Sampling,preservation and quantification of biological samples from highly acidic environments (pH ≤3)

Standard methods for sampling, fixation and quantification of organisms in highly acid environments with pH values at or below 3 are presented. Some important problems are discussed, together with recommendations on how to handle the material. Examples of specific problems are included, especially the effects of fixatives on the cell dimensions of species of Chlamydomonas, Oxytricha and Actinophrys, and on cell numbers of Actinophrys. Mixed populations of heterotrophic protists should be preserved with Lugol's solution, because other fixatives do not permit the recognition of heliozoans.     

Review of rotifers and crustaceans in highly acidic environments of pH values ≤3

A review of the literature on rotifers and crustacean zooplankton in highly acidic environments revealed that data from eleven aquatic environments on three continents (America, Europe, Japan) with a pH 3 are available. Seven sites are influenced by volcanism or weathering processes in the catchment area, four others originated from human mining activities. Species richness was generally low. Only 16 species are found and 1–11 species are reported for each area. These studies clearly show that small littoral or benthic rotifers predominate over crustaceans under highly acidic conditions. In the Lusatian mining area (Germany), all lakes are colonized by zooplankton, even the most acidic one with a pH of 2.3. The core community consists of the rotifers Cephalodella hoodi, C. gibba, Elosa worallii and Rotaria rotatoria, with C. hoodi and E. worallii the most abundant. Larger species, such as the rotifer Brachionus sericus or the cladoceran Chydorus sphaericus, occur at a pH close to 3. A similar pattern is reported from acidic mining lakes in Illinois, U.S.A. Many of these species can also be found in less acidic softwater or even alkaline environments due to the tolerance of a broad range of pH values. Elosa worallii and Brachionus sericus are probably the most acidophilic rotifer species, though at least the latter can also grow at neutral pH in the laboratory. Clear understanding of the pH limits of B. sericus in nature may also have been complicated by the fact that it has probably in the past been wrongly named as B. urceolaris (phenotype `sericus'). The typical B. urceolaris cannot tolerate extremely low pH. Overall, generalist species with a worldwide distribution seem to play the major role in the colonization of anthropogenic highly acidic lakes.     

Corixidae (Hemiptera,Heteroptera) in acidic mining lakes with pH ≤3 in Lusatia,Germany

Corixids are common members of the invertebrate communities of acidic mining lakes. Different qualitative and quantitative sampling methods to capture corixids are introduced. The occurrence of corixids is recorded from mining lakes of Lusatia, Germany, with pH <3, and data on their ecology are summarized.     

Frequency, abundance and distribution of zoosporic organisms from Las Cañas stream (Buenos Aires, Argentina)

Zoosporic organisms are common inhabitants of aquatic environments; however there are few ecological studies made for Argentinean streams. In this contribution the taxonomic composition of zoosporic organisms from a stream and their abundance, frequency and diversity on cellulosic baits were analyzed. Samples of water and floating organic matter (vegetable debris) were taken at four dates and different environmental variables (temperature, dissolved oxygen and nutrient concentrations) were measured. Twenty-one taxa were recovered with the baiting technique. Physicochemical fluctuations affected the structure of the studied community; in spring the greatest species richness was related to high nutrient levels whereas in winter the greatest abundance and diversity was related to low water temperature, nutrient levels and well oxygenated conditions. aquatic environment,     

A new peirosaurid (Crocodilyformes) from the Late Cretaceous (Turonian–Coniacian) of Patagonia,Argentina

Peirosauridae is composed of mid- to large-sized terrestrial mesoeucrododylian crocodyliforms distributed throughout Gondwanan landmasses. Here we describe a new peirosaurid that comes from the upper levels of the Portezuelo Formation (Turonian–Coniacian, Upper Cretaceous) from Loma de la Lata, Neuquén Province, Argentina. This specimen consists of some associated bones belonging to a single individual. In order to facilitate comparisons, we recognise two different peirosaurid morphotypes based on skull shape: broad- and narrow-snouted taxa. The new taxon may be related to broad-snouted taxa, especially Gasparinisuchus peirosauroides. The new taxon here reported has strong heterodont dentition when compared with other peirosaurids. As in related forms, the fourth dentary tooth is caniniform, very large, acute and transversely compressed (much more than other peirosaurids), and the anterior dentary teeth have less globular, sharp serrated crowns. Large interalveolar spaces are present between both mandibular and maxillary teeth, a trait only observed on the new taxon. With this addition, we elevate the number of Patagonian peirosaurids to four. Moreover, it represents together with Lomasuchus palpebrosus the second peirosaurid species described for the Portezuelo Formation.     

Design,synthesis and structure–activity relationships of some novel,highly potent anti-invasive (E)- and (Z)-stilbenes

In our ongoing exploration of the structure–activity landscape of anti-invasive chalcones, we have prepared and evaluated a number of structurally related (E)- and (Z)-stilbenes. These molecules exhibited an extraordinary high in vitro potency in the chick heart invasion assay, being active up to 10 nmol L^?1, a concentration level a 100-fold lower than the lowest effective doses that have been reported for natural analogues. Furthermore, they possess an interesting pharmacological profile in silico.     

Plant–arthropod interactions in gymnosperm leaves from the Early Permian of Patagonia,Argentina

Evidence of plant–arthropod interactions in three orders of gymnosperms is documented in at least five localities from Lower Permian strata of the Río Genoa Formation (Patagonia, Argentina). Arthropod damages were identified in Glossopteris, Gangamopteris, Cordaites and Gingkoites leaves, corresponding to four interactive categories: margin feeding, hole feeding, surface feeding, and oviposition. In addition, a Permian insect trace not previously recorded is described on Glossopteris wilsonii leaves. The diversity of arthropod damage is consistent with the diverse flora of the Río Genoa Formation. In turn, the patterns of arthropod and plant–arthropod interaction provide constraints on the ecology and paleoclimate of Western Gondwana during the Early Permian.     

Nectar sugar composition in angiosperms from Chaco and Patagonia (Argentina): an animal visitor's matter?

 We relate nectar sugar composition with floral visitors in samples from two biogeographic regions from Argentina: Chaco (99 spp. from its southern region) and Patagonia (48 spp. from its central region), using our own data published in earlier papers. The variables to be compared were sugar ratio and sucrose percentage. Differences in the sugar composition were observed when comparing both regions. Bee- and butterfly-visited Patagonian species showed lower sucrose percentages and sugar ratios than Chaquean species; i.e., a convergence in sugar composition was not verified. Moth-visited species showed a wide range of sucrose proportions and sugar ratios in both regions with no significant differences between them. As the differences found in sugar ratio between Chaco and Patagonia, according to the predominant pollinator guilds, may have been influenced by the sample size, we searched for similarities in sugar ratios between plants with the same visitor type in a comparative way, comparing our data pooled together against data by Baker and Baker's (1983a). Our data do not agree with theirs, i.e., no trends can be drawn for bees, moths, and butterflies sugar preferences. The exceptions were the hummingbird-visited species that showed a similar pattern in both cases, i.e., there is a convergence among plants offering nectar with a predominance of sucrose. To evaluate whether closely related species within a family have similar nectar composition and flower visitors, regardless of their region, sugar proportions were compared in several families. Hexose nectars were predominant in Asteraceae, Fabaceae, Solanaceae, and Verbenaceae, while sucrose nectars prevailed in Bromeliaceae and Onagraceae. Nectar composition seems to be a more conservative trait than flower morphology. This may be a reason to explain the absence of a convergence in sugar composition between plants growing in different biogeographical regions that share the same animal visitor guilds. Received August 27, 2002; accepted December 17, 2002 Published online: June 2, 2003     

Phytoplankton of the extremely acidic mining lakes of Lusatia (Germany) with pH ≤3

Most of the flooded, open-cast lignite mining lakes of Lusatia (Germany) impacted by the oxidation of iron sulphides (pyrite and marcasite) are extremely acidic. Of 32 lakes regularly studied from 1995 to 1998, 14 have a pH <3 (median pH 2.3–2.9). These lakes are typically buffered by high concentrations of Fe (III) and have high conductivity (1000–5000 S cm^–1). Concentrations of dissolved inorganic carbon (DIC) and phosphorus are typically extremely low. These factors result in a very different environment for algae than found in neutral and acid-rain impacted lakes. The planktonic algal flora is generally dominated by flagellates belonging to genera of Chlorophyta (Chlamydomonas), Heterokontophyta of the class Chrysophyceae (Ochromonas, Chromulina), Cryptophyta (Cyathomonas) and Euglenophyta (Lepocinclis, Euglena mutabilis). Near-spherical non-motile Chlorophyta (Nanochlorum sp.), Heterokontophyta of the class Bacillariophyceae (Eunotia exigua, Nitzschia), Dinophyta (Gymnodinium, Peridinium umbonatum), other Chlorophyta (Scourfieldia cordiformis) and Cryptophyta (Rhodomonas minuta) are also found.     

Biofilm and planktonic microbial communities in highly acidic soil (pH < 3) in the Soos National Nature Reserve,Czech Republic

Biofilm formation is a typical life strategy used by microorganisms populating acidic water systems. The same strategy might be used by microbes in highly acidic soils that are, however, neglected in this regard. In the present study, the microbial community in such highly acidic soil in the Soos National Nature Reserve (Czech Republic) has been investigated using high-throughput DNA sequencing and the organisms associated with biofilm life mode and those preferring planktonic life were distinguished using the biofilm trap technique. Our data show the differences between biofilm and planktonic microbiota fraction, although the majority of the organisms were capable of using both life modes. The by far most abundant prokaryotic genus was Acidiphilium and fungi were identified among the most abundant eukaryotic elements in biofilm formations. On the other hand, small flagellates from diverse taxonomical groups predominated in plankton. The application of cellulose amendment as well as the depth of sampling significantly influenced the composition of the detected microbial community.

     

Behavior and seasonal variation in the relative abundance of Commerson’s dolphin (Cephalorhynchus commersonii) in northern Patagonia, Argentina

Commerson’s dolphins (Cephalorhynchus commersonii) along the Patagonian coast of South America suffer incidental mortality in fisheries and are the target of a dolphin-watching industry. We describe the daily activity patterns and assess the variation in the relative abundance of the species near the northern boundary of its range. Information was gathered with a spotting scope from a cliff-top vantage point applying the method of scan sampling. Behaviors were categorized as individual feeding, cooperative feeding, directional swimming, socializing, and resting. These behaviors are similar to those observed in other species of small cetacean, but differences were found regarding the patterns of directional swimming and feeding techniques. Hunting tactics favored the association of terns with dolphin groups. No clear dial behavioral pattern was observed, but seasonal changes in the frequency of behaviors were recorded. Group and school sizes were larger during periods with colder sea surface temperature (SST). Seasonal abundance was correlated with SST, suggesting that at higher SST the species forsakes the area, probably in favor of coastal areas to the south with lower SST.     

New anhingid (Aves,Suliformes) from the middle Miocene of Río Negro province,Patagonia, Argentina

During the Miocene in South America, the family Anhingidae constitutes one of the most conspicuous faunal elements. However, the anhingid record from Patagonia is still sparse. The aim of the present contribution is to describe a new species of Macranhinga coming from Colloncuran levels (early middle Miocene) in Río Negro province, north-central Patagonia (Argentina). The new species is represented by an incomplete proximal end of a tarsometatarsus, distal end of a tibiotarsus, and distal end of a humerus. The phylogenetic relationships of the new species within Macranhinga remains unresolved. South American Neogene anhingids share a number of features that suggest they may belong to a monophyletic clade within this family. Anhingid records from the Miocene of Patagonia indicate that the diversity of this family was far more diverse (at least 4 different species) than currently understood, and was possible comparable to that shown by Miocene beds of Mesopotamian in Argentina and Acre in Brazil.

http://www.zoobang.org/urn:lsid:zoobank.org:pub:3FC228E8-4E2C-4DFD-AB91-79F32269CA98     

Synthesis, pharmacological activity and structure affinity relationships of spirocyclic σ(1) receptor ligands with a (2-fluoroethyl) residue in 3-position

In order to develop a fluorinated radiotracer for imaging of ??₁ receptors in the central nervous system a series of (2-fluoroethyl) substituted spirocyclic piperidines 3 has been prepared. In the key step of the synthesis 2-bromocinnamaldehyde acetal 5 was added to piperidones 6 with various substituents at the N-atom. Unexpectedly, this reaction led to 2-benzoxepines 8, which were contracted with acid to afford the spirocyclic 2-benzofuranacetaldehydes 9. The best yields were obtained, when the transformations up to the alcohols 10 were performed without isolation of intermediates. Generally the (2-fluoroethyl) derivatives 3 have higher ??₁ affinity and ??₁/??₂ selectivity than the corresponding (3-fluoropropyl) derivatives 2. The most promising candidate for the development as radiotracer is the (2-fluoroethyl) derivative 3a (WMS-1828, fluspidine, 1′-benzyl-3-(2-fluoroethyl)-3H-spiro[[2]benzofuran-1,4′-piperidine]), which shows subnanomolar ??₁ affinity (K_i = 0.59 nM) and excellent selectivity over the ??₂ subtype (1331-fold) as well as some other receptor systems. The novel synthetic strategy also allows the systematic pharmacological evaluation of intermediate alcohols 10. Despite their high ??₁ affinity (K_i = 6-32 nM) and selectivity the alcohols 10 are 10-30-fold less potent than the bioisosteric fluoro derivatives 3.     

First record of Buller’s Albatross (Thalassarche bulleri) from a fishing vessel in the south-western Atlantic Ocean off Southern Patagonia (Argentina)

Buller’s Albatross, Thalassarche bulleri, is a New Zealand breeding endemic that is frequently observed in the subtropical and sub-Antarctic South Pacific Ocean between Australia and Peru. However, in the South Atlantic Ocean, it is a vagrant, as information on its presence in this region is limited to only a few sightings. Here, we report a new record of T. bulleri in the south-western Atlantic Ocean off Argentina (55°06′13″S, 66°06′44″W) while investigating interactions between commercial fisheries and seabirds. This record provides new information about the distribution of this albatross species and its relation with fisheries outside of its regular range.     

Epilithic Algae Distribution Along a Chemical Gradient in a Naturally Acidic River, Río Agrio (Patagonia, Argentina)

The epilithic algae distribution along a pH gradient and the relationship between the chemical gradient and biomass development were studied in Río Agrio, a naturally acidic river located in Patagonia (Argentina). The epilithic community was monitored during the summer of three consecutive years in sites located above and below the entrance of tributaries. The epilithic community showed differences between sites based on the chemical composition of the water and the precipitates that appear on the streambed of the river. The lowest biomass, diversity, and number of species were found at the most extreme part of the river in terms of pH (ca. 2) and element concentrations. Euglena mutabilis was the dominant species in this section of the river. As pH increased (ca. 3), the community changed to be dominated by filamentous green algae (Ulothrix spp., Mougeotia sp., Klebsormidium sp.) showing luxuriant growths in terms of biomass. With the inflow of a neutral tributary, the pH of Río Agrio increased above 3, and the precipitates of orange-red iron hydroxides appeared. The algal community was not affected by these precipitates or the low P concentrations, along the next 30 km of river downstream from this site. The apparent physical stress that the precipitates impose on algae is in fact a dynamic reservoir of P because diel cycle of Fe could be promoting precipitation and redissolution processes that binds and releases P from these precipitates. Where the pH increased above 6, precipitates of aluminum hydroxides appeared. At this site, the epilithic biomass and density decreased, some algae species changed, but the diversity and the number of species in general remained consistent with the upstream values. The physical stress of the Al precipitates on the algae is added to the chemical stress that represents the sequestering of P in these precipitates that are not redissolved, resulting P a limiting nutrient for algae growth.     

Acanthocephalus tumescens (Acanthocephala, Echinorhynchidae) in Galaxias maculatus (Pisces, Galaxiidae) of Lake Gutiérrez, Patagonia, Argentina

The seasonal distribution of Acanthocephalus tumescens (Acanthocephala : Echinorhynchidae) among Galaxias maculatus (Pisces : Galaxiidae) in Lake Gutiérrez was studied from March 1994 to June 1996. Acanthocephalus tumescens always occurs in the intestine, has an overdispersed frequency distribution, a similar proportion of sexes, and females are larger than males. Mean intensity and prevalence are low and increase with host length. The pattern of the infection shows seasonality, with recruitment in winter and a reproductive period during spring-summer.     

Ectomycorrhizal fungal communities in Nothofagus nervosa (Raulí): A comparison between domesticated and naturally established specimens in a native forest of Patagonia,Argentina

Due to its overexploitation during the past century, Nothofagus nervosa is currently included in conservation and domestication programs, in which ectomycorrhizas play an important role. We aimed to describe the abundance and diversity of ectomycorrhizal fungi (EcMF) in both domesticated and naturally established N. nervosa specimens, and to analyse the influence of age, seasonality and forest management on EcMF communities. The occurrence of arbuscular mycorrhizas (AM) and dark septate endophytes (DSE) was also investigated. Fungal diversity and taxonomic identification were assessed by morphotyping and subsequent ITS-rDNA sequencing. Plant age, seasonality and forest management influenced EcMF communities. Colonization rates were higher than 90 % in all the specimens, and were significantly higher in mature trees and in autumn. The highest EcMF richness and diversity values were registered in domesticated specimens and in autumn. Most EcMF were basidiomycetes, belonging mainly to the Cortinariaceae and Tricholomataceae. Arbuscular mycorrhizas were not detected, while DSE were present within N. nervosa roots. Our results and previously published reports showed that some EcMF are capable of colonizing different Nothofagus species. In addition, the EcMF described in natural ecosystems are different from those colonizing N. nervosa during its cultivation in the nursery. These results improve our understanding of key factors affecting EcMF communities associated with Nothofagus in native forests and nurseries (age, season, forest management, cultivation techniques), and this information is relevant for improving domestication programs.     

A review on the occurrence and taxonomy of heterotrophic protists in extreme acidic environments of pH values ≤ 3

The occurrence and some important taxonomic problems of heterotrophic protists from extremely acidic (pH 3) environments are briefly discussed. Almost all information on the occurrence of heterotrophic protists from extremely acidic environments is restricted to acid mine drainage (AMD) or streams influenced by AMD. Most of the information is provided for ciliates. Very little information is available on the occurrence of flagellates, rhizopods and heliozoa in this environment. Within the ciliates Urotricha, Vorticella and Oxytricha dominate in acidic mining lakes. Actinophrys sp. is the most important heliozoan in these environments. There are many taxonomic problems which are not solved so far. Live observations and taxonomic methods adapted to the extreme chemical matrix are necessary for correct identification.     

First fossil record of Discocephalinae (Insecta,Pentatomidae): a new genus from the middle Eocene of Río Pichileufú, Patagonia,Argentina

A new genus and species of Discocephalini, Acanthocephalonotum martinsnetoi gen. n. et sp. n. is described from Río Pichileufú, middle Eocene of Patagonia, Argentina at palaeolatitude ~ 46°S. The new species is the first fossil representative of the Discocephalinae. This taxon is extant in equatorial to subtropical America, and some species reach warm temperate latitudes (Buenos Aires province). The new genus is distinguished from the other genera of Discocephalini by the combination of these characters: interocular width greater than head length; head massive and quadrangular with the anterior margin almost straight; juga touching each other; labrum thick and curved; triangular ante-ocular process extending beyond the eye; broad spine-like antero-lateral process of the pronotum; pronotum explanate and bean shaped; scutellum triangular with a circular tongue reaching the anterior side of abdominal segment 7; and wings well developed with membrane just surpassing end of abdomen.