CONTENTS & ABSTRACTS

In English. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.

Biology. Ecology

Volume 53 No. 2 June 2004

Variability of genitalia and pheromone communication channels of Archips podana (Scopoli) (Lepidoptera: Tortricidae); 75–87

Ilme Liblikas, Enno Mõttus, Zoya V. Nikolaeva, Ann Ojarand, Anna-Karin Borg-Karlson, Elena I. Ovsyannikova, Igor Ya. Grichanov, Tamara V. Ivanova, and Viktor A. Yemelyanov

Abstract. The large fruit-tree tortrix Archips podana (Scopoli) is a widely distributed species in the whole of Europe. The species is variable in male genitalia. According to the different number and position of apical (A) and lateral (L) spikes on the aedeagus, A, L, 2L, AL, A2L, and 0 (without spike) phenotypes were discriminated. To determine the variability of pheromone communication of A. podana, field trap tests were conducted in different habitats and geographical regions in Estonia (Uhti and Otepää), northwestern Russia (Velikie Luki, Pskov Region), and the North Caucasus (Krasnodar Territory). The optimum content of Z-11-tetradecenyl acetate in pheromone blend, calculated using the Gaussian curve, was on average 61.3 ± 1.3%. This is practically identical to the ratio of 60 : 40 in the mixture of (Z)- and (E)-11-tetradecen-1-yl acetates identified by Persoons et al. (1994, J. Insect Physiol., 20, 1181–1188). Experiments demonstrated that the optimal pheromone composition was the same in Krasnodar, where the L phenotype dominates, and in Velikie Luki and Estonia, where A phenotype males dominate. A deviation of attractive blend from optimum ratio causes a comparable decrease in trap catches for males of different aedeagus forms. The Caucasian subspecies with a lateral spike (male phenotype L), A. podana meridiana Kozl. et Esart., is placed in synonymy to nominotypical species in this paper. Calculation of pheromone communication parameters – channel width and optimal ratio – is an effective tool for ecochemical research and dispenser modelling.

Effect of coloured dissolved organic matter on the attenuation of photosynthetically active radiation in Lake Peipsi; 88–105

Anu Reinart, Birgot Paavel, and Lea Tuvikene

Abstract. On the basis of underwater radiation measurements and laboratory analyses of water samples, the effect of coloured dissolved organic matter (CDOM) on the light field in the largest Estonian lake, Lake Peipsi, was investigated. CDOM variation and its optical properties were compared with two other large European lakes, Vänern and Vättern in Sweden, as well as with 41 small lakes in Estonia, Sweden, and Finland. The light absorption coefficient at 380 nm for filtered water varied from 4.1 to 16.7 m^–1 with the highest values close to the inflow of the Suur-Emajõgi River. CDOM values in L. Peipsi are in the same range as measured earlier in small Estonian and Finnish lakes. Various optical water types (“brown”, “moderate”, “turbid”) were sampled over L. Peipsi. It is shown that the use of GF/F filters results in on average 4% higher absorption values than the use of filters with pore size 0.2 mm, and the effect might be up to ± 20% in clear waters. Comparison of spectral measurements of diffuse attenuation coefficient with three-band spectrometer’s data showed high consistence of datasets. This allows supplementing the existing database of optical properties of lakes in Estonia with new data from L. Peipsi.

Total organic carbon load on the Gulf of Finland from its Russian catchment area; 106–115

Sergey A. Kondratyev, Galina A. Alyabina, Igor V. Bovykin, and Igor N. Sorokin

Abstract. The studies based on the fieldwork of 1991–93 and 1996–98 show that the highest total organic carbon emission in the Russian area of the Gulf of Finland catchment originates from urban areas and forests. The total organic carbon washout from the northern areas of the catchment is about 10% higher than from the southern areas. This is due to differences in the annual runnoff and soil types. The results of the application of a mathematical model to an experimental catchment show that a doubling of the agricultural area would lead to a 19% decrease in the annual total organic carbon load. However, a 4% increase in the annual total organic carbon load would be expected in the second half of the 21st century as a response to future climate change.

History of ecosystem studies of the Gulf of Riga (Baltic Sea); 116–143

Henn Ojaveer and Andris Andrushaitis

Abstract. Compared to some abiotic data, observations on biotic components of the ecosystem of the Gulf of Riga have about two centuries shorter history: the first known notes on flora and fauna date back to the mid-18th century whereas almost continuous ice breakdown data in the Riga harbour exist since the first half of the 16th century. The first scientific cruise, the Russian Baltic expedition, was carried out in 1908–09. Then the first data on planktonic organisms were obtained. Systematic investigations were performed independently in the northern and southern parts of the gulf by the bordering countries since the mid-1920s. However, until World War II most studies were descriptive. In the late 1940s comprehensive ecosystem studies were commenced. Strong emphasis was put on commercial fish stocks with causative and predictive approach. Although some previously initiated studies have been continued or expanded, some long-term datasets were broken in the second half of the 1990s.