Estudio ultraestructural de la ovogénesis en Marphysa sanguinea (Annelida: Polychaeta: Eunicida) en la Laguna de Túnez

Ultrastructural features of oogenesis of the iteroparous and long lived eunicid polychaete Marphysa sanguinea (Montagu, 1815) from the Lagoon of Tunis were studied using both light and transmission electron microscopy methods. The ovaries consist of coelomic germ-cell clusters surrounded by a thin envelope of follicle cells derived from the peritoneum. They are attached to the genital blood vessels. Oogenesis is asynchronous; therefore, germ cells in premeiotic and previtellogenic phases are observed in one cluster. The oogenesis is of the extraovarian type. In each cluster the more differentiated oocytes detach and float free in the coelomic cavity where they undergo vitellogenesis as solitary cells. Inside the ovary, follicle cells are connected to young oocytes by intercellular bridges and data suggest that in the early stages of vitellogenesis, ribosomes, multivesicular bodies and dense bodies are transferred from the follicle cells to the oocytes through the intercellular bridges. Different morphological evidence supports the heterosynthetic (presence of endocytotic vesicles, abundant microvilli adorning the surface of the egg) and autosynthetic (proteosynthetic organelles well developed, formation of blebs by the external membrane of the nuclear envelope) origin of yolk in M. sanguinea. The cytoplasmic material of the mature oocytes is asymmetrically distributed; large lipid droplets (1.5 μm in size) and large yolk spheres (6 μm in size) occupy the vegetal pole of the oocyte while small yolk spheres (2-3 μm in size) and numerous membranous organelles (mitochondria, cisternae of endoplasmic reticulum) occupy the animal hemisphere. Spherical to elongated cortical granules up to 1.8 μm in size are located in the cortex of the mature oocytes. Finally, fibrogranular aggregates (“nuage”) similar to that within the nucleus are observed in the cortical ooplasm located in the animal pole of mature oocytes. These aggregates probably come from the nucleus and represent maternal cytoplasmic determinants of embryonic cell fate. Oocytes that have completed vitellogenesis measure 250–300 μm in diameter.Se estudiaron las características ultraestructurales de la ovogénesis del poliqueto de la familia Eunicidae, Marphysa sanguínea (Montagu, 1815), caracterizado por ser iteróparo y presentar una largo periodo de vida vital. Los ejemplares proceden de la Laguna de Túnez y se estudiaron tanto mediante microscopía óptica como mediante microscopía electrónica de transmisión. Esta especie presenta ovarios consistentes en agrupaciones de células germinales celómicas rodeadas por una envoltura delgada de células foliculares derivado del peritoneo y unidos a los vasos sanguíneos genitales. La ovogénesis es asincrónica, por lo que se observan células germinales en fases premeióticas y previtelogénicas en cada clúster, y es de tipo extraovárico. En cada clúster, los ovocitos más diferenciados se desprenden y flotan libres en la cavidad abdominal donde experimentan la vitelogénesis como celdas aisladas. En el interior del ovario, los ovocitos jóvenes están conectados con células foliculares mediante puentes intercelulares, los cuales según los datos obtenidos, permiten la transferencia de ribosomas, cuerpos multivesiculares y cuerpos densos desde las células foliculares a los ovocitos en las primeras etapas de vitelogénesis. Diferentes pruebas morfológicas apoyan el origen heterosintético (presencia de vesículas endocitíticas, abundantes microvellosidades adornando la superficie del huevo) y autosintético (orgánulos proteosintéticos bien desarrollados, la formación de vesículas a partir de la membrana externa de la envoltura nuclear) del vitelo en M. sanguinea. El material citoplasmático de los ovocitos maduros se distribuye asimétricamente; grandes gotas de lípidos (1,5 μm) y grandes esferas de vitelo (6 μm) ocupan el polo vegetal del ovocito, mientras que esferas pequeñas de vitelo (2-3 μm) y numerosos orgánulos membranosos (mitocondrias, cisternas del retículo endoplásmatico) ocupan el hemisferio animal. Los ovocitos maduros presentan gránulos corticales (entre esféricos y alargados y de hasta 1,8 μm) en el córtex, mientras que en el ooplasma cortical del polo animal se presentan agregados fibrogranulares (“nuage”) similares a los del núcleo. Estos agregados probablemente provienen del núcleo y representan determinantes citoplasmáticos maternos del destino de las células embrionarias. Una vez completada la vitelogénesis, los ovocitos miden entre 250-300 μm de diámetro

Comparación de los ciclos vitales de dos poblaciones del poliqueto Perinereis cf. cultrifera de la bahía de Argel (Mar Mediterráneo)

The benthic phases of the life cycles of two populations of the polychaete Pereinereis cultrifera from the Bay of Algiers were investigated using field surveys. We found no differences in the life cycle of the two populations. In the Bay of Algiers, P. cultrifera reproduces without epitokal modifications. The lifespan of the species probably does not exceed two years. The reproductive period spans most of the year but is more intense in spring from March to May when the sea-water temperature starts rising. A few mature individuals were collected at the end of summer and in winter. The oocytes take 9 to 12 months to mature and their diameter at maturity is approximately 200 µm.Se investigaron las fases bentónicas del ciclo vital del poliqueto Pereinereis cultrifera de la bahía de Argel usando muestreos de campo. No se encontraron diferencias en el ciclo vital de las dos poblaciones. En la bahía de Argelia P. cultrifera se reproduce sin modificaciones de la epitoca. El periodo de vida de esta especie probablemente no excede los dos años. El periodo reproductivo se extiende durante la mayor parte del año, pero es más intenso en primavera, de marzo a mayo, cuando la temperatura del agua del mar empieza a subir. Se recolectaron unos pocos individuos maduros al final de verano y en invierno. Los oocitos necesitan entre 9 y 12 meses para madurar y su diámetro cuando están maduros es de aproximadamente 200 µm

New records of Heliopora hiberniana from SE Asia and the Central Indian Ocean

Coral reefs are among the most diverse ecosystems on the planet. They provide spawning sites for fishes and habitat for a myriad of fauna and flora. They protect coastlines from waves and storms and have important socio-economic value. However, coral reefs, as we know them, are seriously threatened by globalization and climate change [1]. The widespread bleaching of scleractinian corals threatens to destabilize critical ecosystem functions such as reef-building [2], and a growing body of data indicates that coral reefs are being transformed [3,4]. Future reefs are predicted to be dominated by non-constructional taxa [5,6], and the retreat of scleractinians threatens to cripple coral reef ecosystem functioning and endanger the lives of the millions of people that rely on coral reefs for protection, income and nutrition [7]. To detect coral community responses to climate change, and to identify which species may perform critical functional roles on future reefs, accurate taxonomic and systematic information is needed

Polychaetes of commercial interest from the Mediterranean East Coast of Algeria

Three species of polychaetous annelids are commercially collected, as baits, from natural populations along the coast of Algeria. They are collected by semi-professional bait harvesters supplying a variety of local outlets and are used as bait by local fishermen. Bait harvesters commonly use bleaching liquid (10% in sea water) or a KMnO4 (0.5 to 1% in sea water) solution to force Perinereis cultrifera (Nereididae) individuals out of their algal mat. Hediste diversicolor (Nereididae) and Scolelepis squamata(Spionidae) are dug from intertidal mudflats and sandy beaches. Commercial prices and ways of utilization are given for each species. The necessity for the legislative establishment of a regulatory management plan for worm angling is demonstrated

An update to the list of coral reef fishes from Koh Tao, Gulf of Thailand

Twenty-one species are reported for the first time from Koh Tao (Turtle Island) in the Gulf of Thailand. Information and photographs were obtained from local scuba divers in order to census rare (i.e., cryptic species or transient species only present during one season) or not previously recorded fish species living on or near coral reefs from the area. This is the first time that species belonging to the families Antennariidae (genera Antennatus and Histrio), Ophichthyidae (genus Callechelys), Platycephalidae (genus Thysanophrys), Plotosidae (genus Plotosus) and Synanceiidae (genera Inimicus and Synanceia), and reef-fish genera of several families (Pseudobalistes, Balistidae; Cyclichthys, Diodontidae; Bolbometopon, Scaridae; and Hippocampus, Syngnathidae), among others, have been recorded in Koh Tao. Of the 21 species reported for the first time from Koh Tao, 7 species (Antennatus nummifer (Antennariidae), Pseudobalistes marginatus (Balistidae), Monacanthus chinensis (Monacanthidae), Callechelys marmorata (Ophichthyidae), Thysnophrys cf. chiltonae (Platycephalidae), Bolbometopon muricatum (Scaridae) and Synanceia cf. verrucosa (Synanceidae)) are new records for the Gulf of Thailand. To date, 223 species of coral reef fishes belonging to 53 families are known from Koh Tao, including the species found in the present study

Annual variations of the presence of Nereididae (Annelida: Polychaeta) from intertidal rocky shores along the east coast of Algeria

Four species of nereidid polychaetes, Peri­ner­eis cultrifera, P. macropus, Nereis falsa, and Platy­ner­eis dumerilii, were identified during three years in four intertidal rocky shore sites (El-Kala, Annaba, Skikda and Collo) along the east coast of Algeria during the years 2011–2013. Species’ distribution fluctuated according to sites and season. Perinereis cultrifera was observed during most of the year, except in summer. Perinereis macropus was observed at El-Kala, Skikda and Collo mainly in late winter and early spring. Nereis falsa was observed during most of the year in El-Kala and Annaba; this species was also observed in Skikda in 2011 but then disappeared in the last two years of this study. Finally, the presence of P. dumerilii was noticed only in El-Kala for a few months (mainly in March and April). Perinereis cultrifera, P. macropus and P. dumerilii reproduce after acquiring the epitokous form between April and May, when surface seawater temperature starts rising. The largest mature oocytes were about the same for P. cultrifera (279 µm) and P. macropus (278 µm), while this value was smaller for P. dumerilii (166 µm). In contrast to the other three species of nereidid polychaetes, N. falsa reproduces without epitokal modification between July and August when sea temperature was highest. The largest mature oocytes (168 µm) are about the same as P. dumerilii but is much small than those of P. cultrifera and P. macropus.

Spatio-temporal distribution of Myriapods in an anthropized site and a natural site in north-eastern Algeria

Chilopoda and Diplopoda, were studied in two areas located in north-eastern Algeria (anthropized site of Annaba and natural site of El Tarf). Pitfall traps were used to collect individuals during one year (June 2006 to May 2007). In total, 901 Chilopoda and 411 Diplopoda were collected. Spatio- temporal diversities were evaluated for the two taxa. Our results suggest that the soil physico-chemical edaphic parameters such as the quantity of alluvium, the proportion of organic matter or the pH but also climatic parameters such as the amount of precipitation and the relative humidity of air have a significant influence on the abundance and spatial distribution of Chilopoda and Diplopoda with a clear difference of behaviour between the two taxa. The estimation of the intensity of perturbation due to human activities influencing the ecological diversity of the two taxonomic groups studied indicated that Annaba area, which is more anthropized than that of El Tarf, loosed in terms of Chilopoda and Diplopoda diversityLes Chilopodes et les Diplopodes présents au niveau de deux sites localisés dans le nord-est de l'Algérie (site anthropisé d'Annaba et site naturel d'El Tarf) ont été étudiés par piégeage durant une année (juin 2006 à mai 2007). Au total 901 Chilopodes et 411 Diplopodes ont été récoltés. Les diversités spatio-temporelles des deux taxons ont été évaluées. Nos résultats suggèrent que les paramètres physico-chimiques édaphiques tels que le taux de limon, le pourcentage de matière organique ou le pH mais aussi les paramètres climatiques tels que le volume de précipitation et le taux d'hygrométrie qui en résulte ont une influence significative sur l'abondance et la répartition spatiale des Chilopodes et des Diplopodes avec une nette différence de comportement entre les deux taxons. L'estimation de l'intensité des perturbations introduites par l'homme influençant la diversité écologique des deux taxons indique que la région d'Annaba, qui est plus anthropisée que celle d'El Tarf, subit une perte en matière de diversité concernant à la fois les Chilopodes et les Diplopodes

Impacts of a novel shellfishing gear on macrobenthos in a marine protected area: pump-scoop dredging in Poole Harbour, UK

Understanding the impact of bottom-fishing gears at various scales and intensities on habitats and species is necessary to inform management. In Poole Harbour, UK, a multiple use marine protected area, fishermen utilise a unique “pump-scoop” dredge to harvest the introduced Manila clam Ruditapes philippinarum. Managers need to balance the socio-economic benefits of the fishery with ecological concerns across the region, which has required a revision of by-laws that include both spatial and temporal measures. Within an operational fishery, we used a Before-After-Control-Impact sampling design to assess the impacts of pump-scoop dredging on benthic physical characteristics and community structure in an area where there was no dredging, an area newly opened to dredging and an area subject to high levels of historic dredging. A sampling grid was used in each area to best capture any fishing effort in the newly opened area. Core samples were taken to a depth of 30 cm within intertidal mudflats. A significant loss of fine sediments was observed in the site subject to high intensity dredging and a significant change in community structure also occurred in both dredged sites throughout the study period. In the newly opened site this was characterised by a relative increase in species richness, including increased abundance of annelid worms, notably Hediste diversicolor and Aphelochaeta marioni and a decline in the abundance of the bivalve mollusc Abra tenuis. These changes, albeit relatively small, are attributed to physical disturbance as a direct result of pump-scoop dredging, although no difference in the classification of the biotope of the site was observed. This is of particular interest to managers monitoring site condition within areas under the new bylaws as the Manila clam is spreading to other protected estuaries in the region

Insight into aquaculture's potential of marine annelid worms and ecological concerns: a review

Polychaetes are marine annelid worms that can contribute to aquaculture diversification. Its culture has been viable, and commercially attempted, but intensive production has progressed only in few countries around the world. In the countries with no production, marine polychaetes are imported or harvested. A strong and sustained research investment provided to a better understanding of the nutritional requirements and reproduction of some species. Recent studies showed new technical improvements, which can lead to an important progress in productivity and give a new impetus to the polychaete production. Some marine worm species were identified as good candidates for integrated multitrophic aquaculture. The development of cost-effective aquaculture techniques for marine annelid worms is essential to ensure a balance between commercial interests and the preservation of ecosystems. The influence of polychaete aquaculture on the environment and vice versa raise important concerns related to ecological security and sustainability of this activity. This review focus on the main technical improvements and advances that have been made in areas as diverse as: aquaculture potential of polychaetes, reared species, main species used worldwide, and highlights biological and ecological concerns, important challenges and recommendations.This study was supported by the FCT (Portuguese National Board of Scientific Research), through the MARE (Marine and Environmental Sciences Centre) (UID/MAR/04292/2013) strategic programme and through strategic project PEst-OE/MAR/UI0199/2014, granted to MARE. This study has also the financial support of PROMAR Program through the project 31-03-05-FEP42: LIVE BAIT – Annelid polychaetes as live bait in Portugal: harvesting, import and rearing management.info:eu-repo/semantics/publishedVersio