Essential and Nonessential Elements in the Whole Blood of Newly Captured and Adapting to Captivity Okhotsk Sea Killer Whales (Orcinus orca)
Abstract
Killer whales, being the top marine predators, are considered to be one of the most-polluted marine mammals, demonstrating the highest tissue levels of halogenated organic contaminants in some areas of habitat.6 Elemental content in organs and tissues of this species is less explored and limited to determination of several trace elements in the liver, kidney, and muscles.3,4,2
With the objective of evaluation of the blood essential and nonessential elements content and temporal dynamics, 8 young healthy killer whales (4 males, 1000–3450 kg and 4 females, 1150–2200 kg), captured in the summer (early autumn) time of 2014–2015, were examined just after catch, as well as after the 6- and 12-month period of adaptation. The whole blood element profiles of 4 (1 male, 180 kg and 3 females, 130–180 kg) adapting to captivity Pacific bottlenose dolphins (Tursiops truncatus gilli), imported to Russia from Japan in 2016, and surveyed since the second month after catch, were used for comparison.
The blood samples were taken by tail fluke vein puncture, fast-frozen, and kept refrigerated at -20°C until the moment of examination. Concentrations of 23 essential and nonessential elements [lithium (Li), boron (B), sodium (Na), potassium (K), magnesium (Mg), aluminum (Al), phosphorus (P), calcium (Ca), thallium (Tl), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), molybdenum (Mo), cadmium (Cd), stibium (Sb), mercury (Hg), and lead (Pb)] were measured by means of inductively coupled plasma mass spectrometry (Varian 810-MS, USA & Australia) in the “Euro Test” scientific practical laboratory (Moscow) and analyzed in conjunction with routine hematology data and serum chemistry panels.
As a result of the research performed, all out of the total tested elements were revealed in measurable amounts in the whole blood of all of the examined killer whales and bottlenose dolphins. The killer whales’ blood elemental profiles are presented in Table 1.
Based on the results of the study, extremely high levels of Hg, Se as well as the elevated Li and Na concentrations were revealed in the whole blood of the newly captured killer whales in comparison with wild Sarasota Bay bottlenose dolphins1 and human reference data5. The whales showed relatively higher whole blood concentrations of Li, B, Cr, Co, Mo, Zn, Mg, Mn, Al, Na, Hg/Se index and lower levels of Se, As, P then the surveyed Pacific bottlenose dolphins. Progressive 3–16-fold decrease in Hg and Se (in 4 of 6 animals) as well as the tendency in Tl, As, Ni, and Cr increase (at around the human references) were seen in the blood of the killer whales during the first year in captivity. Similar temporal changes in the blood concentrations of Hg and Se were noticed in the adapting bottlenose dolphins.
We didn’t find any data on the essential and nonessential elements content in the blood of wild killer whales in the literature available, and, thus, the basic levels and trends, established in this study, may serve as the first benchmarks for future investigations and comparisons.
Table 1. Element profiles in whole blood of newly captured Okhotsk Sea killer whales
|
Elements
|
Units
|
X±σ
|
Range
|
|
Li
|
mcg/l
|
13.2±1.5
|
10.2–15.0
|
|
B
|
mcg/l
|
73.6±37.0
|
42.4–132.3
|
|
Na
|
mg/l
|
2214.4±147.2
|
1994–2466
|
|
K
|
mg/l
|
2045.0±366.6
|
1676–2766
|
|
Mg
|
mg/l
|
34.8±2.1
|
30.8–36.6
|
|
Al
|
mcg/l
|
113.7±72.1
|
41.3–238.6
|
|
P
|
mg/l
|
350.6±38.0
|
312–430.4
|
|
Ca
|
mg/l
|
55.3±5.8
|
47.4–66.6
|
|
Tl
|
mcg/l
|
0.07±0.02
|
0.04–0.11
|
|
Cr
|
mcg/l
|
107.3±21.5
|
77.9–135.2
|
|
Mn
|
mcg/l
|
71.2±54.2
|
22.9–156.6
|
|
Fe
|
mg/l
|
485.0±56.8
|
419.6–567.4
|
|
Co
|
mcg/l
|
1.0±0.4
|
0.4–1.5
|
|
Ni
|
mcg/l
|
2.9±1.1
|
2.2–5.1
|
|
Cu
|
mcg/l
|
697.5±58.1
|
604.3–784.8
|
|
Zn
|
mg/l
|
4.3±0.5
|
3.8–5.1
|
|
As
|
mcg/l
|
10.0±5.1
|
3.8–21.2
|
|
Se
|
mg/l
|
1.6±0.7
|
0.6–2.8
|
|
Mo
|
mcg/l
|
0.8±0.4
|
0.3–1.5
|
|
Cd
|
mcg/l
|
0.4±0.2
|
0.1–0.7
|
|
Sb
|
mcg/l
|
1.2±1.7
|
0.2–4.0
|
|
Hg
|
mg/l
|
1.8±0.9
|
0.6–3.0
|
|
Hg/Se
|
|
1.1±0.4
|
0.5–1.7
|
|
Pb
|
mcg/l
|
14.3±20.8
|
2.6–64.6
|
* Presenting author
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