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Variability in the degree of euryhalinity of neotropical estuarine annelids
Get PDFEstuaries are highly dynamic, spatially complex systems showing large daily fluctuations in salinity. Estuarine organisms, especially small animals with limited locomotory capacities, are thus expected to have variable ecological and morphophysiological strategies. This paper evaluates the responses to salinity challenges in four species of neotropical annelids along a subtropical estuarine gradient by assessing mortality (i.e., tolerance) and changes in body weight (proxy for water fluxes). We selected the nereidids Alitta sp. and Laeonereis acuta, with broad salinity niches, and the nephtyid Nephtys fluviatilis and the melinnid Isolda pulchella, with either narrow salinity niches or a more restricted spatial range. Worms were weighed, exposed to salinities ranging from fresh water to full-strength seawater (0, 5, 15, 25, and 35) for 1, 6, 12, and 24 h, and weighed again after these exposure times. Their mortality (as absence of body movements or vascular circulation) rates were recorded to assess their ranges of tolerance to these treatments or their degree of euryhalinity. Their integument was characterized histologically to show possible morphological links to their tolerances. Both nereidids displayed stable body weights and thick integuments, compatible with the wide range of salinity tolerance and capacity to maintain body hydration. Body weight of Alitta sp. returned to initial values after 1 h at salinities ≥5. Body weight did not change in L. acuta at salinities ≥15; mortalities occurred only at salinity 0 after 12–24 h. Nephtys fluviatilis showed a thin integument and less variation in weight throughout the whole range of tested salinities, but mortality occurred after 24 h at salinity 0, at its reference salinity (3) and at 35. Isolda pulchella showed a lower capacity to maintain body weight/hydration and a thin integument, compatible with its relative stenohalinity and presence restricted to polyhaline marine sectors. Its weight variation was significant at all salinities except 35; mortality occurred at extreme salinities: 0 and 35. Responses of the four species were compatible with their distribution along the estuarine gradient, as an interesting outcome of their autecological traits, morphophysiological adaptations and evolutionary histories
Habitat use in juvenile and adult life stages of the sedentary fish Hippocampus guttulatus
Get PDFUnderstanding of the spatial distribution and habitat use in different stages of a life cycle represents the essential aspect of threatened species management and conservation. In the present paper, the spatial and temporal patterns of habitat use in juvenile and adult life stages of the long-snouted seahorse Hippocampus guttulatus in the Mar Piccolo of Taranto (Apulia—Italy) (40°28′N, 17°16′W) were examined. From October 2012 to January 2014, monthly visual censuses were conducted in six coastal habitats of a focal area (Buffoluto site). Of a total of 317 individuals of the long-snouted seahorse that were sighted, 148 were juveniles, 82 adult females and 87 adult males. Our results showed significant differences in the habitat use between adult and juvenile life stages of H. guttulatus. Adult individuals were mainly concentrated within Cladophora prolifera beds and the wood poles of a mussel farm at 2–4 m of depth, while juvenile individuals were mainly present in shallower water (0.4–1 m) on artificial hard substrates covered by a brown algae turf. Assessing and describing the habitat use within different life stages of H. guttulatus represent a useful tool to support species conservation by protecting the habitats it uses
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Comparative and integrative approaches to assess the connectivity of four estuarine annelid species : osmoregulation strategies
Get PDFOrientador: Prof. Dr. Paulo Da Cunha LanaCoorientador: Prof. Dr. Maikon Di DomenicoTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Zoologia. Defesa : Curitiba, 26/02/2021Inclui referênciasResumo: As distribuições populacionais atuais e a diversidade genética dos organismos estuarinos são o resultado de uma combinação de fatores históricos e contemporâneos, que influenciam a dispersão e o fluxo gênico entre populações. Devido às rápidas mudanças climáticas que influenciaram direta e indiretamente o nível do mar e a linha de costa em todo o globo, o Pleistoceno afetou profundamente a distribuição e a diversidade genética de vários táxons. Os estuários são ambientes altamente dinâmicos, caracterizados por grandes flutuações de salinidade. Os organismos estuarinos desenvolveram adaptações fisiológicas e ecológicas para lidar com tais variações estuarinas diárias ou sazonais. Este trabalho visa investigar como fatores contemporâneos e históricos modelaram e modelam os atuais padrões de distribuição e a composição gênica de quatro espécies-alvo de anelídeos em três estuários subtropicais do sul do Brasil, explorando vários níveis de organização biológica por meio de uma abordagem bastante integrativa. As espécies-alvo foram escolhidas em função da sua abundância e maior ou menor tolerância às variações de salinidade ao longo de baixios entre-marés dos estuários. Testamos duas espécies com nichos de salinidade mais amplos, os nereidídeos a priori chamados de Alitta succinea e Laeonereis culveri, e espécies com nichos de salinidade mais restritas, o neftídeo Nephtys fluviatilis e o melinídeo Isolda pulchella. A tese foi dividida em quatro capítulos, que avaliaram a importância de forçantes históricas e contemporâneas na distribuição e composição genica das quatro espécies, em diversos níveis de organização biológica: - O primeiro capítulo investigou a tolerância à variação da salinidade e a espessura do tegumento das quatro espécies alvo. Ambos os nereidídeos apresentaram estabilidade de peso corporal e tegumento espesso, compatível com sua eurihalinidade. O neftideo foi nitidamente menos eurihalino, mas tolerou baixas salinidades e água doce, enquanto o melinídeo apresentou um comportamento estenohalino marinho e não tolerou diluição da água do mar. Ambas as espécies apresentaram um tegumento fino. - O segundo capítulo revelou a expressão e localização do cotransportador NKCC por imunofluorescência nos corpos das quatro espécies de anelídeo. Sua expressão não foi homogênea, refletindo claramente o estilo de vida dos anelídeos. Os anelídeos de vida livre (ambos os nereidídeos eurihalinos e o neftídeo estenohalino), exibiram um sinal para NKCC espalhado e detectado ao longo de seus corpos, em contraste com o melinídeo sedentário, no qual o sinal foi restrito às regiões anteriores do corpo em contato direto com a coluna d'água. - O terceiro capítulo investigou a presença das aquaporinas em anelídeos por meio de uma abordagem in sílico, através de uma busca nos bancos de dados públicos, e a confirmou experimentalmente em A. succinea. A filogenia de MIPs dos anelídeos foi reconstruída, potenciais ortólogos das aquaporinas dos vertebrados AQP1-like, AQP8 e as AQP11-like foram recuperados, e a presença de três parálogos de A. succinea foram confirmados por RT-PCR. - O quarto capítulo investigou os padrões de diferenciação genética de populações das quatro espécies-alvo em três estuários subtropicais do sul do Brasil. Alto fluxo gênico foi recuperado para os nereidídeos entre as baías, resultado congruente com os dados do primeiro capítulo e esperado em função de sua eurihalinidade. Marcada segregação foi recuperada para as populações de neftídeo da Baía da Babitonga, como reflexo de seu baixo grau de eurihalinidade e de sua distribuição limitada aos setores oligohalinos mais confinados. Panmixia entre os estuários foi recuperada para o melinídeo, refletindo seu comportamento "marinho" e sua ocorrência restrita aos setores euhalinos. As análises moleculares indicaram a existência de uma nova espécie de Alitta, ainda por ser formalmente descrita. Validaram ainda trabalhos recentes que haviam mostrado que populações antes referidas ao nome específico Laeonereis culveri, pertencem de fato a Laeonereis acuta e Laeonereis pandoensis, ocorrendo em simpatria ou alopatria.Abstract: Present-day distribution and genetic diversity of estuarine animals are the result of a combination of historical and contemporary factors that have influenced both their dispersal and gene flow. For instance, Pleistocene glaciations influenced sea-level and the coastal lines worldwide, strongly affecting the distribution patterns of coastal and estuarine species belonging to different taxa. Estuaries are highly dynamic environments, characterised by regular or irregular salinity fluctuations, and estuarine organisms share a variety of physiological and ecological adaptations to face such daily or seasonal variations. This work aimed to investigate how contemporary and historical factors have modelled and are still modelling the current distribution of four estuarine annelid species from different sectors of three subtropical estuaries of southern Brazil, by exploring different biological organization levels through an integrated approach. The target species were chosen considering their distribution and the variability in the salinity regimes of their ranges of occurrence. We tested two species with broader salinity niches, the nereidids treated a priori as Alitta succinea and Laeonereis culveri, and two species with narrower salinity niches, or more restricted spatial ranges in the bay, the nephtyid Nephtys fluviatilis and the melinnid Isolda pulchella. The thesis was articulated into four chapters, assessing contemporary or historical drivers which potentially led to genetic structure, or lack of it, at diverse organization levels: - Chapter one investigated the tolerance to salinity variation and the integument thickness of the four annelid species. Both nereidids displayed body weight stability and a thick integument, compatible with their high euryhalinity. The nephtyid was distinctly less euryhaline but tolerated low salinities and fresh water, while the melinnid presented a marine stenohaline behaviour and did not tolerate seawater dilution. Both species have a thin integument. - Chapter two revealed the expression and localization of the NKCC cotransporter through immunofluorescence in the bodies of the four annelids. NKCC expression was not homogeneous, and clearly reflected the lifestyle of each species. The free-living/burrowers (both euryhaline nereidids and the stenohaline nephtyid) displayed a widespread signal for NKCC along their bodies, in contrast to the stenohaline sedentary melinnid, in which the signal was restricted to the body regions exposed to the surrounding environment. - Chapter three investigated the presence of aquaporins in annelids through an in silico approach against online databases and experimentally confirmed for the first time their expression in A. succinea. The phylogeny of annelid MIPs was reconstructed, putative orthologs of the vertebrate AQP1-like, AQP8 and the AQP11- like subfamilies were recovered, and three paralogs of A. succinea were confirmed by RT-PCR. - Chapter four investigated patterns of genetic differentiation in populations of the four selected annelid species along three subtropical estuaries from southern Brazil. High genetic flow among the bays was reported for the nereidids, congruent with their high euryhalinity. Segregation was recovered for the nephtyid populations from Babitonga Bay, reflecting their low degree of euryhalinity and their limited distribution to the more confined, oligohaline sectors. Panmixia among the estuaries was recovered for the melinnid, reflecting its "marine" behaviour and its restricted occurrence in the euhaline sectors. As a result of our molecular analyses, we found a putative new species related to the complex A. succinea, and validated the recent findings from other authors that the species name L. culveri, as yet used for local populations of Laeonereis, corresponds in fact to two distinct species, Laeonereis acuta and Laeonereis pandoensis
Polychaete fauna of the Northwest Portuguese Coastal Shelf: ecology, diversity and distribution
Get PDFPolychaetes are one of the larger groups of macroinvertebrates with more than 9000 species recognised, distributed worldwide. Thanks to the broad ecological adaptability and high abundaces, this taxon plays a leading role and is considered an important component of all benthic assemblages.
Our knowledge about the West Iberian Coast polychaete fauna are scarce, and the only studies are recent. In this sense, the aim of this work was to investigate the composition and the spatial distribution of the polychaete fauna along the NW Portuguese Coastal Shelf, focusing on their relationship to environmental factors (depth, grain size, longitude and latitude) and to add new data to the existing biological dataset. A total of 39 sites were analysed, collected in an area of about 5665 km², between 20 and 150 m depth, distributed in a way to cover the overall grain size gradient.
A total of 9352 specimens belonging to 41 families were found, and the analysis based on the abundance of polychaete species revealed five affinity groups: (a) nearshore medium sand characterised by Pisione parapari and Hesionura elongata; (b) very coarse sand that showed the highest abundance of Syllidae and was characterised by Protodorvillea kefersteini and Syllis garciai; (c) fine sand dominated by Spiophanes bombyx and Glycera tridactyla; (d) very fine sand with Nepthys assimilis and Amage sp. and the highest abundance of Paraonidae; (d) mud characterised by Labioleanira yhleni and Ampharete finmarchica. The combination of the environmental variables and the biological data, done with BIOENV routine, demonstrated that depth, grain size and fine contents were the best related with the biological data (rho=0.598). In general, the results agree with the composition and the spatial distribution of the polychaete fauna in other parts of the world; further polychaete assemblages related to mud sediments were firstly recorded in the Northwestern Portuguese Coastal Shelf
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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