Dynamics of pleustonic ostracod populations in small ponds on the Island of Martín García (Río de la Plata,Argentina)

The biogeography and ecological preferences of Neotropical freshwater ostracods are poorly known, and more so the dynamics of populations and habitat selection of species living in pleustonic environments of temporary ponds. In the present survey we analyze the population changes of ostracods living in pleustonic environments of small freshwater bodies on Martín García Island (Río de la Plata, Argentina). Between June 2005 and June 2007, monthly samples of floating vegetation from eight different ponds on the island were collected, and limnological parameters were measured in situ. The results of multivariate logistic regression showed that the presence of ostracods was significantly related to high dissolved oxygen content and high water temperature. In addition, multivariate regression analysis indicated that, when ostracods were present, their total abundance was negatively related to floating vegetation dry weight. Four ostracod species were found: Strandesia bicuspis, Chlamydotheca incisa, Cypridopsis vidua, and Bradleytriebella trispinosa. The seasonal variation in abundances indicated that populations of the most common species, S. bicuspis and C. incisa, were denser during the summer and autumn months. The results of canonical correspondence analysis showed that individuals of S. bicuspis were more abundant at higher temperatures and lower conductivity than C. incisa. Further research is needed to clarify the observed negative correlation between floating vegetation dry weight and ostracod density and the possible differential thermal preference of the two species studied.     

Distribution and taxonomy of shallow marine Ostracods from Northern Socotra Island (Indian Ocean) - Yemen

Forty-seven species belonging to 30 genera of ostracods have been identified from Recent shallow marine sediments collected along the northern coastline of the island of Socotra (Indian Ocean). The systematics and distribution of these ostracods are discussed. Three genera, Loxoconcha, Bosasella, and Xestoleberis are found to have high species diversity. The species Loxoconcha ghardaqensis, Moosella striata are best documented in the Red Sea and Gulf of Aden while Kotoracythere inconspicua and Triebelina sertata were found to be the most widespread species. The fauna shows a close affinity to other ostracod assemblages of the Indo-Pacific region, East African coast and Red Sea.     

Geographic variation in otolith morphology among freshwater populations of Aphanius dispar (Teleostei,Cyprinodontiformes) from the southeastern Arabian Peninsula

Aphanius Nardo is a large genus of teleost fishes in the Old World, with 19 described species. Several of these species have only recently been recognized and additional species can be expected from isolated populations in remote areas. We show here that otolith morphology and statistical analyses of otolith variables can contribute to the detection of genetic differentiation in Aphanius. We studied samples of eight Aphanius dispar populations from the southeastern part of the Arabian Peninsula. Two populations originate from freshwater habitats far inland and probably have been isolated since the late Holocene some 4,000 years ago, three populations come from freshwater habitats with occasional connections to the sea, one population originates from a coastal site, and two were artificially introduced populations. The coastal population is interpreted as possessing the basic otolith type of A. dispar. The basic otolith type also occurs in fishes from the freshwater habitat which is located closest to the coast. Otoliths from the two other freshwater populations with occasional connections to the coast differ slightly from the basic type. However, the two populations from the long‐term isolated freshwater habitats far inland show distinct morphological changes. Our results are consistent with the hypotheses that i) otolith morphology is primarily genetically determined and is little influenced by physical parameters of the habitat, and ii) isolated A. dispar populations may be capable of evolving into new species within short periods of time. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.     

Fungal biodiversity in aquatic habitats

Fungal biodiversity in freshwater, brackish and marine habitats was estimated based on reports in the literature. The taxonomic groups treated were those with species commonly found on submerged substrates in aquatic habitats: Ascomycetes (exclusive of yeasts), Basidiomycetes, Chytridiomycetes, and the non-fungal Saprolegniales in the Class Oomycetes. Based on presence/absence data for a large number and variety of aquatic habitats, about 3,000 fungal species and 138 saprolegnialean species have been reported from aquatic habitats. The greatest number of taxa comprise the Ascomycetes, including mitosporic taxa, and Chytridiomycetes. Taxa of Basidiomycetes are, for the most part, excluded from aquatic habitats. The greatest biodiversity for all groups occurs in temperate areas, followed by Asian tropical areas. This pattern may be an artifact of the location of most of the sampling effort. The least sampled geographic areas include Africa, Australia, China, South America and boreal and tropical regions worldwide. Some species overlap occurs among terrestrial and freshwater taxa but little species overlap occurs among freshwater and marine taxa. We predict that many species remain to be discovered in aquatic habitats given the few taxonomic specialists studying these fungi, the few substrate types studied intensively, and the vast geographical area not yet sampled.     

Recent ostracods (Crustacea,Ostracoda) found in lowland springs of the provinces of Piacenza and Parma (Northern Italy)

The “fontanili” are artificial aquatic ecosystems, typical of the lowland plains of Northern Italy, exploiting natural resurgences of deep groundwater. These habitats are characterized by low variation in hydrologic, hydrochemical and thermal conditions throughout the year. Proper management is required to prevent the spring clogging by biomass accumulation. In spite of their importance as refugia for endangered species, many springs were completely abandoned in the last years and several of them will disappear. We report the results of a study carried out in 2001 on 31 springs of the provinces of Piacenza and Parma, distributed in seven areas defined on hydrological and geological considerations. Physical and chemical variables and parameters of waters were measured and ostracod samples were collected. Most of the springs showed high nitrate concentration, due to a diffuse pollution of agricultural origin. Twelve ostracod species in four families were identified. Ostracod valves were analysed by scanning electron microscopy. Cypria ophtalmica was found in all the springs; other relatively common species were Cyclocypris laevis,Notodromas persica, and Prionocypris zenkeri.The maximum number of species per site was four. Cypridopsis vidua,P. zenkeri, and N. persicashowed a very localized distribution in the study area. The ostracod fauna of the “fontanili” was compared to other species assemblages found in spring habitats and to the available information on recent freshwater ostracods reported for Italy.     

Diversity and abundance of nematode-trapping fungi from decaying litter in terrestrial, freshwater and mangrove habitats

Nematode-trapping fungi are ubiquitous in terrestrial habitats in dung, soils, litter and woody debris and they also occur in freshwater, but only one species has been found in marine habitats. The purpose of this study was therefore to investigate whether nematode-trapping fungi occurred in mangrove habitats. To achieve this we assessed the diversity of nematode-trapping fungi on decaying litter from mangroves, freshwater and terrestrial habitats (22 sites) in Hong Kong. Composite samples (n = 1,320) of decaying litter (wood and leaves) were examined and a total of 31 species of nematode-trapping fungi belonging to four genera, Arthrobotrys, Monacrosporium, and Dactylella were recorded. Twenty-nine species reported in this study are new records for Hong Kong and 16 species are new records from mangrove habitats worldwide. Nematode trapping fungi are therefore present in marine environments. Commonly encountered taxa were Arthrobotrys oligospora and Monacrosporium thaumasium which are abundant in all habitats. A. oligospora, M. thaumasium and Arthrobotrys musiformis were frequent (F > 10%). Twenty-six species were rare (0.16–9.32%). Species richness and diversity was higher in terrestrial than in freshwater and mangrove habitats (ANOVA, P < 0.001). A higher mean diversity was observed on decaying leaves as compared to decaying wood in all habitats (P < 0.001). Based on Shannon diversity index, it was also observed that taxa characterized by adhesive nets were more frequent in all habitats. This can be explained by the fact that these taxa may have a better competitive saprotrophic ability which would allow them to compete favourably in nutrient limited environments. Abiotic factors that could be linked to differences in species diversity between decaying wood and leaves are also discussed.     

Ostracod Assemblages in Relation to Littoral Plant Communities of a Shallow Lake (Lake Świdwie,Poland)

The aims of this study included: specifying values of ecological parameters and Ostracoda species characteristic for different types of plant habitats occurring in lake systems, determining the impact of mud presence on the taxonomic structure and density of the ostracods, tracing seasonal changes in the structures of Ostracoda assemblages identifying the species typical of particular seasons. Various types of rushes and underwater meadows were taken into consideration as lake microhabitats. The research was conducted in the shallow Lake Œwidwie (NW Poland). Multivariate (constrained) ordination methods were used to analyse the relationships between species composition and environmental variables. In the lake and its margins 31 species of the Ostracoda were identified. The development of water vegetation during the vegetation season was conducive to growth in ostracod density. The accessibility of mud in plant habitats had a favourable effect on the general density of ostracods. Species which preferred a high mud content in their habitats included: Cypria ophtalmica, C. exsculpta and Physocypria kraepelini. Species typically encountered in underwater meadow habitats were: Cyclocypris ovum and Cypridopsis vidua. Underwater meadows of charophyte were characterized by the highest ostracod density in the whole lake system, with the average of 7860 ind. m^–2 and the maximum of 17 470 ind. m^–2. Species typically encountered in rush habitats included Notodromas monacha, Dolerocypris fasciata and Metacypris cordata. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Spatiotemporal Variation in Shallow-Water Freshwater Fish Distribution and Abundance in a Large Subtropical Coastal Lagoon

Patos Lagoon is located off the southern Brazilian coast and represents one of the largest coastal lagoons in the world. We estimated hydrological and physicochemical conditions associated with spatial variation in the abundance and diversity of freshwater fishes along the lagoon, and inter-annual variability in abundances of freshwater fishes occurring in its estuarine zone. During our study, the region experienced two periods of average rainfall and two periods with above-average rainfall. The characids Astyanax eigenmaniorum and Oligosarcus jenynsii and the siluriform Parapimelodus nigribarbis were the most abundant freshwater fishes in the estuary during wet periods when water levels were higher and salinity was lower. Increases in abundance of these species in the estuarine area, all of which members of primary-division freshwater families, apparently were associated with pulses of reproduction and passive transport from freshwater habitats located near middle and upper lagoon reaches. Abundance of species from secondary freshwater families, such as poeciliids and cichlids, were less correlated with hydrological conditions, and their patterns of occurrence in the estuary suggest active migration from nearby freshwater habitats draining into this area. Findings indicate that freshwater discharge in the basin and expansion/retraction of freshwaters in the middle-upper lagoon determined patterns of freshwater fish abundance and species richness in the estuarine zone.     

Late Miocene marine ostracods from Santa Maria island,Azores (NE Atlantic): Systematics,palaeoecology and palaeobiogeography

The nine oceanic islands that comprise the Azores archipelago are located in the middle of the northern Atlantic Ocean. In this isolated archipelago, there is a rich fossil record in one of the islands, Santa Maria. In this island, samples were collected in the Upper Miocene composite section of Malbusca outcrop, located in the southern shore of the island, and the fossil marine Ostracoda were studied. This work represents the first report of fossil ostracods from the Azores archipelago. Thirteen species were found, representing seven families and 12 genera (Xestoleberis, Loxoconcha, Callistocythere, Leptocythere, Dameriacella, Aurila, Heliocythere, Pachycaudites, Neonesidea, Cyamocytheridea, ?Quadracythere and Paracypris). Among the identified species, one new species, Leptocythere azorica n. sp., is described. Loxoconcha (two species) was the most diversified genus. The collected species are mainly ornamented and typical of warm waters and epi-neritic habitats (～ 10–50 m of depth).     

Colonization and demographic expansion of freshwater fauna across the Hawaiian archipelago

It is widely accepted that insular terrestrial biodiversity progresses with island age because colonization and diversification proceed over time. Here, we assessed whether this principle extends to oceanic island streams. We examined rangewide mtDNA sequence variation in four stream‐dwelling species across the Hawaiian archipelago to characterize the relationship between colonization and demographic expansion, and to determine whether either factor reflects island age. We found that colonization and demographic expansion are not related and that neither corresponds to island age. The snail Neritina granosa exhibited the oldest colonization time (~2.713 mya) and time since demographic expansion (~282 kya), likely reflecting a preference for lotic habitats most prevalent on young islands. Conversely, gobioid fishes (Awaous stamineus, Eleotris sandwicensis and Sicyopterus stimpsoni) colonized the archipelago only ~0.411–0.935 mya, suggesting ecological opportunities for colonization in this group were temporally constrained. These findings indicate that stream communities form across colonization windows, underscoring the importance of ecological opportunities in shaping island freshwater diversity.     

Current distribution and potential extent of the most invasive alien plant species on La Réunion (Indian Ocean,Mascarene islands)

Abstract La Réunion Island has the largest area of intact vegetation of the islands in the Mascarene archipelago. Biological invasions are the primary threat to biodiversity in the intact habitats of the island (those not already transformed by agriculture and urbanization). Our study aimed to identify areas to prioritize in managing invasive alien plants for biodiversity conservation. We used extensive surveys of 238 distinct untransformed areas on La Réunion to define the current distribution patterns of all invasive species. Using expert knowledge, we compiled maps of the current distribution of the 46 most widespread/important invasive plants at the habitat scale (identified according to vegetation structure). Data from 440 botanical relevés for the 20 most threatening invasive alien plant species across the island and climatic envelope models were used to derive climatic suitability surfaces; these were used to map potential distributions for these species. More than 10 species invade 16.7% of the remaining habitat. Five habitat types are invaded by 25 or more species, and eight have fewer than 10 invasive alien plant species. Cluster analysis based on presence/absence of species in the 18 habitat types produced eight groups of species that invade particular habitats. Potential distribution models show that some species have invaded large parts of their potential range (e.g. Fuchsia magellanica, Furcraea foetida, Hiptage benghalensis), whereas others have the potential to increase their range substantially (e.g. Clidemia hirta, Strobilanthes hamiltonianus, Ulex europaeus). Management implications are identified for both groups. Three broad groups of habitats were identified: (i) intact habitats with a low level of invasion (e.g. subalpine shrubland); (ii) moderately invaded habitats with varying levels of intactness (ranging from windward submountain rainforest to the Acacia heterophylla forest); and (iii) habitats with little remaining intact area and high levels of invasion (e.g. lowland rainforest). Different management interventions are appropriate for these three groups.     

Spatial distribution and seasonality of ichthyoplankton and anthropogenic debris in a river delta in the Caribbean Sea

Temporal changes in larval fish species composition and abundance compared with other components of the seston are described in four estuarine habitats in the Atrato Delta, Colombia. In comparison with zooplankton, fish larvae and egg density and anthropogenic debris abundance were low in the South Atrato Delta. Transparency, water temperature and chlorophyll a were the major factors influencing the spatiotemporal distribution of ichthyoplankton in the delta. The most abundant fish larvae were Astyanax sp. 1, Anchovia clupeoides, Cetengraulis edentulus, Anchoa sp., Bathygbius curacao, Dormitator maculatus, Hyporhamphus sp., Atherinella blackburni, Gobiosoma sp. 1 and Menticirrhus americanus (92·8% of total abundance). Spatial temporal analysis shows that in this delta, shrub (arracachal) and grass (eneal) habitats are important for freshwater and estuarine species, whilst mudflat and mangrove are important for estuarine species and estuarine–marine species, since most flexion and post‐flexion stages of these species were found there. Anthropogenic debris density never surpassed the total ichthyoplankton density, but was ubiquitous. Shrub and mangrove habitats had higher densities of anthropogenic debris, since these are flood‐stem habitats that trap solids.     

Chironomidae from marine coastal environments near St. John's, Newfoundland, Canada

Chironomid larvae and adults were collected from rock pool and intertidal sites between 1990 and 1994 on the exposed Atlantic coast and in more sheltered bays near St. John's. From several thousand specimens collected, 16 chironomid taxa were identified. Two were from intertidal habitats and the remainder occurred in rock pools. In intertidal habitats Halocladius variabilis was abundant in summer among clumps of fine filamentous algae, e.g. Pilayella littoralis. The previous Nearctic records of this chironomid were from Hudson Bay and Greenland although it is widespread in northern Europe. The other intertidal species, Telmatogeton japonicas, was recorded from one site, a rock outcrop on a beach in the mouth of a small stream. This Holarctic species has not been reported previously north of New York on the Atlantic coast. The rock-pool communities were dominated by Psectotanypus dyari, Cricotopus sylvestris, Psectocladius sordidellus gp, Orthocladius dubitatus, Chironomus riparius, and Tanytarsus sp. These taxa are known to tolerate sites with elevated salinity and/or conductivity and thus are present in polluted sites inland. The other eight chironomid species were rare and most were found at only one site. An exception was the Metriocnemus sp. collected in very low numbers at three sites and also collected previously during a survey of rock pools for larval mosquitoes in the same area. The current study shows that a diverse coastal chironomid community is present in the cold ocean habitats of eastern Newfoundland. The community is made up of both arctic and temperate faunal elements with widespread distributions not confined to coastal habitats. Ranges of temperature, salinity, conductivity and pH for the common species occurring in the rock pools are provided. The results suggest that coastal rock pool habitats could be a natural laboratory for studies on the evolutionary ecology of pollution tolerance in chironomids.     

Diversity of the free-living marine and freshwater Copepoda (Crustacea) in Costa Rica: a review

The studies on marine copepods of Costa Rica started in the 1990’s and focused on the largest coastal-estuarine systems in the country, particularly along the Pacific coast. Diversity is widely variable among these systems: 40 species have been recorded in the Culebra Bay influenced by upwelling, northern Pacific coast, only 12 in the Gulf of Nicoya estuarine system, and 38 in Golfo Dulce, an anoxic basin in the southern Pacific coast of the country. Freshwater environments of Costa Rica are known to harbor a moderate diversity of continental copepods (25 species), which includes 6 calanoids, 17 cyclopoids and only two harpacticoids. Of the +100 freshwater species recorded in Central America, six are known only from Costa Rica, and one appears to be endemic to this country. The freshwater copepod fauna of Costa Rica is clearly the best known in Central America. Overall, six of the 10 orders of Copepoda are reported from Costa Rica. A previous summary by 2001 of the free-living copepod diversity in the country included 80 marine species (67 pelagic, 13 benthic). By 2009, the number of marine species increased to 209: 164 from the Pacific (49% of the copepod fauna from the Eastern Tropical Pacific) and 45 from the Caribbean coast (8% of species known from the Caribbean Basin). Both the Caribbean and Pacific species lists are growing. Additional collections of copepods at Cocos Island, an oceanic island 530 km away of the Pacific coast, have revealed many new records, including five new marine species from Costa Rica. Currently, the known diversity of marine copepods of Costa Rica is still in development and represents up to 52.6% of the total marine microcrustaceans recorded in the country. Future sampling and taxonomic efforts in the marine habitats should emphasize oceanic environments including deep waters but also littoral communities. Several Costa Rican records of freshwater copepods are likely to represent undescribed species. Also, the biogeographic relevance of the inland copepod fauna of Costa Rica requires more detailed surveys.     

Long-term bat study on an island in the southeastern Brazilian coast with comparison of richness and composition of species among sites

Although Rio de Janeiro is one of the best sampled states of Brazil for bats, there are still some poorly studied islands on its coast. Hence, we inventoried the bat species of an island on the southwestern coast of Rio de Janeiro, compared five sites sampled within this island, and compared its bat community with seven other sites in the same region. We carried out sampling in July 1995 and from September 2006 to August 2010, comprising 58 samplings. We captured a total of 1502 individuals of 25 bat species with mist nets set far from roosts, or close to or inside roosts. The most abundant species were Artibeus lituratus, Molossus molossus, and Carollia perspicillata. Total sampling effort was 89,400 m² h. The present study was one out of five inventories carried out in the southwestern coast of Rio de Janeiro that registered more than 1000 bat individuals from more than 24 bat species. Long-term inventories on islands are still needed, because they can result in a large number of species and captures as observed in the present study.     

Invertebrate dispersal by aquatic mammals: a case study with nutria Myocastor coypus (Rodentia,Mammalia) in Southern France

Many freshwater invertebrates rely on vectors for their passive dispersal. A wide array of vectors has already been investigated, but dispersal mediated by aquatic mammals remains largely unknown. Since nutria (Myocastor coypus Molina, 1782) live in a variety of aquatic habitats and frequently move around between these water bodies, they have the opportunity to transport hitch-hiking aquatic invertebrates along with them. We investigated the presence of aquatic invertebrates in their fur to evaluate this hypothesis. This study demonstrates the feasibility of ectozoochory in a broad array of freshwater invertebrates by nutria on a local scale. More than 800 invertebrates of 14 different taxa were retrieved from the fur of 10 nutria specimens, including cladocerans, copepods, ostracods, rotifers, bryozoans, dipterans, nematodes, annelids and collembolans. Many of these freshwater invertebrates could survive at least 30 min in the moist fur of nutria. Therefore, we can state that besides modifying aquatic habitats physically by clearing vegetation or digging, nutria may also alter invertebrate communities by introducing new species or genotypes.     

Distribution patterns of freshwater Ostracoda (Crustacea) in the Canary Islands with regards to habitat use and biogeography

In this study biogeographic patterns and habitatrelationships of freshwater Ostracoda wereinvestigated in the Canary Island archipelago. Mostdata were collected from published studies, thoughalso new data from Gran Canaria are presented. In all,22 freshwater species are presently known to theCanaries. Six species, viz. Ilyocypris bradyi,Cypris bispinosa, C. pubera, Herpetocypris chevreuxi, Heterocyprisincongruens, and Sarscypridopsis lanzarotensisare new to Gran Canaria, the first two also being newto the Canaries in general. Testing the influence ofa number of variables on faunal richness indicatedonly a weak association with island area. Distancesbetween islands also proved not significant, and sodid other properties of islands, including age,altitude and precipitation. This was in contrast to acomparison set of data comprising aquatic beetles.Like beetles, however, ostracods did not show a nestedpattern, i.e. faunas of species-poor islands were notsubsets of species-rich island faunas. By having lowendemicity (endemic species lacking in the Canaries),the ostracod fauna resembled island fern floras. Bothgroups of organisms have tiny diaspores (diameter<0.1 mm) and are extensively parthenogeneticsuggesting similar dispersal and founder mechanisms.We identified a pattern (with one exception), wherethose species with distributions extending acrossseveral islands also had wider within-islanddistributions. Many species showed affinities todifferent habitats depending on conductivity of water,altitude and habitat types: whether they werepermanent or temporary, hypogean or epigean, orcharacterized by running or stagnant waters.     

Global diversity of fishlice (Crustacea: Branchiura: Argulidae) in freshwater

The Branchiura of freshwater habitats, consisting of the valid genera Argulus, Chonopeltis, Dipteropeltis, and Dolops, presently contains 113 valid species and 12 undescribed species. The entire group is composed of ectoparasitic species that usually live on fishes. The highest diversity of genera and species occurs in the Afrotropical and Neotropical regions. The diversity of the freshwater species surpasses that of species in marine and brackish waters, but this could be due to inadequate study of the fauna of the latter habitats. One species, Argulus japonicus, has been introduced from east/southeast Asia to all other continents, except Antarctica. Studies of higher level relationships place the Branchiura with either Pentastomida or Ostracoda. Hypotheses about phylogenetic relationships of either the genera or species in this group have not been proposed. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment The present paper was intended as a very brief overview of the known diversity of the Branchiura in freshwaters only, and regrettably is deficient in mention of much information and many relevant citations pertaining to the group.     

Patterns of bird species richness and composition on islands off Arnhem Land,Northern Territory,Australia

The bird faunas of the adjacent Wessel and English Company island chains were sampled at two scales (0.25 ha quadrats and entire islands). Ninety‐six species were recorded from 226 quadrats, with the most frequently recorded species being mistletoebird Dicaeum hirundinaceum, brown honeyeater Lichmera indistincta, silver‐crowned friarbird Philemon argenticeps, bar‐shouldered dove Geopelia humeralis, northern fantail Rhipidura rufiventris and yellow white‐eye Zosterops lutea. At the quadrat scale, vegetation type was a major determinant of the abundance of individual species (and hence species composition), species richness and total bird abundance. Bird species composition and richness at the quadrat scale was also significantly affected by island isolation (particularly the amount of land within 20 km of the island perimeter). Island size had no effect on quadrat‐scale richness or total abundance. However, the abundance of 10 of the 38 most frequently recorded individual species was significantly related to island size, in most cases even when the comparison was restricted to similar habitats. The most striking cases were rufous fantail Rhipidura rufifrons, mangrove golden whistler Pachycephala melanura, brown honeyeater and yellow white‐eye, which were all significantly more abundant on smaller islands. One hundred and seventy‐one species were recorded from the 62 islands sampled. There was a very tight relationship between island size and the number of terrestrial species (73% of deviance explained) and of all species (84% of deviance explained). This relationship was improved (marginally) when isolation was included in the model. Ordination of islands by their terrestrial bird species composition was related to island size and isolation, and suggested an erratic species composition on small islands.