Euryhalinity of subtropical marine and estuarine polychaetes evaluated through carbonic anhydrase activity and cell volume regulation.

Polychaete worms are widespread and diverse in marine and estuarine habitats subject to varying salinity, in areas influenced by tides, demanding physiological adjustment for internal homeostasis. They are typically considered and reported to be osmoconformers, but they are not often studied for their osmoregulation. Here, three species of polychaete worms from distinct coastal habitats have been investigated: the spionid Scolelepis goodbody (intertidal in saline, exposed sandy beaches), the nereidid Laeonereis culveri (estuarine polyhaline), and the nephtyid Nephtys fluviatilis (estuarine oligohaline). The general objective here was to relate ecological aspects and physiology of the studied species. Constitutive whole body osmolality and carbonic anhydrase activity (CAA, relevant for osmoregulation, acid-base balance and respiration) have been assayed. In addition, cell volume regulatory capacity (from whole body cell dissociation) was challenged under hypoosmotic and hyperosmotic shocks (50% intensity), with respect to isosmotic control. S. googdbody and L. culveri, the two species from most saline environments (marine/estuarine), showed higher CAA than N. fluviatilis, which, in turn, displayed a hyperosmotic gradient to water of salinity 15. Cells from S. goodbody and L. culveri showed regulatory volume decrease upon swelling, with S. goodbody showing the largest volume increase. As in other more studied marine invertebrate groups, polychaetes also show variability in their osmoregulatory physiology, related to distinct saline challenges faced in their coastal habitats.

Chaetopterus variopedatus Bioluminescence: A Review of Light Emission within a Species Complex.

Chaetopterus variopedatus has been studied for over a century in terms of its physiology, ecology and life history. One focus of research is on its intrinsic bioluminescent emissions, which can be observed as a blue light emitted from the extremities of individual body segments, or as a secreted mucus. Even though research shows that C. variopedatus is a species complex miscategorized as a single species, all of the variants of this polychaete produce light, which has been investigated in terms of both physiology and biochemistry. Despite decades of study, there are still many questions about the luminescence reaction, and, as of yet, no clear function for light emission exists. This review summarizes the current knowledge on C. variopedatus luminescence in addition to briefly describing its morphology, life cycle and ecology. Possible functions for luminescence were discussed using observations of specimens found in Brazil, along with a comparison of previous studies of other luminescent organisms. Further study will provide a better understanding of how and why C. variopedatus produces luminescence, and purifying the protein and luciferin involved could lead to new bioanalytical applications, as this reaction is unique among all known luminescent systems.

Short communication: Characterization of the expression of microRNAs in the poecilogonous polychaete B. wellingtonensis.

Poecilogony is a type of reproduction in which a species produces different types of larvae. Boccardia wellingtonensis, is a poecilogonous polychaete with females producing planktotrophic and adelphophagic larvae, in addition to nurse eggs, in the same capsule that differ in feeding behavior. It is still unclear why planktotrophs do not feed on nurse eggs during the intracapsular development and arrest its growth, while adelphophagic larvae consume nurse eggs and planktotrophic larvae inside the capsule, hatching as advance larvae or as juveniles. Here we characterized the expression of selected miRNAs from these two types of larvae and from adults in order to begin to understand the molecular mechanisms that regulate expression in this type of poecilogony. Results showed that adults and pre-hatching adelphophagic larvae have high levels of expression of miR-125, miR-87a and let-7, while adelphophages at early developmental stage had low levels of expression of miR-87b. Planktotrophic larvae showed low expression level of let-7. This work represents the first step in understanding the role of miRNAs in the development of different larval types in a poecilogonous species. We also propose to B. wellingtonensis as an interesting biological model to study the evolution of larval modes and reproductive strategies of marine invertebrates.

Trophic structure of the macrofauna associated to deep-vents of the southern Gulf of California: Pescadero Basin and Pescadero Transform Fault.

Newly discovered hydrothermal systems in the Pescadero Basin (PB) and the neighboring Pescadero Transform Fault (PTF) at the mouth of the Gulf of California disclosed a diverse macrofauna assemblage. The trophic structure of both ecosystems was assessed using carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) stable isotopes. The δ13C ranged from -40.8 to -12.1‰, revealing diverse carbon sources and its assimilation via Calvin-Benson-Bassham and the reductive tricarboxylic acid cycles. The δ15N values were between -12.5 and 18.3‰, corresponding to primary and secondary consumers. The δ34S values fluctuated from -36.2 to 15.1‰, indicating the sulfide assimilation of biogenic, magmatic, and photosynthetic sources. In PB high-temperature vents, primary consumers including symbiont-bearing, bacterivores and filter-feeders predominated. The secondary consumers within the scavengers/detritivores and predator guilds were scarce. The siboglinid Oasisia aff alvinae dominated the macrofauna assemblage at PB, but rather than playing a trophic role, it provides a substrate to vent dwellers. In PTF low-temperature vents, only symbiont-bearing primary consumers were analyzed, displaying the lowest δ34S values. This assemblage was dominated by the coexisting siboglinids Lamellibrachia barhami and Escarpia spicata. δ34S values allowed to distinguish between PB and PTF vent communities, to exclude the presence of methanotrophic organisms, and the detection of photosynthetic organic matter input.

Effects of mixtures of anticancer drugs in the benthic polychaete Nereis diversicolor.

The increasing consumption of anticancer drugs through single and/or combinatory chemotherapy worldwide raised concern regarding their toxicity burden in coastal zones. The toxicity of a mixture of three compounds involving the drugs cisplatin (CisPt), cyclophosphamide (CP) and tamoxifen (TAM) was determined on the marine polychaete Nereis diversicolor exposed to an increasing range of their concentrations, respectively: Mix A: 0.1 + 10 + 0.1 ng L-1; Mix B: 10 + 100 + 10 ng L-1; Mix C: 100 + 500 + 25 ng L-1; Mix D: 100 + 1000 + 100 ng L-1. Different endpoints were assessed, including disturbance in the burrowing behaviour, neurotoxicity (acetylcholinesterase - AChE activity), antioxidant enzymes (superoxide dismutase - SOD; catalase - CAT; selenium-dependent glutathione peroxidase - Se-GPx and total glutathione peroxidases T-GPx activities), biotransformation metabolism (glutathione-S-transferases - GST), lipid peroxidation (LPO) and genotoxicity (DNA damage). Biological effects of the mixtures of anticancer compounds on N. diversicolor were compared with previous studies about effects on the same biological model under single-drug exposure conducted with the same molecules. Regarding SOD activity, TAM showed an antagonist effect over CisPt and CP in mixtures C and D. In Mix D, there was a synergistic effect of TAM and CisPt that inhibited CAT activity and an additive interaction of CisPt and CP on the Phase II biotransformation enzyme. Drugs in Mix A also suppressed polychaetes' GST activity, although different from the respective single-drug responses, besides able to induce T-GPx activity, that was not sufficient to avoid oxidative damage and mid-grade DNA damage. Due to the absence of burrowing impairment in Mix A, mechanisms involved in neurotoxicity were other than the one driven by AChE alterations. At the intermediary concentrations (Mix B and C), only LPO occurred. Data from drugs individually may not predict the risks provided by mixtures.

Sublethal effects in Perinereis gualpensis (Polychaeta: Nereididae) exposed to mercury-pyrene sediment mixture observed in a multipolluted estuary.

Sediment-living organisms can be subjected to a multi-pollution condition due to an increase in the diversity of contaminants. Sediment mixtures of Mercury (Hg) and some polycyclic aromatics hydrocarbons like Pyrene (Pyr) are common in heavily industrialized coastal zones. In the present study, greater than (>) and less than (<) probable effect concentration levels (PELs) of Hg and Pyr were assessed using spiked sediments in order to determine combined (Hg + Pyr) effects in uptake, metabolization and oxidative balance in the polychaete Perinereis gualpensis at short and medium-term exposure. Hg + Pyr significantly influenced the uptake/kinetics of Hg and Pyr metabolite 1-OH-pyrene in polychaete tissues during the exposure time compared with separate treatments of each analyte (p < 0.05). Both the Hg-only and Pyr-only exposures significantly influenced both enzymatic and non-enzymatic responses respect to control groups (p < 0.05). The Hg-only treatment showed the worst scenario related to the activation and subsequent inhibition of glutathione S- transferase (GST) and peroxidase (GPx) activities, high levels of Thiol-groups (SH-groups), low antioxidant capacity (ACAP) and enhanced lipid peroxidation (TBARS) in the last days of exposure (p < 0.05). In contrast, ragworms exposed to Hg + Pyr showed a significant increase in both enzymatic and non-enzymatic activity during the first days of exposure and the absence of lipid peroxidation during the whole experiment. Our results suggest different oxidative stress scenarios in P. gualpensis when exposed to >PEL Hg concentration with

A quantitative framework to estimate the relative importance of environment, spatial variation and patch connectivity in driving community composition.

Perhaps the most widely used quantitative approach in metacommunity ecology is the estimation of the importance of local environment vs. spatial structuring using the variation partitioning framework. Contrary to metapopulation models, however, current empirical studies of metacommunity structure using variation partitioning assume a space-for-dispersal substitution due to the lack of analytical frameworks that incorporate patch connectivity predictors of dispersal dynamics. Here, a method is presented that allows estimating the relative importance of environment, spatial variation and patch connectivity in driving community composition variation within metacommunities. The proposed approach is illustrated by a study designed to understand the factors driving the structure of a soft-bottom marine polychaete metacommunity. Using a standard variation partitioning scheme (i.e. where only environmental and spatial predictors are used), only about 13% of the variation in metacommunity structure was explained. With the connectivity set of predictors, the total amount of explained variation increased up to 51% of the variation. These results highlight the importance of considering predictors of patch connectivity rather than just spatial predictors. Given that information on connectivity can be estimated by commonly available data on species distributions for a number of taxa, the framework presented here can be readily applied to past studies as well, facilitating a more robust evaluation of the factors contributing to metacommunity structure.

Description of a new species of Namalycastis (Annelida: Nereididae: Namanereidinae) from the Brazilian coast with a phylogeny of the genus.

The subfamily Namanereidinae represents one of the few groups of Polychaeta strongly adapted to low salinity and freshwater. Recently, some new species of the subfamily have been described, but no new phylogenetic analyses for the group have been undertaken since 1999. Here, we describe a new species of Namanereidinae, Namalycastis caetensis sp. nov., and provide a morphology-based phylogenetic analysis of the genus Namalycastis with the aim of assessing the evolutionary relationships for this new species. The designation of this new species is supported by the presence of elongated falcigers (also known as pseudospinigers, an unusual character in the genus), lack of an anterior cleft in the prostomium, slightly indistinct cirrophores, four pairs of tentacular cirri, and subconical acicular ligulae. Our results suggest that Namalycastis caetensis is closely related to N. geayi and N. fauveli. The existence of poorly-characterized species, from a morphological and molecular point of view, still limits our understanding of Namanereidinae relationships.

Morphological distinction between estuarine polychaetes: Laeonereis culveri and L. nota (Phyllodocida: Nereididae) / Distinción morfológica de dos poliquetos neréididos estuarinos: Laeonereis culveri (Webster, 1879) y L. nota (Treadwell, 1941)

AbstractThe family Nereididae includes more than 500 polychaete species described worldwide, and includes species common in many benthic environments, but some other species may tolerate freshwater or can even thrive in humid substrates in tropical forests. In estuarine environments, nereidid polychaetes can be abundant and relevant as a food source for resident or migratory birds. Laeonereis culveri (Webster, 1879) is a common estuarine species found in tropical and subtropical Atlantic American shores and was described from New Jersey; its median and posterior parapodia have upper notopodial ligules usually longer than the lower ones, and the latter are parallel to the notaciculae throughout the body. L. culveri distribution is from Connecticut to central Argentina; however, this wide distribution might be due to the inclusion of several other species as junior synonyms, despite that some morphological differences were found between them. One of such species is L. nota (Treadwell, 1941), that was described from Texas; its parapodia have notopodial ligules of about the same size, and the lower ones are oblique to the notaciculae. In order to clarify the differences between these two species, and to define which inhabits the Northwestern Caribbean region, topotype materials from these two species and specimens from Chetumal Bay were collected, and their morphological features were compared. Our results indicated that L. culveri and L. nota are different species and that the latter is found in Chetumal Bay. On the basis of mature specimens, L. culveri is hereby restricted to the Northern Gulf of Mexico and Northwestern Atlantic Ocean, and L. nota is reinstated and its distribution extends from Texas, in the Gulf of Mexico to Chetumal Bay, in the Northwestern Caribbean Sea. A key to identify all species in Laeonereis Hartman (1945) is also included.

ResumenLa familia Nereididae incluye especies comunes y frecuentes en muchos ambientes bénticos y cuenta con más de 500 especies en todo el mundo, y algunas pueden tolerar ambientes dulceacuícolas e incluso viven en sustratos húmedos en bosques tropicales. Como ocurre en otras especies estuarinas, los poliquetos neréididos pueden ser abundantes y relevantes como fuente de alimento para aves residentes o migratorias. Laeonereis culveri (Webster, 1879) es una especie común en estuarios, fue descrita de Nueva Jersey, E.U.A.; sus parápodos medianos y posteriores tienen lígulas notopodiales superiores generalmente más largas que las inferiores, y estas últimas son paralelas a las notacículas a lo largo del cuerpo. La distribución de L. culveri comprende desde Connecticut, E.U.A. hasta el litoral central de Argentina; esta amplia distribución podría deberse a la inclusión de otras especies como sinónimos menores, a pesar de las diferencias morfológicas entre ellas. Una de dichas especies, L. nota (Treadwell, 1941) fue descrita de Texas; sus parápodos medios y posteriores tienen lígulas notopodiales superiores de longitud similar a las inferiores, y estas últimas son oblicuas a las notacículas. Para clarificar las diferencias entre estas dos especies y determinar cuál de ellas se encuentra en el Caribe noroccidental, se estudiaron topotipos de ambas especies y se recolectaron ejemplares de la Bahía de Chetumal para comparar sus atributos morfológicos. Nuestros resultados indican que L. culveri y L. nota son especies diferentes y que la última se presenta en la Bahía de Chetumal. Con base en ejemplares maduros, L. culveri se restringe al norte del Golfo de México y Atlántico noroccidental y L. nota se reestablece con una distribución que se extiende desde Texas, en el Golfo de México a la Bahía de Chetumal, en el Caribe noroccidental. También se incluye una clave para la identificación de todas las especies de Laeonereis Hartman, 1945.

Morphological distinction between estuarine polychaetes: Laeonereis culveri and L. nota (Phyllodocida: Nereididae).

The family Nereididae includes more than 500 polychaete species described worldwide, and includes species common in many benthic environments, but some other species may tolerate freshwater or can even thrive in humid substrates in tropical forests. In estuarine environments, nereidid polychaetes can be abundant and relevant as a food source for resident or migratory birds. Laeonereis culveri (Webster, 1879) is a common estuarine species found in tropical and subtropical Atlantic American shores and was described from New Jersey; its median and posterior parapodia have upper notopodial ligules usually longer than the lower ones, and the latter are parallel to the notaciculae throughout the body. L. culveri distribution is from Connecticut to central Argentina; however, this wide distribution might be due to the inclusion of several other species as junior synonyms, despite that some morphological differences were found between them. One of such species is L. nota (Treadwell, 1941), that was described from Texas; its parapodia have notopodial ligules of about the same size, and the lower ones are oblique to the notaciculae. In order to clarify the differences between these two species, and to define which inhabits the Northwestern Caribbean region, topotype materials from these two species and specimens from Chetumal Bay were collected, and their morphological features were compared. Our results indicated that L. culveri and L. nota are different species and that the latter is found in Chetumal Bay. On the basis of mature specimens, L. culveri is hereby restricted to the Northern Gulf of Mexico and Northwestern Atlantic Ocean, and L. nota are reinstated and its distribution extends from Texas, in the Gulf of Mexico to Chetumal Bay, in the Northwestern Caribbean Sea. A key to identify all species in Laeonereis Hartman (1945) is also included.

Trace metals partitioning among different sedimentary mineral phases and the deposit-feeding polychaete Armandia brevis.

Trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) were determined in two operationally defined fractions (HCl and pyrite) in sediments from Ensenada and El Sauzal harbors (Mexico). The HCl fraction had significantly higher metal concentrations relative to the pyrite fraction in both harbors, underlining the weak tendency of most trace metals to associate with pyrite. Exceptionally, Cu was highly pyritized, with degrees of trace metal pyritization (DTMP) >80% in both harbors. Dissolved Fe flux measurements combined with solid phase Fe sulfide data indicated that 98 mt of Fe are precipitated as iron sulfides every year in Ensenada Harbor. These Fe sulfides (and associated trace metals) will remain preserved in the sediments, unless they are perturbed by dredging or sediment resuspension. Calculations indicate that dredging activities could export to the open ocean 0.20±0.13 to (0.30±0.56)×10(3) mt of Cd and Cu, respectively, creating a potential threat to marine benthic organisms. Degrees of pyritization (DOP) values in Ensenada and El Sauzal harbors were relatively low (<25%) while degrees of sulfidization (DOS) were high (~50%) because of the contribution of acid volatile sulfide. DOP values correlated with DTMP values (p≤0.001), indicating that metals are gradually incorporated into pyrite as this mineral is formed. Significant correlations were also found between DTMP values and -log(Ksp(MeS)/Ksp(pyr)) for both harbors, indicating that incorporation of trace metals into the pyrite phase is a function of the solubility product of the corresponding metal sulfide. The order in which elements were pyritized in both harbors was Zn≈Mn

The genus Loimia Malmgren, 1866 (Annelida: Terebellidae) off the Brazilian coast, with description of three new species and notes on some morphological characters of the genus.

Three new species of Loimia were collected along the Brazilian coast, during some independent projects, from shallow to deep waters off the continental slope. These species are L. megaoculata sp. nov., L. armata sp. nov., and L. brasiliensis sp. nov., all herein described and compared with the morphologically most similar congeners. Loimia megaoculata sp. nov., is characterized by having large, dark eyespots, progressively smaller from dorso-laterally towards lateral basal part of prostomium; lobes of segment 1 are distally rounded, roughly circular, barely reaching mid-length of upper lip; uncini have up to 6-7 teeth, including basal-most tooth. Loimia armata sp. nov., lacks eyespots; stout lobes of segment 1 nearly reach level of upper lip; uncini have up to 7-8 teeth, including basal-most tooth. Loimia brasiliensis sp. nov., has two narrow rows of eyespots; lobes of segment 1 are thin, reaching mid-length of upper lip; uncini have 5-6 teeth, including basal-most tooth. We provide a brief discussion on the main morphological characters useful for the taxonomy of this genus, such as presence of eyespots, and morphology of lobes of segments 1 and 3, of mid-ventral pads and neurochaetae. Up to now only two species had been recorded from Brazil, namely L. grubei and L. medusa, both doubtful records, as discussed along this paper.

A new case of poecilogony from South America and the implications of nurse eggs, capsule structure, and maternal brooding behavior on the development of different larval types.

Poecilogony is the production of different larval types within the same species. Although rare, poecilogonous species are ideal systems for testing the evolutionary and ecological implication of different developmental modes in marine invertebrates. Here, we described a new case of poecilogony, the Southern Hemisphere spionid Boccardia wellingtonensis. We used a combination of common-garden experiments, video recordings, and in vitro manipulations of individuals from three sites to (1) document the type of poecilogony, the brooding behavior of the mother, and the hatching process; (2) experimentally measure the effect of nurse eggs on the growth and type of larvae produced; and (3) document variation in the length of the brooding period, number of capsules, larvae, and nurse eggs of mothers from three sites to explore the potential for plasticity in reproductive traits. These results were compared to the previously reported poecilogonous species B. proboscidea, which resembles B. wellingtonensis in size, morphology, ecology, and reproductive strategy but differs in capsule structure. We found that in contrast to B. proboscidea, B. wellingtonensis produced larvae that, in isolation and in the presence of nurse eggs, developed into a wide range of offspring sizes. Mothers brood and hatch the larvae with frequent partial hatching of the brood during the brooding period. Although larvae could not liberate themselves, larvae crossed to other capsules as interconnections between capsules broke during the developmental period, potentially affecting food availability, sibling competition for nurse eggs, and cannibalism. Variation in brooding time and number of capsules deposited among sites suggest local adaptations.

The multitentaculate Cirratulidae of the genera Cirriformia and Timarete (Annelida: Polychaeta) from shallow waters of Brazil.

A large number multitentaculate cirratulids have been described worldwide but most are only known through the original descriptions. Type material, voucher and recently collected specimens from Brazil were revisited in order to reveal their true identity and confirm the records of widely distributed species in this region. Six species are described, three of which are new, Cirriformia capixabensis sp. nov., Cirriformia chicoi sp. nov. and Timarete ceciliae sp. nov. COI and 16S sequences were obtained and used for inter-specific comparisons. Timarete caribous is reported from several localities along the Brazilian coast and a new synonym, Cirratulus melanacanthus, is proposed. The species Timarete oculata, originally described from Brazil and lumped into the Timarete filigera species complex, is herein revalidated and redescribed. The occurrence of the species Timarete filigera and Cirriformia tentaculata is not confirmed from the Brazilian coast. Descriptions, illustrations and a key to genera and species are provided.

Metazoan symbionts of the yellow clam, Mesodesma donacium (Bivalvia), in southern Chile: geographical variations.

Mesodesma donacium is a dominant species on sandy beaches along the Chilean coast. However, the only previous parasite records for this species were obtained for the northern Chilean coast (20° S-33° S), which dealt with cestodes, polychaetes, and copepods. In this study, the symbiotic fauna of M. donacium in its southern distributional range is reported, and the geographical variations in the occurrence of this fauna are evaluated. A total of 565 individuals of M. donacium were captured by local fishermen from 5 localities: Mehuín (MEH) (39° 26' S), Carelmapu (CAR) (41° 44' S), Ancud (ANC) (41° 53' S), Cucao (CUC) (42° 35' S), and Quellón (QUE) (43° 24' S), covering a total distance of 450 km. To collect metazoan symbionts, the valves, mantle, gills, gonad, and digestive gland of each specimen of yellow clam were examined, and symbiont identifications were made via morphological and genetic analyses. The prevalence and mean intensity of infestation were calculated for each symbiotic species. Univariate and multivariate analyses were performed to evaluate the differences in symbiotic load between localities. Seven metazoan symbiotic species were recorded. The most abundant species were Paranthessius mesodesmatis, Monorchiidae gen. sp., and Paravortex sp. The copepod P. mesodesmatis and metacercaria Monorchiidae gen. sp. showed a high prevalence in all localities, but their intensity of infection varied among localities. The turbellarian Paravortex sp. was most frequently associated with ANC and CUC. The digenean Sanguinicolidae gen. sp. was recorded only at CAR, and the polychaete Spionidae gen. sp. was recorded only at MEH. In its southern distributional range, M. donacium was characterized by an absence of cestodes. This absence can be explained by the absence of the definitive host. The local environmental conditions in the southern range of the host could explain the differences in symbiotic composition among localities.

Using stable isotope compositions of animal tissues to infer trophic interactions in Gulf of Mexico lower slope seep communities.

We analyzed the tissue carbon, nitrogen, and sulfur stable isotope contents of macrofaunal communities associated with vestimentiferan tubeworms and bathymodiolin mussels from the Gulf of Mexico lower continental slope (970-2800 m). Shrimp in the genus Alvinocaris associated with vestimentiferans from shallow (530 m) and deep (1400-2800 m) sites were used to test the hypothesis that seep animals derive a greater proportion of their nutrition from seeps (i.e. a lower proportion from the surface) at greater depths. To account for spatial variability in the inorganic source pool, we used the differences between the mean tissue δ(13)C and δ(15)N of the shrimp in each collection and the mean δ (13)C and δ(15)N values of the vestimentiferans from the same collection, since vestimentiferans are functionally autotrophic and serve as a baseline for environmental isotopic variation. There was a significant negative relationship between this difference and depth for both δ(13)C and δ(15)N (p=0.02 and 0.007, respectively), which supports the hypothesis of higher dependence on seep nutrition with depth. The small polychaete worm Protomystides sp. was hypothesized to be a blood parasite of the vestimentiferan Escarpialaminata. There was a highly significant linear relationship between the δ(13)C values of Protomystides sp. and the E. laminata individuals to which they were attached across all collections (p < 0.001) and within a single collection (p = 0.01), although this relationship was not significant for δ(15)N and δ(34)S. We made several other qualitative inferences with respect to the feeding biology of the taxa occurring in these lower slope seeps, some of which have not been described prior to this study.

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.

Four new species of Polycirrus Grube, 1850 (Polychaeta: Terebellidae) from Campos Basin, southeastern Brazil.

Four new species of Polycirrus were collected at the Campos Basin, state of Rio de Janeiro, during a survey coordinated by CENPES/PETROBRAS under the scope of the project, "Environmental Heterogeneity in the Campos Basin". These species are P. nonatoi sp. nov., P. papillosus sp. nov., P. breviuncinatus sp. nov., and P. habitats sp. nov. All these species are herein described and compared with the morphologically most similar congeners. In addition, a key is provided for the identification of the species of Polycirrus which have been originally described for the Brazilian coast.

The role of the invasive polychaete Ficopomatus enigmaticus (Fauvel, 1923) (Serpulidae) as facilitator of parasite transmission in Mar Chiquita coastal lagoon (Buenos Aires, Argentina).

In Mar Chiquita coastal lagoon (Argentina), the reefs of the invasive polychaete Ficopomatus enigmaticus (Serpulidae) serve as concentration areas for invertebrates and vertebrates and as potential foci of parasite transmission (mainly digeneans). To analyse the role of F. enigmaticus as facilitator of parasite transmission, and to evaluate the influence of the habitats selected by 2 species of cochliopid snails (Heleobia conexa and Heleobia australis), on the richness and on the prevalence of the digenean assemblages that parasitize them, 1945 snails were collected from 2 sampling sites. The comparisons between larval digenean communities parasitizing both snail hosts revealed significant differences related to the overall prevalence and the prevalence contributed by birds in the snails collected from reefs. These results support the idea that the reefs may increase the number of links between intermediate and definitive hosts of digeneans, facilitating parasite transmission only when the aggregates of F. enigmaticus become the unique habitat of the snail host. This first report of an exotic species acting as facilitator of parasite transmission in an estuarine area highlights the importance of analysing the effects of the assimilation process of exotic species by recently colonized environments (including the possible effects on parasite transmission).

Community biomass and bottom up multivariate nutrient complementarity mediate the effects of bioturbator diversity on pelagic production.

Tests of the biodiversity and ecosystem functioning (BEF) relationship have focused little attention on the importance of interactions between species diversity and other attributes of ecological communities such as community biomass. Moreover, BEF research has been mainly derived from studies measuring a single ecosystem process that often represents resource consumption within a given habitat. Focus on single processes has prevented us from exploring the characteristics of ecosystem processes that can be critical in helping us to identify how novel pathways throughout BEF mechanisms may operate. Here, we investigated whether and how the effects of biodiversity mediated by non-trophic interactions among benthic bioturbator species vary according to community biomass and ecosystem processes. We hypothesized that (1) bioturbator biomass and species richness interact to affect the rates of benthic nutrient regeneration [dissolved inorganic nitrogen (DIN) and total dissolved phosphorus (TDP)] and consequently bacterioplankton production (BP) and that (2) the complementarity effects of diversity will be stronger on BP than on nutrient regeneration because the former represents a more integrative process that can be mediated by multivariate nutrient complementarity. We show that the effects of bioturbator diversity on nutrient regeneration increased BP via multivariate nutrient complementarity. Consistent with our prediction, the complementarity effects were significantly stronger on BP than on DIN and TDP. The effects of the biomass-species richness interaction on complementarity varied among the individual processes, but the aggregated measures of complementarity over all ecosystem processes were significantly higher at the highest community biomass level. Our results suggest that the complementarity effects of biodiversity can be stronger on more integrative ecosystem processes, which integrate subsidiary "simpler" processes, via multivariate complementarity. In addition, reductions in community biomass may decrease the strength of interspecific interactions so that the enhanced effects of biodiversity on ecosystem processes can disappear well before species become extinct.