The distribution, abundance and recruitment of Chthamalus species were studied for one year at two rocky shores on the central coast of Portugal. Chthamalus montagui is the most abundant intertidal barnacle on the Portuguese mainland. Higher abundance of C. montagui was found on the lower levels of the more sheltered shore, which is closer to the influence of the Tagus estuary. Chthamalus stellatus was also present, in very low densities, and always confined to the lower level of the barnacle zone. Chthamalus stellatus was more common at the shore farther away from the estuary, in which exposure to wave action is higher. The metamorphs of C. stellatus settled at the studied shores are considered to be immigrants from other populations, where the density of adults is sufficient for cross-fertilization to occur. Chthamalus spp. recruited almost continuously throughout the year, with a peak between July and September and a gap during February and March. Variations in phytoplanktonic assemblages and temperature may be the main factors controlling the reproductive season of Chthamalus spp. Recruitment was usually stronger on the lower shore levels but extended for a longer period higher on the shore. Seasonalvariations of C. montagui abundance were greater on the lower levels of the more exposed shore. This is probably due to faster growth and higher mortality of barnacle populations occupying the lower shore levels at the more exposed habitats.

This work aimed to test whether the colour variability featured by the European nudibranch Polycera quadrilineata is consistent with the concept of a single polychromatic species or may hide multiple lineages. Samples from across the geographic range of P. quadrilineata together with representatives from worldwide species with a focus on Atlantic diversity, were gathered and studied using an integrative taxonomic approach. Morpho-anatomical characters were investigated by light and scanning electron microscopy. Bayesian molecular phylogenetics using MrBayes, the Automatic Barcode Gap Discovery species delimitation method, and haplotype network analysis using the PopArt software were employed to help delimit species using the mitochondrial gene cytochrome c oxidase subunit I (COI). The results supported the existence of a second species, here described and named Polycera norvegica sp. nov., only known from Norway where it is sympatric with P. quadrilineata. The COI uncorrected p-genetic distance between the two species was estimated at 9.6–12.4%. Polycera norvegica sp. nov. differs by exhibiting a black dotted or patchy dotted pattern occasionally with more or less defined orange/brown patches, but never black continuous or dashed stripes as in P. quadrilineata. The two species share a common colouration with a whitish base and yellow/orange tubercles. Anatomically, P. norvegica sp. nov. has a weaker labial cuticle, a smaller radula with fewer rows, and only four marginal teeth, a reproductive system with a single lobed bursa copulatrix, shorter reproductive ducts, and a penis armed with two kinds of spines: needle-like and hook-shaped penile spines.

Alien polychaetes belonging to the genus Marenzelleria were recorded from the mouth of the Don River and Taganrog Bay in the Sea of Azov in February–March 2014. Morphological characteristics varied greatly and matched those of two species: M. neglecta and M. arctia. Some individuals did not match the descriptions of both species. A genetic study using different sequences (primarily COI, but also 16S, 28S, cytb and nuclear histone 3a) showed that only M. neglecta was present despite some morphological mismatches. A morphological description of the species according to the new data is presented, together with a revised table of variability of the key numeric characters. Since 2014, Marenzelleria has spread swiftly and become dominant in a considerable part of the Taganrog Bay, making up to 91% of the total abundance/biomass (6800 ind. m−2 and 31.2 g m−2, respectively). Monodominant sites were also present. Its occurrence is 100% in recent surveys. Such a sharp increase seems to be due to a lack of detritophages in the bay; this is supported by the fact that M. neglecta has not formed its specific assemblage. The community structure, if M. neglecta is excluded, is equal to that before the invasion. In the Sea of Azov itself, M. neglecta is not as abundant, but occurs up to the Strait of Kertch and at some sites in the Black Sea. Its spread further into the Black Sea seems possible, as well as into the Caspian Sea via the Volga-Don Canal.

Trochosphekes of Nephthys hombergi Lamarck are readily obtainable at Plymouth when the adult worms are mature from June to September. The worms are dug out of the muddy sand on the lower regions of the shore, and their eggs and sperms obtained by slitting open the body cavity. Fertilizations are easily made in glass finger-bowls of clean sea-water. Although apparently ripe worms have been kept under sea-water circulation in the laboratory, and under a variety of conditions, none has ever been induced to spawn naturally. After some days the body walls of some individuals have split along the back and shed their genital products in that way; these, however, were probably unhealthy and abnormal. A high percentage of the eggs got by cutting open the worms have fertilized and given rise to cultures of strongly swimming larvæ. During the summers of 1932–34 much time and effort were expended in numerous attempts to rear these larvæ, but in no single instance was success obtained. It had been hoped to collect material for a detailed histological study of the development, for it may be of a straightforward and simple type that would throw light on various problems of Polychæte embryology. Although these hopes have not been realized it seems of value to describe the trochosphere of which no entirely satisfactory account exists, in spite of a few references to it by previous writers.

The temperature of the sea and the movements of water carrying with it planktonic organisms have been the subject of study since the early days of marine biological research. As investigation of cold-blooded marine animals progresses, the controlling r61e played by the temperature of the surrounding water upon their breeding, rate of growth, and general metabolism, becomes increasingly evident.

In the past few years considerable attention has been paid to the distribution of the microflora of the salt marshes at Gibraltar Point, Lincolnshire (National Grid reference TF 555576). During these studies it was observed (Turner, personal communication) that blue-green algae (Myxophyceae) were of frequent occurrence in soil samples from the region, but no analyses of the algal flora were carried out. It is well established, however, that blue-green algae are generally present in salt marsh regions (Chapman, 1960 a). Previous studies on the blue-green algae of British salt marshes are few, although detailed investigations have been carried out at Canvey and Ynyslas (Carter, 1932, 1933 a, b) and Scolt Head Island (Chapman, 1939). Some difficulty is experienced, however, in attempting to correlate these results with present day studies, mainly because of the widespread colonization of salt marsh regions within recent years by Spartina townsendii H. & J. Groves, and by the fact that few quantitative data are available. It is hoped that the present communication which is concerned with the blue-green algal flora of the New Marsh at Gibraltar Point, a region dominated by Spartina townsendii, will allow an assessment to be made of the flora prevailing in a developing salt marsh under present-day conditions.

From July 1955 to June 1956 a study of host-parasite relations between three species of marine fish and their Protozoa was made at Plymouth. Callionymus lyra, a bottom-dweller, tends to be more abundant during the summer months, consumes a wide variety of food, and was more heavily infected with Protozoa than were the other two species offish. Gadus merlangus is an active predator, feeding on small fish, and although it has about the same numbers of kinds of Protozoa as does C. lyra, it was less heavily parasitized. G. merlangus, however, was more heavily parasitized with worms than were the other two fish. Microstomus kitt is a sluggish bottom-dweller, feeding on annelids, and, although over 99% were infected with myxosporidia, the intensity of infection was generally low. Very few other parasites were found in M. kitt.

An active predatory habit combined with a taste for a wide variety of food appears to predispose to heavy parasitism. Some evidence for seasonal variations in intensities of protozoan infection in Callionymus lyra was obtained, but for conclusive results more precise methods of measuring numbers of parasites, and further studies carried on over a period of at least three consecutive years, must be made. The report is presented primarily to emphasize the importance of an ecological approach to the study of parasitology.

Todarodes sagittatus (N=1131) were opportunistically sampled from commercial and research trawling in Irish and Scottish waters between 1993 and 1998. The results suggest that the species is common in deep waters (>200 m) to the west of Ireland and Scotland, particularly in late summer and autumn. The size of squid caught was related to depth, with larger squid caught deeper, and is indicative of an ontogenetic, bathymetric migration. Females were more common (sex ratio 1·00:0·46), and attained a larger maximum size (520 mm mantle length (ML)) than males (426 mm ML). Mature females (360–520 mm ML) were caught in deep water (>500 m), between March and November, with a large catch of mature females taken off the west coast of Ireland in August 1996. Mature males (300–426 mm) were found from August to November. Potential fecundity was estimated to range from 205,000–523,500 eggs female−1. Putative daily increments in statoliths indicated a life cycle of slightly over a year, with rapid growth of approximately 1·8 mm d−1 during subadult and adult life. Fish were the most important prey of T. sagittatus and 17 fish prey taxa were identified, of which pelagic species were the most important.

Competition plays an important role in invasion dynamics. According to Elton's biodiversity and invasibility hypothesis, non-native species must be competitively superior to the resident species in order to successfully invade. An invader that is ecologically similar to a native species may cause intense interspecific competition as they both require the same resource. Furthermore, an increase in the density of an invading competitor may enhance the intensity of the competitive interaction, however, this may be reduced if the inferior competitor has a refuge that reduces the amount of time it is in direct contact with the superior competitor. In laboratory-based competition experiments between the non-native caprellid Caprella mutica and two ecologically similar native caprellids Caprella linearis and Pseudoprotella phasma, C. mutica successfully displaced both species from homogeneous artificial habitat patches after 48 hours. Patches that contained a refuge reduced the number of C. linearis being displaced but only when C. mutica was at a low density. Potentially aggressive interactions between C. mutica and the native C. linearis may have caused C. linearis to be displaced from the patches and could have caused significantly higher mortality of C. linearis compared to the controls. This is the first study to show that the non-native C. mutica has the ability to displace ecologically similar native species when the resource space is limited and when the density of C. mutica was significantly (10 times) lower than the density of C. linearis.

Patterns in community structure of meiofauna and macrofauna in relation to Portuguese clam dredging were compared during a 2-y-period off Lagos and Vilamoura, south Portugal. SCUBA divers randomly sampled corer and quadrat samples before and immediately after simulating commercial dredge fishery. Univariate measures (abundance, number of taxa, evenness, diversity and biomass) and multivariate analyses (Cluster, MDS and SIMPER) revealed changes in the meio- and macro-benthic community structure caused by dredge disturbance (short-term effects), with a general decrease in all measures. Macrofauna were found to be more sensitive to dredge disturbance, and aggressive predatory behaviour was observed after disturbance in the continuously dredged area. Nevertheless, higher significant natural changes were found between seasonal periods, indicating that dredging may only cause a small-scale and short-term impact.

Mucus, leaving the pyloric duct in a continuous flow, is conveyed over the epithelium of the aboral part of the pyloric stomach. There nutrients are resorbed and concentrated into the haemal system, which is in close contact with this part of the stomach. It is supposed that this material consists of nutrients in complex form especially destined for the use of gonad development.

The present study investigated the population dynamics of Hepatus pudibundus in the Cananéia region, in southern São Paulo state, Brazil, focusing on population structure, growth parameters, longevity, sex ratio, reproduction and recruitment juvenile period. Sampling was performed monthly at seven stations from July 2012 to June 2014, using a shrimp fishing boat. A total of 1650 specimens were collected: 551 males and 1099 females. The males were larger than females. Reproductive females were captured throughout the study period and juveniles were captured in most months. Both of these demographic categories were positively correlated with temperature. Growth parameters showed differences between sexes: CW∞ = 78.91 mm, k = 0.0066 day−1, t0 = 0.0965 for males and CW∞ = 69.71 mm, k = 0.0053 day−1, t0 = −0.2404 for females. Longevity was estimated at 1.91 and 2.40 years for males and females, respectively. The findings provide a greater understanding of the life cycle in this species. Additionally, since trawl nets are not selective, this study also provides information for better trawl fishery management, addressing not only the target shrimp but also the by-catch species.

1. A study of the adult population of Sagitta setosa J. Müller has been made in the waters off Plymouth by weekly collections with the 2-metre stramin ring-trawl hauled obliquely in the daylight.

2. Measurements of samples and a study of the state of development of the gonads has shown that there were apparently at least six broods of S. setosa during the period September, 1930, to August, 1931, inclusive.

3. The successive broods were apparently spawning in September and October, 1930, and February, April-May, June, and July-August, 1931.

It was recently suggested (Boney & Corner, i960,1962a) that, contrary to the theory of complementary chromatic adaptation, the accessory pigment phycoerythrin might not be involved in photosynthesis by sporelings of the intertidal red alga Plumaria elegans (Bonnem) Schm. but is used primarily as a means of protecting the plant from excess green light in the wave-band 500–540 mμ. This work, however, was done with one species only, and concerning the wider question of marine red algae in general, it seemed possible that the role of phycoerythrin might vary with ecological distribution. Thus, plants completely submerged and thereby excluded from most red light would use their accessory pigments for photosynthesis (energizing chlorophyll a indirectly); but plants adapted to long periods of normal daylight would be similar to Plumaria in relying to a much greater extent on chlorophyll a alone for photosynthesis, and use their accessory pigments as protection against inhibitory green light.

Species of the cyclopoid copepod genus Oncaea are commonly polymorphic. Using material from several localities, forms of O. venusta Philippi, O. mediterranea Claus and O. conifer a Giesbrecht are described, and specimens of two closely related and morphologically similar species, O. ornata Giesbrecht and O. englishi Heron, are compared. The integumental pore signature patterns of all these species are mapped from stained, tissue-free integuments. Each species has its own characteristic pore signature pattern and sexual dimorphism is confined to the urosomal pore pattern. Similarly the prosomal pore patterns of female copepodid 5 do not usually differ from those of adult females, but urosomal patterns are distinct. Juveniles of O. conifera are exceptional in this respect; their prosomal pore pattern lacks the detail of the adult pattern. Differences in the pore signatures of O. ornata and O. englishi confirm their status as separate species. Signatures in the O. conifera ‘group’ may also prove to be distinct. Whereas intraspecific variation in pore signatures may exist at a level below the resolution of this technique, such small morphological differences should be considered to be taxonomically insignificant.

The implications of polymorphism in the process of speciation, and the mechanisms by which the polymorphic forms are maintained are discussed.

Scanning electron microscopy and light microscopy are used to examine the morphology of pores and their associated sensilla. Three types of sensilla are described, peg, short-hair and long-hair sensilla.

A considerable seasonal variation in the vitamin B12 concentration in oceanic surface water has been demonstrated by Cowey (1956).

The present investigation was undertaken to examine any variation with depth.

Data from several sources and original data are presented regarding sightings, strandings and incidental captures of leatherback sea turtles (Dermochelys coriacea) on the Brazilian coast in a 33 year period, from 1969 to 2001. Two of the turtles were small juveniles (curved carapace length=40 cm and approximately 85 cm) and the remaining animals with known carapace size were large juveniles or adults. The origin of leatherbacks observed in Brazil is unknown. Several colonies in South America, including a Brazilian one, in the Caribbean, in western Africa and even in eastern South Africa could be the source of these turtles. The data presented here suggest that more effort should be directed to the assessment of the impact of fishing gear and marine pollution on leatherbacks and that systematic surveys on beaches should be maintained in order to monitor long term fluctuations in stranding levels and spatial stranding patterns. Genetic studies and satellite telemetry would be helpful in clarifying the origin of leatherbacks stranded or incidentally captured on the Brazilian coast.

Measurements of gill dimensions in relation to body weight have been carried out in a mudskipper, Boleophthalmus boddarti. The data was analysed with respect to body weight using logarithmic transformations (log Y = log a + b log W). The slope (b) of the log/log regression lines for the gill area, total filament length, average number of secondary lamellae/mm, bilateral area of an average secondary lamella, and total gill area/g were 1·0496, 0·427, -0·229, 0·851 and 00496 respectively.

These results indicate variations in growth patterns for the different dimensions of the gills. The analysis shows that the increase in gill surface area with the body size is mainly due to an increase in the area of individual secondary lamellae and, to a lesser extent, an increase in filament length and total number of lamellae.

The average weight-specific area for 14 specimens measured (3·6–35·4 g) was 108–15 mm2/g. This value is consistent with results obtained with some other intertidal species.

Marked differences were found in the thickness of the water/blood barrier, which is thinner around the marginal channels. Morphometric diffusing capacity taking this heterogeneity into account was estimated as 0·0208 ml O2 min1 mmHg−1 kg−1.

INTRODUCTION

Morphological studies on the gills of many fish have shown adaptations of the basic structure which can be related to the particular mode of life. Among these adaptations, air-breathing species show many remarkable structural modifications (Munshi, 1976), which extend to the gills forming air sacs in species such as Heteropneustes fossilis (Hughes & Munshi, 1979). Fish which inhabit the intertidal zone, like other seashore animals, are subjected to periodic exposure to air, which may produce problems of water loss and reduction in support for the gills, with consequent collapse and restriction of gas exchange surfaces.

The development of the hydroid of Amphinema dinema (Peron & Lesueur) has been followed in the laboratory until the production of young medusae and the hydroid identified as Perigonimus serpens Allman.

The hydroid of Amphinema rugosum (Mayer) is described for the first time. It is very similar to P. serpens but more robust.

The hydroid has been reared from Rathkea octopunctata (Sars); it is very minute and the hydranths possess a single whorl of long filiform tentacles/

A small Cuspidella hydroid was reared from Mitrocomella brownei (Kramp).

Certain points in the synonymy of these species are discussed. An account of the methods of rearing used is also given.

The Heteractis magnifica assemblage at the tip of the Sinai Peninsula was examined. The actinian size, location, and number of resident anemonefishes were recorded. The anemones were found at depths down to approximately 40 m and the sizes of clustering H. magnifica and clusters were positively correlated with depth. The shallow waters of the anemone assemblage contained few mainly small, solitary actinians. There seemed to be a tendency for solitary actinians to cluster once they reached a certain size-range. The resident anemonefishes Amphiprion bicinctus and Dascyllus trimaculatus were present in very large numbers (approximately 250 and 1800 respectively) and the A. bicinctus home range size was positively correlated with depth.