Concern has been expressed over future biogeographical expansion and habitat capitalization by species of the phylum Cnidaria, as this may have negative implications on human activities and ecosystems. There is, however, a paucity of knowledge and understanding of jellyfish ecology, in particular species distribution and seasonality. Recent studies in the UK have principally focused on the Celtic, Irish and North Seas, but all in isolation. In this study we analyse data from a publicly-driven sightings scheme across UK coastal waters (2003–2011; 9 years), with the aim of increasing knowledge on spatial and temporal patterns and trends. We describe inter-annual variability, seasonality and patterns of spatial distribution, and compare these with existing historic literature. Although incidentally-collected data lack quantification of effort, we suggest that with appropriate data management and interpretation, publicly-driven, citizen-science-based, recording schemes can provide for large-scale (spatial and temporal) coverage that would otherwise be logistically and financially unattainable. These schemes may also contribute to baseline data from which future changes in patterns or trends might be identified. We further suggest that findings from such schemes may be strengthened by the inclusion of some element of effort-corrected data collection.

Contaminants causing sex-altering, endocrine disrupting-like (ED) effects, or otherwise influencing reproduction, have been of growing concern to humans for more than 50 years. They have also been a perturbing, though less well-studied, phenomenon in marine organisms, following the recognition of tributyltin (TBT)-induced imposex and population extinctions in (neo)gastropods in the 1970s. Whilst ED impacts in mammals and fish are characterized by mimicry or antagonism of endogenous hormones by environmental contaminants (acting through Nuclear Receptors which are present in all metazoans) much less is known regarding pathways to effects in invertebrates. Despite the absence of a defined steroidal/mechanistic component, the extent, severity and widespread nature of ED-like manifestations and altered sexual characteristics observed in marine invertebrates gives rise to comparable concerns, and have been a long-term component of the MBA's research remit. The manifestations seen in sensitive taxa such as molluscs and crustaceans confirm they are valuable indicators of environmental quality, and should be exploited in this capacity whilst we seek to understand the pervasiveness and underlying mechanisms. In so doing, invertebrate indicators address aims of organizations, such as the EEA, OECD, UNEP and WHO, charged with management and monitoring of chemicals and ensuring that adverse effects on humans and the environment are minimized (Bergman et al., 2013). In view of the recent general declines in marine biodiversity, and the potential contribution of ED-like phenomena, safeguarding against deleterious effects through increased research which links pollutant exposure with reproductive dysfunction among invertebrates, is seen as a high priority.

During a recent survey of the biodiversity of shallow-water aphotic marine caves of Madeira Island (north-east Atlantic), 12 specimens of the rare deep-sea shrimp genus Bresilia (Caridea: Bresiliidae) were collected from a depth of 15 m. The collected shrimps are described and illustrated as Bresilia saldanhai sp. nov., increasing to five known species of the genus. Morphological characters are compared and discussed, and an updated world key for the genus Bresilia is presented. For the first time, a species of this poorly known genus can be described from a significant number of intact specimens. This occurrence once more demonstrates the strong environmental similarities and evolutionary ties between marine caves and the deep sea.

A preliminary comparative analysis of colony growth and zooid size in the perennial bryozoan Flustra foliacea (Bryozoa: Cheilostomatida) reveals reduced colony growth in the Bay of Fundy relative to growth in the Menai Straits and the Skagerrak, while seasonal fluctuations in zooid size are in synchrony with temperature regimes. Such retrospective morphometric analyses may allow inferences of primary productivity and thermal regimes and provide insights into the life histories of both Recent and fossil bryozoans.

The occurrence of barnacles and crabs on Caretta caretta specimens found in the waters around Italy was analysed. In the seas surrounding Italy balanomorph barnacles occur mainly on turtles frequenting shallow waters and crabs display a strong west–east gradient. Patterns of turtle distribution and movements are proposed. The abundance of turtle-specific barnacles may be dependent on, and so an indicator of, turtle density.

The inconspicuous hydrozoan Clytia hummelincki, first recorded from the Mediterranean Sea in 1996, is presently widespread throughout the middle Mediterranean Sea and the Adriatic Sea. Two surveys carried out in 2003 and 2004 along the coast of the Salento Peninsula, Italy, showed that this species inhabits a belt between 0.5 and 2 m depth in sea urchin barrens and in areas damaged by date mussel fisheries. The comparison between the two surveys indicates that the frequency of the alien increased from 2003 to 2004. The life cycle of C. hummelincki is described for the first time.

The benthic body size miniaturization hypothesis states that deep-sea communities are dominated by organisms of smaller body size, although some field studies have produced contradictory results. Using appropriate sample sets, this study tests this hypothesis by contrasting the benthic communities of the Fladen Ground (North Sea, 150 m) and the Faroe–Shetland Channel (1600 m). Samples were collected for large (500 μm) and small macrofauna (250–355 μm), meiofauna (45 μm) as well as an intermediate sized ‘mesofauna’ (180 μm) to ensure comprehensive coverage of the full meio- and macro-faunal body size-range. The body size structure of the benthos was compared using two methods. The more widely used average individual biomass method involves dividing the total sample biomass by sample abundance. Additionally, body size accumulation curves were constructed by assigning all specimens into a logarithmic size-class and then plotting the cumulative percentage of individuals present in each size-class. The results seem to support the hypothesis that the deep-sea environment is a small organism habitat. Although these findings only represent two locations, the overall body size accumulation curves clearly display a statistically significant shift towards smaller body sizes at the deeper site. The magnitude of the effect is appreciable with median metazoan body size reducing from 14.3 μg wet weight in the Fladen Ground to 3.8 μg wet weight in the Faroe–Shetland Channel. The average individual biomass measurements are shown to be of limited value and can lead to potentially misleading conclusions if the underlying size structure is not analysed in detail.

The jaera albifrons Leach group of species is a common component of estuarine faunas in Britain, where each species may occur in considerable numbers. Some members of the group also occur in less variable, marine localities in Britain and elsewhere, indicating that each species is capable of survival in a wide range of salinity combinations and that the group as a whole is euryhaline (see, for example, Naylor & Haahtela, 1966; Jones & Naylor, 1971). Naylor & Haahtela (1966) showed that the four species of jaera which occur in Britain occupy preferred areas on an estuarine shore such that jaera ischiosetosa Forsman is common on stones in areas affected by freshwater seepage, jaera albifrons Leach occurs on stones either in pools or in parts of the shore where water is retained (around M.t.l.), jaera praehirsuta Forsman occurs on Fucus serratus (L.), and jaera forsmani Bocquet can be found under stones around L.w.s.t.-l.w.n.t. where there is little retention of water. A later investigation by Jones & Naylor (1971) has shown that these habitat preferences persist throughout a 2-year period, and that each of the jaera species is capable of successful reproduction and development in a characteristic pattern of fluctuation in salinity, temperature and exposure to air

A new species of mouthless and gutless free-living marine nematode, Astomonema southwardorum sp. nov., the dominant species from a methane seep pockmark in the North Sea, is described and illustrated. The new species is distinguished by its combination of short cephalic and cervical setae, with the latter being sparsely and irregularly distributed, and also in male specimens by its arrangement of precloacal and caudal setae and its postcloacal papillae. The genus Astomonema Ott, Rieger, Rieger & Enderes, 1982, is rediagnosed. Astomonema brevicauda (Vitiello, 1971) Vidakovik & Boucher, 1987, is considered to be a species inquirenda.

The species-specific abundance and biomass of marine planktonic ciliates were determined at monthly intervals at two stations in Southampton Water between June 1986 and June 1987. The two stations, an outer one at Calshot and an inner one at north-west Netley, were subject to differing marine and terrestrial influences. A total of 55 ciliate taxa were recorded during the sampling period; of these 34 taxa were identified to genus and 16 to species. The heterotrophic ciliate community at both stations was dominated by aloricate taxa which comprised >90% of the community abundance and biomass during some months. The loricate tintinnids were also common, especially at Calshot, during winter months. Oligotrichs dominated the aloricate community at both stations with haptorids prominent at north-west Netley. At Calshot, Strotnbidium sp. dominated the heterotrophic community abundance and biomass throughout the study period, while Askenasia sp., Strobilidium sp. and Tintinnopsis sp. were also common. Strombidium sp. also contributed most to heterotrophic community abundance at north-west Netley. Balanion sp. and Tintinnopsis sp. were also abundant. However, Cydotrichium sp. and Didiniunt sp. dominated community biomass at this station. Most taxa exhibited a seasonal cycle with low winter and high spring and summer abundances. Some taxa reached abundances of >2000 l1 However, maximum abundance of one species of Tintinnopsis was found during winter months. The autotrophic ciliate, Mesodinium rubrum, was also recorded at both stations achieving densities >105l1 at north-west Netley during ‘bloom’ conditions.

Rather little is known of the behaviour of larvaceans, although they are of great importance in the sea as one of the few groups able to exploit the nanoplankton. Of the two larvacean groups, oikopleurids have received most attention: the behaviour of Oikopleura dioica has been studied in detail by Gait (1972, Ph.D. Thesis, University of Washington, Seattle), and some notes on the electrical correlates of behaviour have been given by Gait & Mackie (1971) and by Bone & Mackie (1975) for O. dioica and O. labradoriensis. Much less is known of fritillariid larvaceans and, apart from the brief notes on behaviour by Fol (1872) and by Lohmann (1899) in the course of their classical histological investigations, which were extended by Salensky (1904) and Martini (1909), the only recent investigation of living fritillariids is that of Fenaux (1961) who described the remarkable mode of action of the pyloric cilia.

The seasonal organization patterns of demersal assemblages (fish and cephalopods) in the Gulf of Lions were investigated on the basis of a set of bottom trawl surveys. The use of Partial Triadic Analysis (PTA) provided a detailed representation of: (1) the common part of the spatial organization of demersal assemblages at seasonal scale; and (2) the seasonal variability of each species around this common structure. During the course of the study, demersal assemblages exhibited a strong seasonal stability in their organization patterns and only few species showed a strong seasonal variation in their spatial distribution. Demersal assemblages of the Gulf of Lions were structured primarily on the basis of a non depth coast–open sea gradient, which occurred from the coast to the midshelf region. The influence of depth on the structure of fish assemblages appeared to be only of limited importance and mainly restricted to the continental slope area. The PTA combined with contouring technics could be used to improve our knowledge of community structuring factors, and offers a theoretical framework to assess the reproducibility of multispecies structures.

The copepod parasite Mytilicola intestinalis was first described by Steuer (1902) from the gut of Mytilus galloprovincialis (Lam.) in the Gulf of Trieste. Monod & Dollfus in 1932 recorded the same species from M. edulis from Marseilles. In 1939 the parasite was first recorded on the German North Sea coast by Caspers near Cuxhaven, and in 1947 by Ellenby from Blyth, Northumberland. It is now widespread along the English south coast in M. edulis, but the distribution still shows some irregularities that are discussed in this paper.

I am grateful to Prof. J. E. G. Raymont for facilities at University College, Southampton, and for the use of a research table at Plymouth; to Mr F. S. Russell, F.R.S., and the staff of the Plymouth Laboratory of the Marine Biological Association for their assistance; and to Dr D. P. Wilson for facilities to collect at Exmouth. Dr H. A. Cole and Mr J. N. R. Grainger have kindly given me information from their papers not yet published. Dr D. J. Crisp and Dr H. G. Stubbings have assisted by sending me several samples of mussels, and I am grateful also for information received from several other friends named in the text.

The holotype of the Antarctic octopodid Graneledone setebos was re-examined and found to lack the epidermal warts characteristic of the genus Graneledone. It is similar in its large size to another Southern Ocean species, Megaleledonesenoi. A comparative study of G. setebos and specimens attributed to M. senoi led us to conclude that M. senoi is a junior synonym of G. setebos. Although M. senoi is not valid, the genus Megaleledone can be separated from other genera by the structure of the radula (which lacks marginal plates) and we therefore consider the genus to be valid. We propose the new combination of Megaleledone setebos and have refigured the beaks and radula of the holotype herein and expanded the description. A search of museum specimens and the literature shows that Megaleledone setebos is more common in Antarctic waters than previously supposed.

Luminescence inChaetopterus is an extracellular phenomenon and is due to the secretion of photogenic material by certain glandular cells in definitely circumscribed regions of the body. These gland cells are eosinophihc elements scattered singly or massed together in dense aggiegations in certain regions. They are particularly abundant in the epithelium covering the distal surface of posterior notopodia, and in two glandular areas on the dorsal surface of the aliform notopodia. These two regions also display the brightest luminescence (Nicol, 1952 a).

The relative abundance of the six copepodite stages (CI-CVI) of Calanus helgolandicus Claus (Copepoda: Calanoida) and Pseudocalanus elongatus Boeck (Copepoda: Calanoida) was recorded at a station in the English Channel throughout 1989. There was a pronounced seasonal variation in the abundance of the early stages. Increased recruitment from the nauplii corresponded in both species to rising primary production early in the year, producing small CI abundance peaks in March. The major period of naupliar development occurred after the April/May spring bloom. During seasonal peaks the CI and CII stages typically formed 40% of the copepodites of these species but were scarce at other times. The body carbon weight of Calanus and Pseudocalanus CIs decreased by 38% and 21% respectively from May to August, indicating an increase in food limitation for the nauplii. Summer was passed predominantly in the CIV and CV stage at low abundances.

One hundred and ninety-eight suprabenthic hauls from the English Channel and the Seine Estuary were taken with a modified Macer-GIROQ sledge. Numerically, mysids were the dominant group amongst the peracarids collected with the sledge and 28 species were recorded. Mysid densities were higher in the oligohaline zone (>200,000 ind 100 m-3) of the Seine Estuary than at other stations in the English Channel (where the density was the highest on medium sand stations, ~5000 ind 100 m-3). Two main gradients of mysid distribution were identified: (1) a higher species richness in the western part of the Channel compared with the eastern part of the Channel; and (2) an increasing density gradient from west to east during spring and a decreasing gradient from west to east during the autumn (eastern high abundance of Haplostylus spp. during spring, and western high abundance of Schistomysis ornata and Erythrops elegans during autumn). Mysids showed important diel rhythms with maximum abundance at sunrise and sunset, and low density at night. According to their swimming activities, suprabenthic mysids were classified into three groups: upper organisms with a very strong activity, species with a strong activity and occupying the whole water column near the sea-floor, and lower species with limited swimming activity. Nevertheless, the swimming activity could be modified according to the hydrodynamics of each site. A seasonal cycle of abundance (summer recruitment for dominant species Anchialina agilis, Haplostylus lobatus, Haplostylus normani) was observed on two stations where temporal samples along the year were available.

Glycollic acid is probably a major component of the extracellular organic fraction liberated during phytoplankton photosynthesis and presumably plays an important part in energy transfers in aquatic environments (Fogg, 1966). It has been difficult to investigate these possibilities, however, because of the lack of a reliable and convenient method for the determination of glycollate in natural waters. With fresh water, ionexchange resins have been used for separating and concentrating glycollate which may then be estimated colorimetrically using Calkins's method (Fogg, Eagle & Kinson, 1969). This method is time consuming and is much more difficult and laborious with sea water because of the presence of high concentrations of inorganic ions. Koyama & Thompson (1964) determined various organic acids after extraction from sea water with organic solvents but this method is also laborious and for glycollic acid yields ambiguous results. Andrews & Williams (1971) measured free amino acids and also glucose occurring in sea water in μtgl−1 concentrations by retaining them on a copper chelating resin and a charcoal column respectively and eluting them with ammonium hydroxide or 10% ethanol as appropriate.

Narcomedusae are a small and mostly oceanic group of hydromedusae whose tentacle morphology and comportment sets them off behaviourally and perhaps ecologically from most other medusae. Their tentacles are relatively few in number (2–40), stiff, and noncontractile, with points of insertion located well above the bell margin. Eleven species representing eight narcomedusan genera (Aegina, Aeginura, an undescribed aeginid, Cunina, Pegantha, Solmaris, Solmissus, and Solmundella) were observed and collected in situ in the NW Atlantic, Arctic and Antarctic, using scuba and manned submersibles. In life, the tentacles of narcomedusae are nearly always held upwards over the bell or projected laterally. The major prey were other gelatinous zooplankton, especially salps and doliolids. In the laboratory, these relatively large prey were caught on the tentacles which bend inward and coil at the tips to bring food to the mouth. By extending the tentacles perpendicular to the swimming path, these medusae achieve a relatively large encounter area, thus increasing the probability of contact with prey, for the amount of protein invested in tentacles.

Charybdis hellerii is one of several poorly known non-indigenous crabs in the Caribbean. In this study we report on the reproductive dynamic of a shallow subtidal population that invaded Isla Margarita, Venezuela, south-eastern Caribbean Sea > 15 years ago and has persisted in the region up to date. Male and female crabs, both large and small, were found year-round at the study site. The size–frequency distribution indicated a lifespan of 2–3 years. Charybdis hellerii reproduces continuously but with very low intensity during the year. Small individuals (<25 mm carapace length) were uncommon and intermittently found during the study period. Sex-ratio varied between 0.1 and 0.65 (mean ± SD = of 0.46 ± 0.14) and did not differ significantly from 1:1 ratio during most of the year. The size of the smallest brooding female was 36.81 mm carapace width (CW). Behavioural size at first maturity (movable abdomen) in males and females was estimated to be 22.39 mm CW (confidence limits: 18.35–24.72) and 37.43 mm CW (35.55–39.09), respectively. Reproductive output, estimated as the ratio of embryo to female body dry mass, varied between 0.052 and 0.084 (0.07 ± 0.008). Also, reproductive output was size-dependent with large females allocating proportionally less resources to egg production than small females. The reproductive schedule here reported for C. hellerii disagrees with the generalized idea of exotic populations ‘thriving’ in an environment free of natural enemies (e.g. predators, competitors and diseases).