Benthic nematode and macrofaunal communities are regularly utilized in impact studies. However, very few studies are carried out utilizing both communities. A literature search using the search engine Scopus (www.Scopus.com) covering the last twenty years, using the keywords ‘Macrofauna’ and ‘Disturbance’ then ‘Meiofauna’ and ‘Disturbance’ and finally ‘Macrofauna and Meiofauna’ and ‘Disturbance’, gave 210, 115 and 36 hits respectively. To assess the differential response of meio- and macrofauna to in situ burial a replicated random block designed field experiment was carried out over a 9-month period on an intertidal mud flat. In situ burial was achieved by spreading 4 cm of anoxic mud on top of each treatment plot at two different intensities. Differences in the response of the two faunal communities over time were assessed using both univariate and multivariate techniques. Clear differences in community behaviour over time and in response to the different intensities of disturbance were observed. Overall macrofauna were found to be more sensitive to physical disturbance than meiofaunal nematodes, although, attributes of meiofaunal nematode communities were more sensitive to the initial impacts of disturbance. The observed community-specific responses and sensitivities of meiofauna and macrofauna to the physical disturbance associated with in situ burial highlights the importance of using both faunal types in the assessment of the effects of seabed disturbance in the marine environment.

The assemblage and the temporal changes of benthic macrofauna inhabiting the Phyllochaetopterus socialis (Polychaeta: Chaetopteridae) aggregates were analysed during 2004 and May 2005 in the Mar del Plata harbour, Buenos Aires (Argentina). Species composition, abundance, richness and diversity were estimated from monthly or bimonthly samples obtained by SCUBA diving. Multivariate (MDS) and SIMPER analyses were applied to analyse the structure of benthic communities. In the mats, a total of 57 species (invertebrates and chordates) belonging to 11 phyla were associated to P. socialis: crustaceans and molluscs were the most abundant species and crustaceans and polychaetes were the most diverse groups (14 and 11 species richness, respectively). The mean abundance ranged from 79.67±57.47 ind/250 ml to 718.75 ind/250 ml (mean±SD). The amphipod Monocorophium insidiosum, the gastropod Anachis isabellei and the tanaidacean Leptognathia sp. were the most representative species in the mats. Richness and diversity in P. socialis aggregates were higher than in surrounding sediments. Results show significant differences among months in composition, abundance and feeding guilds of the macrofauna associated with the mats. The assemblage of benthic macrofauna with permanent and temporary organisms in P. socialis aggregates suggests the existence of microhabitats in the mats that provide substrate, refuges for predation and availability of food increasing richness and diversity. These results allow considering P. socialis as an autogenic ecosystem engineer in the Mar del Plata harbour.

In order to provide a better characterization and understanding of the brine shrimp Artemia salina life-cycle, different ecological and biological parameters were taken out monthly during two periods from November 2005 to April 2006 and from November 2006 to April 2007 in Sabkhet El Adhibet (south-east Tunisia). Variation of water temperature, salinity, pH, dissolved oxygen, nutrients (orthophosphate, nitrites, nitrates and ammonium) and phytoplankton density were monitored. The Artemia population was also surveyed. Artemia were present in the site with salinity between 32.2 and 281.7 g l−1 and water temperature between 12.1 and 25.4°C. The pH ranged from 7.6 to 9 and dissolved oxygen concentration from 3.4 to 17.5 mg l−1. Minimum and maximum values of phytoplankton density were 0.19 and 14.59 106 cell l−1. In addition, the nutrient analysis registered showed that nitrate and ammonium represent the major nutrient. The Artemia population density fluctuated between 0.22 and 38.57 individuals per litre. The male:female ratio was dominated by the males. Artemia from Sabkhet El Adhibet showed variability in fecundity (total offspring and brood size) as well as in the ratio encystment/oviviparity. The individual fecundity fluctuates between 29.4 and 70.2 cysts and 17.8 and 69.8 nauplii. Finally, the influence of physical and chemical parameters as well as phytoplankton density over the Artemia population was noticed.

The aim of the present study was to characterize the external morphology and the orientation of burrows constructed by the mangrove crab Ucides cordatus. Data were obtained from two mangrove forests of similar vegetation dominance (Laguncularia racemosa) but differing in flooding heights. These mangroves were located near Barra de Icapara, Iguape City (SP), Brazil, (24°50′36″S–47°59′53′W). A total of 221 burrows were examined (120 on the high mangrove and 101 on the low mangrove). External morphology of the burrows was recorded by photographs for categorization and description. The directions of the burrow openings were recorded using a geological compass and the declivities of the ducts were measured with a clinometer. Females constructed 70.8% at Site A and 69.4% at Site B of the occupied burrows with the opening facing the margin of the river (P < 0.001), whilst males showed no significant difference in the burrow orientation (P > 0.05) at either site. In females, the tendency for burrow orientation possibly has a reproductive connotation as larval dispersal may be favoured and enhanced by the tides. Four groups of distinct tracks related to the morphotypes and developmental stages of U. cordatus were observed. No sediment constructions associated with the burrows were recorded for this species. Declivity of the burrows from juveniles was lower than from adults (P < 0.05), probably caused by the differential growth of the chelipeds in this species.

Competition plays an important role in invasion dynamics. According to Elton's biodiversity and invasibility hypothesis, non-native species must be competitively superior to the resident species in order to successfully invade. An invader that is ecologically similar to a native species may cause intense interspecific competition as they both require the same resource. Furthermore, an increase in the density of an invading competitor may enhance the intensity of the competitive interaction, however, this may be reduced if the inferior competitor has a refuge that reduces the amount of time it is in direct contact with the superior competitor. In laboratory-based competition experiments between the non-native caprellid Caprella mutica and two ecologically similar native caprellids Caprella linearis and Pseudoprotella phasma, C. mutica successfully displaced both species from homogeneous artificial habitat patches after 48 hours. Patches that contained a refuge reduced the number of C. linearis being displaced but only when C. mutica was at a low density. Potentially aggressive interactions between C. mutica and the native C. linearis may have caused C. linearis to be displaced from the patches and could have caused significantly higher mortality of C. linearis compared to the controls. This is the first study to show that the non-native C. mutica has the ability to displace ecologically similar native species when the resource space is limited and when the density of C. mutica was significantly (10 times) lower than the density of C. linearis.

Under the assumption that dislodged intertidal gastropods have developed some adaptations to return to their original habitat, we investigated the cues involved in the navigation ability of Littorina littorea, following a simulated wave-dislodgement. Return rates decreased by 2 and 4-fold in the absence of chemical cues at the surface of the sediment and the rock, respectively. The 19-fold decrease in return rates observed in the absence of both cues suggests their synergistic effect on L. littorea navigation. Chemoreception might be much more involved in the navigation and the survival of intertidal gastropods following wave dislodgement than previously thought.

Larval fish and hydrographic data were collected in Kavala Gulf (northern Aegean Sea) across a fine scale grid of 17 stations in two surveys, carried out in the beginning of July 2002 and 2003. Despite the different taxonomic resolution and excluding the unidentified larvae, 22 taxa were caught in 2002 and 27 in 2003. Seventeen taxa were present in both years' collections. A total of 833 larvae were collected during the two samplings. The adults of several larvae caught, although sometimes at very low concentrations, are species with high commercial value or represent a major proportion of the captured production of the northern Aegean Sea. The larvae of European anchovy (Engraulis encrasicolus) were most abundant in both years followed by the brown comber (Serranus hepatus), the gobies (Gobius sp.) and, only for 2003, round sardinella (Sardinella aurita). Maximum anchovy larval densities reached 4145/10 m2 and 13852/10 m2 in the 2002 and 2003 surveys, respectively. The spatial extent of anchovy larvae was also high as they were collected at 12 stations in 2002 and at 15 in 2003. Besides water circulation, the spatial distribution of fish larvae was largely influenced by temperature, salinity and dissolved oxygen.

The present work aims to determine and analyse the distribution of individuals of different size-classes of the southern stingray, Dasyatis americana, in distinct habitats at Fernando de Noronha Archipelago. The stingrays were visually sampled, quantified and described according to a standard protocol through intensive search method during direct observations. The relationships among individuals of various disc length (DL) classes and their habitat features were described by the correspondence analysis. A total of 356 individuals were sampled. Individuals between 15 and 35 cm DL were observed mostly at the beaches while the greater DLs were strongly related to reef environments. This distribution reflects a tendency of the younger stingrays to occupy the shallow beach areas, while larger individuals move to deeper waters with reef characteristics during the ontogeny.

Population parameters and behaviour of the herbivorous fish Sarpa salpa, present differences between protected and non-protected seagrass meadows of the north-western Mediterranean Sea. Larger individuals are more abundant inside protected areas, where their grazing pressure on seagrass is disproportionately greater than that of smaller fish feeding on algae and seagrass in unprotected areas. The feeding rate (bites per minute per individual) of smaller fish in unprotected areas is relatively high; however, the denser populations of larger fish in protected areas consume more forage because individual mouth gape is greater and larger fish remove more forage per bite. All these differences suggest a higher impact on seagrass meadows inside protected areas.

Respiration in marine bacteria (fraction <0.6 µm) was investigated in 5 distinct coastal ecosystems. Respiration rates were estimated from the decrease of dissolved oxygen (O2) concentrations measured with a fibre-optic oxygen sensor (optode) during short-term incubations (5 to 6 hours) in the dark. Sub-populations of heterotrophic bacteria were defined and enumerated by flow cytometric analysis. Respiration rates ranged from 0.04 to 0.14 µmol O2 l−1 h−1 and were not correlated to total bacteria abundances. In contrast, they significantly increased with the relative proportion of HDNA cells (i.e. high deoxyribonucleic acid content) within the bacterioplankton community. These results stress the need to relate bacterial respiration rates to the absolute and relative abundance of the different cytometrically defined sub-populations found in bacterial assemblages, rather than to total cell counts. This result indicates that only a fraction of bacterial cells may contribute to bacterial respiration, which indicates a reconsideration of the relevance of some previous estimates of bulk bacterial respiration and the related biogeochemical fluxes may be required.

The enzymatic activity of aerobic and anaerobic metabolic pathways in Hyalinoecia artifex, a polychaete inhabiting the deep ocean, is reported. In addition, the allometry of its anaerobic and aerobic enzymatic activity is analysed. The aerobic metabolism was measured using the electron transport system activity technique (ETS), whereas the anaerobic metabolism was estimated using the activity of lactate dehydrogenase (LDH), octopine dehydrogenase (OPDH), alanopine dehydrogenase (ALPDH), strombine dehydrogenase (STRDH), and ethanol dehydrogenase (EtOHDH). The ETS activity was about 296.18 (µLO2 h−1 g−1), which is within the range described for polychaetes and other benthic metazoans. The anaerobic enzymatic activity expressed as µmol NADH min−1 g−1 was: LDH = 0.35, OPDH = 0.11, ALPDH = 12.66, STRDH = 10.78 and SDH = 0.48. The slope of the allometric relationship between specific aerobic metabolism and body size was −0.35. In the case of the allometric scaling of the anaerobic metabolism, only LDH presented a significant relationship, with a slope of b = 0.44. This positive scaling is consistent with the pattern emerging from the scarce literature on the allometry of anaerobic metabolism in marine biota.

A total of 112 flounder, Platichthys flesus, was surveyed for the presence of Pomphorhynchus laevis (Acanthocephala). No acanthocephalans were found in 35 fish, 40 fish were infected with 1–5 thorny-headed worms, and in 37 fish the intensity of infection exceeded 6. The fish surveyed were also studied for the composition of the resident microflora of the terminal portion of the intestine—the characteristic site for P. laevis. It turned out the number of worms was positively correlated with the bacterial count. The bacteria cultured from the material sampled from intestines of infected- and non-infected fish exhibited similar specific composition and the differences were only in the intensity of individual species. The most frequently isolated bacteria, represented the genera: Aeromonas, Pseudomonas and Shewanella. The least frequent were species of Chromobacterium, Escherichia, Providencia and Serratia. The presently reported study results, suggest that bacteria species, constituting physiological bacterial flora, may become, under certain conditions, potentially pathogenic, through substantial increase in their abundance. The factor responsible for disturbing the natural balance in the intestine may be the thorny-headed worm, Pomphorhynchus laevis.

Potential fecundity, number of oocytes in the mature ovary, and realized fecundity, number of eggs extruded and attached to the pleopods of female Nephrops, caught at the start of the incubation period were estimated for females from the eastern and western Irish Sea grounds. Potential fecundity was found to differ significantly between eastern and western Irish Sea stocks, while realized fecundity did not differ between areas. Inter-year comparison of realized fecundity, and effective fecundity (the number of mature eggs on the pleopods of females at the end of the incubation period) in the western Irish Sea stocks revealed no significant variation over time. Egg loss during the transition from oocytes in the ovary to mature eggs increased with female size, ranging from 40% at 25 mm carapace length (CL) to 65% at 40 mm CL. No relationship was found between egg diameter or volume and female size.

Size at the onset of sexual maturity was determined in Munida rugosa based on allometric growth of chelipeds and abdomen, and on the proportion of ovigerous females. The variability of three different measurements of carapace length (CL) used previously for M. rugosa was also evaluated to minimize measurement error. Both sexes had symmetrical cheliped length and allometric cheliped growth over the size-range investigated, but males showed increased allometry beyond 22 mm CL. Females had greater positive allometry in abdomen width than males, but their size at maturity could not be precisely determined because sampled females were too large.

The different stages of embryonic development of the porcellanid crab Pachycheles chubutensis are described, along with the chronology of each stage at 16±1°C. Five different developmental stages (I–V) were recognized including: (i) early cells and 100% of the vitellum; (ii) formation of the embryonic primordium at the animal pole of the egg; (iii) presence of dark pigmentation on the posterior part of the ocular globe; (iv) appearance of chromatophores on mouth parts and in the abdominal zone; and (v) eye pigmentation in circular–oval form, filling the entire surface. The embryonic development lasts from spawning to hatching approximately 21 days, with the second stage being the longest.

Barnacles are the common fouling organisms encountered in coastal waters around the world. In the present study, breeding biology of the intertidal barnacle Amphibalanus amphitrite (=Balanus amphitrite) was studied for a period of two years (July 2003 to June 2005) in the Kudankulam coastal waters. Results showed that A. amphitrite breeds throughout the year in the study area. A high percentage of individuals with free nauplii in the mantle cavity was observed during March 2004 (47.6%) and May 2004 (41.7%). Barnacles with fertilized eggs in the ovary were high during November 2004 (56%), March 2005 (46.7%) and April 2005 (42.8%). Overall, a peak breeding activity was observed during the March–May period. The breeding activity showed a significant positive correlation with surface water temperature and phytoplankton abundance.

Zidona dufresnei (Donovan, 1823) is a big-sized and long-lived snail endemic to the south-western Atlantic where it dwells in sandy bottoms between five and 115 m; females lay big egg capsules from which crawling juveniles emerge. An unusual population of Z. dufresnei inhabits the low intertidal and shallow subtidal zone of San Antonio Bay, the southernmost location of the species, where it faces many threats. The aim of this study is to describe some of the demographic and reproductive characteristics of this population and to compare them to those located in northern zones. Monthly samples of adults and egg capsules were obtained from October to April and their position was recorded; snails and capsules were gathered for examination in the laboratory. Sex-ratio was near 1:1 for the whole sampling period and the size–frequency distributions were similar for both sexes; females were wider and heavier than males at the same shell length. Maximum shell length was 120.5 mm in our study and so no female reached the minimum size at first gonadal maturity reported for other populations (128 mm); female size seems to limit the capsule diameter and the number and size of embryos that are lower than in other populations. Egg capsule and adult densities in the intertidal zone peaked in February and March respectively, averaging 1.34 capsules and 1.91 snails by 100 m2 during the sampling period; egg capsule deposition elapsed from November to March and peaked in December; females select cobble by size to lay egg capsules. Due to its restricted distribution and the low juvenile and adult dispersal, the unusual Z. dufresnei population dwelling in San Antonio Bay seems to be quite vulnerable to diverse anthropogenic impacts.

The reproductive cycles of four limpet species, Patella depressa, Patella ulyssiponensis, Patella vulgata and Patella rustica are described for several locations in northern and central Portugal. Patella depressa and P. ulyssiponensis displayed almost continual gonad activity, with two main spawning periods, September–January and March–June, and minor spawning events dispersed throughout the year. Patella vulgata and P. rustica exhibited highly synchronized reproductive cycles, with well-defined breeding and resting periods. Gonad development in P. vulgata started in September and spawning took place from November–December to March. In P. rustica development started in June and spawning occurred from September–October to December–January. Compared to the 1980s these results suggest that breeding periods are becoming longer in southern species and shorter in northern species.

This study aimed to assess the influence of growth and reproductive cycle on the meat yield and proximate composition of the banded murex (Hexaplex trunculus) from the Ria Formosa lagoon (Algarve coast, southern Portugal). Samples of the edible portion (all soft-body tissues) were analysed monthly during one year. The average meat yield was 37.9±4.6%, with females containing more edible content (39.1±4.7%) than males (36.8±4.2%). The proximate composition comprised 70.7±1.4% moisture, 20.1±1.2% protein, 1.6±0.3% fat, 3.0±0.3% ash, and 4.6±1.2% carbohydrate, corresponding to an energetic value of 119.2±7.5 kcal/100 g wet weight. The meat yield was influenced by specimen size, increasing significantly during growth. Both meat yield and proximate composition presented seasonal fluctuations related to the reproductive cycle, which coincided mainly with the periods of maturation and spawning of this species in the Ria Formosa. Finally, H. trunculus meat yield and proximate composition were compared with similar information available for other marine gastropods.

A total of 870 blue sharks ranging from 70 to 349 cm in total length (LT) were sampled from the swordfish longline fishery in the Mediterranean Sea during the period 1998–2003. Males predominated and the sex-ratio (1:1.8) showed an increase in the proportion of males as size of fish increased. Gonad observation revealed that females smaller than 120 cm LT had immature ovaries with no mature oocytes, while mature ovaries with visible yolky oocytes were present in specimens larger than 203 cm LT. Ovary weight varied from 4–137 g and maximum oocyte diameter was 21.1 mm in mature females. All males smaller than 125 cm LT were immature while males larger than 187 cm LT were mature, as indicated by the presence of heavily calcified claspers, which extended beyond the posterior end of the pelvic fins. Length at 50% maturity (L50) was estimated to be 202.9 cm LT for males and 214.7 cm LT for females. Age estimates using caudal vertebrae ranged from 1 to 12 years, while age at 50% maturity was estimated at 4.9 years for males and 5.5 year for females.