0000000000934782
AUTHOR
Aivars Yurkovskis
Seasonal succession and growth in the plankton communities of the Gulf of Riga in relation to long-term nutrient dynamics
To study temporal changes in phyto- and zooplankton in the Gulf of Riga monitoring data covering the period of 1972–1995 were analyzed. Changes in external nutrient supply have turned P limitation, during the 1980s, into the present deficiency of Si for the spring bloom. Contrary to depletion of the N and Si pools, the internal sources and sinks were responsible for input of P into the pelagic ecosystem in the 1990s. Restructuring of the nutrient pool reshaped the pelagic planktonic communities. Changes of the species composition and food-web relationships occurred. Till the 1990s, an increase of diatoms in the summer phytoplankton and an increase of herbivores in zooplankton took place. La…
Seasonal benthic nepheloid layer in the Gulf of Riga, Baltic Sea: Sources, structure and geochemical interactions
Abstract The sources of particles, as well as the geochemical structure and interfacial exchange were studied for the summer benthic nepheloid layer of the shallow (50 m) Gulf of Riga. The material was sampled at nine stations during three cruises of August 2001–2003 with a main focus on the deep waters. Suspended particulate matter (SPM) and its major (N, Si, P, Al, Fe, Mn, Ca) elements were determined as the principal parameters. The results indicate the summer benthic nepheloid layer as an important component of the environmental regime of the Gulf of Riga. The nepheloid layer develops as a result of the near-bottom hydrodynamics and a corresponding saline structure below the thermocline…