CONTENTS & ABSTRACTS

In English. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.

Biology. Ecology

Volume 53 No. 4 December 2004

Special issue on the Estonian coastal sea

Foreword; 233–235

Jonne Kotta and Georg Martin

Historical review of the literature on phytobenthic investigations in the Gulf of Riga; 236–250

Georg Martin, Erich Kukk, Henn Kukk, and Jonne Kotta

Abstract. Phytobenthic investigations in the area of the Gulf of Riga date back as far as the end of the 18th century. Since then a large number of investigations have been carried out in the area resulting in numerous publications in various local and wide-spread European languages. The aim of the present paper is to give a detailed review of the knowledge concerning the species composition and quantitative distribution of phytobenthos in the area. For historical reasons, a great part of the scientific literature from the area is in the Russian, Estonian, or Latvian language. These works contain valuable information useful now that investigations have become truly international and large-scale around the Baltic Sea. The present paper gives a review of 85 papers or other published materials and presents the most important conclusions and facts. A comparative list of species of macroalgae and phanerogams ever identified from the area is given with references to the authors.

Key words: macrophytobenthos, Gulf of Riga.

Environmental factors affecting the distribution of charophyte species in Estonian coastal waters, Baltic Sea; 251–259

Kaire Torn and Georg Martin

Abstract. Charophyte communities from 77 locations in the Estonian coastal sea were described according to their community structure and complex of environmental factors. The influence of depth, exposure, substrate quality, and salinity on the charophyte community structure was analysed. Depth turned out to be the most important structuring factor for charophyte communities while substrate quality and exposure ranked second. Salinity had no influence on the community structure within the observed interval. The most exposure tolerant species were Tolypella nidifica and Chara aspera. Chara aspera was also least selective about the substrate quality.

Key words: Charophytes, Baltic Sea, depth distribution, substrate quality, salinity, exposure.

Distribution and dynamics of drifting macroalgal mats in Estonian coastal waters during 1995–2003; 260–268

Tiina Paalme, Georg Martin, Jonne Kotta, Henn Kukk, and

Kaire Kaljurand

Abstract. The occurrence of drifting algal mats has become a widespread phenomenon in shallow coastal waters of the Baltic Sea. In Estonian coastal waters the drifting algal mats were found on sandy-clayey bottoms in relatively shallow and sheltered bays. Except for a few localities of the Gulf of Finland, Pilayella littoralis or Ectocarpus siliculosus prevailed in the drifting algal mats. The abundance of invertebrate feeding types (herbivores or detrivores) was related to the physiological state of the macroalgae in the mat.

Key words: Cladophora glomerata, detrivores, drifting macroalgal mats, Estonian coastal waters, herbivores, Ihasalu Bay, Kõiguste Bay, Pilayella littoralis, spatial distribution.

Changes in the feeding behaviour of benthic invertebrates: effect of the introduced polychaete Marenzelleria viridis on the Baltic clam Macoma balthica; 269–275

Jonne Kotta, Helen Orav-Kotta, and Eva Sandberg-Kilpi

Abstract. The exploited feeding areas of Macoma balthica and Marenzelleria viridis were experimentally quantified in laboratory conditions. Our feeding trials showed that M. balthica was able to feed at a much wider surface area than M. viridis. Moreover, in the presence of M. viridis the feeding area of M. balthica and its cumulative increase in time were significantly higher than without the polychaete. These results suggest that M. balthica is superior to M. viridis in terms of feeding. The experiment supports the earlier findings that the presence of M. balthica appears to be a key factor limiting the further expansion of M. viridis in the northern Baltic Sea.

Key words: Baltic Sea, interspecific competition, invasion, Marenzelleria viridis, Macoma balthica.

Cercopagis pengoi (Cladocera) in the Gulf of Finland: environmental variables affecting its distribution and interaction with Bosmina coregoni maritima; 276–282

Arno Põllumäe and Katrin Väljataga

Abstract. The Ponto-Caspian predatory cladoceran Cercopagis pengoi was first found in the Gulf of Finland in 1992. The distribution of the species was followed in 1997–2002 in relation to selected most important abiotic and biotic environmental factors. The abundance of C. pengoi was best explained by thermal stratification and density of Cladocera. The significant negative correlations between the vertical distribution of the small cladoceran Bosmina coregoni maritima and the abundance of C. pengoi indicate that C. pengoi affects the vertical distribution of its potential prey B. c. maritima.

Key words: Cercopagis pengoi, invasion, Baltic Sea, Bosmina coregoni maritima.

Comparison of macrozoobenthic communities between the 1960s and the 1990s–2000s in the Väinameri, NE Baltic Sea; 283–291

Helen Orav-Kotta, Jonne Kotta, and Ilmar Kotta

Abstract. Macrozoobenthic communities were studied in the Väinameri archipelago sea during the summers of 1993–2003. When comparing these data with the historical observations from the 1960s the following conclusions were drawn. (1) During the last 30 years the crustaceans Gammarus locusta, Leptocheirus pilosus, Monoporeia affinis, Bathyporeia pilosa, and Idotea baltica and the polychaetes Harmothoe sarsi and Pygospio elegans have disappeared or their densities have decreased considerably. (2) The majority of these changes were due to the hydrological changes during last 30 years. The decreasing salinity resulted in the disappearance of G. locusta, H. sarsi, and P. elegans and a reduction of the distribution of B. pilosa. (3) The general increase in the eutrohpication of the Baltic Sea had no effect on the species composition of macrozoobenthos whereas on average a fourfold increase in the biomass was observed. (4) The North-American polychaete Marenzelleria viridis invaded the Väinameri in 1995. However, the species has failed to establish at high densities in the study area.

Key words: Baltic, distribution, Furcellaria, macrozoobenthos, Marenzelleria, temporal changes.

Microevolution of eelpout, Zoarces viviparus, in the Baltic Sea; 292–305

Henn Ojaveer, Margit Eero, and Ain Lankov

Abstract. Zoarces viviparus was sampled in various sub-basins of the Baltic Sea (Gulf of Finland, Gulf of Riga, and Baltic Proper) by different biotopes (eurytherm, cold stenotherm, and their transition areas). The somatic growth rate, absolute fecundity, and number of vertebrae differed significantly between the biotopes suggesting the existence of different eelpout populations in the northeastern Baltic. Adaptation of the originally cold stenotherm eelpout enabled the fish to occupy the more productive eurytherm biotope and thus facilitated an increase in the abundance of the species. An important precondition for this was the existence of transitional abiotic conditions that promoted the break of the species through the temperature barrier, but also simultaneous or earlier adaptation of the cold stenotherm invertebrate prey complex to the eurytherm conditions. As a result of adaptations, the phenotype of the species has changed compared to the original (stenotherm) stock. Adaptation of the fish to new conditions has not caused changes in its intraovarian growth.

Key words: Eelpout, Zoarces viviparus, cold stenotherm and eurytherm environment, growth rate, fecundity, number of vertebrae, diet composition, adaptation.

Re-allocation of the Baltic herring fishing possibilities; 306–316

Robert Aps, Hans Lassen, Jake C. Rice, Ksenia Andrejeva, and

Jaan Aps

Abstract. Re-allocation of the Baltic herring fishing possibilities is based on a new biological information on the fish stock identity. Any revised allocation scheme must secure that each country maintains as close as possible its Total Allowable Catch (TAC) share it would be entitled to under the existing allocation scheme irrespective of the area split and independently of how the TAC might be composed. Possible the theoretical solutions to the problem of fishery resource re-allocation are exemplified by an analysis of the proposed split of the management areas for the herring resources in the Baltic Sea. as managed by IBSFC As a basic principle it is proposed that anythis quota re-allocation related mismatch of fishing interests be solved through quota swaps and buying/selling of quotas among the countries. A quota swap may involve different species, for example swapping quotas of cod for quotas of herring. This requires that a price per quota unit be established for the individual species perhaps on a stock level.

Key words: Baltic herring, shared fishery resources, value based fishing quota allocation, fishingfishery quota swaps.

Instructions to authors; 317–320

Copyright Transfer Agreement; 321

Contents of volume 53; 322–324