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1.
Summary Algal assemblages of the Urals and Siberia belong to two biogeographical belts: The equatorial Mediterranean and the Siberian
belt. They differ in the composition of their agla floras. The end of the Famennian and the beginning of the tournaisian were
indicated by smaller differences due to short-term connections of the basins which lie in different climatic belts. The development
of the microfloras of the Urals and Siberias during the late Tournaisian exhibits two different trends. These differences
were intensified during the Visean and reached their climax in the Serpukhovian. In general, redalgae, especially Stacheinaceae,
were predominant in the late Carboniferous basins of the Urals. The Visean and Serpukhovian algae of Siberia comprising usually
more than 20 genera (e.g.Calcifolium, Fasciella, Ungdarella) were widely distributed in the Urals as well as in other provinces of the Mediterranean belt.
The biogeographical zonation based on the study of algal floras confirms the existence of an Eurasian realm in the Mediterranean
belt and several Siberian provinces as well as an intermediate Taimyr-Chukotkian area, which had already been postulated from
earlier foraminiferal studies. All of these provinces exhibit distinct features in the development of their algal associations,
e.g. the Kolyma-Omolon province is characterized by its predominance of green algae, while in the Altai-Sayan and the Verkhoyansk
provinces red algae prevail. These characteristic trends can be observed over rather long stretches of time. 相似文献
2.
V. I. Ermolaev 《Contemporary Problems of Ecology》2009,2(4):388-391
The study deals with phytoplankton biodiversity in mesotrophic Sartlan Lake, a large natural saline water body in the south of West Siberia. Two different approaches are used: floristic and ecological cenotic. The former is good for determining and analyzing the phytoplankton species composition. The latter gives a quantitative estimation of the phytoplankton biodiversity from the equation of information theory: $ H_b = - \sum\limits_{i = 1}^n {\frac{{B_i }} {B}\log _2 \frac{{B_i }} {B}} The study deals with phytoplankton biodiversity in mesotrophic Sartlan Lake, a large natural saline water body in the south
of West Siberia. Two different approaches are used: floristic and ecological cenotic. The former is good for determining and
analyzing the phytoplankton species composition. The latter gives a quantitative estimation of the phytoplankton biodiversity
from the equation of information theory: , where H
b
is the biodiversity (bits); B
i
is the population biomass of the species i; B is the entire phytoplankton community biomass (mg/l). A reliable stable negative correlation exists between the phytoplankton
biomass and species diversity. Analytical equations and a diagram are given to illustrate the correlation between these values.
Original Russian Text ? V.I. Ermolaev, 2009, published in Sibirskii Ekologicheskii Zhurnal, 2009, Vol. 16, No. 4, pp. 623–628. 相似文献
3.
Igor Korovnikov Nikolay Sennikov Taniel Danelian Olga Obut Lauren Pouille 《Annales de Paléontologie》2013
The presence of one of the oldest records of polycystine Radiolaria in the Lower Cambrian sedimentary sequence of the Ak-Kaya section (Gorny Altai) requires a biostratigraphic dating. The trilobites found recently a few tens of meters below the radiolarian-bearing level belong to Calodiscus resimus Repina, Serrodiscus fossuliferus Repina and Alacephalus aff. contortus Repina; they suggest that this part of the Shashkunar Formation can be correlated with the lower part of the Botomian stage. The absence of eyes in the two former species suggests a mode of life buried in the fine pelagic sediments. Indications of the presence of a strongly developed musculature on the third species point to a palaeoenvironment characterized by a relatively high hydrodynamic regime. 相似文献
4.
R. Allen Curry Chad A. Doherty Timothy D. Jardine Steven L. Currie 《Environmental Biology of Fishes》2007,79(1-2):49-60
The muskellunge was introduced in the Saint John River system from stockings in a headwater lake in the 1970s. They have migrated
down the system as far as the river’s first dam, Mactaquac Hydroelectric Facility, at Fredericton and appear to have established
several reproducing populations along the river. This exotic invader represents a potential threat to the severely depleted
Atlantic salmon stocks in the river. We radio-tracked muskellunge over a 2-year period in the middle reaches. Home ranges
extended to ∼100 km in both riverine and lacustrine areas, including 78% of individuals trans-located upstream of the dam
making their way back through the dam successfully. Downstream of the dam, home ranges were <25 km. No spawning areas were
detected. An isotope analyses of diet indicated that the large sub-adults and adults had established the greatest proportion
of their biomass in a more 15N depleted environment typical of areas farther upstream. Isotope mixing models could not accurately determine the proportion
of Atlantic salmon smolts that may have been consumed by muskellunge, but anadromous salmon had ≤7% probabilities of being
in the diet. A bioenergetics model suggested ≤5% of the annual food intake by muskellunge occurs during the smolt out-migration
period. For the Saint John River, the impacts of growing numbers of muskellunge are multi-faceted creating a complex management
challenge. Muskellunge appear to minimally increase predation risk for Atlantic salmon smolts while their increasing numbers
are creating a growing recreational fishery and potential threat to the native fish community and ecosystem. 相似文献
5.
Oxygen concentration profiles have been measured, by means of with microelectrodes in sediments of Lake Baikal and Lake Malawi,
along transects allowing to give a survey of two major ancient Rift lakes: Lake Baikal (Eastern Siberia) and Lake Malawi (East
Africa), along depth transects in the constitutive basins of the lakes and/or of relevant depths with regard to oxygen (including
including the deepest point, 1680 m, in Lake Baikal). Sediment oxygen penetration depths (SOPs) display very different patterns,
depending on the lake in the two lakes. In Lake Baikal, SOPs are variable, show no significant relationship with bathymetric
depth and are surprisingly deep on Akademichesky ridge (> 50.0 mm), emphasizing the distinctive feature of this region in
the lake. While the Selenga river is an important source of eutrophication, the similarity of SOP-values in the Selenga shallow
with those of most other sites suggests either a dilution of organic material by allochthonous matter, or a strong south-to-north
transport of particles. In Lake Malawi, available oxygen is restricted to a maximum of three millimetres of the sediment,
and there is a negative relationship with bathymetric depth, as a result of a steady decline of oxygen concentration with
depth through the water column. Amongst the few parameters known to affect SOPs, the oxygen consumption by the sediment seems
the most significant in both lakes. SOP-values furthermore confirm differences in the trophic status of Baikal and Malawi,
respectively. The importance of oxygen as a factor likely to create ecological segregation for benthic organisms is discussed.
Lake Malawi offers possibilities of bathymetric segregation but no vertical segregation in the sediment. In contrast, no bathymetric
segregation related to oxygen is possible in Lake Baikal, but vertical segregation in the sediment is very likely.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
The study investigated the relationship between five moult stages and the osmoregulatory capacities (OC), moisture content of hepatopancreas (HM%), hepatosomatic indices (HIwet, HIdry) and growth of 6 weight classes of 235 marron (Cherax cainii) and 235 yabbies (Cherax destructor) under laboratory conditions. In each moult stage, OC increased linearly with the increase in wet body weight. Intermoult stage C showed the highest OC significantly lower than premoult stages D0, D1, D2 and postmoult stage AB in every weight class in both crayfish. HM% decreased from AB to D2, while both HIwet and HIdry reduced from C to D2. Percentage dry matter of whole body carcass was highest in stage C and lowest during the AB stage with a significant difference between the two species. Larger than 15-g marron and yabbies differ with each other in OC, HIwet, and HIdry, moult intervals and growth rates. 相似文献
7.
C.A. Richardson M. Peharda P. Kennedy 《Journal of experimental marine biology and ecology》2004,299(1):1-16
Stable oxygen isotope analyses of U-shaped spines removed at intervals along profiles of the outer shell surface of Pinna nobilis (L) were used to reconstruct sea surface temperature (SST) and validate the periodicity of adductor muscle scar rings on the inner shell surface. Elemental ratios (Mg:Ca and Sr:Ca) of spines, determined using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), were compared with the SST estimated from the stable oxygen isotopic composition of the shell deposited at the same time. The elemental ratios and the stable oxygen isotopic composition recorded in the shell were significantly correlated: Mg:Ca ratio=0.0002 (seawater temperature)+0.0095 (r2=0.445), Sr:Ca ratio=0.00005 (seawater temperature)+0.0014 (r2=0.887). The ratios in the spines were highest when the SST was warmest during July and August and were lowest between January and February when the SST was minimal.The positions of the first and second adductor muscle scar rings, unlike the later rings, are often difficult to discern, and in large shells they are obscured by nacre. Seasonal patterns in the elemental ratios were used to characterise the age in regions of the outer shell surface corresponding to the first two years of shell growth. A combination of both elemental ratios and muscle scar rings were used to estimate the age and hence the growth rate of P. nobilis from three locations in the Croatian Adriatic. Annual cycles of shell growth, inferred from the seasonal pattern in the element ratios, were used to determine the season of recruitment of fan mussels at several localities along the Croatian coastline. Pinnids generally settled during late autumn and winter although one shell from Mali Ston Bay settled during the summer. P. nobilis from Mali Ston Bay exhibited the fastest growth reaching a length of ∼60 cm and an age of 9 years, whereas those from Malo jezero grew the slowest attaining a length of ∼50 cm at 12 years of age. 相似文献
8.
Ga Hun Boo Ying‐Xiong Qiu Jung Yeon Kim Put O. Ang Samuel Bosch Olivier De Clerck Peimin He Atsushi Higa Bangqin Huang Kazuhiro Kogame Shao‐Lun Liu Tu van Nguyen Shoichiro Suda Ryuta Terada Kathy Ann Miller Sung Min Boo 《Journal of phycology》2019,55(6):1319-1334
The evolutionary and population demographic history of marine red algae in East Asia is poorly understood. Here, we reconstructed the phylogeographies of two upper intertidal species endemic to East Asia, Gelidiophycus divaricatus and G. freshwateri. Phylogenetic and phylogeographic inferences of 393 mitochondrial cox1, 128 plastid rbcL, and 342 nuclear ITS2 sequences were complemented with ecological niche models. Gelidiophycus divaricatus, a southern species adapted to warm water, is characterized by a high genetic diversity and a strong geographical population structure, characteristic of stable population sizes and sudden reduction to recent expansion. In contrast, G. freshwateri, a northern species adapted to cold temperate conditions, is genetically relatively homogeneous with a shallow population structure resulting from steady population growth and recent equilibrium. The overlap zone of the two species roughly matches summer and winter isotherms, indicating that surface seawater temperature is a key feature influencing species range. Unidirectional genetic introgression was detected at two sites on Jeju Island where G. divaricatus was rare while G. freshwateri was common, suggesting the occurrence of asymmetric natural hybrids, a rarely reported event for rhodophytes. Our results illustrate that Quaternary climate oscillations have left strong imprints on the current day genetic structure and highlight the importance of seawater temperature and sea level change in driving speciation in upper intertidal seaweed species. 相似文献
9.
Andreas Muller 《Biological journal of the Linnean Society. Linnean Society of London》1996,57(3):235-252
In the Central European apoid and masarid fauna, 13 bee species belonging to seven different taxonomic groups and one honey wasp species were found to be equipped with a specialized pollen-collecting apparatus on the face which is used to harvest pollen from nototribic flowers, viz. representatives of the Lamiaceae and the Scrophulariaceae. Pollen from these two plant families plays an important part in the larval nourishment of these hymenopteran species. The pollen-collecting apparatus consists of a peculiar facial pilosity composed of transformed hairs which are thickened at their base and either knobbed apically (Celonites abbreviatus) or extended into a thin tail which is either straight and bent at right angles ( Rophites spp., Anthophora borealis, A. furcata ) or wavy ( Anthidium spp., Anthocopa andrenoides, Osmia aurulenta, O. caerulescens ). Nototribic flowers are worked by pollen-collecting females by rubbing the facial area covered with the transformed hairs over the anthers (Celonites, Anthidium, Anthocopa, Osmia) , by buzzing the pollen amongst the transformed hairs (Anthophora Jurcata) or by a combination of rubbing movements and buzzing (Rophites) . Bee species lacking special morphological devices were observed to perform specialized behaviours when collecting pollen at nototribic flowers. Nototribic flowers, therefore, appear to be difficult to exploit for pollen. The raised position of the anthers in nototribic flowers as a possible means to reduce excessive pollen losses caused by pollen-collecting hymenopterans is discussed. 相似文献