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Mangroves occur in coastal areas and are therefore vulnerable to anthropogenic disturbance and exhibit high rates of deforestation. Mexico is among the countries with the highest degree of mangrove deforestation in America; however, precise data on national mangrove coverage in Mexico is incomplete, making it impossible to accurately ascertain the rate of mangrove loss over time. Precise information is necessary to assess changes at local and regional scales to detect the magnitude, trends, and drivers of the transformation. This study aimed to estimate the loss of mangrove cover in the area of Mahahual-Xcalak (Quintana Roo, Mexico) between 1995 and 2007, to calculate the annual deforestation rate and to identify the drivers of deforestation. Landsat TM and ETM+ images from 1995 and 2007 were used to estimate the loss of mangrove cover using a multitemporal analysis. Semi-structured interviews with local residents of Mahahual and Xcalak were undertaken to identify and validate the drivers of deforestation. The image analysis for the 12-year period showed that 1070 ha of mangrove forest have been lost, with an annual deforestation rate of 0.85%—a relatively high value compared with other mangrove regions in Mexico. The main factor that has triggered the reduction of mangrove coverage is the expansion of anthropogenic land uses (e.g., settlements and roads). This study concludes that conservation and rehabilitation programs need to be implemented so that the Mahahual-Xcalak mangrove environment can continue to provide key ecosystem services. [ABSTRACT FROM AUTHOR]

An approach towards a systematic revision of Marionina Michaelsen, 1890 is made through an historical overview of its nomenclature and definition, and a thorough characterization of its type species, the South Georgian marine littoral Pachydrilus georgianus Michaelsen, 1888. Relevant sections of early enchytraeid literature provide the background for appreciating the complex taxonomic history of the genus and giving a final word as to the controversial validity of its name, authority and date. Marionina in its current acceptation comprises about 100 nominal species, but the paper documents how, since its establishment, the genus has been an artificial assemblage of unrelated taxa, whose taxonomy cannot be sorted out (1) without finding new morphological characters and improving the standard of descriptions, and (2) without using a total evidence approach (morphology and molecules) within a phylogenetic framework. Confusion about the identity of the type species, originally briefly described and only partially figured, is unravelled upon examination of the syntypes available in Hamburg and Berlin. Since neither series proved to be monospecific, a lectotype is designated to assure correct and consistent application of the name in the future. [ABSTRACT FROM AUTHOR]

Twenty-eight littoral ciliates including one new genus and seven new species were collected from King George Island, Antarctica. Among them, 21 species are morphologically and taxonomically described in this paper: Bickella antarctica nov. gen., nov. spec., Chlamydonella apoprostomata nov. spec., Condylostoma spatiosum Ozaki and Yagiu in Yagiu, 1944, Diophrys scutum Dujardin, 1842, Diophrys aff. oligothrix Borror, 1965, Diophrys appendiculata (Ehrenberg, 1838), Euplotes balteatus (Dujardin, 1841), Euplotes dragescoi nov. spec., Euplotes petzi nov. spec., Euplotes rariseta Curds et al., 1974, Euplotes vannus (Mueller, 1786), Hartmannula angustipilosa Deroux and Dragesco, 1968, Hemigastrostyla szaboi Wilbert and Song, 2005, Holosticha antarctica nov. spec., Holosticha apodiademata nov. spec., Holosticha diademata (Rees, 1884), Litonotus sp., Metaurostylopsis marina (Kahl, 1932), Pleuronema coronatum Kent, 1881, Pseudocohnilembus persalinus Evans and Thompson, 1964, Urotricha antarctica nov. spec. The new genus, Bickella nov. gen., is a free-swimming folliculinid having typical Folliculina morphology except for the absence of lorica. [ABSTRACT FROM AUTHOR]

Adaptive evolution of phenotypic plasticity requires that plastic genotypes have the highest global fitness. We studied selection by spatial heterogeneity of interspecific competition and flooding, and by temporal heterogeneity of flooding on morphological plasticity of 52 genotypes of the clonal shore plant Ranunculus reptans. Competition reduced clone size, rosette size, leaf length and stolon internode thickness. Flooding had similar effects and reduced competition. Differences in selection between environments imply potential for either local adaptation or for indirect evolution of phenotypic plasticity. We also detected direct selection for plastic reductions in internode length in response to flooding and for a plastic increase in internode length in response to competition. Plastic responses of some morphological traits to flooding were in line with selection thereon, suggesting that they indeed are adaptive and might have evolved in response to direct selection on plasticity. [ABSTRACT FROM AUTHOR]

1. Biodiversity assessments of lakes depend on the ability to identify the complement of species present, although the degree of sampling required is often uncertain. We utilise long-term data to predict rotifer species richness in three habitats in three Polish lakes using rarefaction sampling methods. 2. Richness in littoral and psammon habitats did not saturate, even with up to 130 samples. Highest richness was observed in psammon habitat (119 species) in Lake Mikolajskie, followed by littoral habitat in Lakes Łuknajno (114 species) and Kuc (110 species). Littoral habitats in Lakes Łuknajno (56%) and Kuc (51%) had the most species not shared with other habitats in the same lake. 3. Species richness (Chao2) estimates ranged between 44 for pelagic and 135 for psammon habitat in Lake Mikolajskie, to 100 for psammon and 137 for littoral habitat in Lake Kuc, and 65 for pelagic and 162 for littoral habitat in Lake Łuknajno. Whole lake estimates were 167, 205 and 171 species, respectively, for these lakes, higher than the 150 to 160 species predicted by Dumont and Segers (Hydrobiologia, 1996, 341, 125). 4. Using standardised sampling, richness was significantly higher in littoral than either pelagic or psammon habitats. Contrasts of standardised rarefaction curves revealed that richness in Lakes Kuc and Mikolajskie was described as well by littoral-only or psammon-only samples, respectively, as by those randomly drawn from across all habitats in the lake. 5. Species richness estimates for Lake Mikolajskie were highest in summer, followed by autumn and spring. Interannual estimates differed by up to 427%, nearly an order of magnitude greater than maximal seasonal variation of 70%. 6. Results indicate that much higher sampling intensity is required to establish species richness than is presently carried out in most lakes. Because many species can be detected only with very intensive sampling, conservation programmes must consider sampling intensity when designing studies. [ABSTRACT FROM AUTHOR]