Alkaline phosphatase activity in south Adriatic Sea

Hrustić, Enis (2013) Alkaline phosphatase activity in south Adriatic Sea. Doctoral thesis, Faculty of Science > Department of Geology.

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Abstract

South Adriatic is oligotrophic basin with moderate eutrophication in deep layers of Mljet Lakes and surface layer of Ombla Estuary due to greater river flow in winter. Phytoplankton growth was dominantly P – limited. The greatest phytoplankton biomass was detected in Small Lake (Malo jezero). The most pronounced P – limitation was coupled with minimal biomass of phytoplankton in South Adriatic Pit. When PO4 was < 0.05 μM, phytoplankton and picoplankton sAPA maxima were detected. PO4 concentration rise from < 0.05 μM towards 0.05 – 0.1 μM was accompanied by shift from intense to weaker AP synthesis in phytoplankton. The most significant phytoplankton biomass developed when PO4 was 0.1 – 0.2 μM. In PO4 range 0.2 – 0.5 μM abrupt fall of phytoplankton biomass, high phytoplankton sAPA and APA of plankton greater than 53 μm in total APA were detected. Fall of phytoplankton sAPA with rising TIN/PO4 was probably connected to phytoplankton growth and assimilation of N and P in ratio < than ambiental TIN/PO4. APA of free enzymes was positively correlated with limitation of phytoplankton growth. Nanophytoplankton synthesized significantly greater amount of AP per biomass than microphytoplankton and picoplankton. Temperature corrected summer means of phytoplankton sAPA at Lokrum and P-1200 were greater than phytoplankton sAPA in North Adriatic and other neighbouring seas. sAPA of picoplankton in South Adriatic was lower compared to North Adriatic. In Great Lake (Veliko jezero) during summer 236 fold greater mean of picoplankton sAPA and 21.6 fold greater mean of phytoplankton sAPA were detected in comparison to winter. Minimal means of total APA and Chl a concentration were confirmed in Great Lake during autumn when the strongest surface currents in Mljet aquatory were expected.

Item Type: Thesis (Doctoral thesis)
Keywords: P - limitation, alkaline phosphatase activity, phytoplankton, South Adriatic
Supervisor: Carić, Marina
Date: 2013
Number of Pages: 131
Subjects: NATURAL SCIENCES > Geology
Divisions: Faculty of Science > Department of Geology
Depositing User: Sonja Borak
Date Deposited: 10 Feb 2014 11:58
Last Modified: 10 Feb 2014 11:58
URI: http://digre.pmf.unizg.hr/id/eprint/388

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