Crabs from the Mithrax–Mithraculus species complex are known for their diversity of lifestyles, habitats, and coloration. This group includes small, colourful, symbiotic species and much larger, reef-dwelling crabs targeted by fishermen. The evolutionary relationships between the species within this complex are not well-defined. Previous studies based upon morphological characters have proposed the separation of this complex into two genera (Mithrax and Mithraculus), but cladistic analyses based upon larval characters do not support this division. A molecular phylogeny of the group may help to resolve this long-standing taxonomic question and shed light on the ecological conditions driving the diversity of these crabs. Using a 550-bp alignment of the 16S rRNA mitochondrial DNA segment we examined the phylogenetic relationships between 8 species within the Mithrax–Mithraculus complex native to the Caribbean. The resulting phylogeny indicates that this complex is paraphyletic, as it includes the genus Microphrys. The analyses revealed a well-supported, monophyletic group containing four species of Mithraculus (M. cinctimanus, M. coryphe, M. sculptus and M. forceps) and supported one pair of sister species from the genus Mithrax (M. caribbaeus and M. spinosissimus). No complete segregation of species, according to genera, was evident, however, from tree topologies. Bayesian-factor analyses revealed strong support for the unconstrained tree instead of alternative trees in which monophyly of the two genera was forced. Thus, the present molecular phylogeny does not support the separation of the species within this complex into the genera Mithrax and Mithraculus. A review of the literature demonstrated considerable phenotypic variation within monophyletic clades in this group.

Twelve hyper-β carotene-producing strains of algae assigned to the genus Dunaliella salina have been isolated from various hypersaline environments in Israel, South Africa, Namibia and Spain. Intron-sizing of the SSU rDNA and phylogenetic analysis of these isolates were undertaken using four commonly employed markers for genotyping, LSU rDNA, ITS, rbcL and tufA and their application to the study of Dunaliella evaluated. Novel isolates have been identified and phylogenetic analyses have shown the need for clarification on the taxonomy of Dunaliella salina. We propose the division of D. salina into four sub-clades as defined by a robust phylogeny based on the concatenation of four genes. This study further demonstrates the considerable genetic diversity within D. salina and the potential of genetic analyses for aiding in the selection of prospective economically important strains.

Two seahorse species, Hippocampus spinosissimus and Hippocampus trimaculatus, sampled in east and west coastal waters of Peninsular Malaysia, fed mostly on crustacean prey; small caridean shrimps and amphipods as adults (both species), and copepods and larval meroplankton as juveniles (for H. trimaculatus only). The similar short relative gut length (~0.4) of both species is consistent with a carnivorous diet. Both species are considered specialists in prey selection, focusing on slow-moving epibenthic, hyperbenthic and canopy-dwelling crustaceans that dwell on the mud-sand seabed, or are associated with seagrass or mangrove areas. In this light, seahorses with their juveniles in shallow waters are vulnerable to coastal reclamation and development.

Coral communities of the Persian Gulf (PG) withstand maximum and annual ranges of water temperatures that surpass those found on the majority of reefs elsewhere. As such, these communities may inform on how coral reefs might adapt to the warmer waters of the future. Depending on the algal symbiont (genus Symbiodinium) harboured, advantages in stress tolerance may be conferred to the coral holobiont. Characterizing the algal component is therefore critical in determining the coral holobiont's tolerance phenotype. Coral associations off the Arabian coastline of the PG have been characterized as biogeographically unique, containing a rare group of taxonomically ancestral and thermotolerant algal symbionts, the Symbiodinium thermophilum group. In contrast, waters off the Iranian coast remain poorly characterized with a notable lack of S. thermophilum group symbionts identified in coral associations to date. Here, we characterize the algal component of two reef building corals (Porites harrisoni and Cyphastrea microphthalma) predominant at three sites spanning almost the entire length of the PG's Iranian coast. Genotyping using the chloroplastic 23S and nuclear ITS2 genes, we demonstrate the presence of S. thermophilum group symbionts. We discuss the probable physical drivers of these associations and highlight the need for further research in these relatively understudied waters.

1. The bacterial content of mud deposits in the Clyde Sea Area has been investigated.

2. The number of bacteria is found to decrease from the surface downwards.

3. The numbers fluctuate very much in the top mud layers, and there is some evidence of bacterial zonation.

4. In the deeper mud layers the bacterial content for any given station is fairly constant.

5. The predominant organisms were found to be water bacteria of the Achromobacter and Chromobacterium type, and large spore-forming bacilli similar to common soil bacteria.

6. The factors affecting the bacterial content of the muds are discussed.

Many stomiatoid fishes possess a peculiar light-organ below and behind the eye, as well as other kinds of photophores. This light-organ, of diagnostic importance, is termed the subocular, postocular or cheek-organ. Stomiatoid fishes, suborder Stomiatoidei, form a suborder of the Isospondyli. Subocularorgans are found in the following groups:

In a former paper (Lebour, 1924) attention was called to the eggs, Calyptopis and first Furcilia stages of Thysanoessa inermis together with the form neglecta, which was regarded as a different species, mainly on account of the size of the eggs shed by the females in glass jars in the aquarium, those of the neglecta form being much smaller than those of the inermis form. Certain differences were also found between the males of the two forms.

Having through the kindness of Mr. C. F. Hickling obtained a number of Thysanoessa from the Atlantic Slope, chiefly in the region of the Smalls trawling ground, I found both forms present, which were usually much larger than those from the Channel, and presented certain other differences. Specimens of the two forms from both localities were sent to Dr. H. J. Hansen, of Copenhagen, who has kindly examined them and pronounced them all to belong to the same species,e.g. Thysanoessa inermis. It is an interesting fact that the specimens from the Smalls district are usually much larger than those from the Channel, and the neglecta form has the long legs much longer and stouter. Specimens from Iceland, for which I am indebted to Dr. Hansen, are also of a large size.

As Hansen has already pointed out (1911, 1915), Thysanoessa inermis which has a wide range of distribution has two forms, a short-legged form, formerly known as Rhoda inermisand a long-legged form, formerly known as Thysanoessa neglecta; these may be referred torespectively as the inermis and neglecta forms.

Late premoult females from precopula pairs of male and female Carcimts maenas (Crustacea: Brachyura) moulted at times of expected high tide in constant conditions in the laboratory. The data presents for the first time evidence of endogenous, circatidal (−12·4 h) moulting rhythms in a crustacean.

Studies on the temporal patterns of moulting in crustaceans have elucidated rhythms of seasonal (annual or biannual), lunar (29·4 d), semilunar (14·7 d) and diel (24 h) periodicities (see Conan, 1985; Fernandez et al., 1994). Examples in the literature of so-called ‘tidal’ rhythmicity of moulting given by Conan (1985) are more correctly referred to as semilunar or neap/spring patterns. There appear to be no reported examples of true tidal (12·4 h) moulting rhythms. Also there is very little evidence in the literature that moulting rhythms phased to geophysical cycles are controlled endogenously. Most studies have been carried out in the field or under L:D cycles in the laboratory and only a few have been undertaken with animals in constant conditions (see Fowler et al., 1971; Bishop & Herrnkind, 1976; Nicol, 1989; Fernandez et al., 1994). Conan (1985) has reported moulting rhythms of circamonthly, circatidal (=circasemilunar) and circadian periodicities but his use of the prefix ‘circa’ is unusual since it more correctly describes free-running rhythms in constant conditions, not environmentally driven rhythms as in the examples quoted. In the present study we sought to determine whether moulting in the shore crab Carcimts maenas (L.) was tidally patterned and endogenous.

Over a period of several days in the summer of 1991 large numbers of premoult female Carcinus maenas were obtained by searching for specimens associated with males in precopular pairs.

The long-standing hypothesis (Thorson, 1946, 1950; Mileikovsky, 1971; Jablonski & Lutz, 1983) that deep-sea invertebrates should reproduce by direct development or by non-feeding (lecithotrophic) larvae is beginning to fall in the light of recent data. Traditional reasoning maintained that planktonic food should be limiting at great depths, and that microscopic, ciliated larvae should be incapable of migration to the euphotic zone. However, in recent years, planktotrophic larvae of two deep-sea gastropods have been collected in surface waters, and planktonic larval development has been inferred from shell morphology and chemistry in several other species (Bouchet & Warren, 1979; Killingley & Rex, 1985). Planktonic larvae have also been collected in the water column of the deep sea (Berg et al., 1985; Smith, 1985; Berg & Van Dover, 1987), particularly near hydrothermal vents. Relatively diverse benthopelagic plankton populations relying primarily on suspended detritus for food are now known from the benthic boundary layer of the deep sea (Wishner, 1980a, b; Gowing & Wishner, 1986). Thus, it is increasingly apparent that planktotrophy may be a common option for deep-sea larval development.

The recent criticism of Thompson and Johnson (7) of the method of determining nitrate in the sea by means of reduced strychnine is held to be unsound.

Preparation of the reagent given due care and pure materials has offered little difficulty.

A possible method for the preparation of nitrate-free sulphuric acid is outlined.

The effect of iodate in concentrations likely to be met in the sea is negligible.

Interference by organic material has been avoided by first centrifuging all samples obtained during periods of plankton activity.

The relative intensity of colour given by nitrate and by nitrite nitrogen is discussed.

Age and growth of the clam Chamelea gallina from dredged, non-dredged and closed areas of the Turkish Black Sea coast were estimated. Von Bertalanffy growth curves were fitted for each sampling site; asymptotic length (L∞) values ranged between 25.995 and 28.883 mm and the growth coefficient (K) from 0.164 to 0.217 per year. Results indicate growth rates were significantly reduced in the far eastern commercial populations compared with those in western populations. According to our results presented here it can be concluded that C. gallina at closed area does not grow as fast as non-dredged stock and this is because of the shortness of closure season. Nevertheless we suggest that fallowing is the major precaution for the recovery of C. gallina stocks in the Black Sea.

Actinians are equipped with cnidae which function in food capture, defence and aggression (Mariscal, 1974). Cnidae cannot be renewed and after discharge they are extruded from the epithelium. Regulation of the spirocyst and nematocyst population must be important, but as yet no quantitative data about this are available for actinians (Picken & Skaer, 1966).

It is shown that sulpholipid is the predominant acetone-insoluble lipid of grass, sphagnum moss, Selaginella, and of some blue-green, green and brown algae.

This sulpholipid is separable into three entities by paper chromatography.

Phospholipid predominates over sulpholipid in red algae, fungi and the fluffy pericarp of the broad bean.

The sulpholipid in these plant tissues gives a single spot on paper chromatogram

A relationship between sulpholipids and photosynthesis is suggested.

Mycteronastes undulatae gen. nov., sp. nov. (Monogenea: Monocotylidae) is described from the nasal cavities of Raja undulata caught off Arcachon in France and off Lisbon (Tagus estuary) and Sines in Portugal. Merizocotyle icopae Beverley-Burton & Williams, 1989, be-comes Mycteronastes icopae n. comb., the type species of Mycteronastes gen. nov. Similarities between M. icopae and M. undulatae include the arrangement of the haptor loculi and hooks, the general disposition of the reproductive system, the presence of eyespots and the habitat (the nasal cavities of the host). However, a distinctive feature is the absence of a copulatory sclerite and bulb in M. undulatae. The diagnoses of the following taxa are amended: Monocotylidae, Merizocotylinae and Merizocotyle.

Callista chione (L.). is a fairly large, handsome bivalve of the family Veneridae. It is found around the coasts of Devon, Cornwall and Wales, though its distribution extends southwards to the Mediterranean. It is usually uncommon but has been found to occur at the eastern end of Whitsand Bay, near Plymouth at a density of about 1 per m2. Several specimens were taken in 1975 while testing a water lift system for the use of aqualung divers. Most of the shells were observed to bear a noticeable growth check in the form of a ridge several millimetres from the shell margin (Fig. 1). This ridge was not found in the older specimens in the laboratory's museum collection. To try to find out the cause of this growth check a tagging experiment was undertaken in 1976, although it was not possible to measure and mark out large numbers; recaptures in the following two years have been sufficient to provide some evidence for the average growth increment of different sizes of shell.

Dyopedos monacanthus inhabits self-constructed mud whips on marine soft-bottoms. Juveniles stay on the mud whip of their mother for extended time periods after they hatch from her brood pouch. During the main reproductive period in the spring, parental females have been observed in the aquarium and collected from the field. Specimens of D. monacanthus have been collected simultaneously from the intake filter from the sea-water laboratory. Several consecutive clutches have been found on the whip of one female. Most juveniles are small (1 mm in size), but they grow to sizes of >2 mm on the whip of their mother. In the aquarium, juveniles usually hatched immediately after the females had been attended by males. They then clung to their mother's whip for about two weeks. Most parental females in the aquarium produced three broods during a time period of about six weeks. In the field an average of 36 parental females m-2 were found in April, and an average number of 75 juveniles clung to each female's whip. The average number of juveniles found on the females’ whips declined in May and June. Many juveniles appeared in the sea-water intake filter starting in mid April. Most juveniles caught in the intake filter were between 2 and 3 mm in size which corresponds well with their size at leaving the female's whip. In mid May, all amphipods disappeared within a few days from the aquarium, when shrimp Crangon septemspinosa started to become more active again. Many big females disappeared in the field at that time too, and in mid June parental females were smaller than in the previous months. The amphipod D. monacanthus belongs in the category of epibenthic suspension-feeding amphipods. It is probably very susceptible to epibenthic predation and extended parental care is primarily a mechanism to lift very small juveniles above the viscous sublayer in the benthic boundary layer.

Data on the diets of harbour seals (Phoca vitulina) from two islands in the Inner Hebrides (Scotland, UK) based on collections of faecal samples made in 1993 and 1994 are presented. The diet included a range of fish and cephalopod species, of which the most important were gadoids, particularly whiting (Merlangius merlangus), along with pelagic scad (Trachurus trachurus) and herring (Clupea harengus). There were significant temporal and spatial (between-island) differences in diet. The relatively high importance of pelagic species and the low importance of sandeels (Ammodytidae) is consistent with previous studies on grey seals (Halichoerus grypus) in the Inner Hebrides but differs from studies based in other parts of Scotland.

The number of eggs produced by a parental stock is central to fisheries advice on recruitment potential. However, stock based estimates of egg production may give a misleading index of recruitment potential in stocks containing several reproductively isolated populations. This paper examines the ability of length, condition and oocyte developmental stage to predict levels of potential fecundity in the sandeel, Ammodytes marinus, in three important fished areas in the North Sea. Our results indicate that regional variation in this relationship exists, with fecundity in central areas of the North Sea being higher than those found just off the north-east UK. Oocyte diameter was also found to have a significant effect on potential fecundity, suggesting a down-regulation of oocyte numbers arising from pre-ovulatory atresia, however, this effect was not apparent in every model tested. Our findings have relevance to the local sustainability of spawning components and thus the regional management of the North Sea sandeel stock.

The reproductive biology of the Jenyns's sprat Ramnogaster arcuata in the Río de la Plata area was studied using macroscopic and histological analysis of ovaries. Samples were collected during two research surveys carried out in June 1998 and June 1999. In addition monthly occurrences of this species from historical data were analysed. Jenyns's sprat specimens were mainly observed in open waters of the estuary during winter months. Most of the females collected during June 1998 and 1999 were in the spawning stage. This pattern differs from fish that reproduce in the estuarine waters of the Río de la Plata, which spawn during spring and summer. These results suggest that conditions of productivity and larval retention in the estuary also remain during winter months. This characteristic might be useful for R. arcuata larvae in avoiding competition with other estuarine spawners. Jenyns's sprat is a multiple spawner with indeterminate annual fecundity. A preliminary estimate of spawning frequency (N = 220) indicated a daily percentage of females with postovulatory follicles of 17.35%, which suggests that this species spawns on average once every six days. Batch fecundity, estimated from counts of hydrated oocytes from 40 females, ranged from 669 to 2026 hydrated oocytes in 1998 and from 570 to 1830 hydrated oocytes in 1999. Batch fecundity was fitted to a linear function of total body weight (without ovary) in 1999. Mean relative fecundity was 234 hydrated oocytes per female gram (ovary free) in 1998 and 155 hydrated oocytes per female gram (ovary free) in 1999, and no significant relationship was observed between this parameter and female size. The dry weight of 100 hydrated oocytes ranged between 3.9 and 6.3 mg, these values being significantly higher than those estimated for other species of the Río de la Plata estuary.