The development of the polychaete Capitella sp. Y from Estero del Yugo, Mazatlán, Mexico was studied under culture conditions. Capitella sp. Y has a lecithotrophic development with the production of ciliated metatrochophore larvae. A high variation in size and duration of the different developmental stages was observed, as with most of the Capitella species previously described. The median survival time was estimated as six months. The Capitella sp. Y population consists of males, females and hermaphrodites (protandrous and proteroginous individuals). Differences in developmental modes among the Capitella capitata species-complex have indicated that Capitella sp. Y do not belong to any of these previously described species. This study has shown that hermaphroditism is favoured when density of individuals is low, especially in protandrous specimens. It is suggested that hermaphroditism, as well as the ability of self-fertilization observed in Capitella sp. Y enhances the success of the population in natural environments.

A new species of Erylus from the Aleutian Islands is described. This is the first record of the genus from the Aleutian Islands. The new species differs from all other known species of Erylus in the presence of different types of monaxonic megascleres, ranging from oxeas, strongyles, styles, tylostyles to tylotes, often with unequal ends and irregular modifications of these types. The lack of a secondary category of asters is also unusual for the genus.

Although the factors influencing patterns of expansion and contraction of polyps and tentacles for tropical anthozoans has been well described there is still little information for temperate species. This study investigated the patterns of tentacle and polyp expansion behaviour of nine species of temperate Anthozoa in response to current flow, turbulence, food availability and time of day (light) at Lough Hyne Marine Nature Reserve (Ireland). In the absence of current flow, Metridium senile, Caryophyllia smithii, Alcyonium hibernicum and Corynactis viridis exhibited nocturnal expansion of polyps or tentacles with contraction occurring in the daytime, while Alcyonium digitatum, Actinia equina and Cerianthus lloydii showed no differences between light and dark periods. The symbiont containing species Anthopleura ballii and Anemonia viridis expanded or raised their tentacles during daylight hours (tentacle contraction is not possible for A. viridis), although in shallow waters (3 m) Anthopleura ballii tentacles were contracted at midday (highest light levels) presumably to prevent damage from ultraviolet radiation. The contraction of tentacles during light periods was considered a predator avoidance response since zooplankton availability did not vary between light and dark periods, while predator abundance (particularly fish) is greater during daylight. Even though M. senile, Alcyonium hibernicum and Corynactis viridis showed little expansion during daylight periods in the absence of current flow, tentacles and polyps were expanded at midday during periods of high current flow. A greater number of expanded polyps and tentacles were also recorded for A. digitatum, Anemonia viridis and Cerianthus lloydii during high flow conditions compared with periods of low/no flow (Caryophyllia smithii not examined). Actinia equina only exhibited tentacle expansion in response to the creation of a turbulent flow regime, which was determined from laboratory observations. Since species demonstrating contraction during daylight in the absence of current flow expanded their tentacles and polyps when subjected to high current flow, the need for feeding appears to be more important than predator avoidance in controlling expansion behaviour.

In September 2004, a rapid assessment survey for non-native species was conducted at 12 harbours along the south coast of England from East Sussex to Cornwall, focusing on communities of algae and invertebrates colonizing floating pontoons in marinas. Over 80 taxa each of algae and invertebrates were recorded, including 20 recognized non-native species. The southern hemisphere solitary ascidian Corella eumyota was recorded in the UK for the first time and was present at three sites. The colonial ascidian Botrylloides violaceus was also recorded as new to the UK, but was very widespread and has probably been present for a number of years but misidentified as the native congener B. leachi, which was infrequent. Other ascidians included Styela clava, introduced at Plymouth in the early 1950s, which was recorded at all locations visited, and Perophora japonica, which was found only at the Plymouth locality where it first occurred in the UK in 1999. The diverse algal flora included nine alien species previously recorded in the British Isles. Range extensions and population increases were noted for the kelp Undaria pinnatifida and the bryozoan Tricellaria inopinata, both first recorded in UK waters during the 1990s. The widespread occurrence of another non-native bryozoan, Bugula neritina, appears significant, since in earlier times this was known in UK waters predominantly from artificially heated docks. The results of this survey indicate that dock pontoon systems in southern England are significant reservoirs of non-native species dispersed by vessels and other means. The proliferation of these structures is therefore of conservation importance. The new UK records highlight the need for periodic monitoring of ports for non-native species.

Kinds and distribution of nematocysts of the cubomedusa Carybdea marsupialis were described by light and scanning electron microscopy. Three kinds of nematocysts were found in tentacles: heterotrichous microbasic euryteles, flattened holotrichous isorhizas and subspherical holotrichous isorhizas. The microbasic euryteles of the tentacles show a characteristic detachable multilayered lancet, already described in the euryteles of Carybdea alata. A possible explanation of the function of the lancet is proposed. The pedalia and the umbrella are armoured by holotrichous isorhizas together with an unidentified kind of small, drop-shaped nematocysts. Gastric cirri, characterized by a rough and ciliated surface, contain heterotrichous microbasic euryteles.

Three new species of free-living marine nematodes: Oncholaimus multisetosus sp. nov., Sabatieria stenocephalus sp. nov. and Setosabatieria coomansi sp. nov. from the Yellow Sea, China are described and illustrated. The male of Oncholaimus multisetosus sp. nov. is characterized by a tail sharply constricted at the junction of the conical and cylindrical sections; two circles of 12–15 pairs of circumcloacal setae each. In the female, the conical section of the tail gradually tapers in a cylindrical section. Sabatieria stenocephalus sp. nov. is characterized by the pronounced sharp-pointed anterior body, sclerotized tooth-like front edge of buccal cavity and 15 tubular-shaped precloacal supplements with the posterior five more closely spaced. Setosabatieriacoomansi sp. nov. can be separated from the other species of the genus by the number (6–8) of cervical setae per file, the number of precloacal supplements (15) and the absence of central strips in spicules and leaf-like extensions of the cuticle lateral to the cloaca. Types are deposited in the College of Marine Life Sciences, Ocean University of China.

The need to use biomonitors representative of the sedimentary compartment has been recognized, particularly in estuaries. Thus, trace metal contamination has been monitored in an infaunal polychaete worm Nereis diversicolor and sediments in the Seine estuary and comparatively in the relatively clean Authie estuary (French coast of the English Channel) over two years taking samples every three months at both sites. No correlations were shown between total metal (Ag, Cd, Cu, Pb, Zn) concentrations in raw sediments and ragworms. Because these worms are known to be good biomonitors of the bioavailabilities of sedimentary trace metals, it follows that total sediment metal concentrations have a poor predictive ecotoxicological value. Using a correction factor to minimize the influence of weight, it is possible to make a good estimation of the average metal concentrations in a population of worms at a given site, sampling only a limited number of specimens. Metallothioneins are often considered to be good biomarkers of the presence of significant availabilities of trace metals. Metallothionein-like proteins (MTLPs) are present in N. diversicolor, but there is no significant relationship between MTLPs and metal concentrations. This situation might result from the importance of metal-containing granules, both extra- and intracellular, in ragworms.

The aim of this study was to determine the abundance of cyanophages over an annual cycle in the Red Sea from the period April 1999 to December 1999 at a range of depths. Cyanophage numbers from 71 water samples were determined by the use of plaque assays using four different Synechococcus strains. The results indicate that cyanophage are found throughout the water column from surface waters to depths of 150 m, with a discrete maximum in the number of cyanophages in the summer months of July, August and September at a depth of 30 m. Eighty-seven cyanophages were isolated and characterized in terms of host range, genome size and possession of a myoviral portal vertex gene. Cyanophages were found to infect multiple strains of Synechococcus from different phylogenetic clades. The genome sizes of cyanophages were also found to be bigger than previously estimated.

Shells inhabited by hermit crabs are unique microhabitats with an abundant epi- and endofauna. Using polychaetes as an example, communities associated with the whelk Stramonita haemastoma, the hermit crabs Clibanarius erythropus and Calcinus tubularis, as well as empty, damaged shells were investigated. No polychaete community was associated with live S. haemastoma: only 30% of the investigated gastropods harboured polychaetes. Hermit crab-occupied shells supported polychaete communities dominated by Spirorbidae in the case of Clibanarius erythropus and by small Sabellidae, Spirobranchus polytrema and Dipolydora armata in Calcinus tubularis. The polychaete fauna associated with empty shells was similar to that on shells previously inhabited by one of the hermit crab species but different from those of the surrounding hard bottom. The reproductive strategy of the some polychaetes species is adapted to life on this small-sized habitat.

A new partially calcified hydroid species of the family Hydractiniidae, was found in offshore waters of the Aleutian Islands (Alaska), dredged from the bottom at 139–145 m depth. This is the third known species of extant calcified Hydractiniidae, and it shows a unique colony structure. The base is heavily calcified and the distal parts are ramified and have a solid chitinous structure. Branches are all in one plane and the colony reaches up to 18 cm in height.

A large quantity of triglyceride was detected histochemically in nutrient-deposit cells of the trophosome in the beard worm (Oligobrachia mashikoi). The lipid extracted from the trophosome was composed of triglyceride, several kinds of phospholipid, free fatty acid, cholesterol, and cholesterol ester. The fatty acid of the triglyceride was comprised mainly of a monoenoic type, such as palmitoleic acid (16:1) and oleic acid (18:1), which accounted for 31% and 37% of the total fatty acids, respectively. In addition, in blood triglyceride, the fatty acid composition was almost the same.

The unicellular cyanobacterial species Synechococcus and Prochlorococcus are known to be vital components of marine ecosystems, especially in the vast oligotrophic areas. Lytic cyanophages infecting unicellular phytoplankton are prevalent and have been demonstrated to act as important constraints on community composition contributing to the seasonal succession in genotypes. Lysogeny in Synechococcus has been documented experimentally in natural environments by prophage induction. At this time it is completely unknown how prevalent lysogeny is among Synechococcus populations. This study was performed to document important features such as size, morphology and the incidence of the T4-like capsid portal protein gene (g20) in a group of lytic Synechococcus cyanophages (35 isolates) isolated from the Gulf of Mexico. A group of Synechococcus isolates (24 strains) were isolated concurrently to investigate the virulence and cross-infectivity of the lytic cyanophages and to determine the frequency of lysogeny by detection of inducible prophage. The host range of the cyanophages toward these Synechococcus strains ranged from 1 of 25 (host of isolation only) to 17 of 25 (68%). Of the 35 cyanophage isolates the large majority were myoviruses (94%) and only two (6%) were of the podovirus type. The expected polymerase chain reaction product for g20 was detected in 20 of the phages (63%). The presence of a detectable g20 was associated with low-infectivity cyanophages at the 90% confidence interval. The Synechococcus strains varied in their resistance to lytic infection from 11% to resistance to all of the phage isolates utilized in testing. The prevalence of inducible prophage-like particles was determined in the Synechococcus strains using mitomycin C and enumerating viruses by epifluorescence microscopy. A statistically significant increase in viruses was detected in 11 of the strains (46%) in response to mitomycin C. There was no observed relationship between the occurrence of prophage induction in the Synechococcus isolates and their resistance to lytic infection. One putative lysogen was induced by continuous high light and contained a prophage-like particle with a single-stranded DNA (ssDNA) genome. Such a prophage-like particle is unlike any prophage described to date, implying that the process of lysogeny is unique in certain marine Synechococcus strains.

During the expedition EASIZ II with RV ‘POLARSTERN’ in 1998 a multibox corer yielded 151 quantitative samples from 26 stations between 120 and 2415 m water depth for benthic community analysis. From this material a total of 235 polychaete species out of 37 families was determined. Forty-seven species are new to science. The polychaete fraction contributed 41.9% to total benthic abundance and 6.5% to total benthic biomass at these stations. Overall mean polychaete abundance (ind m−2) and biomass (g wet weight m−2) at the stations were 1617 and 49, respectively.

Multidimensional scaling procedure clearly grouped the stations into south-eastern Weddell Sea shelf stations, deep-water stations, and stations mostly around the Antarctic Peninsula. Differences between these groups existed in terms of polychaete abundance and biomass as well as species composition, diversity, and evenness.

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.

Comparisons are made between the species currently called Clausophyes ovata and other Clausophyes species. It is concluded that Cl. ovata should be removed to another genus and, consequently, the genus Kephyes gen. nov. is established for it. The relationships of all clausophyid genera are briefly discussed.

A detailed illustrated key to the identification of the European species of the genera Palaemon and Palaemonetes is provided. This key has been elaborated taking into account recent changes in the species composition of both genera for European waters, such as the invalidity of Palaemon garciacidi, which is a synonym of P. longirostris, and the presence of an introduced species, Palaemon macrodactylus that has been recently recorded at different localities along the Atlantic coast. The key is based on external morphological characters to facilitate its use by non-specialists. Data on the coloration, habitat and distribution of all species are also given.

The results of a 25-year study of the population dynamics of the common shrimp, Crangon crangon, in the Bristol Channel are presented. The population size varied seasonally, with maximum abundance occurring in early autumn at the completion of annual recruitment. The number of recruits changed greatly between years, and was positively correlated with both average water temperature from January to August, and river flow rate, and negatively correlated with the Winter North Atlantic Oscillation Index. A wide range of other physical and biotic variables was found to have no significant impact on C. crangon abundance. The positive relationship between temperature and C. crangon abundance observed for the Atlantic coast during this study is the opposite of that found for southern North Sea populations. Similar contradictory responses have been noted previously for flatfish such as sole, Solea solea. This suggests that global variables may act to produce different outcomes for Atlantic and North Sea populations of the same species. Over-winter mortality was found to vary with population size so that the adult C. crangon population in spring was found to be remarkably stable, and little influenced by temperature or other variables. The mortality rate increased with population size producing clear evidence of density-dependent control. It is suggested that this stability is linked to the constant limited availability of suitable habitat, with individuals unable to find shelter vulnerable to a range of predatory fish. Given the pivotal role of C. crangon within the northern European estuarine ecosystems, this stability may be a critical component for the overall stability of the system. A particular feature of this study was the exceptional recruitment observed in October 2002. This did not result in any subsequent increase in adult C. crangon numbers, possibly because there was a synchronous increase in a wide range of predators. While the adult population has remained stable and showed no temporal trend, there has been an increase in both the average magnitude and between year variability in recruitment, which can be related predominately to the recent increase in water temperature. The difficulty of predicting the response of this population to continued climate warming is discussed. If temperature continues to rise, the present power law describing the increase in recruitment with temperature must inevitably break down. If this were to occur, the future trajectory of the C. crangon population could not be predicted, and the continued stability of this ecosystem would no longer be assured.

A SCUBA-based fast repetition rate fluorometer (FRRF) was used to study differences in the functional absorption cross-section of Photosystem II (σPSII) between areas of a coral colony of Astreoporamyriophthalma that were infested with spionid polychaetes vs areas lacking worms. The mean value of σPSII in infested areas (mean±SD=347.62±30.67 Å2) was significantly higher than in the areas that were not infested (316.32±17.49 Å2; P<0.0001). Several physiological mechanisms are discussed that may contribute to the observed differences.

A collection of 17 cyanophage isolates able to infect the heterocystous, filamentous cyanobacterium Nodularia spumigena has been established from the Baltic Sea. These cyanophages have been characterized based on their morphology, cross infectivity and genetic structure. Short fragments (450 bp) of the gene encoding the major capsid protein (g23) were amplified and sequenced from several isolates, and the encoded protein was found to be 99% identical across all the N. spumigena-specific cyanophages tested. These results suggest that the Nodularia-specific cyanophages are very closely related. However, these cyanophages were found to be diverse in terms of their morphology and host range. Cyanophages belonging to two families within the order Caudovirales, Myoviridae and Siphoviridae, were included in the collection of isolates. The cyanophage particles are large in comparison with cyanophages previously isolated from the marine environment, with the largest capsid measuring 127×122×888 nm. Host ranges of the cyanophage isolates varied, some being able to infect up to five genotypically distinct strains of Nodularia spumigena, while others were very specific, infecting only one strain. We conclude that Nodularia-specific cyanophages form a diverse community in surface waters during summer and autumn months and that they may play a role both in the transfer of genetic information between Nodularia lineages and in promoting changes in the genetic structure of the host population.

The caridean shrimp Alvinocaris muricola has been observed forming high density populations over mussel beds on the giant pockmark cold seep site Regab in the Gulf of Guinea at 3150 m depth. Samples were collected using the ROV Victor 6000, a beam trawl and a TV grab from two sites. The specimens were sexed and measured for population structure analysis. In one sample the sex ratio was 1:1, but the other sample had a sex ratio significantly biased towards females. The maximum size of females is larger than males. A sub-sample was used for gametogenesis and fecundity analysis. The oogenesis and spermatogenesis of A. muricola is characteristic of caridean shrimps. The oogonia proliferate from the germinal epithelium and develop into previtellogenic oocytes that migrate to the growth zone. Vitellogenesis starts at 80–100 μm oocyte size and the developing oocytes are surrounded by a monolayer of accessory cells. The maximum oocyte size was 515 μm. There was no evidence of synchrony in oocyte development, with all oocyte stages present in all ovaries analysed. However, seasonal sampling would be necessary to confirm the lack of seasonality in reproduction. In males, the sperm develops in sperm sacs in the testis. As in all caridean shrimp, the broods of A. muricola are held on the pleopods P11 to P14. Total fecundity was related to female size and ranged between 1432 and 5798 embryos. Within a brood all embryos are at the same stage of development, but three different stages were identified in different females, with no clear seasonal trend. The embryos were small, with mean dimensions of 0.66×0.55 mm, suggesting planktotrophic larvae and a potential extended larval development.