Izšķīdušo organisko vielu bioloģiskā izmantojamība bakterioplanktona un fitoplanktona klātbūtnē Rīgas līcī

Abstract

Izškidušo organisko vielu biologiska izmantojamiba bakterioplanktona un fitoplanktona klatbutne Rigas lici Upju izškidušas organiskas vielas (DOM) nepartraukti papildina iesalo udenu ekosistemas, veicinot to produktivitati. Masveida savairošanos Baltijas jura vasaras izraisa galvenokart slapekli fiksejošas cianobakterijas, bet Rigas lica piekraste ari Microcystis aeruginosa. Promocijas darba ir noskaidrota ar huminvielam bagatas alohtonas DOM biologiska izmantojamiba un ietekme uz iesalu udenu bakterioplanktona - fitoplanktona sabiedribam. Upju ienesta DOM tiek paklauta mikrobialai degradacijai jau piekrastes rajonos, bet atklatos udenos bakterioplanktons izmanto autohtonas organiskas vielas. Ar cianobakterijam asocietas heterotrofas bakterijas mineralize alohtono DOM, atbrivojot vienkaršus, viegli izmantojamus slapekla savienojumus (nitratus, nitritus un amoniju), nodrošinot M. aeruginosa ar viegli izmantojamiem slapekla savienojumiem. Atslegas vardi: heterotrofas bakterijas, Microcystis aeruginosa, DOM, DON, Rigas licis

Biological use of dissolved organic matter by bacterioplankton and phytoplankton in the Gulf of Riga River brought dissolved organic matter (DOM) continuously supplements coastal ecosystems, contributing to the productivity increase. Massive proliferation of phytoplankton in the Baltic Sea in summers is mainly caused by nitrogen-fixing cyanobacteria, but in coastal areas of the Riga Gulf also by Microcystis aeruginosa. In dissertation is studied the contribution of brackish heterotrophic bacteria in biodegradation of humic rich DOM and its effect on development of phytoplankton and bacterioplankton communities. Riverine DOM is exposed to microbial mineralization already in coastal areas but in open waters bacterioplankton use autochthonous organic matter. Bacteria associated with M. aeruginosa consume riverine DOM and join ammonification and nitrification process, supplying cyanobacteria with simple nitrogen compounds. Kay words: heterotrophic bacteria, Microcystis aeruginosa, DOM, DON, the Gulf of Riga