The decapod Crustacea from Ascension Island are reported upon on the basis of major expeditions undertaken during 2008 and 2012, including several minor additional collections made in other years. Two species, Gnathophyllum americanum and Corallianassa longiventris are new records for the island bringing the total known marine decapod fauna to 75 species, of which 11 are currently endemic to Ascension Island.

The following paper is to be regarded as the sequel of that published in the preceding number of this Journal, on the rate of growth and distribution of young marine fishes. I am still continuing inquiries of this character, and have now to record the additional results obtained up to the end of March, 1892. I have also described and criticised some of the results of other workers in the same field.

Space is one of the primary limiting resources for organisms on the intertidal rocky shore. This paper examined the effect of reduced density on key traits (mortality and growth) on the intertidal barnacles, Chthamalus montagui and Semibalanus balanoides, on the mid-shore in Plymouth, UK. Intra- and interspecific treatments comprising of C. montagui and S. balanoides were manipulated to reduce densities at two similar sites. Changes in mortality and operculum growth were assessed over an 8-week period using digital photography. Covariates of growth included nearest neighbour distance, competition between closest pairs and initial size. Conflicting patterns were observed when comparing growth rates between treatments and sites. At Site 1, interspecific treatments had a lower growth rate than intraspecific treatments, whereas at Site 2, interspecific growth rates were higher. ANCOVA showed that nearest neighbour distance had no significant effect on growth, but when comparing differences in growth of closest neighbouring pairs, C. montagui treatment showed evidence of competition whereas S. balanoides did not. ANCOVA analysis indicated no difference in growth between each outcome of pair competition, suggesting winners are initially bigger than losers. Comparisons of mortality between treatments indicated mortality over time with no significant differences observed between treatments, but response surface methodology (RSM) revealed no effects of competition on mortality of S. balanoides, but negative effects of both intra- and interspecific competition on C. montagui survivorship. Examination of natural populations of barnacles in the mid-shore indicated there was strong spatial variation in growth rates, perhaps driven by small-scale differences within sites.

The catfish Genidens barbus is a commercial species from South America. The aim of the present study was to examine the inter-annual variability in estuary-specific chemical signatures of otolith cores (Ba:Ca, Mg:Ca, Mn:Ca, Sr:Ca and Zn:Ca ratios) for three estuaries from Argentina and Brazil where adults were collected over multiple years. Secondarily, we evaluated whether the percentages of classification of individuals to their natal origin place are affected by the grouping of several cohorts. Most element:Ca ratios were not significantly different among year cohorts. Results from PERMANOVA revealed significant differences in the multi-element signatures of the otolith core between cohorts for the Plata River estuary (PR) (P = 0.006) and the Patos Lagoon (PL) (P = 0.03), while no significant differences (P = 0.9) were found for Paranaguá Bay (PB). The percentages of spatial classification (discriminant function analyses) decreased to between 15.5 and 25% for PR and PL when cohorts were grouped. This work makes it clear that the temporal variation in the chemical signature of the adult catfish otolith core can greatly affect the percentages of spatial classification.

A new species of Laeonereis from a shrimp farm associated with a subtropical coastal lagoon on the Mexican Pacific coast is described. The new species is characterized by a deep anterior groove on the prostomium, which is shared only with L. culveri. However, longer tentacular cirri extending back to the anterior margin of chaetiger two, the number of papillae of each group on the maxillary ring of the pharynx, and the relative size of the homogomph falcigers in the new species, allow us to separate the two species. Although the species has not been previously detected in the coastal lagoon surrounding the shrimp farm, we postulate that L. watsoni n. sp. is likely to be part of the invertebrate communities of the upper parts of similar coastal lagoons that are common along the tropical coasts of Mexico.

Nesting of hawksbill turtles (Eretmochelys imbricata) was monitored in 2013 and 2014 at 20 nesting beaches along the shores of Melaka, Peninsular Malaysia. Total nest numbers found were 481 and 463 in 2013 and 2014, respectively. The mean clutch size in 2013 of 123.5 ± 32.3 (SD) was similar to that in 2014 (118.5 ± 39.7). The distributions of nests were not uniform among the 20 beaches, and a large number of nests were found in Padang Kemunting, Kem Terendak, and Pulau Upeh, where the beaches were not always long. The nest sites indicated that the hawksbill turtle preferred to build its nest within the woody vegetation zone. The preferred vegetation species was Scaevola taccada. The temporal nesting pattern was year-round in both years, but the peak nesting season was between May and August, in the south-west monsoon season, possibly due to the gentle winds during this period. The turtles tended to nest between 22:01 and 24:00 h. This study provides basic information about hawksbill turtle nesting and insights into their spatial and temporal nesting preferences, which will contribute towards the conservation of this endangered species.

Quantifying exchange of particulate matter between coastal and open waters is an important and often unresolved issue. Here, we apply phytoplankton order richness as an innovative marine tracer to identify the geographic position of a coastal exchange zone in the SE North Sea, including its variability in time and space. Previous observations on dynamics of suspended particulate matter accumulation resulted in a hypothesized boundary between coastal waters (including the Wadden Sea) and open North Sea waters, the so-called ‘line-of-no-return’. Our study along two transects (Terschelling, Noordwijk) in the Dutch coastal zone showed seasonality patterns in phytoplankton order richness, both for diatoms and flagellates. The coastal Wadden Sea was found to be clearly different from the open North Sea, implying that seasonality in Wadden Sea phytoplankton is at least partly driven by local environmental conditions. Seasonality in flagellates was found to be more uniform than seasonality in diatoms. Stations in the coastal North Sea to a distance of 10 km (Terschelling) to 20 km (Noordwijk) from the shore appeared to be at the inside of the ‘line-of-no-return’. Our findings indicate that this approach is a useful aid in exploring mixing of particulate matter between coastal and open waters and to study the responses of phytoplankton communities to environmental drivers.

Understanding demographic processes over multiple spatial scales is vital for the optimization of conservation/management strategies, particularly for commercially harvested taxa such as the brown crab (Cancer pagurus L). Brown crab population genetic structure was investigated at (i) a local scale within the Irish Sea, which included comparisons with the Lundy No Take Zone (NTZ) and (ii) across the NE Atlantic. The results indicate that the brown crab does not exhibit strong spatial structure either within the Irish Sea or at the regional level, suggesting high gene flow within and among the Irish Sea, English Channel and North Sea. Comparisons between the Lundy NTZ and harvested areas revealed similarly high levels of genetic diversity. An intriguing result was that the Lundy NTZ sample exhibited a degree of genetic patchiness (ephemeral geographically unpatterned differentiation) which may indicate elevated recruitment skews within the NTZ. Overall, the results support the view that brown crabs within the sampled area belong to a single genetically panmictic stock and that if breeding stock sizes are maintained genetic drift will not be strong enough to reduce neutral genetic diversity. The highly connected nature of this species requires international cooperation for sustainable management, an important component of which will be the application of more powerful population genomic approaches to assess finer scale aspects of stock structure as well drivers of genetic patchiness reported for the species. This is a timely consideration in light of potential future misalignments between biological and geopolitical stock boundaries in the Irish Sea following Brexit.

A second species of angler-fish, Lophius budegassa Spinola, 1807, is reported from British waters. This species has hitherto been reported only as far north as the Bay of Biscay. This is not thought to be an active extension of the range of this fish but to be due rather to failure to identify it, for specimens (misidentified as L. piscatorius) dating from the last century have been found in the British Museum (Natural History) collection.

The distinctive characters of both species are given.

The higher taxonomic structure of the meiofaunal community was investigated in three eastern Mediterranean lagoons, an open (Vassova), a semi-closed (Piges) and a closed lagoon (Alykes Kitrous). In total, 22 stations representing characteristic features in each lagoon were sampled. Stations were found to support a maximum of 19 meiofaunal taxa with densities ranging from 1 to 10,000 individuals per 10 cm2. Nematodes were dominant at all sites (30–97%) except at the hypersaline sites, where ciliates outnumbered all metazoan meiofaunal taxa (53–77%). Uni- and multivariate analyses were applied to study the community structure. The number of taxa and the meiofaunal density showed strong spatial differences in all three lagoons; however, the main source of variation occurred between the semi-closed and closed lagoons. Both the meiofaunal composition and density were significantly less at the hypersaline sites which had salinity above 100 psu. The meiofaunal distribution pattern was shown to be controlled by abiotic factors, in particular vertical stratification of salinity, bottom water currents and oxygen availability at the bottom water–sediment interface. However, the distribution of feeding resources (e.g. cyanobacteria, phytodetritus) was also found to play a key role in structuring meiofaunal communities.

1. The copper content of sea and river waters can be rapidly determined using the sodium diethyl-dithiocarbamate method followed by extraction with chloroform.

2. This solvent takes up only traces of the natural colouring matters found in waters, but blank estimations should be made with some river waters and occasionally with sea-waters on account of the presence of plankton.

3. Carbon tetrachloride can be used instead of chloroform as solvent, it extracts less per unit volume, but the volume recovered is larger, the resultant yield being identical. Amyl alcohol extracts more than chloroform, but the volume recovered is smaller, the resultant yield being about 0-8 times that of the others. The alcohol takes up more colouring matter from river water, does not separate as readily as the others, and floats, whereas they, more conveniently, sink. For work in hot climates its higher boiling-point may be an advantage.

4. In fresh water iron salts in large excess might cause error; this can be checked by the electro-deposition method.

Although marine phylogeographers have accumulated knowledge of the evolutionary history of various invertebrates, there is a large bias among the taxa regarding genetic data. The order Polycladida is a typical example for which little genetic information at population level is available. Here, we focused on the polyclad flatworm Stylochoplana pusilla, distributed in the Japanese Pacific coastal area. Stylochoplana pusilla is known to have commensal relationships with certain intertidal snails, using snails (mainly Monodonta confusa) as a refugee house. During low tide, S. pusilla hides in the mantle cavity of snails to protect themselves from desiccation and predation. Here, we investigated the genetic structure of S. pusilla using a mitochondrial Cytochrome Oxidase I marker and the species diversity of snails used by it. We found that S. pusilla has high genetic diversity of its populations. While S. pusilla showed a significant genetic differentiation among populations, it was relatively low. In addition, we also showed that S. pusilla used several intertidal snail species which inhabit various coastal environments. The present study suggests S. pusilla has sufficient dispersal ability to connect among its local populations. Also, the range of available snails for S. pusilla may help the connectivity among local populations. We provide important knowledge about this invertebrate taxon with a unique ecology, which has been insufficiently studied.

Rapid shell closure in articulate brachiopods, occurring by a twitch contraction of the the ‘quick’ adductor muscles, is a response to disturbance or to physiological requirements of the organism. The relative simplicity of the closing system permits a detailed analysis of the functional architecture of the mechanism and the underlying principles of skeleto-muscular organization, in terms of (1) basic kinematic properties of the system (speeds and times of closure), (2) hydrodynamic reactions resisting closure, and (3) considerations of muscle physiology and mechanics.

Analyses of shell closure in the brachiopods Terebratulina retusa from the Firth of Lorn, Scotland, and Terebratalia transversa from Puget Sound, USA, reveal (1) shell-closing times of the order of 50 to 70 ms, (2) closing velocities of the order of 3·5 radians s-1, from initial gapes of about 0·05 to 0·2 rad, and (3) muscle moment forces and hydrodynamic reactions with magnitudes of the order of 5 × 10-4 N m (5 g cm). Muscle tensions developed in the ‘quick’ adductor muscle are of the order of 105 N m2, and contraction velocities are of the order of one muscle length per second. Hydrodynamic reactions are a fundamental constraint on the closing mechanism, as determined by the concordance of actual closing events with predictions of a hydrodynamic model.

Specimens of Opisthoteuthis grimaldii were video recorded in a shipboard aquarium and their behavioural traits, such as bottom resting, flat-spreading, web-inversion and ballooning response, were described. Ballooning, as defence response, has been recorded only for cirrate octopod families with an intermediate web (Cirroteuthidae: Stauroteuthidae), and this structure has been supposed to be essential for developing this behaviour. Members of the Opisthoteuthidae family lack an intermediate web, indicating that this is a common defence response in cirrates, expressed in a basic form in the Opisthoteuthidae, offering an illustration of how this behaviour can evolve.

Age and growth of the snipefish was studied based on samples collected in the Portuguese continental waters between 1996 and 1998. Analysis was conducted for two species, Macrorhamphosus scolopax and M. gracilis and for both species combined. Total length ranged from 5.5 to 18.2 cm for M. scolopax and from 5.4 to 17.3 cm for M. gracilis. Length–weight relationships were described for M. scolopax (a=0.00401; b=3.127), M. gracilis (a=0.00459; b=3.006) and both combined (a=0.00240; b=3.282). Age estimation, based on otolith observations, resulted in six and five years maximum age attributed to M. scolopax and M. gracilis, respectively. Back-calculation analysis based on a polynomial relation of the otolith radius on total length provided significantly smaller lengths-at-age compared with observed lengths. The von Bertalanffy growth curves fitted to observed lengths-at-age provided parameters of L∞=15.7 cm, K=0.654, t0=−1.066 for M. scolopax; L∞=14.2 cm, K=0.694, t0=−0.954 for M. gracilis and L∞=15.8 cm, K=0.470, t0=−1.408 for both species combined.

Chromatic polymorphisms in shells may be associated with adaptive characteristics in molluscs. Colouring among Hastula cinerea reveals different patterns in large aggregations of individuals. Although the impacts of temperature are considered critical in the intertidal region, selective effects associated with colouring in H. cinerea shells, in addition to possible physiological consequences, remain an open issue. In this context, H. cinerea is a viable evolutionary model for investigating selective processes related to chromatic polymorphism in shells given its abundance and biological characteristics. Individuals from the same population were classified into three groups according to shell colour: light, reddish and dark. They were then examined with regard to frequency of colour morphs and morphological patterns in each group. Reddish and light-coloured specimens were the most abundant, while those with dark coloration were less common and morphologically distinct from the first two colour morphs. Morphological differences in the anterior region of dark shells, which may be associated with movement ability and lower frequencies in these specimens, suggest possible selective effects on types that are less reflective to light in the intertidal zone.

Typical marine arthropods (crustaceans and halacarid mites), as well as species of recent terrestrial ancestry (insect larvae and mesostigmatid mites) coexist on mangrove pneumatophores. Both groups are affected by desiccation and are less abundant towards the tips of the pneumatophores. The degree of species associations within and between the two groups was investigated. The number of negative associations is higher for marine–marine, as compared to terrestrial–terrestrial and terrestrial–marine species pairs. When environmental stress (as represented by direct sunlight, and elevation on pneumatophores, both resulting in increased desiccation) is considered, associations tend to shift from negative to positive, and this is more obvious in terrestrial–terrestrial species pairs. These results are attributed to the longer co-evolutionary history of the marine species, resulting in a more precise partitioning of the microhabitats, while the relationships between terrestrial species are less stable, and more susceptible to environmental stress.

Some of the limits to the use of serology to identify prey species in the digestive tracts of cephalopods have been evaluated. Cuttlefish, Sepia officinalis, were given meals of krill slurry (Euphausia superba). Protein extracts of contents from four regions of the digestive tract, stomach, caecum, digestive gland and intestine, were tested for prey antigenicity. Digestion times (loss of antigenicity) ranged from 1 to 8 h depending on sampling site. Stomach and caecum emptied rapidly, but meal antigenicity persisted longer in the digestive gland. The Sepia experiments provide a basis for interpretation of results from natural predation by cephalopods).

In this study, polyploidy level was determined by flow cytometry analysis. The effect of polyploidy by colchicine treatment was examined on the growth parameters, malondealdehyde (MDA), as well as activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in response to different levels of salinity in Dunaliella salina. The results of algal growth indicated that 3 M NaCl was the optimal concentration of salt, since the highest enhancement in fresh and dry weight, chlorophyll and carotenoids, soluble sugar, glycerol, protein and starch content was observed in comparison to other concentrations. The amount of these metabolites declined in the concentrations under optimum salinity. The least and highest amounts of MDA were observed at 1 and 4 M NaCl respectively. Polyploidy in optimum concentration of salt, caused further increment of the above growth parameters. In relation to this, in most cases, treatment of 0.1% colchicine was most effective. The beneficial effects of polyploidy in non-optimal conditions were also found in some parameters such as biomass, chlorophyll, carotenoids, proteins and starch. Furthermore, the activity of antioxidant enzymes CAT, SOD and POD showed a positive significant correlation with salt stress and these were maximized at 4 M NaCl. Polyploidy (especially colchicine 0.1%) affected activity of these antioxidant enzymes in some concentrations of salt. Overall, our results suggest that the microalgae has significantly different responses to salt stress based on ploidy levels.

(1) The tidal cycle and that of solar elevation interact to produce patterns in seabed irradiance during the day which change over the springs-neaps cycle. In locations where high water springs is at midday, there is a single peak in seabed irradiance in the middle of the day at neap tides and two peaks in seabed irradiance (one in the morning, the other in the evening) at spring tides.

(2) These cycles also interact to produce a springs–neaps cycle of daily mean irradiance, which is relevant to the growth of benthic algae. The pattern of this cycle will also vary from place to place. In locations where low water springs is in the middle of the day the pattern is straightforward: maximum daily irradiance always occurs at spring tides. However, where high water springs is in the middle of the day, the cycle can reverse as the days get longer. The timing of the switch in the cycle depends upon the water clarity.

(3) Variations in attenuation over the springs–neaps cycle will also be important. In the Menai Strait, a springs–neaps cycle in K is often (but not always) observed, higher attenuations occurring at spring tides when seabed sediments are stirred up by the stronger tidal currents. This will reduce seabed irradiance at spring tides and tend to favour greater irradiance at neaps. In our model runs, K was kept constant because at present it is difficult to predict these changes. However, in our observations there is evidence of greater seabed irradiance at neap tides associated with greater water clarity. Variations in cloud cover during the day can also affect the regular cycles predicted by the model.

The authors are grateful to Professor Ernest Naylor for encouragement and for information on animal behaviour and light. Members of the Marine Optics Group at Menai Bridge helped with the sampling during the experimental work in July 1994.