Acute toxic effects of uranium on two aquatic organisms, Zebrafish (Brachydanio rerio) and Ostracod (Cypridopsis vidua)

In this paper, we concentrate on the acute toxic effects of uranium on two aquatic organisms, Brachydanio rerio (B. rerio) and Cypridopsis vidua (C. vidua). We found that the toxicity of uranium on C. vidua was significantly greater than that of B. rerio. The results show that C. vidua has a higher sensitivity to uranium, even better than the commonly used test model organisms. In addition to its high sensitivity, C. vidua is a simple and cost-effective toxicological test organism. Therefore, C. vidua is an attractive alternative biological detection material. The acute toxicity results of the test are valuable for establishing water quality standards and protecting human health. At the same time, it enriches the relevant data of uranium on biological toxicity, provides clues for the study of the mechanism of toxicity, and deepens the understanding of the harm of uranium pollution to aquatic ecosystems.

Acute toxicity assessment of polyaniline/Ag nanoparticles/graphene oxide quantum dots on Cypridopsis vidua and Artemia salina

Nanotoxicology is argued and considered one of the emerging topics. In this study, polyaniline (PANI)/2-acrylamido-2-methylpropanesulfonic acid (AMPSA) capped silver nanoparticles (NPs)/graphene oxide (GO) quantum dots (QDs) nanocomposite (PANI/Ag (AMPSA)/GO QDs NC) as a nanoadsorbent has a potential for removal of toxic hexavalent chromium (Cr(VI)) ions from water. The acute toxicity of this NC was evaluated on Artemia salina and freshwater Ostracods (Cypridopsis vidua) larvae for 48 h. The measurements were made at 24 and 48 h with 3 repetitions. The 50% effective concentration (EC50) values of the NC were determined after the exposure of these organisms. According to the results of the optical microscope, it was found that both experimental organisms intake the NC. In the toxicity results of Ostracods, the NC had a highly toxic effect only at 250 mg/L after 48 h and the EC50 value was 157.6 ± 6.4 mg/L. For Artemia salina individuals, it was noted that they were less sensitive than the Ostracods and EC50 value was 476 ± 25.1 mg/L after 48 h. These results indicated that PANI/Ag (AMPSA)/GO QDs NC has low toxicity towards both investigated organisms.

Subterranean Waters of Yucatán Peninsula, Mexico Reveal Epigean Species Dominance and Intraspecific Variability in Freshwater Ostracodes (Crustacea: Ostracoda)

The Yucatán Peninsula is a karstic region, rich in subterranean environments with a diverse crustacean stygobiont fauna. In order to gain insights into the biological evolution of the subterranean environments of this region, we evaluated the ostracode species composition of caves and cenotes in five independent sampling campaigns (2008, 2013, 2017–2019). Using morphometric analyses, we evaluated inter-population morphological variability; using molecular analysis based on mitochondrial COI and nuclear 18S rDNA, we evaluated genetic differentiation in selected species. The observed fauna is composed of 20 (epigean) species, presenting a lack of strict stygobionts. Morphometric analyses discriminated up to three morphotypes in each of the three most abundant species: Cytheridella ilosvayi, Alicenula sp. and Cypridopsis vidua. High intraspecific morphological variability was found either in shape or size. Phylogenetic analysis based on COI demonstrated the existence of three lineages on C. ilosvayi, with high support (>0.9). The 18S rDNA sequences were identical among individuals of different populations. A lack of congruence between the genetic markers precluded us from postulating speciation in subterranean environments. It is likely that Late Pleistocene—Early Holocene climate variation related to sea level and precipitation was forcing agent for epigean ostracode dominance in subterranean environments of the Peninsula.

Environmental factors shaping assemblages of ostracods (Crustacea: Ostracoda) in springs situated in the River Krąpiel valley (NW Poland)

We investigated the ostracod assemblage structure in springs of a small lowland River Krąpiel valley. Environmental factors and the potential of ostracods as indicators of spring type were analysed. The analysis involved the type of spring, substrate, physicochemical parameters, and the river valley's hydrological status as environmental factors. A total of thirty ostracod species were recorded. The average count of ostracod individuals in a sample amounted to 100. The assemblages were dominated by juvenile Candona sp., juvenile Psychrodromus sp., Cypria ophtalmica, and Cypridopsis vidua. The spring species accounted for less than 1% of the individual counts, except for juvenile Psychrodromus sp. with 21% and Eucypris pigra with 4%. The average number of taxa per spring was 5. The ostracod assemblages were significantly influenced by limnocrene springs, spring flooding by the river overflow, the presence of coarse leaf litter, the presence of fine organic matter, a high content of NH4 as well as by BOD5, conductivity, pH, Fe, the river habitat modification index (RHM), the habitat modification score (HMS), and the river habitat quality (RHQ). The habitat conditions for the spring species appeared to be enhanced by the domination of mineral substrate over fine particulate organic matter, an elevated pH, the presence of leaf-derived organic matter, and the absence of flooding by the river. The spring species showed no association with the Krąpiel valley hydrological factors.

Toxicity and Hazards of Biodegradable and Non-Biodegradable Sunscreens to Aquatic Life of Quintana Roo, Mexico

Sunscreens have spread widely into aquatic systems over the last 18 years in Quintana Roo, Mexico. This contamination is caused by intensive use as a result of leisure activities, as sunbathers apply the substances intensively (up to 83.75% of tourists and locals). Moreover, 25% of the compounds are mainly released into the water through topical products washing off. On average, 300,000 tourists arrive every week in Quintana Roo, increasing the contamination. In addition, there are no recent studies on sunscreen toxicity and the hazards this represents for the native zooplankton of Quintana Roo. In order to assess their adverse effects, acute toxicity was assessed for nine sunscreens (five non-biodegradable and four biodegradable) in four zooplankton species (Brachionus cf ibericus, Cypridopsis vidua, Diaphanocypris meridana, and Macrothrix triserialis). In total, 21 LC50 values were obtained, which are the baseline values for estimating risk and for determining the expected maximum permissible concentration. Our data on toxicity to freshwater species compared to marine species indicate that freshwater species are more sensitive than marine species. In conclusion, biodegradable sunscreen posed a moderate risk, and non-biodegradable posed a high risk. Our outcomes suggested that the maximum permissible concentrations for the contamination of sunscreens were 8.00E-05 g/L for non-biodegradable and 1.60E-04 g/L for biodegradable sunscreens.

Tropical freshwater ostracodes as environmental indicators across an altitude gradient in Guatemala and Mexico

Ostracodes are bivalve microcrustaceans with calcium carbonate shells that preserve well in lake sediment. They are very sensitive to environmental variables and are therefore powerful tools in paleoclimate and paleoenvironmental studies that cover time periods from decades to millions of years. Detailed knowledge of species ecological preferences and robust taxonomy are prerequisites for such studies. Such information, however, is still lacking for many areas of the world, including the Neotropics. Previous studies in the northern Neotropics were conducted mainly in the karst lowlands of the Yucatán Peninsula, but higher-altitude areas remained relatively poorly investigated. This study was designed to expand our knowledge of the modern, Neotropical freshwater ostracode fauna, across an altitudinal gradient from the karst lakes in the lowlands of El Petén, Guatemala (~100 - 500 m asl), to the mid-elevation water bodies of the Lacandón forest (~500 - 1000 m asl), to the higher-altitude lakes of Montebello, Chiapas, México (~1000 - 1500 m asl). Eighteen ostracode species were identified in 24 lakes. Ostracodes were absent in Lakes Amarillo and Lacandón (mid-altitude), and San Diego (lowlands). Statistical analysis indicated that the most abundant species, Cypridopsis vidua, Cytheridella ilosvayi, Pseudocandona antillana, and Darwinula stevensoni have a continuous distribution along the entire altitudinal gradient. Other species display more restricted distributions, determined by temperature, precipitation and conductivity. For example, Eucypris sp. is restricted to the lowlands, Vestalenula sp. and Cypria sp. were found only at middle elevations, and a Cyprididae species was restricted to the highlands. Species diversity is slightly greater in warm lakes at middle altitudes (Haverage = 1.09) than in water bodies in the lowlands (Haverage = 0.94) and in cooler lakes in the highlands (Haverage = 0.94). LOESS regressions provided ecological preference information for the four most frequent and widely distributed species, with respect to temperature, conductivity, bicarbonate (HCO3-) concentration, precipitation, and pH. Cypria petenensis, Heterocypris punctata, and Paracythereis opesta display higher abundances in lowland lakes, whereas, Cytheridella ilosvayi, and Pseudocandona antillana prefer lowland and mid-elevation lakes. Environmental conditions in the higher-elevation lakes of Montebello favor the presence of Darwinula stevensoni. Such quantitative ecological information will improve ostracode-based paleoenvironmental reconstructions in southern México and northern Guatemala, and our approach serves as a model for future paleoecological studies that employ other aquatic bioindicators, such as testate amoebae, cladocerans, and chironomids.

The development of Neoechinorhynchus buttnerae (Eoacanthocephala: Neoechinorhynchidae) in its intermediate host Cypridopsis vidua in Brazil

The family Neoechinorhynchidae includes seven species ofNeoechinorhynchusfrom freshwater fishes of Brazil. Although severalNeoechinorhynchusspecies are cited infecting different fish species in Brazil, there is a lack of information concerning to their life cycle and the identification of the intermediate hosts. Thus, the aim of the present study was to describe the development ofNeoechinorhynchus buttneraein its intermediate host collected in a fish farm located in Rio Preto da Eva, Amazonas, Brazil. To verify the presence ofN. buttneraein the fish pond, twentyColossoma macropomumwere captured and analyzed, being corroborated the presence of this parasite species. Samples of plankton were also collected, finding the ostracodCypridopsis viduaas the intermediate host. For the description of the larvae development, a laboratory experimental procedure was conducted by feeding the collected ostracods with the eggs of the adult specimens taken from the sampled fish. To observe the stages of development an artificial hatch was performed. Every stage of development was photographed, measured, drawn and described. The time of development of the immature stages ofN. buttneraewas 29 days, reporting the stages: acanthor, acanthella (with eight developmental changes) and cystacanth. As high infections byN. buttneraecauses morphological damages to the intestine and may compromise the quality ofC. macropomumand in consequence the production of fish farmers in the Brazilian Amazon region, the knowledge of its intermediate host and the understanding of its life cycle represents a useful information to prevent and combat infections by this parasite.

Ecology and distribution of living ostracod assemblages in a shallow endorheic lake: the example of the Lake Trasimeno (Umbria, central Italy)

<p>Ostracod assemblages from Lake Trasimeno (Umbria, central Italy), the largest endorheic lake in Italy, were investigated relating their species distribution and ecology to modern physical, chemical and biological parameters. Nineteen living species were collected in the lake<em> </em>(<em>Darwinula stevensoni, Candona (Candona) candida, Candona (Neglecandona) angulata, Fabaeformiscandona fabaeformis, Pseudocandona marchica, Cypria ophtalmica, Ilyocypris gibba, I. salebrosa, I. getica, Cypridopsis vidua, Eucypris virens, Trajancypris clavata, Herpetocypris helenae, Heterocypris salina, H. incongruens, Isocypris beauchampi, Cyprideis torosa, Limnocythere inopinata, </em>and<em> </em><em>L. stationis</em>)<em>. </em>All the identified species belong to the fresh-water Italian ostracod fauna but<em> </em><em>Cyprideis</em> <em>torosa </em>is documented in an oligohaline athalassic lacustrine environment in Italy for the first time.<em> </em>The occurrence of<em> </em><em>Ilyocypris</em> <em>salebrosa </em>represents the southernmost record in Italy and the westernmost in Eurasia. The recovery of<em> </em><em>Limnocythere</em> <em>stationis</em> represents the westernmost record in Eurasia. The distribution of the different ostracods recovered in Lake Trasimeno is linked to the dominant physical and chemical parameters for each ecological niche. Physical and chemical data along with substratum type, grain-size and presence of aquatic macrophytes have been related to different ostracods using a multivariate analyses approach (NMDS, CCA, Spearman’s rank correlation test). These results allow to differentiate several ecological niches within the lake and indicate that the main parameters affecting the ostracod assemblages are the aquatic macrophyte coverage, the Total Organic Carbon (TOC) and, to a lesser extent, temperature and type of substrate.<em> </em><em>Cyprideis</em> <em>torosa </em>and<em> </em><em>Candona </em>(<em>Neglecandona</em>)<em> </em><em>angulata </em>have been recovered both in the distal part of the lake and in the lakeshore area. In both cases they are associated with scarce or absent aquatic macrophytes and low amounts of TOC. The<em> </em>alternate dominance of these two species in the distal deeper assemblages seems to be mainly linked with the bottom oxygen availability, being<em> </em><em>C.(N.) angulata </em>dominant in the most oxygen-depleted sediments and<em> </em><em>C. torosa </em>dominant in higher oxygen conditions.<em> </em>Along the lakeshore area they are often discovered together with other prevailing species, such as<em> </em><em>Cypridopsis</em> <em>vidua </em>that is common in very shallow to shallow<em> </em>(20-140 cm) sites with high TOC content, abundant macrophytes and algae, and Limnocythere inopinata, which dominates slightly deeper areas (around 150-210 cm) where the previous species are almost absent. The Spearman’s rank correlation test showed significant positive correlation between some ostracods and macrophyte species.</p>

Ostrácodos no-marinos de lagos en el altiplano este-centro de México

The ostracode fauna of the neartic-neotropical transitional zone has remained poorly known until this study. Ten ostracode species inhabit ten highland lakes (five maar lakes (phreatic/phreato-magmatic explosion origin), one volcanic-tectonic lake, three natural dams and one man-made dam) in East-central Mexico. Surface sediments from the deepest part and the littoral zone from all studied lakes were collected. Environmental variables (pH, temperature, dissolved oxygen, conductivity, TDS) were measured <em>in situ</em> and parallel water samples for chemical analysis were collected for habitat description. Widely distributed species in the study area (≥5 lakes) include <em>Cypridopsis vidua</em>, <em>Darwinula stevensoni </em>and<em> </em><em>Eucandona </em>cf.<em> patzcuaro. Limnocytherina axalapasco</em> is an endemic species and was collected in three maar lakes and in one man-made dam. Rare species included: <em>Chlamydotheca</em> <em>arcuata</em>?,<em> Fabaeformiscandona acuminata</em>?<em>, Ilyocypris</em> <em>gibba</em>?,<em> Limnocythere friabilis</em>?, <em>Potamocypris smaragdina</em>?<em> </em>and<em> Potamocypris unicaudata</em>?. Highest species richness (6 spp.) was found in the large and shallow Lake Metztitlán (2.6km², 5.5m deep), with the lake water type HCO₃^-&gt;&gt;SO₄^2-&gt;Cl^- -- Ca²⁺&gt;Na⁺&gt;Mg²⁺. The rest of studied lakes (&lt;63m, &lt;27km²) had not more than three species. For instance, only two ostracode species were collected in Lake Alchichica, which is the largest, deepest and most saline studied maar lake.