The relationships between phytoplankton pigments, optical properties and photosynthetic parameters for different phytoplankton functional types (derived by diagnostic pigment indices, DPI) were determined from data acquired in the Benguela ecosystem and the offshore region in October 2002. We observed robust inter-pigment relationships: total chlorophyll-a (TChla) was highly correlated with total pigment (TP) and accessory pigment (AP). However, the regression equations for stations dominated by flagellates differed from the equations for stations dominated by diatoms and dinoflagellates. The pigment ratio TChla/TP and the optical ratio a676/a440 were not constant but increased non-linearly with increasing TChla or TP; complimentarily the AP/TP and a490/a676 ratios decreased. There were significant non linear relationships between the photosynthetic parameters Fv/Fm or σPSII measured by Fast Repetition Rate Fluorometry and TChla or TP. Pigment ratios, optical ratios, Fv/Fm and σPSII were all inter-correlated with high significance. We determined the distinctive bio-optical properties associated with dominant phytoplankton functional types (derived by DPI) that conformed to the classical partitioning: flagellates (nano-plankton, comprising several taxa) had low biomass,low TChla/TP fraction and low Fv/Fm and high σPSII; diatoms and dinoflagellates (micro-plankton) had high biomass, pigment ratios, Fv/Fm and low σPSII.

The molecular diversity of dinoflagellate algae of the genus Symbiodinium in symbiosis with ten species of scleractinian coral, sea anemone and scyphomedusa in the Mediterreanean Sea was investigated by restriction analysis and sequencing of polymerase chain reaction-amplified fragments of SSU and LSU rRNA genes. All species bore Symbiodinium of clade A, apart from Bunodeopsis strumosa, which had clade B. The clade A sequences clustered with a previously described group, ‘temperate-A’, known only from the Mediterranean and Atlantic coasts of the UK and France. It is concluded that clade temperate-A is prevalent, but not universal, in the Mediterranean.

The relationships between three species of thecate hydrozoans, Sertularella crassicaulis, Sertularella ellisii and Aglaophenia tubiformis with three species of encrusting Corallinales, Pneophyllum fragile, Melobesia membranacea and Hydrolithon cf. farinosum from different locations in the western Mediterranean are described. In Aglaophenia tubiformis, algae were observed on the hydrotheca, while in Sertularella spp. they grew on the stem, the branches and the hydrothecae which became completely covered by encrusting, calcified thalli. The polyps were living in the covered theca. The hydroid species hosting Corallinales were a small fraction of the entire assemblages and this evidence suggests that hydroids cannot be considered as a simple, inert substrate. We hypothesize that this specificity could be explained by a different molecular composition of hydroid exoskeletons, and/or production of secondary metabolites that affect organism settlement. Moreover, perisarcal areas close to hydranths were more abundantly covered by algae, probably due to nutrient emission generated by the metabolism of the hydroid.

Rhodoliths were collected in Esperance Bay,Western Australia, using a Van Veen grab from a bed that covered an area approximately 2.2 km2, in depths of 38 ±1 m. Rhodolith abundance (biomass per 0.1 m3), mean size (maximum diameter), and morphotypes were compared among the inshore margin, offshore margin, and middle area of the bed. Accelerator Mass Spectrometry was used to estimate ages of five free-living rhodoliths. Rhodolith taxa included Hydrolithon munitum, Lithothamnion sp., an unidentified Melobesiodeae (a Mesophyllum or Synarthrophyton) and possibly a species of Sporolithon, with lumpy, warty, and fruticose morphologies. The middle area of the bed had significantly greater abundance of rhodoliths than either margin. Biomass of warty rhodoliths was greater in the middle area of the bed whereas fruticose and lumpy rhodoliths had similar biomass across the bed. The <20 mm size-class was the most abundant and these rhodoliths may originate from fragmentation of larger individuals. Radiocarbon age estimates ranged between calibrated ages of AD1050 and modern, indicating that a proportion of living rhodoliths consisted of fossil rhodoliths that had been recolonized. The combination of coastal morphology, gently-sloping sea-floor, hydrodynamics, and rhodolith morphology was representative of rhodolith beds found elsewhere in the world.

The effect of tidal emersion on the epifauna of three common British intertidal macroalgae, Cladophora rupestris (Chlorophyceae), Laminaria digitata (Phaeophyceae) and Fucus serratus (Phaeophyceae) was investigated. Tidally-induced migration of intertidal fauna is well documented, but the aim of this study was to determine the effect of algal complexity on the degree of change in epifaunal community structure between tidal states. The structural complexity of each algal species was determined by measuring the fractal dimension (D) of algal outlines (1.76, 1.23 and 1.11 respectively for the three species). In the case of L. digitata, a weighted value for D was used to take account of the varying morphologies of the holdfast, stipe and blade. The hypotheses tested were: (i) that increased algal fractal complexity is associated with increased abundance and diversity of associated epifaunal communities; (ii) that community composition is significantly reduced during emersion in intertidal algae (due to faunal migration); and (iii) that the degree of migration due to the receding tide is significantly reduced in more geometrically complex algae. Overall, faunal communities associated with C. rupestris were significantly more abundant and diverse than those associated with the other algal species investigated. No significant migration away from seaweeds was observed for any faunal taxon from any of the algal species studied during emersion. However, harpacticoid copepod abundance increased significantly on L. digitata at low tide. It is likely that these copepods were associated with the holdfast or underside of the lamina for protection from desiccation and the elements. This suggested an advantage associated with inhabiting low shore macroalgae during emersion compared with migration into the subtidal zone.

Harmeria scutulata, a cheilostome bryozoan with a circum-Arctic distribution, is an important component of intertidal and shallow subtidal rock communities. In terms of numerical abundance, H. scutulata can reach over 50% of total individuals within Arctic bryozoan assemblages. It is an annual, fast-growing species that loses over 70% of interactions for space with other organisms. Uniquely for a bryozoan, the subcircular colonies have large zooids at the centre ringed by a marginal zone of up to six generations of small zooids. This pattern is shown here to be due to polymorphism, reflecting a functional differentiation between large, feeding zooids (autozooids) and small, non-feeding zooids that brood embryos (gonozooids). The switch from the budding of autozooids to gonozooids occurs more or less simultaneously around the circumferential growing edge of the colony and is irreversible. Colonies apparently produce embryos only near the end of the growing season. Strong wave action and/or ice scour during the winter months destroys most of the colony but it is inferred that some of the gonozooids, which are more thickly calcified than the autozooids, overwinter, surviving into the spring and releasing their larvae to found a new generation of colonies. A formal systematic redescription of H. scutulata is given.

This paper is concerned with comparing the relative performance of small (0.1 m2) and large (0.25 m2) Hamon grabs for sampling the benthic macro-invertebrates from coarse offshore marine sediments. We present results based on an actual survey near the Isle of Wight, UK, but we also summarize and develop a statistical theory as well as demonstrate the theory using a small simulation study. Our results show that: the larger grabs are more difficult to handle, especially from small vessels; for a given sampling area the small grab can provide a more precise estimate of abundance than the larger grab if the individuals are clustered; the smaller grab can detect more species than the larger grab if individuals from the same species are clustered together (in our study, approximately 5% more species); and the smaller grab may undersample larger macrofaunal species and also species that live on larger cobbles.

We present theoretical equations to demonstrate the two samplers abilities to capture cobbles of different sizes. Multivariate techniques suggest that differences in the composition of the fauna collected using the different sized grabs are statistically significant, but small. It is more expensive to process samples from the smaller grab per unit area. However, per grab, the smaller grab is cheaper. We also present a model to demonstrate the effect on species occurrence and abundance.

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.

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 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.

The phylogenetic relationships were analysed based on nucleotide sequences of a mitochondrial gene for cytochrome c oxidase subunit I (COI) for the vestimentiferan tube worm Lamellibrachia juni, which inhabits three extremely acidic hydrothermal vent fields in the South Pacific: the TOTO Caldera in the South Mariana Volcanic Arc, the DESMOS site in the Manus Basin, and the Brothers Caldera in the Kermadec Arc. Six haplotypes were obtained from 34 lamellibrachiids from the three sites. Each haplotype was obtained only from a single site, which suggests that the three populations have been isolated from each other. Haplotypes from the DESMOS site formed a monophyletic cluster. All ten individuals from the TOTO Caldera were classified into the same haplotype, which was shown to form a monophyletic cluster with one of three haplotypes from the Brothers Caldera. The population in the Brothers Caldera was shown to consist of two genetically distinct groups.

Here we present evidence of seasonal reproduction in the deep-sea vent mussel Bathymodiolus azoricus, a dominant member of the Mid-Atlantic Ridge (MAR) hydrothermal fauna in the Azores region. This is the first time that seasonal reproduction has been suggested for any deep-sea vent organism. This discovery was made possible by the use of novel, acoustically-retrievable cages, which allowed us to extend the frequency and temporal range of sampling that was previously limited to the summer months. The main spawning peak, at the Menez Gwen vent field (840 m) occurs in late December–January and shows a correlation with a winter–spring bloom in primary production in the euphotic zone. Our results suggest that this surface-derived material may act as both a food source for the dispersing mussel larvae and as a reproductive cue/supplementary nutritional source for the adult mussels. Further evidence of a dependence on photosynthetic inputs comes from the relationship between particulate feeding levels, which themselves correlate with the phytoplankton peak, and the amounts of storage tissue in the mantle, which ultimately gets converted into gonad. Thus, the pattern and energetics of reproduction in the Atlantic vent mussel B. azoricus closely resembles that found in the coastal mussel Mytilus edulis, which has been described as an adaptation for optimizing the timing of reproduction against a background of seasonally-varying food availability. This discovery emphasizes the complexity of the nutritional pathways found in some deep-sea chemosynthetic environments and highlights the need for more time-series studies.

This paper is the first attempt to study the recruitment of Serpuloideans in a Mediterranean marine cave through the use of artificial substrates placed in three different positions, from the entrance to the interior of the cave. This study provides qualitative and quantitative data concerning Serpuloidea recruitment on panels removed successively after one, three, six and 12 months of permanence in the cave. A homogeneous distribution of juveniles Spirorbidae throughout the cave axis had already been detected after one month of panel immersion. Spirorbids were recorded also on panels removed after three months as well as serpulids, which began to be detected during this sampling time, even though represented by just one species. A significantly different pattern of distribution throughout the cave axis was observed after only six months, while other serpulids were detected for the first time. The pattern of species distribution seemed to reflect the biotic and environmental conditions of the cave. The highest serpuloidean species abundance and diversity was found on panels placed in the intermediate position within the cave. After only one year of panel immersion, a total of 20 taxa (11 Serpulidae and 9 Spirorbidae) was recorded, including five species listed for the first time in the marine caves of the Salento Peninsula.

The life history and reproductive biology of the gammaridean amphipod Melita palmata was studied in the Mar Chiquita coastal lagoon (Argentina). The animals were collected fortnightly or monthly from Ficopomatus enigmaticus reefs from December 2000 to March 2002. The population density reached a maximum of 1556.67±1560 ind/m3 (mean±SD) in March 2001, decreased dramatically after intense rainfalls in winter 2001, and had a minimum value of 141.67±27.54 ind/m3 (mean±SD) in March 2002. Size differed significantly between sexes. The maximum size of males was 11.5 mm and this was 1.4 times longer than the length of females. The average sex ratio (0.44) did not differ significantly from an expected 1:1 value. Ovigerous females were present from December to March, when the temperature was above 18°C. The body size of ovigerous females ranged from 2.9 to 6.81 mm. There was a positive correlation between the brood size and body length of ovigerous females, and the maximum number of eggs per female was ten. Recruitment took place during the whole breeding season; juveniles recruited at the beginning of the season matured at the end of the same season, those recruited late would probably reach maturity in the following season.

Orchomenella crenata is recorded for the first time from the Irish Sea. Some authors have previously questioned the validity of this taxon due to its morphological similarity with Orchomenella nana and have placed it in the synonymy of O. nana. The question of its validity is resolved by the re-description and comparison of both species.

The response of the shore crab Gaetice depressus to predation risk stimuli of either the octopus Octopus vulgaris or crushed conspecifics was examined at two different time phases in the activity rhythm (active and inactive period) by laboratory experiments. When octopus chemical stimuli were introduced to the experimental aquarium, the crab activity decreased in the active period (night) but not in the inactive period (daytime). When the chemical stimuli of crushed G. depressus were introduced, the activity of the crabs increased in the inactive period although the stimuli decreased the activity in the active period. This indicates that G. depressus adjust their anti-predator response according to a combination of the type of predation risk and also the activity rhythm.

Zoeal, megalopal and first crab stages of Pagurus nigrofascia are described and illustrated from laboratory reared specimens. Larvae were reared at temperatures 6°C, 12°C, 18°C, and 25°C. Survival rates of larvae were considerably higher at 12°C and 18°C, but were low at 6°C and 25°C. Larvae and postlarvae of P. nigrofascia can be distinguished from seven morphologically similar species based on adult or larval morphological features. Zoeal stages of this species are distinguished by, for example, setal formulae of maxillule, maxilla and maxilliped 1. The megalopal stage can be identified by the telsonal process, the number of articles of the flagellum of antenna and setal formula on the scaphognathite of the maxilla. Morphological features of P. nigrofascia larvae are similar to those of P. ochotensis, P. kennerlyi and P. pectinatus.

The present study investigates hourly variation in nocturnal abundance fluctuations in a tropical, Caribbean sea grass bed. As expected, results indicate that significant diel variation is present. In addition all dominant species show an abundance peak shortly after sunset, with numbers gradually declining throughout the night. It is therefore suggested that nocturnal samples are not only incorporated into any sampling regime, but that nocturnal samples are taken within two hours after sunset.

The scope for growth (SFG) calculated on measurements of physiological variables in juvenile of the predatory gastropod Chorus giganteus was compared with the actual growth under an energetic point of view. The continuous increase in the amount of food ingested and absorbed by C. giganteus was clearly related to the body size of the snails. The pronounced increase in the metabolic processes of respiration and excretion at the end of the study was related with the high rates of growth experienced by the snails under the experimental conditions. These results were supported by the correlation analysis where ingestion rate (r=0.99), oxygen consumption (r=0.88) and excretion rate (r=0.89) were significantly correlated with the actual growth (P≤0.05). Comparing the estimated growth curve (SFG) with that directly measured on juvenile individuals of C. giganteus, a high similarity in results was observed. The high sensitivity of the scope for growth argues for the use of this index as an adequate tool for estimating the growth of juvenile gastropod molluscs without interference from reproductive processes such as gametogenesis and spawning which may produce corresponding rises and falls in the biomass of individuals. Scope for growth is thus validated as a reliable measurement of the physiological/energetic condition of the organism, representing an effective index for indirect estimation of the growth of a species.

The behaviour of Cerithidea decollata, a common western Indian Ocean mangrove tree climbing gastropod, was studied in Mida Creek, Kenya. At the study site, this snail mainly lived in Avicennia marina dominated areas, i.e. in the mangrove belt between high water spring tide and high water neap tide levels. Not a single individual was found on the less common mangrove tree Lumnitzera racemosa, living just above the A. marina level (together with terrestrial grass), and was very rarely recorded on the common Rhizophora mucronata, bordering the seaward side of the A. marina belt. No significant gradient of C. decollata density was found within the whole 150–200 m wide belt. The majority of C. decollata rested on tree trunks during high tide, creeping on the mud flat below the tree for part of low tide, and returning on the trunks well before being reached by the water. This migratory pattern was more evident at spring than at neap tide, at day than at night time and it was strongly influenced by the shore level of the mangrove zone in which animals resided. While C. decollata from lower shore levels neatly massively migrated twice a day, individuals from upper levels showed a more continuous and irregular activity, sometimes crawling on the mud even at high water of spring tide, when they experience just a few centimetres of water for no more than one to two hours.