Discovery of Algal Fossils from the Hailar Basin and Its Significance

This article reports Chlorococcalean algae fossil in Member 2 of Damoguaihe Formation, Well Haican-5, South of Hailar Basin. They are Pediastrum simplex, P. boryanum, Scenedesmus cf. bijuga, S. cf. dimorphus, S. beierensis sp. nov.     

五种淡水轮虫种群增长参数的比较研究

在32℃培养条件下,实验研究了5种淡水常见浮游轮虫的种群增长参数。通过编制生命表计算其内禀增长率rm(h-1)、净生殖力(R0)和世代时间T(h)分别为:萼花臂尾轮虫-0.091、14.1和34.1;壶状臂尾轮虫-0.055、6.9和38.4;角突臂尾轮虫-0.035、4.9和50.9;臂尾水轮虫-0.038、4.3和46.1以及裂足臂尾轮虫-0.017、2.1和43.7。其中,萼花臂尾轮虫内禀增长率大,繁殖率高,可作为批量培养的首选种类。       

鄱阳湖沿岸带螺类的物种组成及其生境

2011年5月和6月在鄱阳湖沿岸带的62个样点采集了淡水螺类样本并调查了生境类型,分析了淡水螺类的物种组成及其生境分布特征。结果表明:共采集到淡水螺类19种,分属田螺科（8种）、觿螺科（8种）、椎实螺科（2种）和黑螺科（1种）。与前人的研究相比,本次调查的螺类物种数有较大的下降,但田螺科和觿螺科的物种仍是整个螺类群落的主要组成部分。淤泥生境的螺类物种组成与其他生境的差异较大,淤泥生境的螺类物种丰富度显著高于沙土、砂石和水草3种生境（P0.05）,表明螺类对生境具有一定的栖息偏好性。最后详细讨论了淡水螺类种数变化、物种组成及其生境分布的影响因素。       

Ultrastructure of Triangulamyxa amazonica n. gen. and n. sp. (Myxozoa, Myxosporea), a parasite of the Amazonian freshwater fish, Sphoeroides testudineus (Teleostei, Tetrodontidae)

Triangulamyxa amazonica n. gen. and n. sp. (Myxozoa, Ortholineidae), found in the lumen of the intestine of the freshwater fish Sphoeroides testudineus, is described. The fish were collected from the Amazon River near the city of Algodoal, State of the Pará, Brazil. Numerous irregular plasmodia containing different stages of sporogony, including spores, were observed. The plasmodia were lying free in the lumen or had slender pseudopodia-like cytoplasmic processes in contact with intestinal epithelial cells with microvilli projections. Spores, which are equilaterally triangular in valvar view with rounded pointed ends and ellipsoidal in transverse section, are 8.5 μm long, 7.6 μm wide, and 3.8 μm thick. The anterior end of the spores contains two equal drop-shaped polar capsules measuring 2.6 μm in length, each having an isofilar polar filament with 5–6 turns. The characteristics of the spore shape, the spore wall structure and its ridge organization, the plasmodial characteristics and the identity of the host suggest that the parasite is a new genus and species, which is herein designated T. amazonica.     

Contemporary carbon accumulation in a boreal oligotrophic minerogenic mire – a significant sink after accounting for all C-fluxes

Based on theories of mire development and responses to a changing climate, the current role of mires as a net carbon sink has been questioned. A rigorous evaluation of the current net C-exchange in mires requires measurements of all relevant fluxes. Estimates of annual total carbon budgets in mires are still very limited. Here, we present a full carbon budget over 2 years for a boreal minerogenic oligotrophic mire in northern Sweden (64°11′N, 19°33′E). Data on the following fluxes were collected: land–atmosphere CO₂ exchange (continuous Eddy covariance measurements) and CH₄ exchange (static chambers during the snow free period); TOC (total organic carbon) in precipitation; loss of TOC, dissolved inorganic carbon (DIC) and CH₄ through stream water runoff (continuous discharge measurements and regular C-concentration measurements). The mire constituted a net sink of 27±3.4 (±SD) g C m⁻² yr⁻¹ during 2004 and 20±3.4 g C m⁻² yr⁻¹ during 2005. This could be partitioned into an annual surface–atmosphere CO₂ net uptake of 55±1.9 g C m⁻² yr⁻¹ during 2004 and 48±1.6 g C m⁻² yr⁻¹ during 2005. The annual NEE was further separated into a net uptake season, with an uptake of 92 g C m⁻² yr⁻¹ during 2004 and 86 g C m⁻² yr⁻¹ during 2005, and a net loss season with a loss of 37 g C m⁻² yr⁻¹ during 2004 and 38 g C m⁻² yr⁻¹ during 2005. Of the annual net CO₂-C uptake, 37% and 31% was lost through runoff (with runoff TOC>DIC≫CH₄) and 16% and 29% through methane emission during 2004 and 2005, respectively. This mire is still a significant C-sink, with carbon accumulation rates comparable to the long-term Holocene C-accumulation, and higher than the C-accumulation during the late Holocene in the region.     

On the establishment and range expansion of oriental weatherfish (<Emphasis Type="Italic">Misgurnus anguillicaudatus</Emphasis>) in NE Iberian Peninsula

Oriental weatherfish has become an invasive fish species in many temperate areas. In this work we report the presence of an established weatherfish population in northeastern Iberian Peninsula and describe, for the first time in Europe, a clear range expansion. The species was first located in the Ebro River Delta in 2001 and has since been detected in 31 UTM 1 × 1 km quadrates. The capture of over 1,000 weatherfish shows that its population is composed by both juvenile and adult individuals. Weatherfish occupies mostly the web of irrigation channels associated with rice culture, although it has also been detected in rice fields and in the Ebro River. The expansion of the species in the area seems to be limited by water conductivity. An additional location for the species in the Ter basin (some 300 km to the north) suggests that inter-basin expansion could be occurring. This new fish invasion reinforces the need to implement strict controls to the trade and culture of ornamental fish.     

River-reef connectivity in the Meso-American Region

The accumulation and seasonal impact of riverine discharge on coral reefs of the Meso-American Region (MAR) were estimated using a numerical simulation of river runoff dispersion. River-reef connectivity, or source-sink dynamics of terrestrial runoff was further assessed from more than 400 watersheds of the region onto discrete coral reef areas. Using land use for 2003 and 2004 in the MAR, this work builds upon a Regional Ocean Modeling System simulation of the MAR validated by ocean color satellite data, and on the monthly river nutrient and sediment load and discharge provided by the World Resources Institute using the N-SPECT model. Analysis of the variability of simulated runoff transport to the reefs showed that reefs of the Mesoamerican Barrier Reef System (MBRS) were mostly impacted from June to September, following the peak time of river discharge. At that time, the coastal and oceanic circulations contribute quickly to expel the runoff from the MBRS. High runoff concentration waters leaving the eastern coast of Honduras during the months of October to December return to the southwestern MAR in March as they are entrained in a cyclonic gyre. Coral reefs of the MAR are thus impacted twice, first from the coastal side with runoff of local origin and later from the oceanic side with runoff from mixed origin. High probability of connectivity between rivers and remote reefs is established as this study revealed that river runoff from the north shore of Honduras has a wide-spread impact on most of the coral reefs of southern Belize, while watersheds on the Gulf of Honduras are mostly connected to coral reefs in the northern shore of Honduras. Although the level of remote influence (or runoff concentration reaching the reef) is lower than the local, the cumulative effect of numerous remote river-reef connections remains significant. Communicated by Biology Editor Michael Lesser     

The species flocks of lacustrine gastropods: <Emphasis Type="Italic">Tylomelania</Emphasis> on Sulawesi as models in speciation and adaptive radiation

Endemic radiations provide splendid opportunities for studies in evolutionary biology. Species flocks in ancient lakes, such as in Tanganyika, Malawi or Baikal, have featured prominently in evolutionary biology, viewing these “evolutionary theatres” as hotspots of diversification. However, following a century of neglect, the endemic evolution of limnic cerithioidean gastropods in the two central lake systems on the Indonesian island of Sulawesi (i.e. Lake Poso and the lakes of the Malili system, e.g. Danau Matano, Mahalona and Towuti) also provide instructive model cases for the study of speciation mechanisms, adaptive radiation and annidation (i.e. niche exploitation). We here discuss the evolutionary and taxonomic implications of the lacustrine species flocks in Tylomelania from these lakes in Sulawesi as an exceptional endemic assemblage of morphologically distinct viviparous pachychilid gastropods. This first comprehensive compilation of data on both ancient lake systems, Poso and Malili, offers a new perspective on ecological differentiation in this radiation. Presented here within the framework of the theory of evolutionary ecology it provides a research program for acquiring a synthetical perspective that includes morphology, molecular genetics, ecology and biogeography. In this context, it will be possible to compare the species flocks of these truly “Darwinian snails” on Sulawesi with the long enigmatic, so-called thalassoid (i.e. marine-like) gastropod radiation in East African’s Lake Tanganyika.     

Global diversity of rotifers (Rotifera) in freshwater

Rotifera is a Phylum of primary freshwater Metazoa containing two major groups: the heterogonic Monogononta and the exclusively parthenogenetic Bdelloidea. Monogononta contains 1,570 species-level taxa, of which a majority (1,488) are free-living fresh or inland water taxa. Bdelloidea contains 461 “species,” only one of which is marine, but with many limnoterrestrial representatives or animals of unknown ecology. Actual numbers may be much higher, considering the occurrence of cryptic speciation in Monogononta and the unsatisfactory nature of taxonomic knowledge. Rotifers, mostly monogononts, occur in all types of water bodies, worldwide. They are particularly diverse in the littoral zone of stagnant waterbodies with soft, slightly acidic water and under oligo- to mesotrophic conditions. The rotifer record is highest in the Northern hemisphere, which may be due to the concentration of studies in those regions. Diversity is highest in the (sub)tropics; hotspots are northeast North America, tropical South America, Southeast Asia, Australia, and Lake Baikal, endemicity is low in Africa (including Madagascar), Europe, the Indian subcontinent, and Antarctica. Although the lack of fossil evidence and of molecular phylogenetic studies are major hindrances, contrasting hypotheses on the origin and evolutionary history of Brachionus, Macrochaetus, and Trichocerca are presented. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment