Efecto del pulso de inundación sobre el ensamble de ostrácodos (Ostracoda: Podocopida) en microambientes en la Ciénaga Río Viejo, Colombia / Effect of the flood pulse on the ostracod assemblage (Ostracoda: Podocopida) in microenvironments in the Ciénaga Río Viejo, Colombia

Resumen Introducción: Las ciénagas hacen parte de la llanura de inundación de un río y son influenciadas por el pulso de inundación, fuerza que modula los cambios anuales en las variables bióticas y abióticas. Los ensambles biológicos tienen diferentes respuestas a este pulso y podrían presentar cambios en la composición y abundancia. Objetivo: Evaluar cómo se modifican las condiciones físico-químicas en los microambientes de vegetación flotante y el ensamble de ostrácodos a lo largo de un pulso de inundación en la Ciénaga Río Viejo, Santander, Colombia. Métodos: Se caracterizaron las variables físico-químicas de los microambientes de plantas acuáticas flotantes durante las cuatro fases hidrológicas del pulso de inundación: aguas bajas, altas, ascenso y descenso, en tres estaciones donde el pulso tuvo mayor efecto. Ostrácodos dulceacuícolas fueron recolectados de estos microambientes, identificados y contados. Resultados: Las condiciones ambientales dentro de los microhábitats fluctuaron siguiendo el pulso de inundación en el sistema. Se encontraron tres familias taxonómicas y seis especies de ostrácodos. No hubo diferencias en la composición y abundancia del ensamble de ostrácodos en el espacio y el tiempo, lo que sugiere que están protegidas contra los cambios ambientales causados por las fluctuaciones hidrológicas. La abundancia de especies cambió en respuesta a la variabilidad ambiental. Strandesia cf. sphaeroidea y Keysercypria sp. 2 están asociadas con aguas más someras y con mayor cobertura de vegetación acuática densa. Otras especies mostraron ser tolerantes a fluctuaciones hidrológicas y pueden estar relacionadas con la plasticidad ecológica, como Cytheridella ilosvayi, Diaphanocypris meridana y Stenocypris major, que han sido registradas en una variedad de ambientes acuáticos y con distribuciones a escala continental. Conclusiones: Los pulsos de inundación indujeron cambios ambientales en la Ciénaga de Río Viejo, pero los microhábitats con cobertura de vegetación flotante parecen estar protegidos contra el pulso hidrológico, permitiendo así que las comunidades de ostrácodos permanezcan casi sin alteraciones durante un pulso de inundación. Este conjunto de datos actualizado de agua dulce tropical contribuye a llenar los vacíos de conocimiento relacionados con la idoneidad del hábitat y la distribución de las comunidades de ostrácodos en Colombia.

Abstract Introduction: Swamps are lowland shallow tropical lakes in rivers floodplains, characterized by annual flood pulses that modulate changes in biotic and abiotic variables. Biological assemblages have different responses to flood pulses, remaining either undisturbed or with significant changes in composition and abundance. Objective: To evaluate how physical and chemical conditions are modified in mixed macrophytes microenvironments and ostracod species assemblages throughout a flood pulse in Rio Viejo swamp, Santander, Colombia. Methods: We characterized physical and chemical variables of microenvironments of aquatic floating plants, during four different hydrologic periods of the flood pulse: low, high, rising, and descending waters, at three stations where the flood pulse have the most important effect. Freshwater ostracods were collected from such microenvironments, identified, and counted. Results: Environmental conditions within microhabitats fluctuated following the flood pulse in the system. Three taxonomic families and six species of ostracods were observed. No differences in the composition and abundance of the spatio-temporal ostracod assemblages were observed, suggesting that they are buffered against environmental changes driven by hydrological fluctuations. Species abundance changed in response to environmental variability. Species such as Keysercypria sp. and Keysercypria sp. 2 are associated to shallower waters and more likely to dense aquatic vegetation cover. Other species showed to be more tolerant to hydrological fluctuations and may be related to ecological plasticity, species such as Cytheridella ilosvayi, Diaphanocypris meridana and Stenocypris major that have been recorded in a variety of aquatic environments and with distributions at continental scale. Conclusions: Flood pulses induced environmental changes in Rio Viejo Swamp, but microhabitats in mixed macrophyte cover seems to be buffered against the hydrological pulse, thus allowing almost undisturbed ostracod assemblages throughout a flood pulse. This updated tropical freshwater dataset contributes towards filling the knowledge gaps related to habitat suitability and distribution of ostracods communities in Colombia.

Adverse effects of contamination by fipronil and its derivatives on growth, molting, and gene expression in the mysid crustacean, Americamysis bahia, in Japanese estuaries.

Concentrations of fipronil (Fip) and several of its derivatives were detected in samples from four rivers and four estuaries in Japan. LC-MS/MS analysis detected Fip and its derivatives, except for fipronil detrifluoromethylsulfinyl, in almost all samples. The total concentrations of the five compounds were approximately two-fold greater in river water (mean: 21.2, 14.1, and 9.95 ng/L in June, July, and September, respectively) compared to those in estuarine water (mean: 10.3, 8.67, and 6.71 ng/L, respectively). Fipronil, fipronil sulfone (Fip-S), and fipronil sulfide (Fip-Sf) represented more than 70 % of all compounds. This is the first report to demonstrate the contamination of estuarine waters of Japan by these compounds. We further investigated the potentially toxic effects of Fip, Fip-S, and Fip-Sf on the exotic mysid, Americamysis bahia (Crustacea: Mysidae). The lowest effective concentrations of Fip-S (10.9 ng/L) and Fip-Sf (19.2 ng/L) on mysid growth and molting was approximately 12.9- and 7.3-fold lower than Fip (140.3 ng/L), suggesting they had higher toxicity. Quantitative reverse transcription polymerase chain reaction analysis revealed that ecdysone receptor and ultraspiracle gene expression were not affected after 96-h of exposure to Fip, Fip-S, and Fip-Sf, suggesting that these genes may not be involved in the molting disruption induced by Fip, Fip-S, and Fip-Sf. Our findings suggest that environmentally relevant concentrations of Fip and its derivatives can disrupt the growth of A. bahia by promoting molting. However, further studies are required to elucidate its molecular mechanism.

Egg production and life history of Alona guttata Sars, 1862 (Cladocera, Chydoridae): implications for colonization of temporary ponds / Produção de ovos e história de vida de Alona guttata Sars, 1862 (Cladocera, Chydoridae): implicações para a colonização de lagoas temporárias

Cladocerans are a diverse group of species that show rapid responses to changes in environmental conditions. This adaptive capacity has important implications for egg production and life cycle, especially in transitory environments such as temporary waterbodies. The present study investigated the life history and egg production of Alona gutatta Sars, 1862 (Crustacea, Cladocera), an abundant and frequent species from a high-altitude temporary pond (Lagoa Seca, Minas Gerais, Brazil). Newly hatched neonates were monitored in relation to time of maturation, number of eggs produced per female and time of survival. Neonates required a mean of 8 days to mature. A. guttata survived for a mean of 30.9 ± 8.1 days and produced 2 eggs per brood, generating a mean of 10.95 ± 6.41 neonates during the entire life cycle. The rapid development, short time to produce eggs and long life cycle are important adaptations to the adverse environmental conditions of temporary aquatic environments, which can contribute to the rapid colonization of Alona guttata in transitory ecosystems.

Os cladóceros formam um grupo diverso de espécies que apresentam respostas rápidas às mudanças nas condições ambientais. Essa capacidade adaptativa tem implicações importantes para a produção de ovos e para o ciclo de vida, especialmente em ambientes transitórios, como corpos d’água temporários. O presente estudo investigou a história de vida e a produção de ovos da espécie Alona guttata Sars, 1862 (Crustacea, Cladocera) coletada em uma lagoa temporária de altitude (Minas Gerais, Brasil). Organismos recém eclodidos foram observados (em condições de laboratório) em relação ao tempo de maturação, número de ovos produzidos por fêmea e tempo de sobrevivência. Os neonatos levaram em média 8 dias para atingir o primeiro estágio de maturação. As fêmeas produziram 2 ovos por ninhada e geraram uma média de 10,95 ± 6,41 neonatos durante todo o ciclo de vida. A. guttata apresentou uma média de 30,9 ± 8,1 dias de sobrevivência. O rápido desenvolvimento, o pouco tempo para a produção de ovos e o ciclo de vida longo são adaptações importantes às condições ambientais adversas de ambientes aquáticos temporários, que podem contribuir para a rápida colonização de Alona guttata em ecossistemas transitórios.

Effects of low pH on the coral reef cryptic invertebrate communities near CO2 vents in Papua New Guinea.

Small cryptic invertebrates (the cryptofauna) are extremely abundant, ecologically important, and species rich on coral reefs. Ongoing ocean acidification is likely to have both direct effects on the biology of these organisms, as well as indirect effects through cascading impacts on their habitats and trophic relationships. Naturally acidified habitats have been important model systems for studying these complex interactions because entire communities that are adapted to these environmental conditions can be analyzed. However, few studies have examined the cryptofauna because they are difficult to census quantitatively in topographically complex habitats and are challenging to identify. We addressed these challenges by using Autonomous Reef Monitoring Structures (ARMS) for sampling reef-dwelling invertebrates >2 mm in size and by using DNA barcoding for taxonomic identifications. The study took place in Papua New Guinea at two reef localities, each with three sites at varying distances from carbon dioxide seeps, thereby sampling across a natural gradient in acidification. We observed sharp overall declines in both the abundance (34-56%) and diversity (42-45%) of organisms in ARMS under the lowest pH conditions sampled (7.64-7.75). However, the overall abundance of gastropods increased slightly in lower pH conditions, and crustacean and gastropod families exhibited varying patterns. There was also variability in response between the two localities, despite their close proximity, as one control pH site displayed unusually low diversity and abundances for all invertebrate groups. The data illustrate the complexity of responses of the reef fauna to pH conditions, and the role of additional factors that influence the diversity and abundance of cryptic reef invertebrates.

Performance of the SSI development function compared with 33 other functions applied to 79 arthropod species' datasets.

The development rates of arthropods are temperature-dependent. Studies aiming to predict the dynamics of arachnid, crustacean, and insect populations in nature often require the derivation of development functions representing this phenomenon. A previous study (Quinn, B.K., 2017, J. Therm. Biol. 63, 65-77) identified 33 development functions commonly used in past studies on temperature-dependent development of arthropods, and illustrated that: (1) most of 99 past studies only applied one or few (2-5) development functions to their data without considering others; and (2) most of a subset of 79 studies' data were not fit with the actual best function for them, resulting in sometimes substantial differences in model performance and predictive ability. However, that study did not test the class of development functions based on theoretical enzyme thermodynamics, including the Sharpe-Schoolfield-Ikemoto (SSI) function. Herein, the meta-analyses done in that previous study were redone, after fitting all 79 reanalyzed datasets with the SSI function. Estimates of the intrinsic optimum temperature (TΦ) for development of each tested species were also derived using the SSI function and compared among taxa. Including the SSI function in analyses did not change the conclusions of the previous study concerning development function usage, choice, and consequences. Notably, the SSI function performed as well as or relatively better than other functions of comparable or lower complexity in terms of R2, AICC-based rankings, ΔAICC values, and prediction errors, which may recommend its more widespread use in future studies. Overall differences in TΦ were found among arthropod subphyla, as well as between most species pairs. Most TΦ estimates produced herein were novel, and could be used to make inferences about or comparisons among arthropod taxa in future studies.

Effect of diclofenac and naproxen and their mixture on spring barley seedlings and Heterocypris incongruens.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a popular group of drugs used worldwide. These drugs are also available over the counter, which implies that their consumption is not strictly regulated. They are released through wastewater and feces and can have adverse effects on the environment. The present study aimed to evaluate the effect of two NSAIDs, diclofenac (DCF) and naproxen (NAP), and their mixture (DCF + NAP) on spring barley seedlings and ostracods Heterocypris incongruens. The tested drugs had a negative impact on bivalve ostracods and the studied plants. DCF was the most toxic toward ostracods, while spring barley seedlings were affected the most by NAP. The application of the tested compounds and their mixture resulted in a decrease in fresh weight yield and the content of photosynthetic pigments. In addition, an increase in H2O2 and proline content and changes in the activity of antioxidant enzymes (POD, APX, CAT, and SOD) were observed.

Characterization of the foxl2 gene involved in the vtg expression in mud crab (Scylla paramamosain).

Forkhead box protein L2 (Foxl2) is involved in multiple physiological processes, such as ovarian development, granulosa cell differentiation, ovarian follicle development, and oocyte growth. In this study, a Spfoxl2 gene encoded 530 amino acid protein with characteristic forkhead (FH) domain was identified from transcriptome data of mud crab Scylla paramamosain and validated the accuracy by PCR technology. Meanwhile, the orthologues of the Spfoxl2 gene in other 14 crustacean species were identified with the same method. Further multiple sequence alignment analysis revealed the Foxl2 was highly conserved, especially in the FH domain, even completely identical in several species. Besides, the semi-quantitative PCR (Sq-PCR) result showed Spfoxl2 gene was mainly expressed in the gonad (testis and ovary). Further quantitative real-time PCR (qRT-PCR) result demonstrated its expression level in the testis was significantly higher than that in the ovary (p < 0.01). In addition, the qRT-PCR result showed that in zoea V, megalopa, and larval I, the expression level of Spfoxl2 in megalopa is the highest. In addition, a putative Foxl2 binding site was identified on the promoter region of Spvtg, and knockdown of Spfoxl2 mediated by RNAi technology increased the expression of Spvtg in the ovary, suggesting Spfoxl2 might be the upstream negative regulator of Spvtg. Overall, this study provided new insights into the role of Spfoxl2 in ovary development through regulating Spvtg expression in S. paramamosain.

Identification of putative key genes for thermal adaptation in the Japanese mantis shrimp (Oratosquilla oratoria) through population genomic analysis.

Little is known about the mechanisms underlying the relationship between genetic variation and the adaptation of Oratosquilla oratoria populations to different habitat temperature. Here, the genome-wide genetic information of three O. oratoria populations were obtained by IIB restriction site-associated DNA (2b-RAD) sequencing and 2403 single-nucleotide polymorphisms (SNPs) were identified. Based on the 2403 SNPs, we found a remarkable genetic differentiation between the Yellow Sea and the East China Sea groups of O. oratoria. Furthermore, 63 SNPs are thought to be associated with different sea temperatures. Based on the 63 SNPs, it is hypothesised that the long-term temperature differences may contribute to the variation of genes associated with multiple biological functions, such as material metabolism, cytoskeleton, cellular processes, inflammatory response and hormonal regulation. This study provides new information for elucidating the molecular mechanisms underlying the relationship between genetic variation and the adaptation of Oratosquilla oratoria populations to different temperature.

Visual metamorphoses in insects and malacostracans: Transitions between an aquatic and terrestrial life.

Arthropods operate in an outrageous diversity of environments. From the deep sea to dense tropical forests, to wide open arctic tundra, they have colonized almost every possible habitat. Within these environments, the presence of light is nearly ubiquitous, varying in intensity, wavelength, and polarization. Light provides critical information about the environment, such as time of day or where food sources may be located. Animals take advantage of this prevalent and informative cue to make behavioral choices. However, the types of choices animals face depend greatly on their environments and needs at any given time. In particular, animals that undergo metamorphosis, with arthropods being the prime example, experience dramatic changes in both behavior and ecology, which in turn may require altering the structure and function of sensory systems such as vision. Amphibiotic organisms maintain aquatic lifestyles as juveniles before transitioning to terrestrial lifestyles as adults. However, light behaves differently in water than in air, resulting in distinct aquatic and terrestrial optical environments. Visual changes in response to these optical differences can occur on multiple levels, from corneal structure down to neural organization. In this review, we summarize examples of alterations in the visual systems of amphibiotic larval and adult insects and malacostracan crustaceans, specifically those attributed to environmental differences between metamorphic phases.

Using larval barcoding to estimate stomatopod species richness at Lizard Island, Australia for conservation monitoring.

Stomatopods (Crustacea, Stomatopoda) are well studied for their aggressive behavior and unique visual system as well as their commercial importance in Asian and European countries. Like many crustaceans, stomatopods undergo indirect development, passing though several larval stages before reaching maturity. Adult stomatopods can be difficult to catch due to their inaccessible habitats and cryptic coloration. By sampling larvae from the planktonic community, less effort is required to obtain accurate measures of species richness within a region. Stomatopod larvae were collected between 2006 and 2015 from the waters around the Lizard Island reef platform in Eastern Australia. Cytochrome oxidase I (COI) mitochondrial DNA sequences were generated from each larval sample and compared to a database of COI sequences tied to adult specimens. Of the 20 species collected from Lizard Island as adults which have COI data available, 18 species were identified from larval sampling. One additional species identified from larval samples, Busquilla plantei, was previously unknown from Lizard Island. Nine larval OTUs were found not to match any published adult sequences. Sampling larval stomatopod populations provides a comparable picture of the adult population to benthic sampling methods and may include species richness beyond what is measurable by sampling adult populations.

Elevated Magnesium Concentrations Altered Freshwater Assemblage Structures in a Mesocosm Experiment.

Magnesium (Mg) is a mining-related contaminant in the Alligators Rivers Region of tropical northern Australia. A mesocosm experiment was used to assess Mg toxicity to aquatic freshwater assemblages. Twenty-five 2700-L tubs were arranged, stratified randomly, on the bed of Magela Creek, a seasonally flowing, sandy stream channel in the Alligator Rivers Region of northern Australia. The experiment comprised 5 replicates of 4 nominal Mg treatments, 2.5, 7.5, 23, and 68 mg L-1 , and a control. Phytoplankton biomass, and diatom, zooplankton, and macroinvertebrate assemblages present in the treatment tubs were sampled before and after Mg addition. A significant negative relationship between phytoplankton biomass and Mg was observed 4 wk after Mg addition as measured by chlorophyll a concentrations (r2 = 0.97, p = 0.01). This result was supported by reductions in some major phytoplankton groups in response to increasing Mg concentrations, in the same experiment and from independent field studies. There was a significant negative relationship between zooplankton assemblage similarity (to control) and Mg concentrations (r2 = 0.96, p = 0.002). Seven weeks after Mg addition, macroinvertebrate assemblages were dominated by 3 microcrustacean groups (Ostracoda, Cladocera, and Copepoda), each reaching maximum abundance at intermediate Mg concentrations (i.e., unimodal responses). The responses of phytoplankton and zooplankton were used to derive assemblage effect concentrations (Mg concentrations resulting in x% of the assemblage change [ECx]). Magnesium concentrations resulting in assemblage EC01 values were <3 mg L-1 . Together with candidate guideline values from other laboratory- and field-based lines of evidence, the mesocosm EC01 values were incorporated into a weight-of-evidence framework for a robust regulatory approach to environmental protection. Environ Toxicol Chem 2020;39:1973-1987. © 2020 Commonwealth of Australia. Published by Wiley Periodicals LLC on behalf of SETAC.

Temperature elevation stage-specifically increases metal toxicity through bioconcentration and impairment of antioxidant defense systems in juvenile and adult marine mysids.

Metals are of serious concern due to their toxicity, persistency, and accumulation potential in aquatic animals. However, limited information is available on the combined effects of metal with temperature elevation, which is one of the future climate changes suggested for the oceans. In this study, the effect of temperature elevation was investigated by analyzing toxicity, bioconcentration, and antioxidant response in juvenile and adult marine mysids upon exposure to 20 °C and 25 °C for 48 h and 96 h. Based on LC50 values, toxicity of metals was highly reliant on temperature, exposure period, and age. Elevation in temperature significantly increased the whole metal toxicity in juveniles. Bioconcentration was elevated by increasing exposure period and metal concentration. Significant elevation of malondialdehyde (MDA) and depletion of glutathione (GSH) was measured in juveniles, while significant elevation of both MDA and GSH was detected in adults. Subsequently, enzymatic activities of antioxidant enzymes in catalase (CAT) and superoxide dismutase (SOD) increased significantly in adults at 48 h and 96 h, whereas most activities were significantly lowered in juveniles at 96 h. These results suggest that the early life stage of marine mysids is more sensitive to the combined effect of metal and temperature than adult stage due to an impairment in the induction of the antioxidant defense system.

Laboratory culture of the California Sea Firefly Vargula tsujii (Ostracoda: Cypridinidae): Developing a model system for the evolution of marine bioluminescence.

Bioluminescence, or the production of light by living organisms via chemical reaction, is widespread across Metazoa. Laboratory culture of bioluminescent organisms from diverse taxonomic groups is important for determining the biosynthetic pathways of bioluminescent substrates, which may lead to new tools for biotechnology and biomedicine. Some bioluminescent groups may be cultured, including some cnidarians, ctenophores, and brittle stars, but those use luminescent substrates (luciferins) obtained from their diets, and therefore are not informative for determination of the biosynthetic pathways of the luciferins. Other groups, including terrestrial fireflies, do synthesize their own luciferin, but culturing them is difficult and the biosynthetic pathway for firefly luciferin remains unclear. An additional independent origin of endogenous bioluminescence is found within ostracods from the family Cypridinidae, which use their luminescence for defense and, in Caribbean species, for courtship displays. Here, we report the first complete life cycle of a luminous ostracod (Vargula tsujii Kornicker & Baker, 1977, the California Sea Firefly) in the laboratory. We also describe the late-stage embryogenesis of Vargula tsujii and discuss the size classes of instar development. We find embryogenesis in V. tsujii ranges from 25-38 days, and this species appears to have five instar stages, consistent with ontogeny in other cypridinid lineages. We estimate a complete life cycle at 3-4 months. We also present the first complete mitochondrial genome for Vargula tsujii. Bringing a luminous ostracod into laboratory culture sets the stage for many potential avenues of study, including learning the biosynthetic pathway of cypridinid luciferin and genomic manipulation of an autogenic bioluminescent system.

Temporal variation of antibiotic resistance genes carried by culturable bacteria in the shrimp hepatopancreas and shrimp culture pond water.

The increasing prevalence of antibiotic resistance genes (ARGs) is a challenge to the health of humans, animals and the environments. Human activities and aquatic environments can increase ARGs. Few studies have focused on the temporal variation of aquatic bacteria with multiple ARGs in aquatic environments affected by human production activity. We studied culturable bacteria (CB) carrying ARGs, including sul1, sul2, floR, strA and gyrA in the shrimp hepatopancreas (HP) and in pond water during shrimp culture. The relative abundance of ARGs carried by CB in HP was higher than that in water (P < 0.05). However, CB carrying ARGs generally varied in random pattern. The correlation of sul2 abundance was significantly positive in HP, while that of strA abundance was significantly negative in water (P < 0.05) during shrimp culture. Among all of the CB, 33.59% carried multiple ARGs. Temporal distance-decay analysis indicated that CB carrying ARGs in water were more resistant to the effects of human activity. CB carrying ARGs varied temporally in HP and pond water during shrimp culture. These results demonstrate that multiple ARGs are carried by CB, and these varied with the phase of aquatic culture.

Molecular cloning and characterization of genes encoding chitinase and N-acetyl-ß-glucosaminidase in Dolerocypris sinensis.

Chitinases and N-acetyl-ß-glucosaminidase (NAG) are important in molting and growth of crustaceans. In ostracods, the genes encoding these enzymes have not been characterized. The aim of the present study was to clone the genes encoding chitinase (DsChi) and NAG (DsNAG) from the ostracod, Dolerocypris sinensis, elucidate the phylogenetic relationships between the cloned genes and known chitinolytic enzymes, and determine the expression patterns of these genes at different stages of growth in the presence of an environmental pollutant. The genes were amplified from the genomic DNA of the organism using polymerase chain reaction (PCR). The products from PCR were cloned and characterized with bioinformatics tools, and their expression patterns at different growth stages were determined using real-time quantitative PCR (qRT-PCR). Nine and five introns were identified in DsChi and DsNAG genes, respectively. When compared with protein sequences available in GenBank, chitinase from D. sinensis was most closely related to that of Macrobrachium nipponense (61 % homology). The NAG of D. sinensis was most closely related to that of Limulus polyphemus (55.6 % homology). Based on phylogenetic analysis of known chitinases from crustaceans and insects, the D. sinensis chitinase tightly clustered in the same branch with chitinases from species within the Malacostraca class. In contrast, NAG of D. sinensis was clustered with NAG from F. candida.The level of expression of DsChi mRNA was significantly higher than that of DsNAG throughout the period of growth (p < 0.05). Treatment of D. sinensis cells with fenoxycarb significantly downregulated the expressions of DsChi and DsNAG throughout the period of growth (p < 0.05). These results show that the protein products of DsChi and DsNAG possess remarkable biochemical properties characteristic of a chitinase and NAG, respectively.

Characterization of Miscellaneous Effluent Discharges from a Mobile Offshore Drilling Unit to the Marine Environment.

A study was performed to evaluate the potential biological impacts from 8 different miscellaneous discharges from an oil and gas mobile offshore drilling unit (MODU) including deck drainage, desalination unit waste, boiler blowdown, fire control system test water, noncontact cooling water, and bilge water. Samples were evaluated for toxicity using a rapid (<1 h) initial screening test (echinoderm [Dendraster excentricus] fertilization test), and if toxicity was found, further testing was conducted using 3 chronic whole-effluent toxicity tests. This additional testing included the embryo larval development 72-h echinoderm (D. excentricus); 7-d mysid (Americamysis bahia) survival, growth, and fecundity invertebrate test; and 7-d topsmelt (Atherinops affinis) survival and growth fish test. Toxicity identification evaluations were performed on 3 discharges that consistently elicited a toxic response during whole-effluent toxicity testing. To place the results of the toxicity testing into the context of environmental risk, the spatial extent of potential biological effects was investigated using the CORMIX mixing zone model. The output of the modeling indicated that discharge of selected effluents did not result in concentrations, or duration of exposure, that would elicit toxic effects to organisms living in the surrounding environment. The present study provides a comprehensive data set that was used to characterize potential toxicity and environmental risk of MODU "miscellaneous discharges" which could help inform future risk assessments of these discharges. Environ Toxicol Chem 2019;38:2811-2823. © 2019 SETAC.

Theoretical considerations in determining allometric growth within instars of crustaceans, with special reference to Americamysis bahia.

Allometry in crustaceans is typically considered growth over several instars primarily because crustaceans are presumed to grow only during ecdysis (discontinuous growth). Using theoretical distributions of the sizes of two morphometric variables over several instars, four theoretical instar allometry models are postulated: continuous allometry (indiscrete and discrete); discontinuous allometry (indiscrete and discrete); mixed allometry (simple or complex); and two-rate continuous allometry. The estimates of proportions of allometry within the instars are determined using Y = f(X) and X = f(Y) for variables X and Y. The amount of allometry in each variable is estimated using the mean ± standard deviation on the independent variable. Application of these theoretical instar allometry models using carapace and abdomen sizes in six instars indicates Americamysis bahia experiences two-rate continuous allometry, rather than "traditional" discontinuous allometry, with 85% or more of total growth occurring in the intermolt phase, and with the abdomen accounting for about 60% of the expansion.

Inducers of settlement and metamorphosis of the shrimp Hippolyte inermis Leach in Posidonia oceanica.

Larvae of the caridean shrimp Hippolyte inermis persist in the plankton of the Mediterranean up to about one month. Since they need to reach appropriate coastal areas for their recruitment in seagrass meadows, we hypothesized that leaves of Posidonia oceanica or, alternatively, algae present in their epiphytic biofilms, might be physically recognised as target substrates and trigger larval metamorphosis and settlement. Chemical cues could improve the finding of suitable habitats for settlement. Thus, the effects of leaves of P. oceanica and biofilms of the diatom Cocconeis scutellum parva, seasonally abundant in the leaf epiphytic stratum, were investigated along with the effect of volatile organic compounds (VOCs) extracted from the epiphytic diatom. The physical induction with P. oceanica accelerated larval settlement, stimulating an earlier and faster metamorphosis of larvae. C. scutellum parva produced a weaker effect on settlement; however, diatom's VOCs had evident influence and accelerated metamorphosis and settlement. We concluded that such chemical cues as the VOCs produced by epiphytic diatoms, reinforce the effect of physical cues for the identification of suitable settlement locations for this shrimp.

Deep-sea benthic communities in the largest oceanic desert are structured by the presence of polymetallic crust.

Based on the specimens collected during three deep-sea cruises, and deposited at the Muséum National d'Histoire Naturelle (MNHN) in Paris, we analysed the diversity of benthic communities within the EEZ of French Polynesia. The literature and the MNHN database allowed us to inventory 471 species of invertebrates, among which 169 were newly described. We mainly found data for Mollusca, Crustacea, Brachiopoda and Crinoidea. We also found samples from other taxa, which still remain unidentified within the collections of the MNHN. Although this inventory is incomplete, we demonstrate that the deep waters of French Polynesia host unique benthic communities and endemic species. Using diversity and multivariate analyses, we show that the deep-sea benthic communities are structured by depth, habitats, geography and also by the presence of polymetallic crust. Furthermore, by focusing on the molluscs of the central area of French Polynesia, we show that the spectrum of shell size differs among deep-sea habitats. Specifically, shells tend to be smaller on encrusted seamounts than on island slopes. Together with the size range of organisms, low abundance, rarity and endemism designate these habitats as sensitive. These results should thus be taken into account in the evaluation of the expected impact of mining activities on biological communities.

A review on the application of Bacillus as probiotics in aquaculture.

Probiotics use in aquaculture has gained attention as microbial candidates to maintain the health and the well-being of many aquaculture animals. Among the many microbial candidates, probiotic Bacillus has sporulation capacity that makes them survive harsh environmental conditions, are non-pathogenic and non-toxic when fed to fish, and can produce antimicrobial substances making them more suitable candidates compared to other probiotics. In this review, we discussed the necessity of using the probiotic Bacillus in sustainable aquaculture as a good alternative to improve feed utilization, stress response, immune response and disease resistance, maintenance of tissue integrity, and as well improvement of water quality for sustainable aquaculture. Therefore the findings of current researches about the effects of Bacillus application to improve the culture of aquatic animals for future research and development of Bacillus application in aquaculture have been summarised.