Ostracod Communities Research Articles

Benthic community history in the Changjiang (Yangtze River) mega-delta: Damming, urbanization, and environmental control

AbstractThe coastal environment of the Changjiang delta has been influenced by recent anthropogenic activities such as dam construction and increased sewage and fertilizer inputs. Previous work examined the compositional shift of marine plankton to assess ecological impacts of these activities on marine ecosystems in the Changjiang discharge area. Here we used benthic marine ostracodes collected in the Changjiang estuary and the adjacent East China Sea in the 1980s and the 2010s, respectively, to investigate temporal changes of the benthic community and controlling factors for the benthic fauna. Our results revealed more shoreward distribution of some well-known offshore ostracode species in the 2010s compared with the 1980s and a relatively more important role for environmental processes (e.g., bottom-water temperature, bottom-water salinity, and eutrophic conditions of surface water) than spatial processes (e.g., the flow of ocean currents) in structuring ostracode compositions. The temporal changes in the ostracode community are likely attributable to the combined effects of reduced fresh water and sediment discharge and eutrophic conditions of the Changjiang due to the many dams constructed along the Changjiang and population expansion in the Changjiang Basin. Results of redundancy analysis and variation partitioning suggest that ocean currents facilitated environmental filtering of ostracode species such that they could disperse to preferred environmental conditions. These findings highlight the potential uses of marine microfossils to better understand ecological impacts on benthic ecosystems in vulnerable Asian mega-deltas and provide insights into the integration of metacommunity concepts in disentangling dynamics of marine benthic communities.

Response of lake-catchment processes to Holocene climate variability: Evidences from the NE Tibetan Plateau

Investigating the so-called Third Pole Environment (TPE) became a major concern during the last decades since it was recognized that the high-altitude region of the Tibetan Plateau (TP) is a key area for the understanding of cause-effect mechanisms driven by climate change and geodynamic processes. Studies on the hydro-climatic evolution during the Late Quaternary were mainly carried out by single lake records or alternatively by individual terrestrial sites. Integrated source-to sink studies considering lake–catchment interactions were extremely seldom utilized. We investigated such relationships in the Kuhai Basin on the north-eastern Tibetan Plateau and analysed sedimentary processes based on 30 onshore sections and three sediment cores from different locations and water depth in the lake basin. Grain size variations, ostracod assemblages, geochemical proxies and absolute dating (luminescence, radiocarbon, 210Pb/137Cs) were applied as key indicators that reveal interacting sediment fluxes under different hydro-climatic settings during the Younger Dryas interval and the Holocene. Our results indicate that wind-induced transportation processes and allocation of respective aeolian sands in the catchment are attributed to distinct phases of reduced effective moisture availability during summer time. Those phases corresponded to weak summer monsoon influence during the Younger Dryas interval, the Early Holocene (11.6–7.5 ka), dry-cold interlude (DCI: ca. 4.5–3.0 ka), Dark Ages Cold Period (DACP: ca. 1.8–1.1 ka) and the Little Ice Age (LIA: ca. 0.6–0.1 ka). Contemporaneous low lake levels during these periods corresponded with respective aeolian sand flux and variable composition of mixed sediments (fluvial and aeolian) in lake deposits. Different flux rates at the core sites could be assigned to local conditions in respect to inflow behaviour of individual drainage systems and nearshore morphology. Aeolian deposits in the catchment were not always preserved and underwent re-mobilisation during succeeding episodes and/or erosion during phases of high water availability. Wetter climatic conditions during the Mid-Holocene (ca. 7.5–5.1 ka), Roman Warm Period (RWP: ca. 2.8–1.5 ka) and Medieval Climate Anomaly (MCA: ca. 0.9–0.6 ka) revealed significant lake level rise due to enhanced river discharge, well documented by highest suspended flux rates, disappearance of ostracod communities at core sites and very low sand input. Climate shifts during the Holocene were linked to variations in effective moisture supply under the influence of the Asian summer monsoon (ASM) and the interplay with the mid-latitude westerlies (MLW). Cold-dry phases were likely a response to North Atlantic climatic anomalies transmitted by the MLW across the TP.

Composition and distribution patterns of marine planktonic ostracods (Crustacea, Ostracoda) in the Adriatic Sea - a historical perspective

This study provides the first comprehensive results on species composition, seasonal and horizontal distribution of the planktonic ostracod community in the open waters of the whole Adriatic Sea. Samples were collected during the “Andrija Mohorovičić” oceanographic expedition (1974-1976) in all four seasons at 35 stations located along eight latitudinal transects in the northern, central and southern part of the Adriatic Sea. Fifteen ostracod species and two subspecies belonging to the family Halocyprididae were identified. The dominant species were Archiconchoecia striata, Porroecia spinirostris and Proceroecia macroprocera. Additionally, Paraconchoecia oblonga was recorded for the first time in the Adriatic Sea. The highest abundance and diversity of planktonic ostracods were found in the deep South Adriatic. Conversely, ostracods were scarce in the shallow North Adriatic area. As the transitional zone between these two regions, the Central Adriatic was characterized by high ostracod diversity, but a short period of dominance in the zooplankton assemblage. The horizontal distribution of planktonic ostracods in the Adriatic Sea could be linked to periodical ingressions of Eastern Mediterranean water masses and gyre currents, especially in the Central and the South Adriatic.

The rare Holsteinian (Mazovian) interglacial limnic deposits in the Książnica outcrop at Krzczonów (near Świdnica), Sudetic Foreland

The article presents the results of research on peats, muds and sands filling a palaeocavity within alluvial fans of the Bystrzyca River valley, in the Sudetic Foreland of SW Poland. In the 534-cm deep research profile in the central part of a palaeolake, 267 samples were collected at an interval of 2 cm and lithologically (structural and textural studies), palaeobotanically (studies of diatoms, pollen plant macrofossils and fossil wood), palaeozoologically (Cladocera, Mollusca and Ostracoda), geochemically (chemical elements and isotopes) and palaeomagnetically analyzed.The profile consists of three parts: organic with mineral layers (lower), mineral (middle), and organic (upper). The palynological diagram was divided into three zones that represent local sets of pollen zones. This diagram, although incomplete, is clearly indicative of the younger part of the Holsteinian (Mazovian: pollen III and IV periods interglacial). The upper part of the diagram consists of four local pollen zones that are correlated with stadial and interstadial periods. Analysis of several samples of fossil wood shows the widespread presence of Pinus remains and numerous fragments of rhytidome (bark) of Betula. Development of the peat layer (1.36–0.68 m depth) started with paludification of the forest with the Betula forest. Analysis of Cladocera shows the presence of chitin armor components (species: Chydorus sphaericus, Alona rectangula and ephippia of Alona rectangula) in three samples.Lithological, Cladocera and palaeo-magnetic research, supported by geochemical studies, indicate the existence of at least three main phases. The lake originated during the younger part of the Holsteinian (Mazovian) Intergalcial as an oxbow within the valley, where the deposition of variously thick (up to 1.5 m depth) peats, organic and minerogenic silts (the first stage). In the second phase, a closed, fairly deep late Holsteinian lake continued to exist under relatively warm conditions with mainly mineral deposition from the slope. The lake became shallower and wider, and then more open and better oxygenated (with through-flow). In the final phase the lake was completely filled by organic sediments under interglacial conditions. The absence of diatom, molluscan and ostracod communities indicates an acid lacustrine environment at this time. The fluvial and limnic deposits are sealed by overlaying Saalian (Odranian) till.

Effects of flood pulses on persistence and variability of pleuston communities in a tropical floodplain lake

Large rivers in tropical regions can experience strong variations of abiotic factors owing to the occurrence of flood pulses. Both man-made and natural floods can cause pulses with varying intensity and duration. Here, we test the hypothesis that ostracod communities in the pleuston of floating plants are persistent during regular pulses and more variable during extreme floods. Ostracod communities were monitored in the Manezinho Backwater of the Upper Parana River floodplain (Brazil) for 83 months (seven hydrologic cycles). Flood pulses directly influenced the abiotic variables, which in turn were correlated with the species composition and abundance of ostracods. Variability in the species composition differentiated only between the limnophase of cycle 4 (L4: 2009) and the subsequent extreme flood of cycle 5 (P5: 2009–2010). The longer duration and higher intensity of the extreme flood can increase the exchange of organisms through the aquatic connections between the lake and the river and can potentially trigger the hatching of dry-resistant eggs, increasing variability in ostracod species composition. The absence of significant differences in the species composition variability between the other succeeding periods shows that these communities are persistent and buffered to the effects of natural pulses of short durations.

Biodiversity of ostracod communities (Crustacea, Ostracoda) in a tropical floodplain

Neotropical floodplains harbour both floating and rooted plants and are associated with rich ostracod communities. After dry seasons, flooding causes recruitment in 2 ways: floods bring in allochthonous macrophytes with associated pleuston communities, and these rising water levels rehydrate plants and attached (ostracod) eggs that dried at the onset of the dry season. We analysed the ostracods communities in the Araguaia River floodplain (Brazil) during 2 hydrological periods (dry and rainy) and evaluated the species distribution in relation to abiotic and biotic factors. We compared the ostracod fauna of 6 lakes in the dry and rainy period and 17 lakes in the rainy period. We tested the hypothesis that the highest values of ostracod community attributes (richness, density, and evenness) occur in the rainy season owing to the influx of allochthonous individuals and the rehydration of the dried autochthonous macrophytes. We indeed observed the highest richness and diversity of ostracods in the rainy season; the homogenizing effect of the flood pulse at the onset of the rainy season caused a more homogeneous fauna (lower beta diversity) during that hydrological period. The distribution of species showed a significant effect of both abiotic factors (local) and hydrological period (regional).

Evaluation of quantitative sampling methods in pleuston: An example from ostracod communities

We address two methodological questions related to sampling pleuston in floodplain lakes, using ostracod as model group: (1) we test the homogeneity of ostracod communities by comparing samples from the edge and from the centre of the floating Eichhornia crassipes patches, (2) we test if there is a clear difference between two methods of sampling. According to the ecological attributes evaluated, there was no significant difference between edge and centre of the patches, while both sampling methods were equally efficient to represent the ostracod communities.

Variability in ostracod communities (Crustacea, Ostracoda) in connected and isolated tropical floodplain lakes

Floodplains mostly consist of primary and secondary riverbeds, connecting channels and lakes that are either isolated from rivers and channels for most of the year, or lakes that are connected to rivers and channels for most (or all) of the year. We hypothesize that the differences in invertebrate communities, as calculated by beta-diversities, will be higher in isolated than in connected lakes. We use ostracod communities in the pleuston of the floating macrophyte Eichhornia crassipes in the Upper Parana River floodplain to test this hypothesis. We have observed significant differences in species composition between the two types of lakes. However, although beta diversity values are indeed slightly higher in isolated than in connected lakes, these differences are not significant. This lack of clear effect of isolation on beta diversity could be owing to the fact that the period of isolation since the last homogenizing flood pulse had not been long enough, or because differences in degree of isolation become altogether insignificant in periods of low water flow.

近60年来武汉东湖介形虫组合变化及其环境意义

早在1957年前人就对武汉东湖介形虫的属种进行了调查，当时共记载了6属8种及1新种。如今时隔60年后，武汉东湖的深度、面积和水质状况等发生了巨大变化，这些变化可能会造成水生生物群落的改变。本文于2014年再次调查了武汉东湖现代介形虫的物种分布情况，共发现介形虫8属15种，其中仅有2种介形虫与1957年的报道相同，介形虫的物种和生物群落组成都发生了很大变化。综合1957年和2014年武汉东湖的生态条件和水环境数据，本文认为介形虫群落组成的变化灵敏地反映了上世纪50年代以来武汉城市化和工业化等人类活动引起的湖泊环境变化过程。 Ostracod species had been identified and described by previous studies in the Lake Donghu, Wuhan in 1957. However, the environment and water conditions of Lake Donghu have been changed dramatically in the past 60 years, which may cause the succession in ostracod assemblage. In this paper, the species distribution of modern ostracod in Lake Donghu was investigated again in 2014. There were 15 species of 8 genera of ostracods, of which only two species were the same as those reported in 1957, and the ostracod species and community composition have undergone great changes. We summarized the ecological conditions and water environment data of Lake Donghu in 1957 and 2014, and suggested that the changes of the ostracod community assemblages sensitively reflected the processes of human-induced deterioration of water quality in Lake Donghu.

Distribution and community structure of Ostracoda (Crustacea) in shallow waterbodies of southern Kenya

The current study presents the ostracod communities recovered from 26 shallow waterbodies in southern Kenya, combined with an ecological assessment of habitat characteristics. A total of 37 waterbodies were sampled in 2001 and 2003, ranging from small ephemeral pools to large permanent lakes along broad gradients in altitude (700–2 800 m) and salinity (37–67 200 µS cm−1). Between 0 and 12 species were recorded per site. Lack of ostracods was associated with either hypersaline waters, or the presence of fish in fresh waters. Three of the 32 recovered ostracod taxa, Physocypria sp., Sarscypridopsis cf. elizabethae and Oncocypris mulleri, combined a wide distribution with frequent local dominance. Canonical correspondence analysis on species–environment relationships indicated that littoral vegetation, altitude, surface water temperature and pH best explain the variation in ostracod communities. Presence of fish and water depth also influence species occurrence, with the larger species being more common in shallow waterbodies lacking fish. Based on Chao’s estimator of total regional species richness, this survey recovered about two-thirds (60–68%) of the regional ostracod species pool. Scanning electron micrographs (SEM) of the valve morphology of 14 ostracod taxa are provided, in order to facilitate their application in biodiversity and water-quality assessments and in palaeoenvironmental reconstruction.

Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil, central Tunisia

One hundred and seventy collected samples from Jebil section have been carefully studied for their ostracod content and referred to 41 species belonging to 20 genera. Their vertical distribution allowed to distinguish five successive associations of ostracod assemblages; two of which are correlated with the Early Lutetian, one with the Late Lutetian, another association with the Bartonian and the last one with the Priabonian. Community structure of the collected ostracod fauna has been studied; three indices have been calculated for each sample: Shannon (diversity), Margalef (richness) and Equitability indexes. In the lower and the middle part of the Formation, they indicate a stable environment supporting high diversity ostracod communities; whereas in the upper portion the environmental conditions were unstable characterized by low diversity. The results of a multivariate statistical method, using the cluster analysis and the Detrended Correspondence Analysis of the 41 ostracod species and the 170 samples, have led to conclude that the most effective environmental factor in the study area is the paleodepth and of less importance oxygenation and salinity. Thus, it allowed to distinguish four palaeoenvironmental intervals within the Cherahil Formation: the first one represented by taxa that are known from the shallower parts of the shelf; the second interval includes the majority of the encountered species of inner neritic shelf with normal salinity; the third one, corresponding to an outer neritic domain; and the last interval refers to a circalittoral environment, is comprised mainly of Cytherella angulata and of Soudanella laciniosa triangulata.

Disentangling environmental, spatial, and historical effects on ostracod communities in shallow lakes

Community structure is determined by a variety of ecological mechanisms, including environmental control, dispersal, and historical contingency. Recently, many studies have focused on the relative relevance of environment and dispersal in shaping metacommunities. Historical contingency (e.g., priority effects) rarely has been considered, although it could have a key role. In this context, the use of paleoecological methods could help assess the influence of past events on the present-day communities. In this survey, we compare living ostracod assemblages (i.e., biocoenoses) and subfossil assemblages (i.e., taphocoenoses) from 22 steppic shallow lakes and determine the relative contribution of environmental and spatial components on both assemblages. In addition, we estimate the role of putative priority effects of past assemblages on contemporary ones. Our results indicate a high concordance between both assemblages (Procrustes analysis; r = 0.877; P = 0.001). However, environment dominates over space in explaining the biocoenoses, whereas in taphocoenoses space dominates over environment. Furthermore, the contemporary metacommunity structure was related not only to pure environmental and spatial effects (suggesting species sorting and dispersal constraints) but also notably to pure historical effects, suggesting a significant major role of earlier habitat occupation in these ecosystems.

Are aquatic assemblages from small water bodies more stochastic in dryer climates? An analysis of ostracod spring metacommunities

Metacommunity ecology describes community organisation considering both environmental and spatial processes. We tested the relative importance of environmental and spatial factors on spring ostracod assemblages from four European regions characterised by different climatic conditions (e.g. aridity). Pure and shared effects of environment and space were calculated using redundancy analysis and variation partitioning. Both environmental and spatial variables significantly explain assemblage variation, although with different relevance among areas. The amount of variation explained by environmental factors decreased with increasing climate aridity. The reduced size of spring habitats makes them prone to drying events, which are more frequent in dryer climates. Frequent disturbances may lead to local extinctions followed by colonisations from nearby sites, in a source–sink dynamics. Early recolonisation leads to random assemblages and reduces the match between organisms and environmental conditions. As a consequence, a low amount of community variation can be explained by environmental variables. Conversely, the settled communities from wetter climates best fit the ecological characteristics of sites, and deterministic processes, such as species sorting, dominate the assemblages. In conclusion, in the studied regions, ostracod communities from small water bodies of dryer climates seem to be mainly driven by stochastic dynamics when compared to more continental areas.

Invasive South American floating plants are a successful substrate for native Central African pleuston

Eichhornia crassipes, commonly known as water hyacinth, is a free-floating perennial aquatic plant native to South America, which has been widely introduced on different continents, including Africa. E. crassipes is abundant in both the Congo (Africa) and Amazon (South America) River catchments. We performed a comparative analysis of the ostracod communities (Crustacea, Ostracoda) in the E. crassipes pleuston in the Amazon (South America) and Congo (Africa) River catchments. We also compared the ostracod communities from the invasive E. crassipes with those associated with stands of the native African macrophyte Vossia cuspidata. We recorded 25 species of ostracods associated with E. crassipes in the Amazon and 40 in the Congo River catchments, distributed over 31 ostracod species in E. crassipes and 27 in V. cuspidata. No South American invasive ostracod species were found in the Congolese pleuston. Diversity and richness of Congolese ostracod communities was higher in the invasive (Eichhornia) than in a native plant (Vossia). The highest diversity and abundance of ostracod communities were recorded in the Congo River. The result of principal coordinates analysis, used to evaluate the (dis)similarity between different catchments, showed significant differences in species composition of the communities. However, a dispersion homogeneity test (PERMDISP) showed no significant differences in the variability of the composition of species of ostracods (beta diversity) within Congo and Amazon River catchments. It appears that local ostracod faunas have adapted to exploit the opportunities presented by the floating invasive Eichhornia, which did not act as “Noah’s Ark” by introducing South American ostracods in the Congo River.

Givetian ostracods of the Candás Formation (Asturias, North-western Spain): taxonomy, stratigraphy, palaeoecology, relationship to global events and palaeogeographical implications.

Asturian ostracods of the Givetian carbonate Candás Formation are documented for the first time from the Peran-Perlora and Carranques reference sections. More than 1,200 specimens were extracted from 44 samples by means of the hot acetolysis method. In all, 75 taxa are described herein, of which 21 are formally described and one, Evlanella peranensis Maillet n. sp., is new. All the taxa are marine benthic and belong to the Eifelian Mega-Assemblage. The assemblages recognized are representative of semi-restricted to shallow open-marine palaeoenvironments above the storm wave base. The stratigraphical distribution of the taxa shows a strong faunal renewal in the top of the Candás Formation. Long-ranging taxa found at the base of the formation, of which many are known from the base of the Middle Devonian, disappear within the base of the member C and are replaced above, around the Middle/Upper Givetian boundary, by more cosmopolitan taxa characteristic of the Frasnian. The lower half of the member C is also characterized both by unstable environments and occurrence of some short-ranging opportunistic ostracod taxa. This renewal within shallow water ostracod communities is probably a consequence of the global Taghanic Biocrisis, leading world-widely to extinctions in several faunal groups. Faunal affinities with Givetian ostracod taxa reported in other areas of the world reflect the commonly accepted palaeogeographical patterns. Close relations between the Cantabrian Zone (NW-Spain), the Armorican Massif (W-France), the Mouthoumet Massif (S-France) and North Africa (Morocco and Algeria) suggest a narrow oceanic space between the western European terranes and the northern Gondwanan margin that involves an advanced phase of closure of the Medio-European Ocean.

Diversity of ostracod communities (Crustacea, Ostracoda) across hierarchical spatial levels in a tropical floodplain

Assessing and evaluating the mechanism and patterns of species distribution across multiple hierarchical spatial levels, such as in floodplains, are important for understanding the factors that influence the structure of communities. The species composition may vary at these spatial levels or between the spatial levels along the hierarchical scale. Thus, using the additive partitioning in species richness, Shannon index, and Simpson coefficient, we tested the hypothesis that the alpha and beta components of ostracod diversity are unevenly distributed along the hierarchical spatial levels in the Upper Parana River floodplain (Brazil). The results obtained by PCoA and diversity partitioning allowed us to conclude that dispersal is efficient, and that at higher spatial levels (floodplain, systems, and environments), the establishment of a new population of ostracods depends on both abiotic and biotic factors. However, at lower levels, spatial factors such as plants architecture and other biotic factors, e.g., competition, may have greater influence on community structure.

Effects of river bed regulation on habitats and communities: A case study for ostracods in the Oder River, Poland

The effects of damming, groyne building, and channelizing on habitats and ostracod assemblages in the Oder River, one of the six largest European river systems, were analyzed. Regulation works had been conducted on the river from the 18th to the beginning of the 20th century. Main objectives of the study were to detect the effect of river bed regulation on attributes of habitats and ostracod communities. The values of nitrogen were the highest in the dammed stretch and the lowest in the channelized one. As for conductivity, TDS (total dissolved solids) and salinity were the highest in the groyned stretch. Hardness had the highest values in the channelized and groyned stretches. The lowest visibility was noted in the dammed stretched. The stretch influenced by damming was dominated by habitats with a considerable proportion of detritus in sediments. In the stretch influenced by groynes, the proportions of habitats with mineral and organic substrates were similar and the proportion of habitats covered with vegetation was the highest. Habitats with rocky, sandy bottoms dominated in the channelized stretch and nearly half of the habitats were covered with vegetation. The highest ostracod density characterized the groyned stretch (658 ind · m−2), was moderate in the case of the dammed stretch (290 ind · m−2) and the lowest in the channelized one (107 ind · m−2). Bradleystrandesia reticulata, Candona neglecta, and Limnocythere inopinata dominated in the groyned and channelized stretches. Cypridopsis vidua, Darwinula stevensoni, and Pseudocandona compressa dominated in the dammed stretch. The type of river bed regulation significantly differentiated both habitats and ostracod assemblages. Differences among ostracod assemblages were related to particular species, but also regarding density and evenness. The degree of vegetation coverage and detritus content in the sediments were strong predictors for ostracod community composition.

Biogeography and relevant ecological drivers in spring habitats: A review on ostracods of the Western Palearctic

Springs are relevant environments from an ecological point of view. The microhabitat-mosaic structure of these ecotones often harbors high biodiversity. Due to the temperature stability of permanent springs and to the persistence over geological time scales of their aquifers, these environments may act as refugia and as potential speciation sites for aquatic fauna. In this study, we review the current knowledge on the diversity and distribution of ostracods associated with ambient springs in the Western Palearctic area, and on the ecological factors that have been reported to affect their occurrence. Literature mining revealed 37 papers, allowing to gather information on 92 ostracod taxa belonging to 31 genera, found in 612 springs out of a total of 743. More detailed information available from 20 studies carried out in the Central-Eastern Alps and Northern Apennines allowed us to conduct a focus study on a more restricted geographic area. Several species have very low frequency, occurring in just one or two springs. Rare or endemic species were frequent, whilst only one non-native species (Chlamydoteca incisa) was found. Species richness varied from 1 to 9, and it was greater in pool springs than in flowing springs and seepages. Correspondence analysis on the presence-absence data unveiled biogeographical patterns in spring ostracod community composition. The variation in community composition was partly organised along altitudinal, latitudinal, water-temperature, and conductivity gradients, and spring typologies affected assemblage structure as well. Springs are important areas for biodiversity conservation at the continental and regional scale. Nevertheless, relatively few investigations have dealt with the human impacts on springs and their biota, and conservation guidelines are largely missing.

The Holocene to Recent ostracods of the Azores archipelago (NE Atlantic): Systematics and biogeography

Abstract This is the first report on the systematics and the biogeography of the Holocene to Recent shallow marine Ostracoda of the Azores archipelago (Portugal). Twenty species are herein reported, comprising 10 families and 14 genera ( Neonesidea , Leptocythere , Callistocythere , Cyprideis , Carinocythereis , Aurila , Heterocythereis , Urocythereis , Loxoconcha , Semicytherura , Xestoleberis , Sclerochilus , Lanceostoma and Cylindroleberis ). Eight new taxa are reported for the Azores: 5 new records — the species Neonesidea longisetosa (Brady, 1902), Cyprideis torosa (Jones, 1850), Aurila prasina Barbeito-Gonzalez, 1971, Semicytherura aff. cornuta (Brady, 1868) and Sclerochilus hicksi Athersuch and Horne, 1987 (cf. also online Supplementary data) — and 3 new species, Callistocythere insularis n. sp., Semicytherura brandaoae n. sp. and Lanceostoma simplex n. sp., which are here described. Based on our results, the Azorean shallow-water marine ostracod communities (from the intertidal down to circa 90 m depth) appear to be less diverse than similar communities found elsewhere. The biogeographical relationships of the Azorean shallow water marine ostracods are mainly with the Eastern Atlantic, with only a few species occurring on the Western Atlantic shores of America. In contrast with the usual pattern of strong biogeographical relationships of the Azorean marine fauna and flora with the Mediterranean and the Macaronesian archipelagos, the similarity of the ostracod fauna between the Azores and the Macaronesian archipelagos (Madeira and Canary Islands) is very weak, probably as a result of a gap in the taxonomic knowledge of the benthic ostracods of the latter archipelagos.

Ostracod communities associated to aquatic macrophytes in an urban park in Rome, Italy

The relationship between ostracod and macrophyte communities has been seldom studied, especially in urban parks. The main purpose of this research is to explore such a relationship in the area of Rome (Italy), and in particular in the Appia Antica Regional Park, to provide information about the environmental characteristics influencing both the assemblages and to document for the first time the distribution of freshwater ostracods in an area inside the city of Rome. The survey has considered different water bodies: springs, channels, ditches, and a pond. Chemical and physical parameters were measured seasonally in conjunction with the ostracod sampling in 13 sites. The ostracod assemblage includes 11 species whereas the macrophyte community is formed by 17 species. Their link with the measured abiotic parameters has been studied through statistical analyses. The results clearly separate the investigated area in one sector where COD and phosphates are the driving factors and another sector where inorganic nitron ions, pH, and conductivity are the main influencing factors. Although the macrophyte community is clearly affected by human pressure, the relationship with the ostracod assemblages seems well established and identified by exclusive pairs or groups of species. Among them, the Cypria lacustris–Lemna minuta duo is of considerable importance, being L. minuta an exotic species, known as an invasive weed in some areas of Europe and spread in Italy only recently. The fact that the 13 sites were characterized by different public access regulation has been partially mirrored by both ostracod and macrophyte distribution since the majority of the sites characterized by the highest diversity are those with restricted access. In general, notwithstanding the anthropic pressure, the occurrence of different kinds of water bodies has allowed the development of ostracod and macrophyte associations, which are rarely represented in an urban park.