Microphytobenthos (MPB) contributes up to half the primary production of estuaries. These microorganisms are sensitive to changes in sediment temperatures, particularly the extreme temperatures during exposure periods. This study investigates the physiological responses of MPB to freezing temperatures at two locations near Hobart, Tasmania during winter. Photosynthetic parameters were measured at 2 mm intervals to a depth of 10 mm. FV/FM values at three different distances from the shoreline at Kings Beach and Browns River in winter were between 0.584 and 0.617. rETRmax values were between 24.696 and 20.773. Maximum α values peaked in the subsurface rather than at the sediment surface. In vitro laboratory experiments (down to −5°C) showed little difference in response between the control and treatment groups, indicating no apparent effects of short term freezing on the MPB. Little change in photosynthetic parameters in response to freezing was probably associated with the resistance of light-harvesting reactions to freezing temperatures, recovery of the plasmalemma integrity or cryoprotection. Sediment composition and species composition were similar at both sampling sites. Therefore, responses of MPB were not due to species and grain size composition.

The specific humoral immune response of sea bream, Sparus aurata (L.), against Vibrio anguillarum O1 and Photobacterium damselae subsp. piscicida (Phdp) after immunization with commercial and experimental bacterins was analysed quantitatively and qualitatively. Specific anti-V. anguillarum O1 and anti-Phdp levels provoked by the adjuvanted commercial vaccine reached higher levels in comparison to the aqueous commercial and experimental bacterins. Infection of vaccinated fish with V. anguillarum O1 bacterial cells acted as a boost of the humoral immune response, except for the sera of the group vaccinated with the adjuvanted vaccine. Infection with Phdp acted as a boost of the humoral immune response mainly for the group vaccinated with a monovalent Phdp bacterin and to a lesser degree for the group vaccinated with the aqueous commercial vaccine. Western blot analysis of the sera against V. anguillarum O1 whole cell antigens revealed strong reactions to only a few antigens below 54 kD and above 15 kD and weak reactions to other antigens. Similar reactions were observed from the sera isolated from the controls. Western blot analysis of the sera against Phdp whole cell antigens revealed strong reactions to only a handful of antigens below 20.7 and below 6.4 kD. Sera from the control group, as in the case of V. anguillarum O1, reacted with Phdp whole cell antigens. No differences regarding antigen reactions between monovalent and bivalent formulations were noted, in contrast to the adjuvanted and aqueous bacterins.

Two new species of free-living marine nematodes, Litinium dispariseta sp. nov. and Wieseria minor sp. nov. are described from an abyssal plain with a water depth of 4117–5035 m near the Southern Kyushu-Palau Ridge in the tropical Western Pacific Ocean. Litinium dispariseta sp. nov. is characterized by having distinct inner labial setae two times longer than the outer labial setae, wrench-like amphideal foveas, a single preanal midventral supplementary seta and a short cylindrical tail with bluntly rounded tip. It differs from congeners by its distinctly long inner labial setae relative to the outer labial setae (two times longer vs shorter or equal in length) and peculiar wrench-like amphideal foveas (vs horseshoe shaped or ovoid with round to oval anterior aperture). Wieseria minor sp. nov. has a clavate tail, a character found only in the four congeners W. glandulosa (Kreis, 1929), W. longiseta (Allgén, 1947), W. clavata Gerlach, 1956 and W. inaequalis Gerlach, 1956. However, Wieseria minor sp. nov. differs from these congeners by its much smaller body size (1045 µm vs 2120–3125 µm) and oblong amphideal foveas with double contour (vs a single oblong or ovoid loop). An emended diagnosis for Wieseria and pictorial keys for Litinium and Wieseria are provided.

This study constitutes a first attempt to investigate sex differences in osmoregulatory capacity and metabolic responses in relation to hyper- and hypo-osmoregulation in the intertidal euryhaline crab Uca tangeri. Adult male and female specimens from Cadiz Bay, Spain (36°23′–37′N 6°8′–15′W), were acclimated to three different environmental salinities (12, 33 and 55 psu) during 7 days, and several parameters were assessed in haemolymph (osmolality, glucose, amino acids, triglycerides and lactate) as well as in metabolic key organs (hepatopancreas, anterior and posterior gills: glycogen, free glucose, amino acids and triglycerides). Specimens from both sex exhibited high and similar hyper- and hypo-osmoregulatory capacities. However, metabolite levels were differentially affected upon acclimation to low and high salinity in several metabolic organs and haemolymph of male and females: (i) glycogen in gills, (ii) free glucose in gills and hepatopancreas, (iii) amino acids in hepatopancreas, (iv) triglycerides in haemolymph, hepatopancreas and posterior gills, and (v) lactate in haemolymph. The results suggest the occurrence of differential metabolic adjustments upon hyper- and hypo-osmoregulation related to sex in the intertidal euryhaline crab U. tangeri.

A new species of Ophlitaspongia (Porifera: Microcionidae) from wave-exposed sublittoral rock in the north-east Atlantic is described and compared to the two other species recorded from the genus in the north-east Atlantic. The species known as Ophlitaspongia seriata is considered to be a junior synonym of Halichondria panicea. Consequently, the name O. papilla has been reinstated. The other recorded species O. basifixa, is from deep water. Ophlitaspongia basifixa has characters which differentiate it from Ophlitaspongia sp. nov. The genus Ophlitaspongia has been separated from related genera and reinstated for species in the North Atlantic.

A new species of calanoid copepod, Centropages aegypticus sp. nov. collected from the Egyptian coasts of the northern Red Sea is described. This species is unique in having two pointed conical processes on the dorsal surface of cephalosome in both sexes, female genital compound somite with irregular-surface outline of the right swelling part and transverse dorsolateral row of spinules on the left side, 2-segmented exopod of the female leg 5, asymmetrical medial processes of the female leg 5, of which the left one is longer and medially-curved and the right one with oblique row of thick spinules, and a club-shaped medial seta on the third exopodal segment of the male leg 5. The new species is similar to C. tenuiremis, but is not assigned to the same species group as the latter species or to any other groups.

When Michaelsen (1923) described a species of didemnid from Heligoland, he stated that it was very similar to Leptoclinum maculosum Milne Edwards (1841), so far as may be judged by external appearance, but since no adequate description of this latter existed he proposed to call his Heligoland form by a new name, Didemnum helgolandicum, rather than use an old name which might well be wrong. Neither Michaelsen nor Hartmeyer, who described further details of D. helgolandicum (1924), was able to compare it directly with specimens of D. maculosum from the Channel coasts whence it was first described by Milne Edwards. Through the kindness of the directors of the Zoological Museum of Copenhagen and of the Biological Station of Roscoff I have been able to obtain specimens of both these forms and to compare them with specimens collected around Plymouth and on the coast of North Wales, and with specimens of D. candidum Savigny, collected at Naples, and from the Red Sea, and of Trididemnum alleni Berrill, collected around Plymouth.

The summer vertical distribution of appendicularian species was analysed at 22 stations in the central Cantabrian Sea by means of vertical tows covering the surface, thermocline and deep layers. According to their preference for shallower waters, the appendicularian species could be arranged on the series Oikopleura longicauda (Vogt), Oikopleura fusiformis (Fol), Fritillaria pellucida (Quoy & Gaimard) and Oikopleura rufescens (Fol), with Oikopleura dioica (Miiller) in an uncertain position, probably closer to the end of this series. Principal components and correlation analyses suggest that a temperature gradient causes this pattern, which agrees with previous findings made at very different temporal and spatial scales. By means of particle-size spectra, it is shown that those oikopleurids that prefer cold, deep waters, O. fusiformis and O. rufescens, co-vary with a coefficient of particle-size quality. The lower the temperature, the lower the proportion of small, ingestible particles to large inlet-filter-clogging particles. This is proposed as an important reason for the presence of inlet filters in oikopleurids.

The in situ growth rates of marine planktonic ciliates from Plymouth Sound were determined after fractionating the natural community into several size categories to remove predators of different sizes. Total community in situ growth rates varied from 0·01 to 0·57 d−1 according to fractionation treatment, with the four most abundant taxa, comprising three species of Strombidium, and Mesodinium rubrum, achieving maximum in situ growth rates of between 0·41 and 0·68 d−1. These values are approximately half the maximum theoretical rates calculated indirectly using an equation which relates ciliate growth to cell size and temperature. Given the conservative nature of in situ growth rate measurements, the growth rates reported here appear appropriate for a natural ciliate community growing within a nutritionally favourable environment.

Abundant species are typically also viewed as ecologically dominant, and are frequently used to characterize the communities in which they live. Such characteristic assemblages may also be used as indicators of environmental conditions, such as relative stability. Fossil and modern turritelline gastropods are often the most abundant species in the marine assemblages and communities in which they occur, forming ‘turritelline-dominated assemblages’ (TDAs). We use data on modern Turritella bacillum from waters around Hong Kong as a case study to analyse fluctuations in abundance over 25 years. While turritellines were not always dominant in the area surveyed (~1650 km2), populations were notably persistent, and rebound after decline of abundances occurred within ~5 years at some sites. δ18O sclerochronology suggests that individuals were ~1–2 years old. It is also notable that T. bacillum was found to be abundant at salinities as low as 10–15 psu, despite the general characterization of turritellines as fully marine. Comparison with data on modern T. communis in the western English Channel corroborates this pattern, as localized sites of high abundance also appear transient. These results have implications for the interpretation of TDAs in the fossil record: they may signify the cumulative result of short-lived, spatially restricted populations, possibly resulting from essentially stochastic larval settlement. This suggests that the palaeoenvironmental setting of fossil TDAs does not always control their occurrence on short temporal scales.

The blue crab Callinectes sapidus is an important ecological and commercial species. It plays a fundamental role in the structure and function of coastal benthic food webs, with global catches of ~74,357 tons. This is the most exploited portunid species in Brazil. However, few studies about the ecology and population dynamics of C. sapidus have been published. This study aimed to analyse the preferred areas for the spatial distribution of juveniles and moulting individuals of C. sapidus in shallow areas of the Patos Lagoon estuary and the adjacent marine reproductive area, and their relation to water and sediment characteristics. Juveniles and moulting individuals preferred the embayment of the upper estuary, where the sediments are finer, with higher contents of organic matter and the presence of submerged vegetation. There was also a temporal variability in the abundance of juvenile size classes, with two marked increments of smaller individuals: (1) in late spring and summer and (2) in winter, indicating two recruitment peaks. Unusual environmental conditions in the summer of the first year, with an increase of fine sediments and organic matter, combined with low salinities in the adjacent marine area, allowed recruitment of individuals there. We suggest better attention to the embayment around the Marinheiros Island (considered here as upper estuary) for management and protection measures due to the overlapping of recruitment preferences of the blue crab, pink shrimp and fish species in this area.

The ultrastructure and dimensions of the solenocytes of Branchiostoma lanceolatum are reviewed briefly. The functional ability of these units is calculated upon theoretical grounds in a manner similar to that applied to flame cells. Their more delicate construction would suggest that Branchiostoma would have great difficulty in maintaining any significant osmotic pressure difference between the medium and its body fluids.

Among the polychaetes, the family Cirratulidae is one of the most challenging taxonomically because most of the currently used diagnostic characters change during ontogeny. It is therefore necessary to use a combination of characters to make an accurate identification. The present work is the first of a planned revision of the genus Cirratulus from coastal zones of Argentina. The examined material came from the two largest natural history museums of the country, and showed several morphotypes. Some specimens corresponded to described species, but others were undoubtedly undescribed. Among the previously known Cirratulidae, Cirratulus jucundus (Kinberg, 1866) and Cirratulus patagonicus (Kinberg, 1866), formerly distributed for Antarctica are now also present in coastal continental areas of Argentina. The new species Cirratulus mianzanii sp. nov. is described from subtidal areas off Peninsula Valdés, Patagonia. This species is distinguished from its congeners by the segmental origin of both tentacular filaments and first pair of branchiae in the junction between the peristomium and first chaetiger. Branchiae arise some distance from the notopodium but not at the dorsal midline of the body. Ventral groove present along the body, with a fine dark midline. Capillary chaetae are serrate seen under an optical microscope, and the segmental origin of neuro- and notopodial spines is different from other species of the genus.

The general larval characters of the genus Spirontocaris are summarized by Gurney (1937b), but since his paper was written there have been published descriptions of S. spinus var. lilljeborgi (see Lebour, 1937) and of S. pusiola (see Bull, 1938). The four British Columbian species described by Needler (1933) must also be taken into consideration. With our present knowledge of all these species the description must be slightly modified. We now know the larvae of all the British species of this genus with the exception of the typical form of S. spinus. The specimen from which the larvae were hatched was intermediate between the typical S. spinus and the var. lilljeborgi and was regarded as the latter. The following species are British: S. polaris, S. spinus and its var. lilljeborgi, S. gaimardi, S. pusiola, S. occulta and S. cranchi. S. polaris is a northern form, the only British records being from the Shetlands. It has an abbreviated development, described by Stephensen (1912b, 1916, 1935).

The specimens conform to a type which appears to be fairly well known to Grimsby fishermen, and fish merchants, and which is always regarded by them as the offspring of the parents mentioned in the title. The object of the present note is to discuss the probabilities of the correctness of this diagnosis as fully as the material allows. The form can hardly be said to be rare, since within two years I have secured three specimens, while I have heard of several others having been present in the market. In some old manuscript notes kindly lent me by my friend Mr. G. L. Alward I find descriptions which apply to two fish of the same type, while Dr. Günther tells me that he has received several from London fish merchants.

The Amphipoda dealt with in this paper were collected in August, 1906, by Dr. Allen, to whom I am indebted for the opportunity of examining them.

The collection contained thirty-five species (belonging to twenty families), of which one only, Tryphosites alleni, is new to science. Five others, Stenothoe richardi, Syrrhoites walkeri, Syrrhoe affinis, Eusirus biscayensis, and Rhachotropis rostrata, are recorded for the first time since their original discovery. The geographical range of five species has been considerably extended, viz. Syrrhoe affinis, Tmetonyx similis, Sympleustes glaber, Epimeria parasitica, and Laetmatophihis tuberculatus; the four last forms have not been hitherto recorded with certainty south of Norway.

The hitherto unknown hydroid of the anthomedusa Bougainvillia pyramidata has been found in the Firth of Clyde, and medusae from it have been reared to maturity. The hydroid and the stages of development of the medusa are described and figured, and the species is compared with B. ramosa. The seasonal occurrence and distribution of the medusa are discussed.

The hydroid Bougainvillia muscoides (M. Sars) has also been found in the Firth of Clyde. Medusae have been reared from it, and a description, with figures, of the stages of development is given. The specimens found in 1901 in this area and described by Browne as Thamnitis sp. are shown to be young medusae of B. muscoides. The geographical and bathymetric distribution of the species and the seasonal occurrence of the medusa are described and discussed.

There are six species of Chaetognatha that are usually taken in Scottish plankton samples from the appropriate localities. These are

Sagitta setosa J. Müller, from lower salinity water such as that found in the southern and central North Sea and the Irish Sea.

S. elegans elegans Verrill, from mixed oceanic and coastal water.

S. serratodentata Krohn, from surface and subsurface warm oceanic water of fairly high salinity.

S. maxima (Conant), from cold deep water.

Eukrohnia hamata (Möbius), from cold deep water.

Sagitta lyra Krohn, from warm deep water.

All are valuable indicator species (Meek, 1928; Russell, 1935, 1939; Fraser, 1937, 1939). Of these, the first five have occurred in somewhat varying numbers and distribution according to hydrographic conditions every year since at least 1935, except possibly during the period 1940–45 when no investigations were made. S. lyra has been taken in most of these years, but was not found in 1935, 1936 or 1937. It was, perhaps, most abundant in 1948, and one specimen was taken in that year from the Moray Firth, though its presence there must be regarded as distinctly unusual.

Spadella cephaloptera (Busch) is widely distributed throughout the Scottish area as a bottom-living form and is therefore not included here as planktonic.

There are several other species which occur only occasionally in the Scottish plankton either as individual specimens or in small numbers in specialized localities: for convenience these may be termed unusual species. They are as follows.

Sagitta elegans arctica Aurivillius, which has occurred in several years in the Faroe-Shetland Channel associated with the community characterized by Eukrohnia hamata and Calanus hyperboreus.

There are few adequate descriptions of British members of the ascidian family Didemnidae and little attention has been given to the larvae. In the autumn of 1947 a didemnid was collected from the intertidal zone in the Menai Strait, North Wales. This ascidian agrees superficially with Leptoclinum maculosum Edwards, as figured by Milne Edwards (1842) and by Alder & Hancock (1905–1912), although differing somewhat from the diagnosis of Didemnum maculosum (Edwards) given by Harant & Vernières (1933). It is closer anatomically to the D.fulgens (Edwards) of Harant & Vernières, but differs in colour. In most features the colony and zooid closely resemble the descriptions given by Michaelsen (1923) for his species D. helgolandicum Michaelsen, and it is probable that this is the species to which it should be assigned. Nevertheless, the name D. maculosum has been retained since it is under that name that it has probably appeared in most faunistic lists.

Until recently all accounts of didemnid larvae have described three anterior adhesive organs. This was the number given by Giard (1872) for Diplosoma gelatinosum Edwards, and by Lahille (1890) for Trididemnum tenerum Verrill and Polysyncraton lacazei Giard. Berrill (1947), however, has described a new species of didemnid, Trididemnum alleni Berrill, the larva of which has only two anterior adhesive organs, a condition not previously found in any ascidian larva.

The larva (Fig. IA) of the colonies found in the Menai Strait resembles that of T. alleni in many features. The trunk is about 0.35 mm. long from the tip of the adhesive organs to the base of the tail.

The writer has recently reared a species of hydroid at Plymouth, which, in the vegetative state, might easily be confused with Slauridium productum Wright, 1858. The original creeping stolon from which the colony developed was found on a piece of dead Eunicella verrucosa (Pallas) dredged by the S.S.Salpa near Stoke Point on March 9th, 1936.

When isolated in a finger-bowl with “outside” sea water the stolon bore no polyps and showed no sign of activity, but three weeks later a single polyp had developed (Fig. 3). From its close resemblance to the figures given by Hartlaub (1895) for S. productum, it was at first assumed to be this species and was carefully watched and fed in the hope of rearing the medusæ from it. After a period of time, however, when the colony had increased considerably in size, styloid gonophores were developed.

The type of growth of the fully grown colony is shown in Figures 1 and 2. The stems are elongated and slender, bearing polyps at intervals. Polyps are borne at the summit and also on branches of the main stems. These branches usually arise from one side only of the main stems and it is probable that under natural conditions in the sea these main stems are really stolons. It is also likely that in nature the intervals between the polyps are fairly short. The whole colony has a faint yellow-brown colour which becomes reddish-brown in the polyps and the upper part of the hydrocaulus.