A Heavy percentage of the mussels obtained from various parts of the Fal Estuary, during October and November, 1927, had the gills in an exceedingly abnormal condition (31.8% among 1488 recorded). Occasional mussels from other localities (Padstow, Teignmouth, Yealm, Saltash) have been observed to have slightly abnormal gills, though perhaps in the majority of these the condition was due to the presence of a large female pea-crab, Pinnotheres pisum. In the Fal Estuary mussels the abnormal conditions were doubtless correlated with some factor in the environment, the percentage of pea-crabs in these being so low (4–8%) that their presence could have no relation to the abnormal condition of the gills.

In order to induce metamorphosis in cyprids of the parasitic barnacle Loxothylacus panopaei (Gissler) (Cirripedia: Rhizocephala: Kentrogonida), we tested a number of compounds (ZR-512, 20-hydroxyecdysone, 3-isobutyl-l-methylxanthine and phorbol-12,13- dibutyrate) all known to cause metamorphosis in thoracican barnacles. Only one agent, phorbol-12,13-dibutyrate, had an effect and induced cypris larvae to complete metamorphosis without previous attachment. This suggests that diacylglycerol-activated protein kinase C plays a role in the metamorphosis of kentrogonid rhizocephalans.

Rhizocephalans are highly specialized crustaceans adapted for parasitic life on decapods. The juvenile parasite passes through an internal growth stage, where a root-like trophic organ invades the tissue and haemocoelic fluid of the host (for detailed information on rhizocephalan life history, see Haeg, 1992). As in free-living barnacles, a cyprid larva is the settling stage, and in thoracicans a juvenile barnacle is formed underneath the carapace of the cyprid larva. However, the rhizocephalans develop a so-called kentrogon, which accomplishes the injection of the primordial parasite (Glenner & Høeg, 1995). The degree of specialization towards a specific host means that the cypris larvae of rhizocephalans are extremely selective in their choice of substrata. They will not settle unless a specific host or part of a host, e.g. the gills, is offered. For this reason, the study of settlement and metamorphosis of these species has met with great difficulties.

In my paper on the Reproduction of Fishes occurring at Plymouth, published in this Journal, vol. i, p. 10, 1889, I identified as the egg of the pilchard, a pelagic egg commonly found in the tow-net in summer, and distinguished by three obvious characters, namely: (1) an unusually large perivitelline space; (2) a single large oil-globule in the vitellus; (3) a completely subdivided yolk. I also stated that ripe spawning pilchards occurred off Plymouth between June and October, but always at some distance from land, being usually taken in mackerel nets worked to the south of the Eddystone. My identification of the egg, taken in the sea, was founded upon a comparison between it and the eggs pressed from the ripe but dead female pilchards obtained from mackerel fishermen. The latter eggs were already dead, and did not float, but sank in sea water, but they possessed a single oil-globule, and the yolk in them consisted of a number of yolk-spheres. The large perivitelline space was absent, because it is only formed when living eggs are extruded into sea water.

Raffaele had previously described two kinds of pelagic eggs found at Naples, which he recognised, from their divided yolk and the characters of the larvæ hatched from them, as belonging to some species of Clupeoid. The larger of these eggs he attributed to Clupea pilchardus, but did not give his reasons. This egg is in all respects similar to that identified as belonging to the pilchard by myself at Plymouth. It is well known that the sardine of the French coast and of the Mediterranean is the same species of fish as the pilchard of Devon and Cornwall.

1. Sixty specimens of B. haineri, of five successive year groups, were obtained in December, 1933, and a further 33 preserved specimens taken in the winter of 1925 were examined.

2. The mean ages contained for successive year groups from the size distribution and from individuals settled on those of the preceding year, yielded results in good agreement with one another.

3. First-year individuals do not spawn. All older individuals had ripe genital products in the 1933 material, and early embryos in the 1925 material.

This study addresses aspects of the phylogenetic relationships of the commercial Tehuelche scallop, Aequipecten tehuelchus s.l. (Bivalvia: Pectinidae), from southern South America using molecular techniques. The Tehuelche scallop presents two different putative subspecies, A. t. tehuelchus and A. t. madrynensis, and a potentially related sympatric species, Flexopecten felipponei. The Tehuelche scallop is a very important component of ecosystems and is the target of artisanal fisheries in the northern Patagonian gulfs of Argentina. Despite its importance, the systematic relationships of these taxa have not been fully addressed. The main goal of this study is to place the Tehuelche scallop within a partial phylogenetic framework of the family Pectinidae. Scallops were sampled at 10 localities distributed along the south-western Atlantic Ocean. Phylogenetic reconstructions were carried out from two mitochondrial (12S rRNA and 16S rRNA) and two nuclear markers (28S rRNA and H3) using Bayesian, maximum likelihood and maximum parsimony analyses. Our phylogenetic analysis indicates that the two putative subspecies of the Tehuelche scallop together with F. felipponei form a monophyletic clade, without differentiating at the specific level. Observed differences would be the result of phenotypic plasticity, probably caused by environmental factors. However, further analysis using genes with faster evolution rate are needed to corroborate it. Our phylogenetic analysis resolved to Aequipecten as polyphyletic. The Tehuelche scallop has a basal position within the Argopecten group and we recommend that it should be transferred to this genus. The relationship between the hypotheses about the origin of the Tehuelche scallop implicit in the literature and our results are discussed.

Gigantocypris is a good swimmer, capable of moving fast enough to overtake a variety of zooplanktonic Crustacea and chaetognaths. It swims smoothly without violent accelerations and decelerations. Previous reports of unstable weak swimming in this species stem from the study of overheated animals; Gigantocypris is stenothermal, adversely affected at temperatures above about 15°C. Gigantocypris is nearly neutrally buoyant (sinking speed 0·2 mm s−1) and is capable of hovering for long periods with the aid of slight movements of the propulsive antennae. When swimming quickly Gigantocypris achieves an average speed of 164 mm s−1 (9·6 mm body length; 391 antennal beats min−1) at 12·5°C. It is unlikely that Gigantocypris performs significant diurnal vertical migrations. The heart of Gigantocypris is large and beats at ca 100 beats min−1. Macrocypridina is a faster swimmer (<52·3 mm s−1 (8·3 mm body length) at 12·5°C with an antennal frequency of 583 beats s−1), but each beat is accompanied by great accelerations and decelerations. Macrocypridina is dense, sinking at 40 mm s−1. Macrocypridina is eurythermal, its swimming speed increasing steadily between 11·5 and 20°C.

Reef encrusting calcifiers (non-scleractinian species) constitute assemblages that participate in the carbon cycle at coral reefs. Despite their apparent secondary role in building the reef framework, they contribute to the reef consolidation binding sediments and inducing larval recruitment from other epilithic invertebrates. The contribution of encrusting calcifiers on reef accretion was examined by the assessment of their rate of carbonate deposition on four different simulated reef microhabitats using calcification accretion units (CAUs) during 12 months at Playa Las Gatas and Islote Zacatoso, two coral communities from the coast of the Mexican Pacific. Encrusting calcifiers from Playa Las Gatas, the most impacted site, showed a rate of carbonate deposition (mean ± SD) four times higher than at Islote Zacatoso (10.02 ± 3.22 g CaCO3 m−2 d−1vs 2.48 ± 1.01 g CaCO3 m−2 d−1). Overall, the rate of carbonate deposition on surfaces protected from sedimentation and light was up to 1.8 times higher than on exposed ones (11.40 ± 4.35 g CaCO3 m−2 d−1vs 6.18 ± 3.13 g CaCO3 m−2 d−1). Carbonate deposition by calcareous algae was higher on the well-lit exposed surfaces while filter-feeding invertebrates showed the major contribution on the shaded cryptic surfaces. Although rate of carbonate deposition by encrusting calcifiers seems to be lower than hermatypic corals, it seems to be relevant on coral reefs affected by anthropogenic impacts where coral calcification is low. Under global demise of coral reefs by environmental degradation and climate change, encrusting calcifiers may become relevant for the process of carbonate deposition.

The presence of suctorian ciliates attached to the cuticle of heavily ornamented free-living marine nematodes, especially the family Desmodoridae, has been reported. Observations of nematode hosts and their attached ciliates were made from samples extracted from very fine muddy sands of tropical Australian sea grass meadows. Measurements of the point of attachment of the ciliates revealed that they tend to position themselves near the anus/cloaca of the nematode host.

Feeding regime is an important concern for sea urchin aquaculture. However, optimal feed regimes have not been established for land-based sea urchin ventures using a formulated feed. In this study, we investigated the effects of short-term continuous and intermittent feeding regimes on food consumption, growth, gonad production and quality of the sea urchin Strongylocentrotus intermedius (54.90 ± 2.28 mm of test diameter) fed a formulated feed. The results showed that (1) compared with initial conditions, all involved traits except a* (test diameter, test height, body weight, gonad weight, gonad index, gonad moisture, L* and b*) showed significant increase at the end of the experiments; (2) only the longest term feed regime tested in this trial (S2) significantly negatively affected growth and gonad production of S. intermedius fed a formulated feed; (3) there was a trend but this was not significant for inhibiting gonad development of S. intermedius in intermittent feeding regimes and there was no change in the gonad colour and sweetness; (4) S0.5 (fasting half day and then feeding half day) is the optimal intermittent feeding regime for S. intermedius fed a formulated feed. To our knowledge, the present study is the first report of finding an effective intermittent feeding regime for land-based cultured sea urchins of relatively large size, and thus has direct application potential in the field of aquaculture.

This investigation aimed to study the relative growth, morphological sexual maturity and fecundity of the swimming crab Achelous spinicarpus in a tropical region, on the south-eastern continental shelf of Brazil (25°S). Biometry of all specimens was conducted, including measurements of the cephalothorax, cheliped, abdomen and gonopods. Relative growth was described based on the equation for allometry (y = axb), and size at sexual maturity was determined from inflections in relations involving the cheliped, gonopods (males), and abdomen (females), as dependent variables, related to the cephalothorax width (independent variable). Fecundity was estimated by the gravimetric method. The relations of the length of the chelar propodus and carpal spine to the carapace width without the lateral spines (CW) showed positive allometry in both sexes, with a significant variation in the constant ‘b’ for males between the developmental stages (juvenile and adult) and the size at maturity estimated at 37 mm CW. In females, the abdomen was most appropriate for the estimate of morphological maturity, which occurred at a smaller size (32 mm CW), with a change in the growth pattern between the stages, passing from isometric (juveniles) to positive allometric (adults). The gonopods also showed different growth rates between developmental stages, in synchrony with the variables of the cheliped. Mean fecundity for the species was 53,984 eggs, with a positive correlation between the number of eggs exteriorized and the size of the female; the equations allowed interconversion between these variables, due to the adjustment of the power function (r2 ≥ 86%).

The annual gametogenic cycle in the blue mussel, Mytilus edulis L. was investigated from May 2010 to May 2011 in two locations in north-western Iceland. Food availability (chlorophyll-a) was high in early spring at both sites, with a summer maximum in July in Steingrimsfjördur but an autumn maximum in September in Patreksfjördur. Gonad development started in November at both sites, with ripe gametes still visible in the follicles, and continued throughout the year, except for a very short time prior to spawning in Steingrimsfjördur. Gametes developed mostly between November and May. Spawning was protracted, lasting from July to early winter at both sites. The main spawning events occurred from August (11.7°C) to October (9.4°C) in Patreksfjördur, but from July (9.8°C) to October (8.6°C) in Steingrimsfjördur

The status of the prayine siphonophore genus Prayoides, monotypic for the species Prayoides intermedia Leloup, 1934, is reviewed in the light of recent collections made by the submersibles ‘Johnson-Sea-Link’ I and II. It is concluded that the genus is not valid, and that the species name should be reduced to that of a junior synonym of a Praya species. The bracts of the two Praya species, P. dubia (Quoy & Gaimard (1833) 1834) and P. reticulata (Bigelow, 1911) are re-described, as in the past there has been much confusion as to their true identity.

1. Historical Review.

The history of our knowledge of this subject is complicated and curious, and is not quite correctly narrated in any English publication, not even by Balfour in his account of the development of Crustacea (Comparative Embryology, vol. i). The story begins with the establishment and definition of the genus Phyllosoma by Leach in 1818. Various succeeding zoologists included descriptions of species of Phyllosoma in their works, but the result of all previous investigations are included by Milne Edwards in the comprehensive account of the genus given in his Hist. Nat. des Crustacés, vol. ii, 1837. The state of knowledge at that time may be briefly summarised as follows:—The Crustaceans known by the name Phyllosoma had been found near the surface of the ocean in various parts of the world. They varied in size from less than half an inch to two inches. They were, when alive, of glassy transparency; the body was remarkably flat, and expanded horizontally, while the limbs were long, slender, and biramous. The body consisted of three parts; firstly, a head having the form of an oval leaf, bearing at its anterior extremity a pair of eyes on long stalks and two pairs of simple antennæ. The mouth was situated beneath the middle or posterior third of the head, and surrounded by an upper and lower lip, a pair of maxillæ, and the first pair of maxillæ. The second pair of maxillæ and the first pair of maxillipeds were rudimentary and situated behind the mouth. The second part of the body was the thorax, quite as flat but not so large as the head; it was usually broader than long.

The relationship between body size and population growth rate λ has been studied in two species of opportunistic polychaetes, Dinophilus gyrociliatus and Ophryotrocha labronica, which colonize harbour environments. These species exhibit a semi-continuous iteroparous reproductive strategy, are phylogenetically closely-related but differ in body size and in some aspects of their sexuality. Ophryotrocha labronica is about 4 mm in body length, displays only slight sexual dimorphism and its sex ratio is biased towards the female sex in the ratio 2:1. Dinophilus gyrociliatus is about 1 mm in length, the males are extremely small and the sex ratio is strongly biased (3:1) in favour of the females. In spite of the considerable differences in all traits of their life histories and in many demographic parameters, the growth rates of the two populations are very similar. The analyses carried out have shown that the rapid attainment of sexual maturity of D. gyrociliatus gives it an advantage that offsets the greater fecundity of O. labronica. It is very likely that the reproductive peculiarities of D. gyrociliatus help to raise the population growth rates. The ‘saving’ on the male sex achieved both by the shift of the sex ratio in favour of the females and by the reduction in the males' body size would appear to enable D. gyrociliatus to grow at the same rate as O. labronica, a larger and more fecund species.

It has been argued by Johannesson & Johannesson (1990b) that the pattern of common genetic variation in Littorina saxatilis (Olivi) and Littorina neglecta Bean indicates gene flow in sympatric populations of these ‘species’. They suggest that L. neglecta is not a good species. We report that a gene diversity analysis of polymorphism in Aat-1 suggests that L. saxatilis and Littorina arcana Hannaford Ellis also show common features in allele frequency distribution. This casts doubt on the argument of Johannesson & Johannesson (1990b) from enzyme polymorphism data on Aat-1 that L. neglecta may simply be an ecotype of L. saxatilis. It seems likely that the similarities are due to operation of the same selection factors on all these species.

The greater number of the species given in this list are new records for the Plymouth region. Recent records for some rare species have also been included.

The distribution of sole (Solea solea) eggs and larvae were described from two cruises conducted in April and May 1995 along the French coast of the eastern English Channel and the Belgian coast of the Southern Bight of the North Sea. Sole migration was investigated using larval stages and univariate spatial analysis as geostatistics (variograms). Important environmental parameters were selected by comparison with larval distribution. Path analysis was used to remove spatial correlation and to define links between abundance and environmental variables.  Sole larvae were found to be coastal throughout their development. Strong links between larval distribution and environmental parameters were identified, particularly for the younger stages which were found in higher abundance in areas of high chlorophyll-a concentration. The association was not direct, suggesting that the larval spatial distribution was influenced by an undetermined, intermediate variable, such as larval prey. Sole larvae are retained in the coastal area throughout ontogeny despite the strong hydrodynamics which characterize the region. Larval distribution resulted from behavioural mechanisms as well as environmental influences.

The hypothesis is proposed that inorganic ammonia may be adsorbed on particulate matter in the sea. The random distribution of such particulate ammonia would account for the frequent ‘contamination’ reported in ammonia analyses and for the finding of nitrifying bacteria associated only with particulate matter, but never with sea water itself.

One juvenile specimen of the vadigo Campogramma glaycos was caught on 5 December 2000 in Piran Bay (northern Adriatic). This represents a northernmost extension in the known range of this species in the Adriatic Sea (and Mediterranean), and first record of a juvenile specimen in the Adriatic Sea.