Nuria Méndez

Variability in reproductive mode and larval development within the Capitella capitata species complex

Summary A comparative analysis was carried out of reproductive mode, larval development pattern, and larval growth rate under identical conditions of three members of the Capitella capitata species complex: Capitella sp I from New York, US, Capitella sp M from shallow hydrothermal vents off Milos, Greece, and Capitella sp S from an intertidal flat on Sylt, Germany. In addition, three populations from salmon farms, Capitella K (Kilmelford, Scotland), Capitella Cm and Capitella Ct (Cranford, Ireland), are described for the first time. Three development patterns were observed: planktotrophic (Capitella K and Ct populations), lecithotrophic (Capitella spp I, M and Cm populations), and direct development (Capitella sp S). Experiments with planktotrophic larvae from the Capitella K population at different temperatures, in the presence and absence of light and with several kinds of substrate were not successful in inducing settlement, although differences in the duration of larval survival were observed. Overall, major differences in reproductive modes and larval development patterns were observed among representatives of different species and populations reared under identical culture conditions. In contrast, such modes and patterns are consistent across generations. Whereas larval type and developmental mode appear to be determined largely by genetic factors, environmental conditions have an important influence on the timing of key developmental processes, such as settling and growth.

Annelid assemblages in soft bottoms subjected to human impact in the Urías estuary (Sinaloa, Mexico)

Abstract The annelid fauna inhabiting soft bottoms was analysed during February and April, 1997 in the Urias estuary which is mostly surrounded by mangrove swamps, but is also subjected to the effect of several anthropogenic activities. Classification and ordination techniques were used to perform the characterisation of the system based on the annelid assemblages according to environmental variables (mainly organic matter content and percentage of mud). Three zones were found: (1) ‘very polluted zone’, in front of a slaughterhouse and a fish processing factory with a total lack of macrofauna due to the strong enrichment of the sediment in organic matter; (2) ‘polluted zones’, characterised by the sporadic presence of oligochaetes in front of a domestic sewage effluent, by the dominance of Capitella capitata close to a thermoelectric plant, and by the dominance of Streblospio benedicti and oligochaetes in the surroundings of an upstream shrimp farm; (3) ‘unpolluted zones’, in the mouth of the estuary and an area surrounded by mangrove trees, with low organic matter content in sediment, high diversity and no dominant species.

Fouling polychaete worms from the southern Gulf of California: Sabellidae and Serpulidae.

Abstract Members of the tubicolous polychaete families, Sabellidae and Serpulidae, constitute two of the most important groups in the marine fouling biota. This paper describes three fouling sabellids and six serpulids from the southern Gulf of California and provides information about the reproductive biology of these species. The invasive species, Branchiomma bairdi and Ficopomatus miamiensis, are established in the southern Gulf of California as self‐sustaining populations outside of their native range of the Caribbean Sea. Hull fouling is considered the most probable vector for the translocation of B. bairdi to the eastern Pacific, while the presence of F. miamiensis is most likely due to shrimp aquacultural activities. Hydroides elegans is probably an invasive species in the study area and is common as fouling on ships and piers in the Caribbean, Gulf of Mexico, the Turkish Levantine coast, Hawaii and California. Hydroides brachyacanthus has been widely recorded in the Mexican Pacific. Demonax pallidus and Megalomma coloratum constitute new records for México. Hydroides elegans, H. recurvispina and Vermiliopsis multiannulata are new records for the Mazatlán port. Hydroides cruciger, H. brachyacanthus, H. elegans, H. recurvispina and Megalomma coloratum have separate sexes without sexual dimorphism. Branchiomma bairdi and D. pallidus are simultaneous hermaphrodites, although asexual reproduction via scissiparity is documented in B. bairdi. Sperm morphology (spherical nucleus, rounded or subtriangular cap‐like acrosome and a long flagellum) suggests that the species recorded here are free‐spawners with external fertilisation or ect‐aquasperm type. This taxonomic effort is greatly enhanced by the integration of synonymies, characterisations and image collections with annotations archived in Morphbank.

Branchiomma bairdi : a Caribbean hermaphrodite fan worm in the south-eastern Gulf of California (Polychaeta: Sabellidae)

Branchiomma bairdi , a fouling non-indigenous sabellid polychaete has been detected in the south-eastern Gulf of California, representing the first record in the eastern tropical Pacific, as its original distribution is the Caribbean Sea. The species was commonly found as isolated specimens but small aggregates with 4–12 individuals were also found on floating docks, on dock pilings, buoys and on hulls of vessels in the port of Mazatlan. Branchiomma bairdi is a simultaneous hermaphrodite with male and female gametes developing separately in the same segments. The sperm morphology suggests that the species is a free-spawner with external fertilization (ect-aquasperm type). A complete diagnosis is provided and a discussion about its systematics, reproduction and ecology is included.

Effects of the pharmaceutical fluoxetine in spiked-sediments on feeding activity and growth of the polychaete Capitella teleta

The marine-estuarine polychaete Capitella is an indicator of organic pollution and plays important roles in sewage waste cycling. The antidepressant fluoxetine can be accumulated in streams and sewage effluents and it could pose a hazard to infauna. Effects of fluoxetine on feeding and growth of Capitella teleta were investigated through the exposure to 0, 0.001, 0.03, 0.3 and 3.3 μg/g dry weight sediment-spiked fluoxetine during 18 days. No effects of fluoxetine concentrations were observed on egestion rates, body weight and size-specific egestion rates. Fluoxetine favoured the occurrence of males with abnormal genital spines. This suggests that fluoxetine can have important reproductive implications. Further studies are recommended to assess potential detrimental effects on benthic infauna inhabiting close to sewage treatment plants.

Trace metals in two populations of the fireworm Eurythoe complanata from Mazatlán Bay: effect of body size on concentrations

Trace metal concentrations (Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn) were measured in two populations of the polychaete Eurythoe complanata collected in Mazatlan Bay (southeastern Gulf of California). With the exception of Cd, the trace metal concentrations fell within the ranges of other species of polychaetes collected elsewhere. The population of E. complanata collected from a site near to the sewage outfall (2.1 km) showed higher levels of Cu and Pb (following the same tendency of sediments) than the population from a site located 16 km away from the sewage outfall, where Cd worm concentrations were higher. Size-dependent relationships were observed for Cd, Ni, Pb and Zn only and the correlation was negative for the four elements. Evidently, this reveals different metabolic requirements in young (small) and old (larger) polychaetes.

Life cycle of Capitella sp. Y (Polychaeta: Capitellidae) from Estero del Yugo, Mazatlán, Mexico

The development of the polychaete Capitella sp. Y from Estero del Yugo, Mazatlan, Mexico was studied under culture conditions. Capitella sp. Y has a lecithotrophic development with the production of ciliated metatrochophore larvae. A high variation in size and duration of the different developmental stages was observed, as with most of the Capitella species previously described. The median survival time was estimated as six months. The Capitella sp. Y population consists of males, females and hermaphrodites (protandrous and proteroginous individuals). Differences in developmental modes among the Capitella capitata species-complex have indicated that Capitella sp. Y do not belong to any of these previously described species. This study has shown that hermaphroditism is favoured when density of individuals is low, especially in protandrous specimens. It is suggested that hermaphroditism, as well as the ability of self-fertilization observed in Capitella sp. Y enhances the success of the population in natural environments.

Effects of cadmium on sediment processing on members of the Capitella species-complex.

The effect of cadmium on sediment processing by laboratory-cultured specimens of Capitella sp I and Capitella sp B was investigated. Specimens were exposed to 0, 60, 90 and 140 microg Cd g(-1) dry weight sediment for a 10 day period (two census days) to observe effects of cadmium on their feeding activity. Under unstressed conditions, Capitella sp I specimens were larger, had higher biomass and produced more fecal pellets than Capitella sp B. Cadmium concentrations had no effect on pellet production and body mass of the studied populations. However, cadmium exposure time significantly affected Capitella sp B pellet production and body mass of both populations following different trends: after 10 days of exposure, the average processed sediment per unit worm mass decreased in Capitella sp I but increased in Capitella sp B. The latter population did not reduce its feeding activity in the presence of cadmium maybe related to the fact that it is derived from a highly polluted environment. This study has shown an unimpaired response of Capitella sp I and Capitella sp B to cadmium in their sediment processing activity, which indicates the potential importance of this species complex in the trophic transfer of metals from sediments to other marine organisms.

Checklist of soft-bottom polychaetes (Annelida: Polychaeta) of the coastal lagoon Estero de Urías (Sinaloa, Mexico)

A checklist of 53 soft-bottom species of polychaetes from the coastal lagoon Estero de Urias is presented here. Depth, sediment temperature, salinity, grain size, organic matter content, and dissolved oxygen ranges where polychaete species were found are provided. Twenty-six species are reported for the first time for the Estero de Urias coastal lagoon. This is the first report of the sabellid Amphicorina gracilis, the spionid Marenzelleria viridis, and the syllid Exogone ( Parexogone ) molesta for the Pacific coast of Mexico.

Preliminary observations of cadmium and copper effects on juveniles of the polychaete Capitella sp. Y (Annelida: Polychaeta) from Estero del Yugo, Mazatlán, México

Se investigaron los efectos de cadmio (Cd) y cobre (Cu) sobre juveniles cultivados de Capitella sp. Y. Organismos juveniles de siete dias de edad fueron expuestos a 13 (control), 60, 160, 240 y 340 mg Cd L-1 y a 17 (control), 50, 120 y 150 mg Cu L-1 durante 30 dias. La mortalidad se incremento significativamente al aumentar las concentraciones de Cu y, en las exposiciones a Cd, solamente fue evidente a 340 mg L-1. El tamano corporal y la produccion de heces fecales disminuyeron antes en los especimenes expuestos a Cu que en los expuestos a Cd, especialmente en las concentraciones mas altas de Cu. Estos resultados indican que los juveniles son mas sensibles al Cu en terminos de mortalidad, alimentacion y crecimiento. La produccion de hemoglobina fue inhibida debido a la escasez de alimento en el sedimento experimental, mas que a exposicion a los metales. La formacion de tubos no fue afectada por la presencia de metales ni por la escasez de alimento. Este estudio sugiere que concentraciones entre 50 y 150 mg L-1 de Cu y de 340 mg L-1 de Cd, podrian afectar la dinamica poblacional de esta especie en ecosistemas naturales