Arthropod assemblages comprising mites, crustaceans and hexapods are characterized here for mangrove pneumatophores in south-eastern Africa. Initial sampling showed that pneumatophore assemblages differed markedly from benthic sediment assemblages, not only in being more species rich, but also in having lower abundances. Differences among pneumatophore arthropod assemblages were observed in comparisons of two mangrove stands (in the Durban region) and habitats within each stand. Strikingly higher arthropod abundances were found in assemblages associated with pneumatophores on the seaward fringes of the mangrove stands, as compared to those situated inside the mangrove stands or along minor waterways. These differences in abundance are ascribed to differences in physical conditions among habitat types, relating to wetting frequency and sunlight exposure. The assemblages associated with minor waterways varied among themselves according to variations in salinity. Temporal variation in abundance showed that some species peaked in summer and others in winter, indicating effects more closely related to terrestrial seasonal patterns, than to seawater temperature. This study highlights the uniqueness of the mangrove pneumatophore arthropod assemblages, and the need for further investigation into these in order to better understand mangrove meiofaunal ecology.

Three exposed sandy beaches were selected to compare fluctuations in density of the most abundant species, and to verify the influence of spatial and temporal variations on the community structure. Sampling was carried out every three months, from June 1993 to May 1995, on Fora, Prainha, and Boqueirão Beaches. The first two beaches were classified by Dean's morphodynamic index (Ω) as intermediate, and the last as reflective. Slope, beach width and median grain size were significantly different among the beaches. Two-way analysis of variance revealed significant differences in species richness only among the beaches. No significant differences in density of the macrofauna between beaches and season were observed. However, Prainha Beach showed a higher temporal variation of the density of the macrofauna (and higher standard deviation) than the other two beaches. Emerita brasiliensis (Crustacea: Decapoda), Excirolana braziliensis (Crustacea: Isopoda), and Pseudorchestoidea brasiliensis (Crustacea: Amphipoda) were the most abundant species. Canonical correspondence analysis calculated the influence of the temporal variation as 27·5%; the influence of the environmental variation on community structure was 20·9%. The results suggest that in spite of the long-term fluctuations in species density, the beaches did not have temporal differences in the species richness and total density macrofauna during the study period.

The macrofauna of samples collected with a box-corer from northern Adriatic Sea muddy bottoms in five survey campaigns from 1985 to 1993 has been analysed separately in sediment strata of varying depth. Samples were collected before, during and after the dumping of large amounts of inert particulate material that covered the seabed and caused an almost total defaunation. After this disturbance the seabed was recolonized by a new community. This new community differed from the original one mainly on account of the abundance of Mysella bidentata, a small bivalve filter or surface deposit-feeder. In the original community M. bidentata was confined to the more superficial sediment layers (0–5 cm) at low population density. In the new community it was very abundant and evenly distributed even in the deep layers (5–20 cm). Analysis of species association performed on data from each of the 54 corer samples collected in the last sampling period, points to a marked association between M. bidentata and Nephtys incisa in deeper sediment layers. Deep layer colonization by Mysella in association with the burrowing polychaete N. incisa suggests a case of commensalism between these two species.

This study monitored the abundance of the tropical/subtropical seaweed Caulerpa sertularioides (Chlorophyta: Bryopsidales) from a sandy beach from Balandra Cove, on the south-eastern coast of the Baja California Peninsula, Mexico, between April 1998 and April 2000, including consecutive El Niño and La Niña events. El Niño conditions, indicated by relatively high seawater temperatures, were associated with a high population abundance (April–June 1998), whereas La Niña conditions, indicated by relatively low temperatures, were associated with the absence of C. sertularioides (April–June 1999 and April 2000). Caulerpa sertularioides was present during other times of the year during the study period, but never with the high abundance reached during El Niño conditions. Seaweeds of temperate affinity occurring in Baja California, such as Gelidium robustum (Rhodophyta: Gelidiales) and Macrocystis pyrifera (Phaeophyceae: Laminariales), decreased sharply in abundance during El Niño conditions. Therefore, the biogeographic affinity of seaweeds from Baja California might be helpful in predicting the effects of El Niño and La Niña on their abundance, with implications for resource management and for the prediction of the effects of long-term oceanographic changes on seaweed distribution.

Chlorophyll-a (chl-a) distribution and associated physical (temperature, salinity) and chemical (dissolved oxygen) conditions off northern Chile (Humboldt Current System), during the austral summer (February–March) and autumn (May) of 1994, were studied in the region bounded by ∼18–24°S and 70–72°W (out to ∼200 km from the coast; 0–100 m depth); within this region, nutrients were measured in an area of persistent coastal upwelling (∼19–22°S, out to 80 km from the coast). Temperature and salinity distributions, as well as nutrient concentrations, indicated the occurrence of active upwelling during both cruises. Also, and together with maps of geopotential anomaly (0/200 dbar) and depth of the thermocline (15°C isotherm), their distribution suggested the presence of a mainly equatorward flow, anticyclonic eddy-like structures, and intrusions of warm (>19°C), high salinity (>35·0 psu), subtropical water towards the coast. A tongue of cooler and lower salinity water, and of lower flow fields, extended from the coast towards the offshore zone during both sampling periods, in association with higher chl-a concentrations (>1 mg m−3, >20 mg m−2 between 0 and 25 m depth) and predominance of net-phytoplankton (>20 μm). The comparison of these results with those for the winter and spring of 1993 in the same area suggest a relatively weak seasonal signal in chl-a concentration during the 1993–1994 period, with higher water column concentrations during the summer and spring periods in the selected upwelling area, though surface chl-a concentrations for the whole of the area did not vary significantly.

The purpose of the present study was to assess the relationship between sediment composition and biological community structure in mixed sands and gravel deposits of the eastern English Channel. Although some species are clearly associated with particular sediment types, the results confirm the lack of correspondence between community composition of the benthos and particle size distribution in unconsolidated sand and gravel deposits. The results also suggest that sample-to-sample variability commonly recorded in the species composition of macrofauna may reflect significant under-sampling by conventional grab sampling techniques. The implications of this for environmental monitoring and impact studies is discussed.

The macrofauna of molluscs associated with soft bottoms in the Bay of Cádiz (southern Spain) was studied monthly from February 1994 to January 1996. The number of species (63) is high for a soft bottom and is related to environmental characteristics (growth of macrophytes) and the biogeographical setting of the studied area. Corbula gibba (∼90%) was the dominant species in this taxocoenosis together with the gastropod Nassarius pygmaeus and the bivalves Pandora inaequivalvis, Parvicardium exiguum and Macoma melo. The most frequent species during the two years was also the bivalve Corbula gibba (100%) followed by the gastropods Nassarius pygmaeus, Tricolia tenuis, Rissoa membranacea and the bivalve Macoma melo. Total abundance of the taxocoenosis in both years reached higher values in spring. The dynamics of the ecological indices such as diversity or evenness, and the species richness showed a similar pattern in both years, with low values of diversity and evenness together with high species richness in spring and summer months and the reverse in autumn and winter. The qualitative correspondence analysis of monthly samples shows an ordination related to seasonality in both studied years, however the values of Jaccard's coefficient do not indicate significant boundaries among the monthly samples. The quantitative correspondence analysis shows an ordination and grouping of samples related to the biology of species, particularly with the recruitment of C. gibba, the dominant species. The existence of similar trends in the structure of the taxocoenoses over both years, and the seasonality highlighted by the qualitative correspondence analysis, seems to indicate a certain stability of the ecosystem.

Dynamics of the Abra alba muddy fine sand community of the Rance Basin (western English Channel), initially sampled in one station by Retière at the beginning of the 1970s after the tidal power station built at the mouth of the estuary went into service, was reassessed from 1995 to 1997. Results showed a more ‘mature’ community in 1995–1997 with an increase in the number of species. After a short period, in spring 1995, during which the structure of the community was comparable to those described in 1972–1973, the assemblage was characterized by a great interannual structural stability. Densities of dominant species seem to fluctuate around a mean value comparable to the carrying capacity of the biota for these species. The recruitment of the dominant species with a long life span appears low compared to the densities of adults but seems sufficient to assure the replacement of individuals. Our results suggest that the pattern of massive recruitment followed by high mortality rates could not be the general rule and that a pattern of moderate recruitment followed by low post-settlement mortality of recruits should be more frequent.

The morphology and stomatogenesis of the marine scuticociliate Paranophrys magna, collected from a crab-culturing pond in Qingdao, China, were studied. It possessed typical characteristics of the genus Paranophrys. The stomatogenesis of this species corresponds basically with the results provided in previous studies for this genus, the main sequence develops can be generalized as follows according to the Qingdao population: (i) in the proter: the remnant of the parental paroral membrane generates the new paroral membrane and the scutica; and (ii) in the opisthe: both the paroral membrane and scutica originate from the proliferation of the anterior part of the secondary primordial field, membranelles 1&2 derive from the posterior part of the secondary primordial field, while membranelle 3 from the proliferation of the parental scutica which form the primary primordial field.  Some differences between our results and previous descriptions are compared and discussed.

The introduction of non-indigenous marine plankton species can have a considerable ecological and economic effect on regional systems. Their presence, however, can go unnoticed until they reach nuisance status and as a consequence few case histories exist containing information on their initial appearance and their spatio–temporal patterns. Here we report on the occurrence of the non-indigenous diatom Coscinodiscus wailesii in 1977 in the English Channel, its subsequent geographical spread into European shelf seas, and its persistence as a significant member of the diatom community in the north-east Atlantic from 1977–1995.

Fresh weight (FW), dry weight (DW), carbon and nitrogen content were measured for specimens of Laminaria saccharina (Heterokontophyta: Phaeophyceae) sampled in the eastern English Channel in order to conduct a biometrical study. The aim was to relate carbon and nitrogen masses of the algae to a simple and rapid morphological measurement of the total length of the sporophyte. These relationships were highly significant and appeared very useful to express the standing biomass of L. saccharina in terms of carbon or nitrogen and then to consider dynamic processes such as primary production. Variations in tissue carbon (C) and nitrogen (N) were examined over a complete seasonal cycle. Average carbon and nitrogen content ranged from 23·9 to 31·4% and 2·23 to 3·42% of the total dry weight, respectively. Variations in C/N ratio showed a clear seasonal pattern with an increase in the early spring corresponding to strong photosynthesis and growth.

Dinophysis sacculus (Dinophyceae) is a potential producer of diarrhoeic shellfish poisoning (DSP). Population dynamics of this dinoflagellate was followed in the Varano lagoon, south-east Italy, with the objective of determining the seasonal abundance of D. sacculus and the relationship to environmental factors. The seasonal occurrence of this dinoflagellate showed a rather wide temporal distribution and increases in cell numbers were observed in late June and November. Dinophysis numbers seasonal changes appeared to be dependent on chemico–physical factors and dissolved nutrients. Three morphologically distinct forms of D. sacculus were found during the sampling period (March 1997–February 1998) related to the life history of the species and not to environmental conditions. In this mussel fishery, D. sacculus presence and proliferation were not associated with biotoxicity.

Seasonal distribution of the ciliated protozoa was studied in the west part of Kaštela Bay during 1995. These are the first data of the annual distribution of four size categories of non-loricate ciliates and tintinnines in the coastal area of the central Adriatic Sea. The maximum densities of ciliated protozoa were recorded during the spring and autumn, when they could act as important factors of ‘top-down’ control. Contributions of non-loricate ciliates and tintinnines to the total of ciliated protozoa were 72 and 28%, respectively. The highest density of non-loricate ciliates was registered at the surface in September (1400 ind l−1). Annual variability of the non-loricates density was mostly influenced by changes in numbers of the second (103–104 μm3) and third (104–105 μm3) size categories and they constituted 86% of the total non-loricate counts. Non-loricates with biovolume <103 μm3 were the most abundant during the colder part of the year while those with biovolume >105 μm3 dominated during the summer. The highest density of tintinnines (718 ind l−1) was recorded at 5-m depth in May. Quantitatively, the most important tintinnin species was Helicostomella subulata. The results suggest a complex influence of biotic and abiotic factors on the annual distribution of ciliated protozoa.

This is the first report of egg release by the oviparous excavating sponge Cliona viridis. Adult specimens of excavating (α) and massive (β) sponge forms for the presence of oocytes were monitored from 11 May to 12 July 2000, in a shallow-rocky coast of the north-west Mediterranean. The immediate environment around the sponge was sampled for the presence of eggs. Spawning occurred synchronously in the study area at temperatures above 19°C. Oocytes were released in clusters enclosed in adhesive maternal tissue. They contained symbiotic zooxanthellae. Free, adhesive egg-masses drifted in the water or adhered to erect algae in the vicinity of the sponge. Morula stages and larval release are described.

Zooplankton was collected by a diver-towed net close to the substratum at four depths (0, 6, 12 and 18 m) over a 17 month period in three locations in Lough Hyne, Co. Cork, Ireland. Zooplankton was identified to phylum or class levels and mean numbers were calculated for each taxon, site and depth. Seasonality was observed in several meroplanktonic groups (Echinodermata, Nemertea, Mollusca and fish postlarvae), and in gelatinous zooplankton. Depth preference was found to be statistically significant in the polychaetes (larvae and pelagic species), molluscan and ascidian larvae. However, the influence of depth on overall zooplankton community composition was found to be negligible. Sampling location, adjacent substrata and flow conditions were found to influence zooplankton in that area.

The anatomy of the hook apparatus that attaches egg strings to the fish parasites Haemobaphes cyclopterina, Lernaeocera branchialis, Lernaeocera lusci, Lernaeenicus sprattae, Sarcotretes scopeli and Pennella balaenoptera (Copepoda: Pennellida) is described and illustrated. The hook rises from a cupulate base, extending posteriorly and anteriorly in the body cavity. The suspension of the apparatus in the trunk of the different species differs, but the function is similar. The hook tip enters the genital antrum, nearly penetrates the proximal end of the egg string, and continues into a notch on the antrum wall. The apex of the egg string acquires a concave depression like the finger end of a glove. In this way the string is mechanically attached inside the female genital segment. The mobile ectoparasites Lepeophtheirus salmonis and Hatschekia hippoglossi have hooks which function similarly, but perforate the strings.

Mercury determinations were carried out in mussels (Bathymodiolus azoricus) from three Mid-Atlantic Ridge hydrothermal vents (Lucky Strike, Menez Gwen and Rainbow) and shrimps (Rimicaris exoculata and Mirocaris fortunata) from Rainbow. Among the three hydrothermal vents, mussels of Menez Gwen show the highest levels of total Hg and comparing mussels and shrimps from Rainbow the former show more Hg than shrimps. Mussels from different hydrothermal vents are exposed to different kinds of environment which may result in distinct bioaccumulation processes. Detoxification processes in shrimps are related to the low concentrations found. When compared with coastal species from unpolluted sites, mussels show higher concentrations of total Hg and shrimps lower levels. The methyl-mercury concentrations found were very low, not exceeding the detection limit of the technique.

The composition in terms of protozoan functional groups of three sublittoral areas (Castro Urdiales, Santoña and Isla) in the Cantabrian Sea was analysed. The different protozoan species were identified, and their density and biomass was measured. The pigmented protozoa were the most important group in the three areas throughout the year, followed by the bacterivores in Castro Urdiales and Santoña, and the non-selectives in Isla. Bacterivores constituted the most significant group in terms of biomass, after which came that of non-selectives. The parameters with the strongest influence on distribution in functional groups (respect to biomass) were pH, phosphate, organic matter and bacterial biomass, other significant factors being salinity, nitrate and mean grain size. Functional groups expressed as number of species were affected principally by phosphate, pH and, to a lesser extent, temperature and salinity. Statistical analysis using the present data, data regarding functional groups from previous studies in the same areas, and data from other areas, indicate that marine areas show similar characteristics. In the areas covered by the present study, there was a decrease in the number of algivore species and a rise in non-selective species, while bacterivores and pigmented protozoa maintained similar values. In comparison, freshwater areas showed noticeably lower percentages of algivore species and a significantly higher number of bacterivore species.

Developmental stages of a haemogregarine were found within polychromatocytes and erythrocytes in Giemsa-stained blood smears from six evileye pufferfish (Amblyrhynchotes honckenii) caught at Koppie Alleen in the De Hoop Nature Reserve, South Africa. This unusual haemogregarine, Haemogregarina (sensu lato) koppiensis sp. nov., was characterized by encapsulated gamonts with recurved tails, features more common in haemogregarines infecting amphibian and reptilian erythrocytes than in those from fish. Haemogregarina koppiensis is only the third species of fish haemogregarine to have been described from South Africa.

Enhydrosoma curvirostre is redescribed from archived and new material with particular attention to the structure of the mouthparts and other details of the fine structure not previously reported. It is shown that the species cannot be maintained in Enhydrosoma but is more closely related to Cletodes, the genus in which the original author placed it. However, it is shown that the species must be assigned to a new genus, Spinapecruris, as a result of possessing autapomorphies on the maxillule (only seven setae on the basis), thoracopods 2–4 (a large spine on the distal margin) and possibly the caudal ramus (proximal insertion of seta VII) and lacking apomorphies which may define Cletodes.