natural Radionuclide ◽  
Absorbed Dose ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Wet Weight ◽  
Concentration Factors

Concentrations of the natural radionuclide 210Po in the livers of 81 individual specimens of three fish species collected from waters of the Otago continental shelf, New Zealand, have been measured: spiny dogfish (Squalus acanthias), 4·2 ± 1·8 Bq kg-1 wet weight (mean ± standard deviation, n = 48); elephant fish (Callorhinchus milii), 136 ± 39 Bq kg-1 (n = 7); and red gurnard (Chelodonichthys kumu), 38 ± 13 Bq kg-1 (n = 26). Separate measurements showed that only a negligible fraction of the 210Po was supported by decay of the 210Pb parent (210Po/210Pb activity ratios were 15, 134 and 5·9 respectively for the three species), indicating that direct uptake of 210Po into the liver balances losses from excretion and radioactive decay. The radiation dose from 210Po in the livers accounted for between 88% and 99% of the total internal absorbed dose received by the fish species. The activity of 210Po in sea water from the study area was 0·9–2·2 mBq L-1, yielding concentration factors for 210Po in liver tissue in the range 3 × 103 to 100 × 103. No significant monophasic relationships were observed between the 210Po results and the measured concentrations of the elements Cd, Cu, Fe, Mn, Zn and Pb, except that Pb and 210Po were correlated (r = 0·511) in C. kumu.

scholarly journals Leopard Seals (Hydrurga leptonyx) in New Zealand Waters Predating on Chondrichthyans

2021 ◽  
Vol 8 ◽  
Author(s):  
Krista van der Linde ◽  
Ingrid N. Visser ◽  
Rick Bout ◽  
Chris Lalas ◽  
Lara Shepherd ◽  
...  
Keyword(s):  
New Zealand ◽  
Dna Sequencing ◽  
High Frequency ◽  
Marine Ecosystem ◽  
Marine Ecosystems ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Frequency Of Occurrence ◽  
Morphological Examination ◽  
Hydrurga Leptonyx

Leopard seals (Hydrurga leptonyx) are top-order predators that prey on a wide variety of species including crustaceans, cephalopods, fishes, birds, and pinnipeds. While multiple diet studies have been conducted worldwide, there are no previous accounts of leopard seals predating on chondrichthyans. As part of a wider study on the diet of leopard seals in New Zealand (NZ) waters, researchers and citizen scientists recorded 39 observations of predation and collected 127 scats (166 total records) between 1942 and 2019. Predation on chondrichthyans was detected in 23.1% (n = 9) of observations of predation and 7.1% (n = 9) of scats (the latter via morphological examination and DNA sequencing). From both observations of predations and scats, three chondrichthyan species or genus were identified; elephantfish (Callorhinchus milii), ghost sharks (Hydrolagus spp.) and spiny dogfish (Squalus acanthias). While this is the first published record of leopard seals feeding on chondrichthyans, the relatively high frequency of occurrence within our NZ records, and that certain individuals appeared to target this type of prey, indicates that these species could constitute a substantial, or important, part of the diet for some leopard seals in this region. As chondrichthyans form an important part of the NZ marine ecosystems, our recognition of an additional top-order predator of these species contributes to understanding the overall health of, and future impacts of predators on, the wider NZ marine ecosystem.

scholarly journals Time course of the establishment of uterine seawater conditions in late-term pregnant spiny dogfish (Squalus acanthias)

1988 ◽  
Vol 137 (1) ◽  
pp. 443-456
Author(s):  
G. A. Kormanik
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Time Course ◽  
Sea Water ◽  
Ammonia Concentration ◽  
Squalus Acanthias ◽  
Total Carbon ◽  
Spiny Dogfish ◽  
Ionic Form ◽  
Carbon Dioxide Content

The gestation period for embryos of the spiny dogfish, Squalus acanthias (L.) lasts for nearly 2 years. During the latter part of this period the pups remain in the uterus and the fluid surrounding the embryos resembles sea water with respect to the major ions, but is low in pH (approx. 6), high in partial pressure of carbon dioxide (approx. 3 mmHg; 1 mmHg = 133.3 Pa), low in total carbon dioxide content (approx. 0.2 mmol l-1), and may have a total ammonia concentration of up to 22 mmol l-1. Thus the conditions under which the pups complete their development in utero is quite remarkable. The derivation of these conditions was examined in late-term pregnant females, from whose uterine horns the pups had been removed, by monitoring changes that occurred in instilled uterine sea water. The mother is responsible for reducing the pH, reducing the total carbon dioxide content and elevating the partial pressure of carbon dioxide to the levels observed in fresh-caught females, in less than 24 h. The ammonia concentration is also elevated, but this takes rather longer. The decreased pH is responsible for the accumulation of ammonia in the uterine sea water, and it also serves to protect the pups from the toxic effects of NH3, by converting it to the relatively non-toxic ionic form, NH4+. The reasons for the establishment of these uterine seawater conditions are still not evident.

Polonium-210 in cartilaginous fishes (Chondrichthyes) from south-eastern Australian waters

1993 ◽  
Vol 44 (5) ◽  
pp. 727 ◽  
Author(s):  
JD Smith ◽  
PH Towler
Keyword(s):  
Absorbed Dose ◽  
Naturally Occurring ◽  
Elasmobranch Species ◽  
Wet Weight ◽  
The Mean ◽  
Concentration Factors ◽  
Cartilaginous Fishes ◽  
Lead 210 ◽  
Mean Concentration

A study was made of the concentration of the naturally occurring radionuclide polonium-210 in the livers of cartilaginous fishes (chondrichthyans) caught in the waters of Port Phillip Bay, Victoria, Australia in 1991. Five elasmobranch species had 210Po concentrations in the range 1-31 Bq kg-1 (wet weight) and one holocephalian species, the elephant fish (Callorhynchus milii), was exceptional with a 210Po range of 60-270 Bq kg-1 (n=3, mean 180 Bq kg-1). Lead-210 was present at 0.1- 1.1 Bq kg-1 and activity concentration ratios of 210Po:210Pb were all greater than 1, indicating that the 210Po could not all have grown in from in situ decay of 210Pb within the chondrichthyan liver. The concentration of 210Po in the livers appeared to be species related. Concentrations of the trace metals Cu, Fe and Zn showed no correlation with the 210Po and were not species-related. The mean concentration of 210Po measured in Port Phillip Bay water was 0.32 mBq kg-1. This yields concentration factors of 3.2 × 103 to 8.4 × 105 for unsupported 210Po in the livers of the chondrichthyans. The total 210Po (using Q=20) exposes the livers to a weighted absorbed dose of up to 140 mGy year-1 (16�Gy h-1), which is >99% of the total internal dose and three orders of magnitude greater than the external dose based on estimated levels of 40K.

scholarly journals Parasitic fauna of spiny dogfish Squalus acanthias L. off New Zealand

1984 ◽  
Vol 14 (1-2) ◽  
pp. 157-166 ◽  
Author(s):  
Jadwiga Wierzbicka ◽  
Danuta Łangowska
Keyword(s):  
New Zealand ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Parasitic Fauna

Metabolic Rate and Energy Expenditure of the Spiny Dogfish, Squalus acanthias

1978 ◽  
Vol 35 (6) ◽  
pp. 816-821 ◽  
Author(s):  
J. R. Brett ◽  
J. M. Blackburn
Keyword(s):  
Energy Expenditure ◽  
Metabolic Rate ◽  
Key Words ◽  
Swimming Performance ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Metabolic Rates ◽  
Performance Curve ◽  
Power Performance ◽  
General Energy

The metabolic rate of spiny dogfish, Squalus acanthias, was determined in both a tunnel respirometer and a large, covered, circular tank (mass respirometer). Swimming performance was very poor in the respirometer, so that a power–performance curve could not be established. Instead, resting metabolic rates were determined, with higher rates induced by causing heavy thrashing (active metabolism). Routine metabolic rates were measured for the spontaneous activity characterizing behavior in the circular tank. For fish of 2 kg mean weight, the metabolic rates at 10 °C were 32.4 ± 2.6 SE (resting), 49.2 ± 5.0 SE (routine), and 88.4 ± 4.6 SE (active) mg O2∙kg−1∙h−1. Assuming that the routine rate represents a general energy expenditure in nature, this is equivalent to metabolizing about 3.8 kcal∙kg−1∙d−1 (15.9 × 103 J∙kg−1∙d−1). Key words: dogfish, metabolic rates, energetics, respiration

Osmoregulation by the Prenatal Spiny Dogfish, Squalus Acanthias

1982 ◽  
Vol 101 (1) ◽  
pp. 295-305 ◽  
Author(s):  
DAVID H. EVANS ◽  
AIMO OIKARI ◽  
GREGG A. KORMANIK ◽  
LEIGH MANSBERGER
Keyword(s):  
Sea Water ◽  
Electrical Potential ◽  
Fluid Flows ◽  
Maternal Plasma ◽  
Water Levels ◽  
Squalus Acanthias ◽  
Rectal Gland ◽  
Na Efflux ◽  
Uterine Fluid ◽  
Electrochemical Equilibrium

Late in gestation of the ovoviviparous dogfish, Squalus acanthias, the uterine fluids are essentially sea water, while the plasma of the ‘pup’ is similar to that of the female, i.e. isotonic to sea water/uterine fluids, with significantly less Na and Cl, and substantial concentrations of urea. Early ‘candle’ embryos are bathed in ‘candle’ fluid and uterine fluid which contains Na and Cl concentrations intermediate between maternal plasma and sea water levels, K concentrations above sea water levels, and urea concentrations slightly below those found in the maternal plasma. Both fluids are isotonic to sea water and maternal plasma. Incubation of ‘candles’ with associated embryos in sea water for 4–6 days resulted in significant increases in ‘candle’ fluid Na and Cl concentrations, and a decline in ‘candle’ fluid K and urea levels. However, under these conditions, the ‘candle’ embryo is still able to regulate plasma Na, Cl, K and urea concentrations. The efflux of Cl is approximately 5 times the efflux of Na from the prenatal ‘pup’; however, both effluxes are equivalent to those described for adult elasmobranchs. The transepithelial electrical potential (TEP) across the ‘pup’ is −4.4 mV in sea water, which indicates that both Na and Cl are maintained out of electrochemical equilibrium. Cloacal fluid flows vary diurnally with Na and Cl concentrations significantly above those of the plasma. Rectal gland efflux can account for 50–100% of the Na efflux, but less than 25% of the Cl efflux. Removal of the rectal gland resulted in an increase in plasma Na and Cl concentrations 48 or 72 h after the operation, but in both cases it appears that some extra rectal gland excretory system balances at least some of the net influx of both salts. Our results demonstrate that even very young ‘candle’ embryos of S. acanthias are capable of osmoregulation, and that older embryos (‘pups') osmoregulate against sea water intra-utero and display the major hallmarks of elasmobranch osmoregulation, including a reduced ionic permeability and a functional rectal gland for net extrusion of NaCl. In addition, it appears that other pathways exist for salt extrusion in addition to the rectal gland. Note:

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