Pomatoschistus Microps Research Articles

Health status of Pomatoschistus microps populations in relation to pollution and natural stressors: implications for ecological risk assessment

Effects induced on wild populations by recurrent environmental contamination may difficult the ecological risk assessment of punctual pollution events such as oil spills. Here, the issue was addressed by comparing the health status of Pomatoschistus microps populations from four NW Iberian estuaries, using an integrated chemical–biological monitoring. Despite high seasonal variability, the parameters measured discriminated estuaries with different contamination levels and associated biological effects with chemical and abiotic stress. The decreased health status of fish from polluted sites strengthens the need of considering pollution-induced background effects and seasonal variability when assessing impacts and risks of oil and other chemical spills.

Macroinvertebrates and fishes as biomonitors of heavy metal concentration in the Seixal Bay (Tagus estuary): Which species perform better?

The present study aims to evaluate the utilization of several benthic macroinvertebrate and fish species as bioindicators of heavy metal contamination in a relatively enclosed estuarine area, the Seixal Bay (Tagus estuary, Portugal). 266 specimens of 16 taxa were captured during four sampling campaigns and the concentration of lead, chromium, nickel, copper, zinc, cobalt and cadmium were quantified in fish muscle and whole soft body of the invertebrates, as well as in suspended particulate matter in the water column and sediments. Larger predator fishes with higher mobility presented low levels of contamination, probably due to their feedings sites being located outside the bay in less contaminated areas. The species of the Gobiidae family, Pomatoschistus microps, Pomatoschistus minutus and Gobius niger presented higher values of non-metabolic elements (Pb, Ni and Cd) while Scrobicularia plana, Nereis diversicolor, Carcinus maenas and Palaemon serratus were more associated to the accumulation of Cu, Cr and Zn. Nephtys hombergii and Crangon crangon, showed intermediate concentrations of all metals. These results points out to a future possible utilization of S. plana, N. diversicolor, P. serratus and C. maenas and of Pomatoschistus species as bioindicators of heavy metal contamination in ecological quality monitoring programs.

Is parasitism in fish a good metric to assess ecological water quality in transitional waters? What can be learned from two estuarine resident species?

Fish-based indices are becoming important bioassessment tools for estuaries since the European Water Framework Directive included fish as a biological quality element to be monitored for the assessment of ecological status of those systems. In particular, data on species composition and abundance of the ichthyofauna must be used to evaluate the ecological status of European estuaries, but other factors like measures of fish health are also considered important metrics. These indicators of fish health include infections by parasites. The common goby, Pomastoschistus microps, and the Lusitanian toadfish, Halobatrachus didactylus, are fairly sedentary fish, very abundant in Portuguese estuaries, and were used to investigate if parasitism in fishes in transitional waters is a good metric to reflect anthropogenic impacts in the environment. No significant relationships were observed between the parasite levels in these two species and the intensity of human pressures, either at a large or small spatial scale. Results obtained also are contrary to the generalized idea that a higher proportion of parasitized fish necessarily reflects a decrease in their condition as a result of habitat degradation. A high degree of temporal and ontogenetic variability in the parasite levels of both P. microps and H. didactylus was detected, which make it difficult to establish the scores for this hypothetical metric even if significant relationships between parasite levels and human pressures are identified in the future. Therefore, the present work does not uphold the hypothesis that parasitism in fish is a good metric to assess ecological water quality in transitional waters.

Tributyltin in blood of marine fish collected from a coastal area of northern Kyushu, Japan

We investigated levels of the pollutant tributyltin (TBT) in blood of pufferfishes (six species), Japanese sea perch, red sea bream, Japanese common goby, Japanese flounder, rockfish, conger eel, and sea mullet collected off the coast of northern Kyushu, Japan. We found considerable levels of TBT (1.4–190ng/mL) accumulated in the blood of these fish. Blood TBT concentrations were 1.3–22.5times liver concentrations and 4.9–78times muscle concentrations, except in conger eel and mullet. We detected TBT (16–111ng/mL-blood) in the plasma of the fine-patterned puffer (Takifugupoecilonotus) year-round, without any apparent seasonal trend. These results suggest that fish inhabiting coastal areas of Kyushu, Japan, continue to be contaminated with TBT.

Acute toxic effects of pyrene on Pomatoschistus microps (Teleostei, Gobiidae): Mortality, biomarkers and swimming performance

Pyrene has been reported as one of the most important polycyclic aromatic hydrocarbons (PAHs) found as environmental contaminant in estuaries and coastal areas. Therefore, in the present study, the acute effects (96h) of pyrene on the common goby Pomatoschistus microps, a key species in several European estuaries and lagoons, were assessed through individual exposure of juveniles to 0.125, 0.25, 0.5 or 1mgL−1 of pyrene. Mortality, swimming performance and several biomarkers were used as effect criteria. The 96h median lethal concentration (LC50) was 0.871mgL−1 and the swimming performance of fish was significantly decreased at all the pyrene concentrations tested. A significant increase of bile metabolites was found at increasing concentrations of pyrene (LOEC=0.125mgL−1) indicating the production of metabolites during the biotransformation of the toxicant. Pyrene significantly inhibited the activity of head acetylcholinesterase at 0.5mgL−1 and muscle cholinesterases at 1mgL−1. A bell-shape pattern response in the activity of muscle lactate dehydrogenase and isocitrate dehydrogenase (IDH) was found, with a significant increase of IDH at 0.25mgL−1, suggesting changes in the pathways of energy production. A bell-shape response for the antioxidant enzyme glutathione peroxidase and a less evident bell-shape response of glutathione S-transferase and glutathione reductase were also found. Lipid peroxidative damage was found in liver (0.25mgL−1) and gills (0.50mgL−1). It should be noted that although the concentrations of pyrene tested in the present study are higher than those that have been found in estuarine water and sediments, the occurrence of pyrene as single environmental contaminant is rare; in fact, the most common situation is the contamination by several PAHs, a considerable part of them sharing toxicological properties with pyrene and thus with a high probability of inducing additive or synergistic effects in simultaneous exposures. The findings of the present study are ecologically relevant and should be taken into consideration in the management of estuaries contaminated by petrochemical products. Moreover, effects of pyrene in this species should be further investigated.

Application of an integrated biomarker response index (IBR) to assess temporal variation of environmental quality in two Portuguese aquatic systems

Estuaries are extremely productive systems faced with great anthropogenic pressure, namely from contaminants of both metallic and organic nature which may affect the ecological quality of these systems. Moreover, it is known that contaminants fluctuate seasonally and this could influence the health status of organisms. In order to identify the most affected seasons and areas in two Portuguese aquatic systems with strong anthropogenic influences, a method that combines several biomarker responses into a general “stress index” denominated “integrated biomarker response” (IBR) was applied using the stress responses in the liver of common goby Pomatoschistus microps collected from two sites within both estuaries (Ria de Aveiro and Tagus). Parameters included in the IBR were the biomarkers superoxide dismutase (SOD), catalase (CAT), ethoxyresorufin-O-deethylation (EROD), glutathione s-transferase (GST), metallothioneins (MT), lipid peroxidation (LPO) and condition indices (RNA:DNA ratio and Fulton's condition factor K. Pollutant concentrations in the sediment (metals and PAHs) were also analyzed. Biomarkers in P. microps in Ria de Aveiro lagoon (sites A and B) showed distinct seasonal variation. In site A, IBR highlighted the spring as the season with highest biomarker responses, and RNA:DNA as the most contributing biomarker, while in site B the most impacted season was the summer, associated to the responses of MT and antioxidant enzymes (CAT and SOD), probably as a result of levels of Hg in the sediments. In both sites within the Tagus estuary (C and D) the IBR showed that biomarker responses were higher in autumn, with CAT, EROD, GST and LPO as the most altered biomarkers. In this season the levels of PAHs, Pb and Cr were the highest. Overall, the IBR index provides an integrated approach for assessing the health status of organisms and to identify temporal patterns of contamination.

Assessing food web dynamics and relative importance of organic matter sources for fish species in two Portuguese estuaries: A stable isotope approach

Stable carbon and nitrogen isotopes (δ 13C, δ 15N) were used to analyse food web dynamics of two of the main estuaries of the Portuguese coast: Tejo and Mira. The ultimate sources of organic matter supporting production of some of the most abundant and commercially important fish species were determined; and seasonal, inter- and intra- estuarine differences in the trophic relations among producers and consumers were identified. Stable isotope analysis was performed in different producers, primary consumers (main prey items for fish) and fish species ( Solea solea, Solea senegalensis, Pomatoschistus microps, Dicentrarchus labrax, Liza ramada, Diplodus vulgaris and Atherina presbyter) of two areas in each estuary, in July and October 2009. Model calculations showed that the main prey for the fish species in the Tejo estuary used mostly salt marsh-derived organic matter as nutritional sources, with no marked differences between the sampled months. Trophic levels of fish species from the same estuary differed at multiple scales: inter-species, seasonally and spatially (both between and within estuaries). Significant differences in isotopic composition of fish species were more pronounced spatially (between the two sampled areas in the estuary) than seasonally (between sampled months). Trophic relationships in both estuaries demonstrated that organic matter is transferred to higher trophic positions mainly through benthic pathways. This shows the flexibility of these species to share resources and to exploit temporary peaks in prey populations. The present results showed that extensive disturbance in intertidal habitats from both estuaries may potentially change the balance of organic matter in the base of these complex food webs.

Short-term variability of multiple biomarker response in fish from estuaries: Influence of environmental dynamics

Short-term variability in biomarker responses and the effects of temperature and salinity variation were explored in three fish species ( Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps) occurring in the Tejo estuary. Short-term variability in biomarkers was observed in all species although no pattern was discerned over time (days to weeks). Antioxidant enzymes activity (superoxide dismutase (SOD) and catalase (CAT)) showed low temporal variability, indicating some constancy or baseline level in antioxidant responses. Only CAT activity in S. senegalensis was correlated with temperature, suggesting that exposure to contaminants triggered antioxidant acclimation. Higher short-term variability was observed in xenobiotic biotransformation enzymes activity (phase I ethoxyresorufin O-deethylase (EROD) and phase II glutathione S-transferase (GST)). Yet a significant correlation between EROD and GST in D. labrax and S. senegalensis suggests a concomitant response to contaminants. Moreover the lack of correlation between xenobiotic biotransformation enzymes and abiotic variables on concordant time scales, suggest a high specificity of these biomarkers to chemical exposure, rather than high variability due to environmental dynamics.

High site fidelity and low site connectivity in temperate salt marsh fish populations: a stable isotope approach

Adult and juvenile fish utilise salt marshes for food and shelter at high tide, moving into adjacent sublittoral regions during low tide. Understanding whether there are high levels of site fidelity for different species of coastal fish has important implications for habitat conservation and the design of marine protected areas. We hypothesised that common salt marsh fish species would demonstrate a high site fidelity, resulting in minimal inter-marsh connectivity. Carbon ((13)C) and nitrogen ((15)N) stable isotope ratios of larvae and juveniles of five common salt marsh fish (Atherina presbyter, Chelon labrosus, Clupea harengus, Dicentrarchus labrax, Pomatoschistus microps), seven types of primary producer and seven secondary consumer food sources were sampled in five salt marshes within two estuary complexes along the coast of south-east England. Significant differences in (13)C and (15)N signatures between salt marshes indicated distinct sub-populations utilising the area of estuary around each salt marsh, and limited connectivity, even within the same estuary complex. (15)N ratios were responsible for the majority of inter-marsh differences for each species and showed similar site-specific patterns in ratios in primary producers, secondary consumers and fish. Fish diets (derived from isotope mixing models) varied between species but were mostly consistent between marsh sites, indicating that dietary shifts were not the source of variability of the inter-marsh isotopic signatures within species. These results demonstrate that for some common coastal fish species, high levels of site fidelity result in individual salt marshes operating as discrete habitats for fish assemblages.

Seasonal variation of assemblage and feeding guild structure of fish species in a boreal tidal basin

Species composition, abundance, feeding relationships and guild structure of the fish assemblage in the Sylt-Rømø bight, a tidal basin in the northern Wadden Sea, were investigated to show seasonal differences and the importance of functional groups in this area. The tidal flats and in shallow subtidal areas were sampled using a beach seine and a bottom trawl net was used for deeper subtidal areas and tidal gullies. Species richness of fish was highest in summer where 26 species were caught, while the lowest richness was recorded in winter (17 species). Clear differences in species richness and abundance were found between shallow areas and deeper parts of the bight. Clupea harengus and Ammodytes tobianus were the most abundant species in deeper areas, while Pomatoschistus microps and Pomatoschistus minutus dominated shallower waters. Gut contents of 27 fish species were identified and the guild structure analyzed by UPGMA clustering of niche overlaps. Calanoid copepods (19.9%), Crangon crangon (18.2%) and mysid shrimps (8.4%) were the most abundant prey items of all fish species combined. Seven feeding guilds were present in the fall and winter, and eight and six in spring and summer, respectively. Fish feeding on calanoid copepods and C. crangon were present year round, whereas the occurrence of other guilds varied between seasons. Species composition of prey changed through seasons and, for some fish species, even the feeding mode itself varied with season. Most noticeable, 11 fish species changed guilds between seasons. We found a convergence in summer towards abundant prey items, whereas in winter diet overlap was lower. This is the first investigation of guild structure of almost all fish species present in a Wadden Sea area, and shows that consideration of seasonal differences is essential when determining feeding relationships of fish in temperate areas.

Multi-biomarker responses to estuarine habitat contamination in three fish species: Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps

Several biomarker responses were determined in three fish species, Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps, from two estuaries of the Portuguese coast, Ria de Aveiro and Tejo. Both estuaries have significant anthropogenic influences from multiple sources (industrial, agricultural and shipping activities), which was evident from sediment chemical characterization concerning metal (copper, zinc, nickel, lead and chromium) and polycyclic aromatic hydrocarbon (PAH) concentrations. Spatial variability in fish responses was observed across species for most biomarkers of exposure [the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST), and metallothionein concentrations (MT)] and effect biomarkers [lipid peroxidation (LPO), RNA to DNA ratio (R:D), protein and lipid content]. In general, the interspecific differences in biomarker responses were greater than the spatial differences, due to differences in the behavior and habitat use of the species. Nevertheless, similarities were also observed considering both chemical load and biomarker responses. In highly polluted sites fish showed in general a significant antioxidant enzyme induction, associated with decreased R:D values, while fish from the least impacted site had little enzyme induction and better condition indices (high R:D and low LPO values). EROD activity was also higher for all species in the Tejo than Ria de Aveiro estuary, despite the generally higher total PAH measured in Ria de Aveiro, most likely due to a higher proportion of 4 and 6-ring PAHs, considered more toxic than low molecular weight PAHs, in the Tejo. In conclusion, this multi-biomarker approach considering multiple species provided improved understanding of the diverse responses and effects of exposure to contaminants and the effective risk it poses for different fish species.

A neighbour is a neighbour? Consumer diversity, trophic function, and spatial variability in benthic food webs

The short ecological history and the environmental conditions characterising the Baltic Sea make it inhabitable for only few species, resulting in a functional poverty of the system (number of functional groups and number of species within each group). Thus, it is a well-suited system for studies on biodiversity and ecosystem functions, particularly when moving from observation of patterns to determination of mechanisms behind observed relationships, such as the importance of species richness for trophic functioning. Predators in the benthic community are predominately generalists, with a potential for overlap in trophic function. Through analysis of stable isotope ratios ( 13C: 12C and 15N: 14N), we determined the trophic position of epibenthic consumers and estimated spatial variability in isotope ratios of food web components at nine shallow sandy sites. There were significant differences in isotope ratios both within species and for species assemblages between bays. The secondary consumer signatures in bivariate δ-space showed a partly overlapping transition from benthivores ( Crangon crangon, Pomatoschistus microps) to more pelagically feeding predators ( Gasterosteus aculeatus). At two sites (one sheltered, one moderately exposed), the gut contents of generalist predators revealed feeding on abundant prey and confirmed the potential for overlap in diets. Focusing on members of the benthic trophic pathway, we assessed the influence of secondary consumer diversity on trophic transfer, with temporal separation of resource use as a mediator of biodiversity effects. In a laboratory experiment, we were able to show temporally separated foraging for two epibenthic carnivores and that mechanisms behind the biodiversity effect differed in time. Many food web properties, such as function, resilience and resistance are linked to the diversity and characteristics of nodes and links in the food web ( e.g. degree of redundancy, connectedness and trophic level) and our study provides information on some dimensions of the trophic niches of abundant species in shallow soft-bottom food webs.

Studies on the abnormalities of scales in the tumour appeared on the skin of Japanese common goby

Studies on the abnormalities of scales in the tumour appeared on the skin of Japanese common goby

Trophic interactions between preadult and adult Pomatoschistus minutus and Pomatoschistus microps and young Platichthys flesus occurring in inshore waters of the Gulf of Gdańsk (Southern Baltic)

Trophic interactions between preadult and adult Pomatoschistus minutus and Pomatoschistus microps and young Platichthys flesus occurring in inshore waters of the Gulf of Gdańsk (Southern Baltic) We intended to estimate if shallow inshore waters of the Gulf of Gdańsk can be considered important feeding grounds for the fishes under investigation. We also examined whether competition for food exists between the investigated fishes which co-exist. The study was carried out at Sopot and Chałupy stations from summer 2001 to autumn 2003. The results showed the high importance of Neomysis integer, which exclusively lives in coastal waters, in the diet of all three investigated fish species. It indicates that they utilize this zone as a feeding ground. The obtained dataset also led to the conclusion that fish trophic niches overlap by about 40%.

Factors influencing epibenthic assemblages in the Minho Estuary (NW Iberian Peninsula)

The epibenthic community of the Minho Estuary was studied during the summer of 2006. Diversity was generally low and a total of 14 fish and five crustacean taxa were identified. Multivariate analysis revealed two site clusters (A and B). Water conductivity and percentage of fine sand were the abiotic variables that most contributed to the spatial distinction between clusters. The species contributing the most to the average similarity within Cluster A were Crangon crangon and Pomatoschistus microps, while in Cluster B was Atyaephyra desmarestii. Possible factors responsible for the low diversity of the epibenthic community in Minho Estuary were the low macrozoobenthic abundance and diversity, and the high abiotic oscillations between tides (mainly salinity) acting on the ecosystem.

Myxobolus albi n. sp. (Myxozoa) from the Gills of the Common Goby Pomatoschistus microps Krøyer (Teleostei: Gobiidae)

A recent investigation into the myxozoan fauna of common gobies, Pomatoschistus microps, from the Forth Estuary in Scotland, revealed numerous myxosporean cysts within the gill cartilage. They were composed of polysporous plasmodia containing myxobolid spores that were morphologically different from the other known species of Myxobolus and from the myxosporeans previously recorded from this host (i.e. the ceratomyxid Ellipsomyxa gobii, infecting the gall bladder, and the kudoid Kudoa camarguensis, infecting the muscle tissues). Spores were ovoid, 9.4 x 9.1 microm with a thickness of 6.6 microm, with two pyriform polar capsules, the polar filaments of which had four to five turns. Molecular analysis of the parasite's small subunit rDNA region, based upon a contiguous sequence of 1,558 base pairs, discriminated it from other myxosporean species that have been characterized so far. A comparison of the spore morphology and the molecular sequences determined for this new isolate with other myxozoans described to date, confirmed its identity as a previously unknown myxobolid supporting the proposal that this isolate be elevated to the species level as a new species within the genus Myxobolus. A phylogenetic analysis places this new myxobolid, Myxobolus albi n. sp., in a basal position of a clade containing the majority of Henneguya spp. sequenced to date and various Myxobolus spp.

Seasonal changes in community composition and trophic structure of fish populations of five salt marshes along the Essex coastline, United Kingdom

European intertidal salt marshes are important nursery sites for juvenile fish and crustaceans. Due to the increasing threat of habitat loss, the seasonal changes of salt marsh fish communities need to be understood in order to appreciate the ecological and economic importance of the saltmarsh habitat. This study was the first in Great Britain to investigate the seasonal changes of salt marsh fish communities and the variation in community structure between closely located marsh habitats. Between February 2007 and March 2008, five marshes on three estuaries of the Essex coastline were sampled using flume nets to block off intertidal creeks at high tide. Fourteen fish species were caught. The community overall was dominated by three species that made up 91.6% of the total catch: the common goby Pomatoschistus microps (46.2% of the total catch), juvenile herring Clupea harengus (24.3%), and juvenile and larval sea bass Dicentrarchus labrax (21.2%). Cluster analysis demonstrated clear seasonal patterns, with some community structures unique to specific marshes or estuaries. The marsh fish community shifts from a highly diverse community during spring, to a community dominated by D. labrax and P. microps in autumn, and low diversity during winter months. Gravimetric stomach content analysis of fish community identified three main trophic guilds; macroinvertivores, planktivores and omnivores. The macroinvertivore feeding guild contained D. labrax and P. microps, the two most frequently occurring species. This investigation demonstrates the importance of British salt marshes as nursery habitats for commercial fish species.

Acute effects of copper and mercury on the estuarine fish Pomatoschistus microps: Linking biomarkers to behaviour

The main objective of the present study was to investigate possible links between biomarkers and swimming performance in the estuarine fish Pomatoschistus microps acutely exposed to metals (copper and mercury). In independent bioassays, P. microps juveniles were individually exposed for 96 h to sub-lethal concentrations of copper or mercury. At the end of the assays, swimming performance of fish was measured using a device specially developed for epibenthic fish (SPEDE). Furthermore, the following biomarkers were measured: lipid peroxidation (LPO) and the activity of the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH), glutathione S-transferases (GST), 7-ethoxyresorufin- O-deethylase (EROD), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GPx). LC 50s of copper and mercury (dissolved throughout metal concentrations) at 96 h were 568 μg L −1 and 62 μg L −1, respectively. Significant and concentration-dependent effects of both metals on swimming resistance and covered distance against water flow were found at concentrations equal or higher than 50 μg L −1 for copper and 3 μg L −1 for mercury (dissolved throughout metal concentrations). These results indicate that SPEDE was efficacious to quantify behavioural alterations in the epibenthic fish P. microps at ecologically relevant concentrations. Significant alterations by both metals on biomarkers were found including: inhibition of AChE and EROD activities, induction of LDH, GST and anti-oxidant enzymes, and increased LPO levels, with LOEC values ranging from 25 to 200 μg L −1 for copper and from 3 to 25 μg L −1 for mercury (dissolved throughout metal concentrations). Furthermore, significant and positive correlations were found between some biomarkers (AChE and EROD) and behavioural parameters, while negative correlations were found for others (LPO, anti-oxidant enzymes and LDH) suggesting that disruption of cholinergic function through AChE inhibition, decreased detoxification capability due to EROD inhibition, additional energetic demands to face chemical stress, and oxidative stress and damage may contribute to decrease the swimming performance of fish. Since a reduced swimming capability of fish may reduce their ability to capture preys, avoid predators, and interfere with social and reproductive behaviour, the exposure of P. microps to copper and/or mercury concentrations similar to those tested here may decrease the fitness of wild populations of this species.

Einnischung von fünf Grundeln (Teleostei, Gobiidae) der Ostsee und ihre Deutung mit Hilfe der Präadaptationstheorie

Niche occupation by 5 goby species (Teleostei, Gobiidae) in the Baltic Sea and its interpretation by means of the theory of pre-adaptation The habitats and prey of five goby species were investigated near the shore of the Lubeck Bight (SW Baltic) during the period 1989–1991. Observations showed that Gobius niger is a macrobenthos feeder, Pomatoschistus microps a meiobenthos feeder; Pomatoschistus pictus prefers meiobenthos as well as plankton while Pomatoschistus minutus feeds on benthos of every size, as well as planktonic cope-pods when offered in surplus; Gobiusculus flavescens is generally a plankton feeder but, when this component is in short supply in the summer, changes to macrobenthos. P. pictus and P. microps existed at different depths; G. flavescens and P. minutus presented countercurrent densities in shallow habitats during the course of a year. This adaptability of behaviour in habitat and prey choice can be explained by the modification ability of pre-adaptional genes in the goby genomes. After having invaded species-poor habitats such as the brackish Baltic Sea, wide niche dimensions are initially occupied. The niche is here considered to be an attribute of the species as well as of the habitat according to GUNTHER (1950). Hence, innidation is defined as a process which implies specialization by loss of most preadaptations and leads to the optimal use of the ecosystem by the species. This process of a single species corresponds to the maturation of successions of whole biocoenoses.

Parasitological diversity of the common goby,Pomatoschistus microps(Krøyer, 1838), in estuarine systems along the Portuguese coast

Summary Parasitological diversity of the common goby Pomatoschistus microps along the Portuguese coast was studied based on samples collected using beam trawls in five coastal estuaries (Ria de Aveiro, Tagus, Sado, Mira and Guadiana estuaries) between May and July 2006. The classes Digenea, Cestoda, Nematoda and phylum Mastigophora were found, with Digenea Cryptocotyle sp. and Lecithochirium musculus being the most abundant taxa. Prevalence and mean abundance of Cryptocotyle sp. were highest in Ria de Aveiro (74%) and Mira estuary (28.05), respectively, whereas L. musculus values of both indices were highest in Sado estuary (prevalence = 64%; mean abundance = 11.77). Values varied along the Portuguese coast; the discriminant analysis based on the number of parasites showed some overlap between estuaries, although successfully separating the Sado and Mira estuaries. Overall, variations in estuaries were explained by different environmental pressures, leading to differences on host abundance and life-history of the parasites. Feeding behaviour and habitat selection therefore play a crucial role in shaping the biology, ecology and parasite assemblages of the common goby along the Portuguese coast.