*Correspondence author: Ekaterina V Lepskaya, Laboratory for Fisheries Ecology, Kamchatka branch of FSBSE, All-Russian Research Institute of Fisheries and Oceanography, KamchatNIRO, 18, Naberezhnaya, Petropavlovsk-Kamchatsky, 683000, Russia
How to cite this article:Ekaterina V Lepskaya, Denis N Chulchekov, Vladimir V Kolomeytsev, Timur A Kanapatskiy. Primary Production and P/B of Phytoplankton on Western Kamchatka Shelf. Oceanogr Fish Open Access J. 2019; 10(5): 555799. DOI: 10.19080/OFOAJ.2019.10.555799
Radiocarbon measuring of primary production of phytoplankton on the shelf of Western Kamchatka in June-July of 2014 revealed difference among the values in the coastal shallow water area, on the depth fall and in the deep-water stations in the entrance to Shelikhov Gulf. Values of P/B were different also, and that should be considered at ecological monitoring of the area.
Keywords: Primary Production of Phytoplankton P/B The Sea of Okhotsk Western Kamchatka Shelf
The shelf of Western Kamchatka is reckoned as one of the most productive parts of the Sea of Okhotsk , known as one of principle high-latitude eutrophic zones of the World Ocean . Complex ecosystem research, of the Sea of Okhotsk, including estimation of primary production of phytoplankton (Рp), was accomplished in the early 1990th. Targeted Pp measurements on the shelf of Western Kamchatka (in the middle part) were provided at 5 stations only . In the other parts of the Sea of Okhotsk Рр was recalculated based on the chlorophyll-а concentration  or on the nutrients stocked .
Geological researches have been provided on the shelf of West Kamchatka since the early 2000th, and estimation of local productivity of sites of the sea interesting for oil-drilling companies is getting vital in this connection. For essence, assessment of aquatic biological resources damage in case of drilling on the shelf uses Р/В of phytoplankton. The purpose of this research was to assess the current level of primary production in the northern part of the Western Kamchatka shelf on results of radiocarbon measurements and to recalculate Р/В of phytoplankton for locations with different depths.
Measurements of Рр were accomplished during cruise of the R/v «TINRO» at 12 stations in the northern part of the Western Kamchatka shelf limited by 54.5 – 58.18 N and 155.09 – 155.31 E (Figure 1) in the period from June 18 to July 10 in 2014. Measuringthe temperatures of the water at every station was carried with using the hydrological complex Sea Bird Electronics (USA), consisted of the hydrological probe SBE Sea logger CTD model 25, the sampler Carousel SBE model 32 and the onboard control unit with sampler Deck Unit SBE model 33. The configuration mentioned provided collecting on-line hydrological data with simultaneous taking samples for evaluation of Рр on the surface and in the thermocline, usually coinciding with the horizon of the maximal oxygen concentration.
The primary production of phytoplankton was to measure by 14C method [6, 7]. Samples of water with phytoplankton poured into 2 transparent and 1 dark plastic flasks 0.5 l, and added 0.2 ml of solution of marked bicarbonate with the strength (R) 1018600 impulse minute-1 ml-1, and exposed in running water in the transparent containers on the deck during 24 hours. After the exposition the water samples were filtered through membrane filters Vladipor with the filtering surface diameter of 35mm and the filtering pore diameter 0.31-0.45 μm in vacuum <0.2 atm. The filter-deposited phytoplankton activity was estimated using the scintillation counter Tri-Carb 2800TR on preliminary washing the filters with the sediments by hydrochloric acid 0.05 N. Рр was calculated from the equation
where Rs – sample radioactivity after 24-hour exposure, impulse minute-1; R – added 14C solution radioactivity; [HCO3– bicarbonate concentration, mg С l-1; 1000 – coefficient to
recalculate per 1 l.]
The bicarbonates were measured at every station in
sampling horizons by the method of direct titration . Light
attenuation coefficient at different depths was calculated from
empiric curves, obtained for July at 5 stations near the coast
of Kamchatka in 1992 . It was found for the sea and Pacific
Ocean waters that euphotic layer power largely depends on the
aquatic transparency , and hence the euphotic zone depths
(EZD) were evaluated as:
where EZD – the euphotic zone depths (m), DS – the aquatic
transparency (m). This correlation was obtained in the analysis
of the curves of the «depth – light attenuation» at the stations
with known aquatic transparency [3, 9].
Daily integral primary production (Pt) was calculated from
multiplication of the means for two horizons (surface and
thermocline) of the daily primary production by the euphotic zone
depths , taking that EZD is generally coinciding with the layer
between sampling horizons for evaluation of Рр. The number of
the microalgae cells was evaluated in the Naumann chamber of
1 ml after a single counting in the microscope OLYMPUS BX40 at
10- and 20-fold magnification in the water samples collected for
evaluation of Рр. Biomass (В) was calculated from multiplication
of the number of every microalgae species by individual volume
of the cells, taking the cell density as 1, and Р/В – as the ratio Pt
to В under m2 in the EZD.
The aquatic transparency was evaluated from Secchi’s white
disk. Stations were reckoned as shallow water in case of the
depth less than 50 m. The stations in the depth range 100–250 m
was thought as at the depth fall, and lower 300 m – as the deepwater
stations near the entrance of Shelikhova Gulf.
During the research period the phytoplankton consisted
of diatoms and autotrophic dinophyts microalga. Up to 90% of
the biomass of diatoms at majority of stations were Chaetoceros
(C. concavicornis, C. debilis, C. decipiens), somewhere Eucampia
zodiacus, Dactyliosolen fragilissimus, Coscinodiscus sp.,
Thalassiotrhix sp. dominated. At several stations up to 4% of the
phytoplankton biomass consisted of the dinophyts Alexandrium,
Heterocapsa, Scrippsiella and the autotrophic representative
The values of the integral primary production of plankton
(Pt) in 2014 in the coastal shallow-water sites (the stations 1–3,
5–7) were highly variable, being averaged in the coastal waters
473 mg C m-2 day-1. Positive gradient in the distribution of the
values was observed along the coast from the south to the north.
The Pt was minimal at the depth-fall sites (the stations 4, 11,
12) everywhere , and the mean was 14,4 mg C m-2 day-1. In the
deep-water sites nearest to Shelikhov Gulf the value was like
the coastal sites (averaged 319 mg C m-2 day-1). The biomass
of phytoplankton (B), like Pt in the coastal stations, varied
extensively (Table 1), averaged being 1978 mg m-2. Very similar
values were observed at the depth-fall (the station 12). The
mean value for these sites was 2799 mg m-2.
The mean value at the deep-water stations in the entrance to
Shelikhov Bay was 687 mg m-2. The evaluation of P/B indicated
that the value varied in all zones and averaged was 0.3 for the
shallow-water sites, 0.02 for the depth-fall sites and и 0.6 for the
deep-water sites. Measuring Pt and P/B in the Sea of Okhotsk in
1992 was made in August generally in more southern area .
Only 4 stations in 1992 were situated within the southern part
of the research of 2014. According to reports , Pt averaged
for the stations was 1158 mg m-2 day-1. Unfortunately, there
were no values of B for the stations mentioned. As for WesternKamchatka in the whole and central part of the Sea of Okhotsk,
Pt was 650 mg m-2 day-1 and P/B – 1.6. In this way, the data we
have obtained are generally comparable, what implies reliability
of the methodological approach and next calculations.
The values of P/B obtained for the waters of the Sea of
Okhotsk near Kamchatka, where exploration work is being done,
were comparable to earlier data. These data are recommended
to use in making simulations of ecological consequences of
anthropogenic activities in the area. Moreover, the depth of the
activities should be considered depending on the site specifics
(coastal shallow-water, depth-fall or deep-water sites), latitudal
and seasonal trends.
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