Naslov
Alkaline phosphatase activity in the NE Adriatic

Autori
Hrustić, Enis ; Carić, Marina ; Garić, Rade

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Proceedings of the tenth international conference on the mediterranean coastal environment / Özhan, Erdal - Dalyan : MEDCOAST, Mediterranean Coastal Foundation, 2011, 521-532

ISBN
978-605-88990-8-7 2

Skup
Tenth international conference on the mediterranean coastal environment (Medcoast 2011)

Mjesto i datum
Rodos, Grčka, 24.10.2011. - 30.10.2011

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Adriatic Sea; Alkaline phosphatase activity; Coastal channels; Deep chlorophyll maximum; Microtidal estuary; Nutrients; Phytoplankton composition; P-limitation; Thermohaline gradient; Transition zone

Sažetak
Velebit and Pag channels represent the deepest part of the north Adriatic Sea (80 - 110 m). Research was carried out during summer stratification period in July 2007. and winter mixing period in February 2008. at 8 stations deep to shallow profile in Pag Channel PC (P3, P2, P1), Velebit Channel VC (V4, V3, V2, V1) and Zrmanja Estuary (N1). The focus was directed to hydrographic parameters, nutrient analysis and alkaline phosphatase activity in phytoplankton APAP (1.2 - 53 μm cell size). In summer, deep chlorophyll maxima DCM (50 m and deeper) were developed along the channels. APAPmax (22.08 nM PO43- h-1) was detected in the Velebit Channel (V1). Specific APAPmax (Chl a to C biomass approximation) confirmed the highest phosphate deficiency stress in surface layer (0 – 4 m) of the most outer station P3 (123.00 nmol PO43-/μg C h) what was two orders of magnitude greater than average in the rest of the investigated area. Extremely low specific APAP detected in chlorophyll maxima depths (0.01 - 0.05 nmol PO43-/ μg C h) suggest probably greater share of smaller phototrophs (< 1.2 μm) in formation of deep chlorophyll maxima as well as unknown APAP remained uncaptured (> 53 μm ; < 1.2 μm). Low phosphate concentrations (0.01 - 0.05 μM), slightly higher organic P concentrations (0.02 - 0.20 μM) and high TIN/PO43- ratios (32 - 359) indicated P-limitation. In winter, outer stations in Pag Channel (P3 and P2) had deeper chlorophyll maxima (> 60 m) with lower Chl a concentrations (0.51 - 0.69 μg/l) than in middle (P1-V2) and lower part (V2-V1) of the channel system where maxima (0.7 - 6.05 μg/l) were positioned in range (17 – 25 m). Winter APAP are in the same order of magnitude as in summer but specific APAP are in average 45% of summer ones. Specific APAP in both seasons were decreasing from outer to inner stations. Sharp salinity gradients, horizontal and vertical, existing in the lower part of the channel system in both seasons, define the area as outer part of microtidal Zrmanja Estuary. General increase of average nutrients and Chl a concentrations from Pag and Velebit Channel towards mainland and opposite direction of specific APAP trend, reveals Zrmanja river flow rate as significant factor controlling the trophic gradient along the channel system as well as P- limitation.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Kemija, Biologija

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