Sphaeroma Serratum Research Articles

Seasonal Variation (Winter vs. Summer) Crustacean Fauna of the Oualidia Lagoon, Morocco

The Oualidia lagoon on the Atlantic coast of Morocco provides important ecosystem services such as aquaculture, fisheries, tourism and high ecological and biological productivity. This is the first study to describe the spatio-temporal distribution of the crustacean community and potential controlling factors in the coastal waters of the Oualidia lagoon. Crustaceans were sampled with a Van Veen grab during two surveys in winter and summer 2013, and taxonomic composition and diversity were determined at 43 sampling sites. Of the eighteen crustacean taxa recorded, fifteen were new to Oualidia Lagoon. Sphaeroma serratum was the most abundant species in both seasons. Organic matter and chlorophyll a content were higher, temperature and salinity were lower in winter than in summer. The structure of the crustacean assemblages was characterised by the formation of two main clusters, organised according to a downstream gradient. Canonical Correspondence Analysis (CCA) showed that granulometry, organic matter and salinity strongly influenced the distribution pattern of crustaceans in the lagoon.

Analysis of the structural characteristics and spatial organization of macrobenthic fauna in Oualidia lagoon, Morocco

Morocco is a very rich country in terms of wetlands, including bays, estuaries, lagoons, lakes, and rivers, among others. However, many of them need to be well managed and better exploited, thus requiring baseline descriptive studies to assess faunal patterns and trends. Oualidia lagoon is not an exception. In fact, the studies conducted to date in the lagoon mainly focused on its oceanographic features and aquaculture capacities. The present paper presents the first study on the whole macrofaunal assemblages of Oualidia lagoon, having as main objectives analyze the composition and structure of the assemblages, as well as their relationships with the main environmental variables explaining their spatial distribution variability in the enclosed ecosystem of the Oualidia coastal lagoon. The benthic macroinvertebrates of Oualidia lagoon were studied in summer 2013 based on 43 stations spread over the whole lagoon by using a Van Veen grab. Two replicate samples were collected for macrobenthos and one additional replicate for sediment analyses at each station. Also, single water salinity and temperature measurements were recorded at each station. Fifty-one species from seven different taxa were recorded, among which mollusks (37%), polychaetes (25%) and crustaceans (25%) dominated in terms of species number. Peringia ulvae, Abra alba, Sphaeroma serratum, Cerastoderma edule and Corophium sp. accounted for 88% of total abundance. The benthos was structured along a downstream–upstream gradient, showing three assemblages, named according to the IndVal index: (1) Diopatra cf. marocensis, (2) Peringia ulvae, and (3) Cerastoderma edule, while the main factors driving their distribution were granulometry and salinity. The Biotic and Environmental analysis showed that the combination of granulometry and salinity was the major factors controlling the spatial distribution of the macrozoobenthos in the Oualidia Lagoon.

Effects of commercial formulations of glyphosate on marine crustaceans and implications for risk assessment under temperature changes

Glyphosate-based formulations are the most commonly used herbicides worldwide with the risk of potential contamination of aquatic bodies. The present study assessed the response of four marine crustaceans to three different brands of herbicides Roundup®Platinum, Efesto® and Taifun® MK CL.T, under two selected temperatures of 20 °C and 30 °C. The harpacticoid copepod Tigriopus fulvus, the anostracan Artemia franciscana, the amphipod Corophium insidiosum and the isopod Sphaeroma serratum were chosen as testing organisms. Effects of herbicides and temperatures were assessed by estimating lethal concentrations. The results showed that the high temperature rises the toxicity of glyphosate with an increase of mortality of all the tested species. This is an important aspect for future risk assessments of pesticides under global climate change scenarios. Efesto® resulted the most toxic brand, showing C. insidiosum the most sensitive with 96 h-LC50 values of 3.25 mg/L acid equivalent (a.e.) at 30 °C and 7.94 mg/L a.e. at 20 °C followed by T. fulvus while A. franciscana and S. serratum were the less sensitive. This study provides important information for assessing the toxic effects of three different brands of glyphosate-based herbicides on non-target marine organisms suggesting that they should be carefully managed to minimize any negative impact on marine organisms.

Solar orientation in Sphaeroma serratum from Ghar El Melh lagoon (Northern Tunisia)

Preliminary studies carried out on a population of Sphaeroma serratum have shown that this isopod uses the mechanism of sun compass to orient in the water. However, it appears that several environmental factors can influence this mechanism. The aim of this study was to check the sun compass in a population collected in the Ghar El Melh lagoon. Orientation experiments were realized in spring 2019: control experiments were carried out in the field, at the edge of the lagoon of Ghar El Melh lagoon (GMLE) and in an open space at the Faculty of Science of Tunis (FST). The experiments were carried out during three periods of the day: around 9:00, 12:00, and 15:00 using a circular arena filled with water, with (L) and without (S) the possibility of landscape view. Data analyses were performed using statistical tests of circular distribution data. To analyze the intervening factors in the solar orientation behavior of S. serratum a multiple regression analysis adapted to circular data (SPLM - spherically projected linear models) was used. Orientation angles were used as response variables, while factors as: landscape view (L or S), locality of the experiment (GMLE or FST), solar azimuth (azim), sky cloud degree (0–8), sun (visible, covered, shape, not visible) and time of the experiment, were used as influencing variables. The results showed that also the Ghar El Melh S. serratum use the sun azimuth to orient in the water. It resulted that the locality of the experiment significantly influenced their orientation, while the time of experiment had a minor effect.

Complete mitochondrial genome and the phylogenetic position of a wood-boring Isopod Sphaeroma terebrans (Crustacea, Isopod, Sphaeromatidae)

In this study, we determined the complete mitogenome of Sphaeroma terebrans (Crustacea, Isopod, Sphaeromatidae), which was the first one in the family Sphaeromatidae. The mitogenome of S. terebrans was 15,540 bp in length and contained 13 protein-coding genes, 21 tRNA genes, 2 rRNA genes, 1 control region, and 2 unknown fragments which is longer than 200 bp. The overall base composition was 30.1% A, 14.9% C, 21.3% G, and 33.7% T. Six start codons (ATA, ATC, ATG, ATT, ACG, GTG) and three stop codons (TAA, TAG, T–) were found in the protein-coding genes. The size of 21 tRNA genes ranged from 51 to 66 bp, tRNA-Gly was not found. All nodes strongly supported that S. terebrans was placed as sister to Sphaeroma serratum in the maximum likelihood tree.

Diversity and ecology of crustaceans from shallow rocky habitats along the Mediterranean coast of Egypt

Spatio-temporal patterns of the distribution of crustaceans from shallow hard bottoms along the Alexandria coast (Egypt, Mediterranean Sea) were studied during a complete year cycle and also in relation to potential drivers of change (both biotic and abiotic), including variation in habitat-forming species. Overall, the crustacean assemblages appeared poor, including only 14 species belonging to Amphipoda (five species), Isopoda (five species), Tanaidacea (two species), Cirripedia and Decapoda (one species each). The distribution patterns of crustacean assemblages appeared significantly variable both in the spatial and in the temporal dimension on a rather unpredictable basis, albeit variation was related to changes in dominant algal and invertebrate habitat formers. High variability and low species richness observed suggest that the analyzed assemblages are selected by local unfavorable environmental conditions. In fact, the crustacean hard bottom fauna is composed by a bulk of tolerant forms, including the dominant Tanais dulongi, Apohyale perieri, Dynamene bidentata, Sphaeroma serratum, Elasmopus pectenicrus, and Jassa marmorata. Their spatio-temporal dynamics, as well as those of the remaining species, and correlations with the variation of habitat formers and environmental variables are reported. This is a baseline assessment of the crustacean diversity along the Mediterranean coast of Egypt, thus having paramount importance for understanding the predicted future changes of biodiversity for the area.

Seasonal variation of peracarid assemblages in natural and artificial marine environments of the Southwestern Atlantic Ocean

The diversity and seasonal variations of two assemblages of marine benthic peracarids were studied between a natural rocky shore and an artificial harbour area over a 12-month period. Samples were obtained monthly in La Estafeta, a rocky intertidal zone with low human impact, and Mar del Plata Harbour, a polluted environment, between March 2011 and March 2012. The two sites differed markedly in the composition and abundance of species across all seasons: the tanaid Tanais dulongii was most abundant in La Estafeta rocky shore, followed by the amphipods Monocorophium acherusicum, Hyale grandicornis, Ampithoe valida, the isopod Idotea balthica, the tanaid Leptochelia sp. and the isopod Sphaeroma serratum. In contrast, M. acherusicum was most abundant in the harbour area, followed by T. dulongii, S. serratum, Ericthonius punctatus, I. balthica, Caprella equilibra and C. dilatata. Total density of peracarids varied between months in La Estafeta rocky shore and Mar del Plata Harbour. In La Estafeta rocky shore mean density increased from March to May 2011 (autumn in the southern hemisphere; ca. 45,000 ind/m2), decreased sharply until August and then increased in January 2012. In Mar del Plata Harbour the mean density was lower from March to October (ca. 500,000 ind/m3), then increased and reached a maximum in January 2012 (more than 1,500,000 ind/m3), and decreased until the following March. This study suggests that the differences in peracarid assemblages, diversity and seasonality could be related to an effect of temperature, but we should not rule out a synergistic effect of other factors, such as pollution, food availability and hydrodynamic factors.

The first complete mitogenome of the South China deep-sea giant isopod Bathynomus sp. (Crustacea: Isopoda: Cirolanidae) allows insights into the early mitogenomic evolution of isopods.

In this study, the complete mitochondrial (mt) genome sequence of the South China deep‐sea giant isopod Bathynomus sp. was determined, and this study is the first to explore in detail the mt genome of a deep‐sea member of the order Isopoda. This species belongs to the genus Bathynomus, the members of which are saprophagous residents of the deep‐sea benthic environment; based on their large size, Bathynomus is included in the “supergiant group” of isopods. The mt genome of Bathynomus sp. is 14,965 bp in length and consists of 13 protein‐coding genes, two ribosomal RNA genes, only 18 transfer RNA genes, and a noncoding control region 362 bp in length, which is the smallest control region discovered in Isopoda to date. Although the overall genome organization is typical for metazoans, the mt genome of Bathynomus sp. shows a number of derived characters, such as an inversion of 10 genes when compared to the pancrustacean ground pattern. Rearrangements in some genes (e.g., cob, trnT, nad5, and trnF) are shared by nearly all isopod mt genomes analyzed thus far, and when compared to the putative isopod ground pattern, five rearrangements were found in Bathynomus sp. Two tRNAs exhibit modified secondary structures: The TΨC arm is absent from trnQ, and trnC lacks the DHU. Within the class Malacostraca, trnC arm loss is only found in other isopods. Phylogenetic analysis revealed that Bathynomus sp. (Cymothoida) and Sphaeroma serratum (Sphaeromatidea) form a single clade, although it is unclear whether Cymothoida is monophyletic or paraphyletic. Moreover, the evolutionary rate of Bathynomus sp. (dN/dS [nonsynonymous mutational rate/synonymous mutational rate] = 0.0705) is the slowest measured to date among Cymothoida, which may be associated with its relatively constant deep‐sea environment. Overall, our results may provide useful information for understanding the evolution of deep‐sea Isopoda species.

Distribution of four isopods (Peracarida: Crustacea) in shallow waters of the Bizerte Lagoon (Tunisia, SW Mediterranean Sea)

The distribution of four isopods – Idotea balthica basteri (Pallas, 1772), Idotea chelipes mediterranea Charfi-Cheikhrouha, 1996, Sphaeroma serratum (Fabricius, 1787), and Paracerceis sculpta (Holmes, 1904) – at Menzel Jemil (Bizerte Lagoon, North Tunisia) was analysed and then related to the variation of temperature, depth and plant biomass. The abundance of isopods showed monthly fluctuations with maxima in August and minima in December 2010. The most dominant species was I. b. basteri followed by S. serratum, with a spatial gradient in the distribution pattern of isopod species in the study area. The high density of juveniles in algae and seagrass highlights the important role played by this habitat as a nursery for species. Both dominant species were tolerant to temperature variations, with some preference values (19.73–27.73°C in I. b. basteri; up to 28°C in S. serratum) and salinity (36.7–38.6 psu in I. b. basteri; 39–39.2 psu in S. serratum). Multiple regression analysis between environmental variables and species abundance showed a positive relationship with biomass of Gracilaria bursa-pastoris and Ulva lactuca for the two species of Idotea and Sphaeroma, respectively, while abundance of P. sculpta was positively related to temperature. Biotic and environmental linking (BIOENV) analysis confirmed the greatest influence of temperature and vegetation biomass on the temporal distribution of these isopod species. A spatial distribution pattern according to successive depths was revealed.

Ultrastructure and mineral composition of the cornea cuticle in the compound eyes of a supralittoral and a marine isopod.

The cuticle of the cornea in Crustacea is an interesting example of a composite material compromising between two distinct functions. As part of the dioptric apparatus of the ommatidia within the complex eye it forms transparent micro-lenses that should as well maintain the mechanical stability of the head capsule. We analyzed the ultrastructure and composition of the isopod cornea cuticle of the terrestrial species Ligia oceanica and the marine Sphaeroma serratum. We used a variety of tissue preparation methods, electron microscopic techniques as well as electron microprobe analysis and Raman spectroscopic imaging. The results reveal various structural adaptations that likely increase light transmission. These are an increase in the thickness of the epicuticle, a reduction of the thickness of the outer layer of calcite, a spatial restriction of pore canals to interommatidial regions, and, for S. serratum only, an increase in calcite crystal size. In both species protein-chitin fibrils within the proximal exocuticle form a peculiar reticular structure that does not occur within the cuticle of the head capsule. In L. oceanica differential mineralization results in a spherically shaped interface between mineralized and unmineralized endocuticle, likely an adaptation to increase the refractive power of the cornea maintaining the mechanical stability of the cuticle between the ommatidia. The results show that the habitat and differences in the general structure of the animal's cuticle affect the way in which the cornea is adapted to its optical function.

Investigating the use of Sphaeroma serratum (Crustacea, Isopoda) as bio-indicator for heavy metals pollution in Lake Timsah, Suez Canal using alkaline comet assay technique

Pollution of the environment with heavy metals is a serious problem that is recognized in most countries in the world. Lake Timsah as an important lake in Suez Canal is highly polluted and receiving different sources of contaminations. However, attention and alarm thresholds of these parameters only concern the toxic effects of the polluting substances studied and do not take into consideration the question of chronic exposure at low doses of noxious chemicals. The physico-chemical parameters only provide snapshots of the condition of a water body and don’t provide the integrative measure of overall health of any water body. On the other hand, crustaceans are used as bio-indicators in various aquatic systems in bio-accumulation experiments and in field studies. The crustacean isopod, Sphaeroma serratum which is found in large numbers at Lake Timsah was used for further investigation for detecting its DNA damages cause by the pollution. The comet assay technique which derives its name from the comet-like shape that cells with damaged DNA acquire was applied in this study in order to investigate on what level such poor water conditions in Lake Timsah can deform the DNA of its biota. It is recommended than other tests as it requires only a very small number of cells and these cells do not need to be undergoing active division. The present study confirmed the applicability of the alkaline comet assay technique as a sensitive tool for environmental monitoring. Also, it can be suggested that aquatic S. serratum which is a very tolerant species can resist pollution and can be used as a reliable bio-indicator of DNA damage.

Size at the onset of maturity (SOM) revealed in length–weight relationships of brackish amphipods and isopods: An information theory approach

In amphipods and other small-sized crustaceans, allometric relationships are conventionally analysed by fitting the standard model Y = a·Xb (X and Y are, e.g., body length and weight, respectively) whose scaling exponent b is assumed to be constant. However, breakpoints in allometric relationships have long been documented in large-sized crustaceans, ultimately determined by ontogenetic, abrupt variations in the value of b. Here, the existence of breakpoints in length–weight relationships was investigated in four amphipod (i.e., Gammarus aequicauda, Gammarus insensibilis, Microdeutopus gryllotalpa, and Dexamine spinosa) and three isopod species (i.e., Lekanesphaera hookeri, Sphaeroma serratum, and Cymodoce truncata) from three Mediterranean lagoons. The power of two candidate linear models fitted to log10-transformed data – a simple model assuming a constant exponent b and a segmented model assuming b to vary after a breakpoint - was compared using a parsimonious selection strategy based on the Akaike information criterion. The segmented model with a breakpoint provided the most accurate fitting of length–weight data in the majority of the species analysed; non-conclusive results were obtained only for D. spinosa and C. truncata, of which a limited number of specimens was examined. Model parameters were consistent for amphipod and isopod species collected across the three different habitats; the generality of the results was further supported by a literature search confirming that the identified breakpoints corresponded with ontogenetic discontinuities related with sexual maturation in all the species investigated. In this study, segmented regression models were revealed to provide a statistically accurate and biologically meaningful description of length–weight relationships of common amphipod and isopod species. The methodological limitations of the approach are considered, while the practical implications for secondary production estimates are discussed.

First record of the exotic isopod Sphaeroma serratum (Crustacea: Isopoda) from Uruguayan waters (southwestern Atlantic)

The isopod Sphaeroma serratum (Fabricius, 1787) is reported from Uruguay for the first time and it is considered an introduced species in the region. The species was found very abundant and specimens were collected under the rocks in an intertidal area at La Paloma port in 2002 (34º39´S, 54º08´W). The specimens we examined fully agree with previous descriptions. Considering that this species has been reported as introduced in Argentina and Brazil, here we hypothesized the potential routes of introduction to Uruguay.

Epibiotic bacterial community of Sphaeroma serratum (Crustacea, Isopoda): relationship with molt status

Sphaeroma serratum is a marine isopod species that inhabits seashores from Europe to West Africa. The individuals live under stones in direct contact with reduced sediments and harbour a diverse bacterial community on the cuticle of their pleopods. We investigated the diversity of these epibiotic bacteria on male (pubescent and senescent) and female specimens with electron microscopic obser vations and molecular tools. The microbial community of S. serratum was shown to be composed of at least 5 bacterial morphotypes observed on the pleopodal cuticle in all male specimens. Using fluorescence in situ hybridization, we identified 5 major phylogenetic groups (α-, β-, γ- and δ-Proteobacteria and Archaea) whereas denaturing gradient gel electro - phoresis (DGGE) of PCR-amplified 16S rRNA gene fragments of epibiotic bacteria revealed 50 bands. The bacterial community associated with S. serratum seems more diverse than in other marine crustaceans, such as Rimicaris. The relative diversity of this bacterial community was also studied in relation to the molt cycle. The comparison of DGGE band patterns of several individuals from female, pubescent male and senescent male groups revealed that the bacterial community diversity was dependent on the sex and the age of the individuals and more generally on the molt status.

CRUSTACEANS AS BIOMARKERS OF POLLUTION IN THE BLACK SEA WITH HEAVY METALS EXPOSURE TO HEAVY METALS

Benthic fauna (zoo benthos) of subpralitoral Black Sea is extremely abundant and diverse. Especially were numerous mollusks and crustaceans. Last play an important role in cleaning up coastal zone, and therefore were chosen as test object. The study conducted on crustaceans and as a comparison to sea water, seaweed and mollusks of the Black Sea revealed an uneven accumulation of heavy metals in aquatic water due to their location in the food chain. The data obtained show that the species of Decapoda (Callinoctes sapidea) and Isopoda (Sphaeroma Serratum) are able to accumulate heavy metals intensively other taxonomic groups of marine aquatic organisms that may be the result of their adaptation to living in polluted conditions of the environment. The sensitivity of crustaceans such as Sphaeroma serratum to heavy metals makes it possible to use the latter as bioindicators of pollution in border areas of land and sea coast of the Crimea.

Widespread atypical mitochondrial DNA structure in isopods (Crustacea, Peracarida) related to a constitutive heteroplasmy in terrestrial species

Metazoan mitochondrial DNA (mtDNA) is generally composed of circular monomeric molecules. However, a few exceptions do exist and among them two terrestrial isopods Armadillidium vulgare and Porcellionides pruinosus have an atypical mtDNA composed of linear monomers associated with circular "head-to-head" dimers: a very unusual structure for animal mtDNA genome. To assess the distribution of this atypical mtDNA among isopods, we performed RFLP and Southern blot analyses on mtDNA of 16 terrestrial (Oniscidea family) and two aquatic isopod species: the marine Sphaeroma serratum (suborder Flabellifera, sister group of Oniscidea) and the freshwater Asellus aquaticus (Asellota, early derived taxon of isopod). The atypical mtDNA structure was observed in 15 terrestrial isopod species and A. aquaticus, suggesting a wide distribution of atypical mtDNA among isopods. However, a typical metazoan mtDNA structure was detected in the marine isopod S. serratum and the Oniscidea Ligia oceanica . Our results suggest two possible scenarios: an early origin of the atypical mtDNA in isopods followed by reversion to the typical ancestral mtDNA structure for several species, or a convergent appearance of the atypical mtDNA structure in two isopod suborders. We compare this distribution of the atypical mtDNA structure with the presence of a heteroplasmy also observed in the mtDNA of several terrestrial isopod species. We discuss if this transmitted heteroplasmy is vectored by the atypical mtDNA and its impact on the maintenance of the atypical mtDNA in isopods.

Preliminary assessment of Ostreopsis cfr. ovata acute toxicity by using a battery bioassay

Ostreopsis cfr. ovata toxicity was estimated through acute bioassays using four crustacean species (Artemia franciscana, Tigriopus fulvus, Corophium insidiosum and Sphaeroma serratum). The epiphytic dinoflagellate showed significant toxicity towards all tested crustaceans, which have usually exhibited the highest mortalities with increasing the dinoflagellate cell concentrations. Furthermore, our results evidenced a higher sensitivity of A. franciscana larvae to Ostreopsis, compared with the other species. The results of our bioassays highlighted the usefulness of employing a base-set of different species rather than one derived from a single species, in order to obtain more reliable information on the algal toxicity.

<htm>Alometria e crescimento sexual e etàriamente diferenciados em <i>Sphaeroma serratum</i> (Crustaceae, Isopoda) da baía da Guanabara (Brasil)<htm>

Alometria e crescimento sexual e etàriamente diferenciados em Sphaeroma serratum (Crustaceae, Isopoda) da baía da Guanabara (Brasil) JARBAS DE MESQUITA NETO

Are metals of antifouling paints transferred to marine biota?

Because of its high toxicity, TBT (trybutiltin) was banned since 2003, which resulted in a greater re-use of Cu as based-biocide in antifouling paints (AFP). The aim of this work is to determine if metals form of AFP are transferred to benthic organisms from Guanabara Bay (GB) (Rio de Janeiro, Brazil). Metal concentrations were measured in two main fouling algae species Ulva flexuosa and U. fasciata and one isopod species, Sphaeroma serratum, in two GB marinas areas from sites with artificial substrate covered by AFP and natural substrate.In addition, control samples were collected in an adjacent open ocean area. Concentrations of Cd, Cr, Cu, Pb and Zn were determined by Atomic Absortion Spectrophotometry. Higher concentrations of Cu, Pb and Zn were detected in both algal species from GB in relation to control areas. Among samples of algae and isopod species from GB, populations collected over artificial surfaces covered by AFP presented significantly higher metal concentration than population of rocky natural substrate. Our data showed that the leaching of metals by antifouling paints present on decks and boats are being taken up by algae and isopods. These results indicate that antifouling coatings are the main source of heavy metal to biota of GB marina area.

Tipos estruturais de pigmentação e redescrição de Sphaeroma serratum (Fabricius) (Isopoda, Flabellifera, Sphaeromatidae) da Marina da Glória, Rio de Janeiro, Brasil

Sphaeroma serratum (Fabricius, 1787) has its first occurrence recorded from Brazil, by means of especimens collected at rock shores of Marina da Gloria, Baia de Guanabara, Rio de Janeiro. The species is redescribed with illustrations. Structural patterns of pigmentation of studied population are here presented.