Gargiulo, G. M.El Bakkouri, B.Crisafulli, A.Donato, M....
7页
查看更多>>摘要：Ceratophyllum is a genus of perennial, freshwater plants with an essentially cosmopolitan distribution. In this study, we report for the first time, the presence of somatic polyploidy and chromosome number variation in a C. demersum population from Calabria (Italy). Observations on mitotic divisions and chromosomal behaviors as well as DNA measurements have been carried out using standard chromosome counting and Image Cytometric analysis. The estimations of DNA amounts were carried out using the interphase-peak method. Chromosome number variation was detected in different plants from the studied population, as well as in a single individual. The relative DNA value of nuclei confirmed that all the studied individuals presented polysomaty. Anomalies during the different mitotic phases were also observed. The data strongly suggest that these anomalies associated to the endoreduplication could be the cause of the several numbers detected. An attempt to compare our data with those reported in literature is discussed. However, the detection in Calabrian population of different chromosome numbers, even in a single individual, strongly suggests that a revision of karyological data in this genus seems necessary. The data reported represent the first contribution to understanding the basic cytogenetics in this genus.
查看更多>>摘要：Spatial patterns of aquatic species are indicative of the quality of the in-stream water quality as well as that of the surrounding watershed. The relationships among aquatic species diversity, water quality, and watershed characteristics are not well explored in the Himalayan watershed. In this work, we analyzed the impacts of in-stream water quality, watershed socio-environmental conditions, and spatial predictors on the species composition of aquatic plants and macroinvertebrates. We collected macrophytes, phytoplankton, and macro-invertebrate samples and measured with dissolved oxygen and electrical conductivity of the lakes and rivers of the Setikhola watershed, Central Nepal. The watershed landscape variables such as landcover types, population density, and topography along with spatial factors derived from the spatial connectivity matrices were used as explanatory variables to explore species composition using redundancy analysis. We reported 39 macrophyte species, 105 phytoplankton species, and 35 families of macroinvertebrates. The macrophyte species belonging to the family Potamogetonaceae were dominant, as were the phytoplankton species belonging to Bacillariophyceae; most macro-invertebrates belonged to families in the order Diptera. We report a significant impact on watershed human population density as well as the electrical conductivity of the water on aquatic species composition. Inclusion of spatial factors increased model predictive performance of macrophyte and phytoplankton species composition. This study can help in a robust understanding of aquatic systems in relation to corresponding socioenvironmental settings to manage them with optimal benefits for the ecosystems and people.
查看更多>>摘要：Dedicated insights into the diversity, spatial and temporal distribution of rice weed communities, as well as underlying ecological factors, are critical for developing effective ecological weed management strategies in these agroecosystems, leading to the preservation of biodiversity and ecosystem services in a sustainable agriculture framework. To fulfill this aim, 108 vegetation releve ' s were conducted at 23 sites of rice paddies throughout 9 counties in the north of Iran at various altitudes, during three different phenological stages of rice. Data from vegetation releve ' s was analyzed using TWINSPAN, resulting in the identification of four main plant community types related to the different stages of rice growth: Echinochloa crus-galli-Paspalum distichum, Spirodela polyrrhiza-Lemna minor, Monochoria vaginalis s.l.-Marsilea quadrifolia, and Cyperus difformis-Ammannia baccifera. Complementary direct (canonical correspondence analysis) and indirect gradient analyses (detrended correspondence analysis) confirmed these communities' separation and indicated that the most significant environmental factors affecting plant community distribution were soil water content and soil pH. Moreover, out of 72 segetal species of investigated rice paddies, 12 species were alien to Iran, indicating that this agroecosystem provides an important source for the introduction, distribution, and possible spread of alien species into other adjacent ecosystems. Our findings contribute to the knowledge of detecting patterns of weed composition and distribution in rice paddy ecosystems, as well as their interpretation in relation to environmental gradients. They can support the establishment of ecological weed management practices in northern Iran's paddy fields.
查看更多>>摘要：Natural hybridization has been considered as a source of taxonomic complexity in the genus Potamogeton (Potamogetonaceae). The identity of broad-leaved Potamogeton individuals morphologically untypical and tentatively determined as P xcooperi, from a recently discovered locality in Croatia, southern Europe, was investigated with molecular markers. In the sample studied, the presence of an additive ITS sequence pattern of two species, namely P. crispus and P. perfoliatus, was detected, which proved tentative morphological identifi-cation of the hybrid as P. xcooperi. Investigation of the rpl32-trnL intergenic spacer of chloroplast DNA evidenced that P. crispus was the female parent of the studied Potamogeton hybrid. Potamgoeton xcooperi, the hybrid be-tween P. crispus and P. perfoliatus, is known from several countries worldwide, with the majority of localities in the northern part of Europe. The newly discovered station of P. xcooperi in Croatia is the first in this country and the southernmost in Europe. Sparse records of at least part of the rare Potamogeton hybrid taxa reflect still insufficient state of knowledge on its distribution and diversity and the need for extensive, regional taxonomic studies of aquatic genera.
Aben, Ralf C. H.Junior, Ernandes S. OliveiraCarlos, Anderson R.van Bergen, Tamara J. H. M....
10页
查看更多>>摘要：Severe eutrophication threatens freshwater systems around the world. The application of aquatic buffer zones with plants, for example around agricultural lands, can increase nutrient retention and thereby reduce nutrient loading to downstream systems. However, not much is known about greenhouse gas (GHG) emissions from these buffer zones and how they are affected by nutrient loading and the dominant plant species. Here, using a full factorial mesocosm experiment with different nutrient loadings (20-4000 mg N and 1-200 mg P m(-2) d(-1)) and plant types (e.g. submerged and free-floating species), we show that emissions of methane (CH4) and nitrous oxide (N2O) were strongly related to nutrient loading, leading to total greenhouse gas emissions up to 177.84 g CO2-eq m(-2) d(-1). Overall, total GHG emission (as the sum of CH4 ebullition and diffusive water-atmosphere emission of CH4 and N2O in CO2 equivalents) was not significantly affected by plant species. CH4 ebullition was significantly lower in experimental units with submerged plants that rooted in the sediment as compared to non-rooted plants, possibly related to rhizosphere CH4 oxidation fueled by radial oxygen loss or plant-mediated transport that limits the build-up of gaseous CH4 in the sediment. We conclude that aquatic buffer zones that experience intense nutrient loading (e.g. due to release of sewage or agricultural fertilizer) can be GHG emission hotspots and recommend careful consideration of environmental conditions (e.g. the organic carbon content), expected nutrient loadings, and alternatives, prior to their construction.
Diniz, Ugo MendesNadia, Tarcila de LimaMello, Marco Aurelio RibeiroMachado, Isabel Cristina...
8页
查看更多>>摘要：Mangroves are unique ecosystems supported by very small plant assemblages. Those few plants tend to be insectpollinated and make generalized interactions, which leads to competition for pollinators. Mangroves are poorly studied in terms of pollination ecology, and we still do not know how those interactions scale up to form networks. We described the pollination network of a Neotropical mangrove to understand how plant species share pollinators and to gain insight into network assembly in a species-poor ecosystem. We assessed year-round pollination interactions in a mangrove in north-eastern Brazil comprising three entomophilous plant species and described the topology of the resulting network in terms of nestedness, specialization, and modularity. We also assessed the relative importance and niche breadth of different pollinator groups using centrality metrics. The network had highly imbalanced node classes, comprising three zoophilous plant species and 29 insect species from the orders Diptera, Hymenoptera, and Lepidoptera. Pollinator species were mostly peripheral and rarely interacted with all plants, while plant species formed a generalized core. A single dominant fly species, Palpada albifrons, visited all plants and made most interactions, softening the separation between modules. The network was nonetheless moderately specialized due to several exclusive interactions with a taxonomic signal. These taxon-specific interaction patterns point to idiosyncrasies in mangrove pollination systems instead of the expected generalized interactions with non-selective insects. However, the mangrove's reproductive dynamics seems to be dominated by a single pollinator species, and its network topology is heavily influenced by the low plant richness resultant from strong environmental filters.
查看更多>>摘要：Kees den Hartog, born in Den Helder (The Netherlands), with artistic bow tie, was a versatile aquatic ecologist. He became appointed in 1970 as extra ordinary professor in botany and general ecology at the Vrije Universiteit Brussel (Belgium) and in 1973 as professor in the aquatic ecology at the Universities of Nijmegen and Wageningen (The Netherlands). Kees den Hartog and his Laboratory of Aquatic Ecology made important and famous contributions to the knowledge of aquatic ecosystems dominated by macrophytes. According to Kees den Hartog, the study of these macrophyte-dominated ecosystems was incomplete if it did not include other organisms such as macroinvertebrates and fish.
NSTL
Elsevier