Estonian Journal of Ecology最新文献

{"title":"Notes on the External Morphology, Ecology, and Origin of Megalomys Desmarestii (Sigmodontinae, Cricetidae, Rodentia), the Extinct Giant Rat of Martinique Island, Lesser Antilles/Markmed Martinique'i Saare (Vaikesed Antillid) Valjasurnud Hiidroti Megalomys Desmarestii (Sigmodontinae, Cricetidae, Rode","authors":"A. Miljutin","doi":"10.3176/ECO.2010.3.04","DOIUrl":"https://doi.org/10.3176/ECO.2010.3.04","url":null,"abstract":"The giant rat of Martinique Island, Megalomys desmarestii (Fischer, 1829) became extinct at the end of the 19th or the very beginning of the 20th century. Little is known about its habits. The goal of this research was to reconstruct its ecology using the external and craniodental morphological characters of available museum specimens. On the basis of ecomorphological analysis some suggestions are made about the locomotor abilities, ecological strategies, adaptive evolution, and origin of this rodent. It is proposed that M. desmarestii foraged mostly on the ground and sheltered in burrows. Its main food was seeds and fruits, including nuts. It was crepuscular rather than strictly nocturnal or diurnal. The general trends of its adaptive evolution were: (1) increasing body size, (2) transition from an arboreal to a terrestrial/subterranean way of life, and (3) adaptation to eating hard-covered fruits. Thus, the ancestor of M. desmarestii was probably smaller and had arboreal or semiarboreal habits. The granulated structure of the soles of M. desmarestii's feet supports a close relationship with Nectomys.","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115723203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Release of available nitrogen from river-discharged dissolved organic matter by heterotrophic bacteria associated with the cyanobacterium Microcystis aeruginosa","authors":"S. Purviņa, Christian Béchemin, M. Balode, Celine Vérité, C. Arnaud, S. Maestrini","doi":"10.3176/ECO.2010.3.02","DOIUrl":"https://doi.org/10.3176/ECO.2010.3.02","url":null,"abstract":"The use of riverine dissolved organic matter by the heterotrophic bacteria associated with a culture of the cyanobacterium Microcystis aeruginosa and release of simple nitrogen compounds were studied in an experimental series. Bacteria reduced the bulk of dissolved organic nitrogen (DON) by half, but when associated with M. aeruginosa, DON was excreted and its concentration rose by 13%. During the stationary growth phase bacteria released ammonium, doubling the concentration of ammonia as well as of nitrates. Bacteria associated with M. aeruginosa consumed riverine DON and joined the ammonification and nitrification process, supplying cyanobacteria with simple nitrogen compounds.","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127855807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The First Finding of the Ponto-Caspian Mysid Shrimp Hemimysis Anomala G. O. Sars (Mysidae) in the Estonian Coastal sea/Ponto-Kaspia Paritolu Musiidi Hemimysis Anomala Esmaleid Eesti Rannikumeres","authors":"J. Kotta, I. Kotta","doi":"10.3176/ECO.2010.3.05","DOIUrl":"https://doi.org/10.3176/ECO.2010.3.05","url":null,"abstract":"The aim of this paper was to provide new data on the nektobenthic crustacean Hemimysis anomala in the Estonian coastal sea using trawling data on the density of mysid species. The non- native shrimp was found for the first time in the Estonian coastal sea in 2009. The species was found only once at the outer Parnu Bay, the Gulf of Riga. The habitat where the species was found was characterized by coarse sand mixed with gravel, clay, and algal debris. The species was associated with the native mysid Neomysis integer. As the abundance of H. anomala was low, it is likely that the species does not affect the structure and functioning of phyto- and zooplankton communities or compete with fish fry for food.","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134159931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of environmental factors on the distribution of caddisfly (Trichoptera) communities in medium-sized lowland streams in Latvia","authors":"Agnija Skuja, V. Spuņģis","doi":"10.3176/ECO.2010.3.03","DOIUrl":"https://doi.org/10.3176/ECO.2010.3.03","url":null,"abstract":"The understanding of community structuring factors is a fundamental issue in community ecology. The objectives of the study were (1) to identify the distribution of the caddisfly community along the stream continuum; (2) to ascertain hydrochemical, hydrological, substrate, and catchment factors responsible for the distribution of communities; and (3) to summarize the key variance types determining the variance in caddisfly communities. Standard methods were used to investigate hydrological and hydrochemical parameters of nine medium-sized streams in 2003. Sampling and processing of samples of macroinvertebrates followed AQEM methods. A total of 28 taxonomic units of caddisflies were analysed. The upper reaches of streams revealed a relatively low abundance of caddisflies while the middle reaches had high abundances. The abundance in the lower reaches varied in a wide range. TWINSPAN separated the caddisfly species into two distinct groups. One group represented lithal habitat and rheophilous species. The other represented stream reaches with fine mineral sediments rich in organic matter of different size. Hydrochemical and physical variables explained the majority of variance in the preferences of caddisflies to bottom type and other environ- mental parameters, while all studied variables together explained up to 58% of the data variance. Thus, caddisflies could be used to study the influence of local and regional factors on stream ecosystems. The results of the present study could be also applied in practice to solve problems related to the evaluation of the ecological quality of running waters using benthic macro- invertebrates.","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130306564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cool winters versus mild winters: effects on spring plankton in Lake Peipsi.","authors":"R. Laugaste, J. Haberman, K. Blank","doi":"10.3176/ECO.2010.3.01","DOIUrl":"https://doi.org/10.3176/ECO.2010.3.01","url":null,"abstract":"The influence of two winter periods with a different duration of the ice cover on Lake Peipsi (Estonia) on plankton and nutrient content was analysed. The winters of 2005 and 2006 were cold with ice duration of 140 days, whereas the winters of 2007 and 2008 were mild with about 50 and 15 days of ice duration, respectively. Total phosphorus (TP) concentration was lower, while silicon content and the nitrogen-phosphorus ratio (TN : TP) were markedly higher in the springs after the short winters of 2007 and 2008. The high Si concentration and TN : TP ratio persisted throughout the growing season of those years. Unicellular centric diatoms showed a sharp increase in April 2008, while the large filiform diatom Aulacoseira islandica dominated in the cool winters and after ice break-up. The high spring peak of diatoms was followed by their low biomass in summer. In May 2008, total zooplankton biomass, cladoceran biomass, and rotifer biomass were two times and that of copepods three times as high as in the Mays after the long-lasting ice cover. In the Junes after the mild winters the biomasses of total zooplankton and both crustacean groups (Cladocera, Copepoda) were about two times as high as the corresponding indicators for the Junes after the cool winters. The biomass of rotifers, on the contrary, was two times lower in the Junes after the warm winters because the numerous cold stenotherms Polyarthra dolichoptera and Synchaeta verrucosa had totally disappeared from zooplankton. The influence of ice duration on phyto- plankton is most likely indirect, acting through nutrients, and on zooplankton direct, acting through water temperatures. The springs after warm winters related positively to zooplankters' mean weight, zooplankton-phytoplankton biomass ratio, and the timing of the clear water period.","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126991165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Macro- and meiozoobenthos in some small stratified lakes of Estonia.","authors":"H. Timm, T. Möls, T. Timm","doi":"10.3176/ECO.2010.2.03","DOIUrl":"https://doi.org/10.3176/ECO.2010.2.03","url":null,"abstract":"Macro- and meiozoobenthos (300 samples with a 225 cm 2 Boruckij grab and 180 with a 6.38 cm 2 corer) from unvegetated, soft-bottom areas in ten small stratified lakes were studied in July-August 1998-1999. The sampling sites were located just above, in the middle, and below the position of the metalimnion in each lake. Chironomidae and Oligochaeta were common in both macro- and meiozoobenthic samples but more abundant (by an order of magnitude) in the latter because the smallest individuals were included. The meiobenthic samples were dominated by planktonic crustaceans, particularly Cyclopoida, with respect to abundance while most of their biomass was formed by the macrobenthic animal groups. Eumeiobenthos sensu stricto, such as Nematoda, Ostracoda, etc., were scarce. Thirty-three variables (abundance, biomass, and number of taxa in different samples) were related to water layer (epi-, meta-, and hypolimnion), sampling depth, lake, year, and O2 saturation %. Most variables depended on lake but not on year. Abundance and biomass of the studied taxa and the number of taxa of macrozoobenthos per sample decreased significantly from the epi- to hypolimnion, except for Chaoborus flavicans, which was more abundant in deeper layers of water. From the results of ANOVA, it was concluded that the biomass and abundance of Chaoborus, biomass of Hydrachnidia, abundance of Chironomidae and other 'large' animals in the meiobenthic samples, as well as the number of taxa of macrozoobenthos per sample did not follow the layers but only the depth. The distribution of the biomass of macrozoobenthic Chironomidae as well as the total biomass and abundance of macrozoobenthos without Chaoborus were more tied to separate layers. For the majority of individual taxa no dependence on depth was found. Discriminant analysis revealed a rather weak separation of the water layers in summer by the benthic characteristics. An index formed of 33 variables of zoobenthos with the highest statistical significance for testing the depth effect (Depth Index) revealed the most apparent changes in environmental conditions in the upper part of the metalimnion.","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128047797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal distribution and richness of fish species in the Badagry Lagoon, south-west Nigeria","authors":"O. O. Soyinka, M. Kuton, C. Ayo-Olalusi","doi":"10.3176/ECO.2010.2.05","DOIUrl":"https://doi.org/10.3176/ECO.2010.2.05","url":null,"abstract":"We recorded 37 fish species representing 21 families in the Badagry Lagoon, south-west Nigeria. Adult stages of 13 (35.14%) of them were freshwater, 7 (13.51%) estuarine, and 19 (51.35%) near-shore marine species. The seasonal variation in the fish catch composition of the lagoon was attributed to the seasonal fluctuation in salinity. Availability of food organisms was also noted to affect the seasonal distribution of the fish fauna. Other physical features such as temperature and pH varied slightly, while the concentration of dissolved oxygen was higher in the dry season than in the rainy season. The highest species richness was observed in September with 11 species, while the lowest with the smallest abundance was observed in February with 5 species. The most abundant species during their occurrence were Cynoglossus senegalensis (7.92%), Tilapia mariae (7.17%), and Ilisha africana (6.04%). Species richness and total abundance were found to increase during the rainy season.","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131891244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Eutrophication level of Phragmites australis habitats at a shallow coastal lake, Paljassaare Peninsula, Tallinn.","authors":"T. Elvisto","doi":"10.3176/ECO.2010.2.01","DOIUrl":"https://doi.org/10.3176/ECO.2010.2.01","url":null,"abstract":"The eutrophication level of a lake situated in the centre of the Paljassaare Peninsula, Estonia, was estimated using chemical characteristics of common reed (Phragmites australis). Comparison with other Estonian waterbodies revealed considerable differences. The N and P concentrations in the leaves and the N concentration in the stems of P. australis during the phenophase of early flowering were in Paljassaare (data from 11 sampling sites) 1.5-2-fold higher than in the eutrophic Lake Vortsjarv, in the high-productivity delta of the Kasari River, and in the Vaike Vain Strait. For P in stems the differences were even greater. The N/P ratio in P. australis shoots indicated N limitation in the lake and seashore on the Paljassaare Peninsula (N/P ratio 6-11), the Kasari River delta (ratio 8), and the Vaike Vain Strait (ratio 12), but P limitation in the oligotrophic Lake Tanavjarv (ratio 21). In the eutrophic Lake Vortsjarv the accessibility of N and P is probably balanced (N/P ratio 15). As large amounts of nutrients have accumulated in the lake on Paljassaare, the process of its growing over has accelerated during the last decade.","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126895357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temporal and spatial variation in the zooplankton : phytoplankton biomass ratio in a large shallow lake","authors":"K. Blank, R. Laugaste, J. Haberman","doi":"10.3176/ECO.2010.2.02","DOIUrl":"https://doi.org/10.3176/ECO.2010.2.02","url":null,"abstract":"INTRODUCTION Research of large lakes is highly complex as such lakes expand over a large area and are affected by an enormous number of different climatic and environmental factors (Blenckner, 2008). Various specific indicators and indexes are needed to facilitate the understanding of the state (and its changes) of large lakes. The zooplankton : phytoplankton biomass ratio ([MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]) largely reflects the type (effectiveness) of the food web in a water body and hence the nature of the ecosystem. Indirectly, it characterizes dominating groups in phyto- and zooplankton, feeding relationships between them and fish, as well as the pressure of fish on zooplankton. The [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] ratio can be used as a marker criterion for the evaluation of the trophy of a water body and its ecosystem and, particularly, for permanent monitoring of a water body. This ratio decreases with the rise of the trophic state (Gulati, 1983; Andronikova, 1996; Jeppesen et al., 1999, 2000, 2005; Haberman & Laugaste, 2003). It is widely recognized that phytoplankton is influenced most by nutrients (bottom up) while zooplankton is influenced both by consumers (top down) and algae (bottom up). This causes their different seasonal dynamics and complicated relevant ratios. Thus, the values of the [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] ratio are fluctuating within and across years. This variability has not been thoroughly analysed. Some data concerning this ratio for L. Peipsi have been published on the basis of plankton sampled up to the end of the last century (Haberman, 1996; Haberman & Laugaste, 2003; Noges & Noges, 2006). As the situation in the lake has changed markedly during this decade, a new analysis of the ratio has been initiated. About two decades ago, the ecosystem of the lake was in a quite good balance, and an effective algal food web prevailed in the open water (Noges et al., 1993). Since the late 1990s and during the 2000s, the ecosystem of the lake lost its stability. The proportion of cyanobacteria in the biomass of summer phytoplankton increased consistently: from 20% to 70% in L. Peipsi sensu stricto (s.s.), and from 30% to 90% in the southern lake parts (Laugaste et al., 2007). An appreciable concentration of microcystins was detected in the lake water in the summer months of the 2000s (Tanner et al., 2005), and the biomass of the genus Microcystis exceeded 20 g [m.sup.-3] in the southern lake parts in some years. At the same time, a continuous decline in zooplankton (Haberman et al., 2008) and changes in fish population (Kangur et al., 2008) were observed. The stock of planktivorous smelt (Osmerus eperlanus eperlanus m. spirinchus Pallas) and vendace (Coregonus albula (L.)) decreased drastically, and the abundance of piscivorous pikeperch (Stizostedion lucioperca (L.)) increased but, owing to over-fishing, the amount of pikeperch is modest (Kangur et al., 2008). Noges ","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130404514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative study of three alternative methods of aging Baltic flounder (Platichthys flesus)","authors":"T. Drevs, T. Raid","doi":"10.3176/ECO.2010.2.04","DOIUrl":"https://doi.org/10.3176/ECO.2010.2.04","url":null,"abstract":"Age reading is a major source of uncertainty in the assessments of fish stocks. The paper presents preliminary results of alternative approaches to estimating the age (year-class) structure of Baltic flounder, Platichthys flesus. The size structure of catches and the weight distribution of otoliths were analysed using Bhattacharya's method to distinguish between different cohorts (year classes). The traditional counting of annual growth zones on otoliths yielded the greatest number of age groups (12). Age determination by Bhattacharya's analysis of otolith weight frequencies enabled to distinguish between 7 cohorts. Bhattacharya's analysis of length frequencies of the same material allowed distinguishing 5 or 6 different groups. Theoretical weight distributions of otoliths, calculated by Bhattacharya's method for age groups 1 and 6, were not significantly different from the corresponding distributions of weights of otoliths obtained by the method of counting annual rings. The importance of random selection of individuals for the determination of the age structure of catch by annual rings of otoliths is emphasized.","PeriodicalId":262667,"journal":{"name":"Estonian Journal of Ecology","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134215591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}