Changes in weight, histology and visual appearance of ovaries from a field population of Pecten maximus (Pectinidae: Bivalvia) were followed for one year. Ovaries containing fully-grown oocytes were found throughout the year, though the degree of filling varied. Spawning activity of varying intensity occurred from late March to September. Recovery with increase in gonad index followed the spawning in spring, but there were no signs of gonad growth during a stepwise decline in gonad index from June to September. Gonad index increased to a new maximum between October and December. Oogenesis seemed to be active in filled ovaries throughout the year, and no classical resting period with empty gonads was seen. Prior to and during the spring phytoplankton bloom, recruitment of young oocytes appeared inhibited in some ovaries, leading to increased accumulation of large oocytes.

1. On storing, sea water suffers a decrease in pH value. The amount of change varies from that produced by adding 1·0 c.c. of N/100 acid to 100 c.c. of sea water, up to that due to adding about 2·5–3·0 c.c. The decrease is due to the production of carbonic acid by organisms.

2. The change corresponding to 1·0 c.c. of acid, as above, is equivalent to that produced by the complete oxidation of 3 milligrams per litre of a hexose sugar, which requires 3·2 mgrms. per litre of oxygen. This is the minimum value, from 8·0–9·6 mgrms. corresponds to the higher values of acid. Figures for oxygen consumption by estuarine waters, which are available for an approximate comparison, show that 1·5 mgrms. of oxygen is not often exceeded in estimations by means of alkaline permanganate. The highest of this series is 5·6 mgrms. It is suggested that the different results given by the two methods are due to the fact that respiratory changes taking place in the water during storage set free much of the organically combined carbon before the oxidation by permanganate has been started. Determinations on freshly drawn filtered sea water give, according to Raben, 7·5 mgrms. of hexose or 8·0 mgrms. of oxygen consumed.

3. It is probable that the change in pH value on storing indicates the amount of plankton present, at any rate when sewerage contamination is negligible. It appears that water near the surface, at 20–25 metres and sometimes at the bottom, 70 metres, is particularly subject to change during storage. Four cases out of seven showed marked decreases in pH value at 20–25 metres, and two others exhibited the change to a less marked degree.

4. The total amount of carbon, reckoned as hexose, which is set free during storage by respiration in sea water at E1 is about twice that photosynthesised between July and December, taking for this the minimum value 3 mgrms. per litre, namely a total of 6 mgrms. per litre. Considering the column of water from bottom to surface, this is equivalent to about 500,000 kilograms per square kilometre in the English Channel off Plymouth.

An investigation into the natural regime of coastal suspended solids before discharge of potash mining waste is described. Regular samples of suspended material were taken over the period September 1968 to August 1970. Statistical analyses showed significant differences in suspended solid values between the months and between inshore and offshore sampling stations. There was no significant difference between sampling points along the coast. The inshore suspended solid values were low from May to September. At other months and at the offshore stations there was a gradual change from summer (low) to winter (high) values and vice versa.

Sea temperature, sea state, tidal range and river flow correlated significantly with suspended solid values. It is suggested that wave action, tidal currents and river flow control most of the variation in load of suspended matter off the N. Yorkshire coast. The significant negative correlation between temperature and suspended solid values is not regarded as a causal relationship. Low temperatures are associated with high wave activity and high river flow rates; factors which are more likely to have a causal relationship with suspended solid loads than temperature. Thus, suspended matter variations off the Yorkshire coast are probably determined by physical rather than biological temperature-dependent processes.

From multiple linear regression analyses, sea state, tidal range and river flow were found to account for 64·1% of the variation of the inshore suspended solid values and 52·4% of the variation of offshore values. Using the multiple regression equations as mathematical models it was possible to derive accurate predictions of the natural suspended solid load.

Scanning microscope investigations were carried out on mandibles, labrum and paragnaths of several species of Mysidacea and Euphausiacea. Gut content analyses were in agreement with morphological observations. It appears that the morphology of the peri-oral structures and especially of the mandibles reflect the feeding habits, and that the well known relationships between the size of the molar process and the incisor one, i.e. a large molar process is associated with herbivorous feeding, is not always verified. Bacescomysis abyssalis and Bentheuphausia amblyops are believed to be mostly saprophagous, Boreomysis inermis and Meganyctiphanes norvegica are mostly phytophagous, Hemimysis speluncola is omnivorous, while Siriella armata and Thysanopoda orientalis are carnivorous species.

The sea cucumber Apostichopus japonicus is a deposit-feeder and vital for marine benthic ecosystems. Hypoxia can influence the behaviour and even lead to massive mortality in A. japonicus in the wild. It is important to understand the molecular responses of A. japonicus when exposed to acute changes in dissolved oxygen (DO) concentration. In this study, RNA-seq provided a general overview of the gene expression profiles of the respiratory tree of A. japonicus exposed to DO of 8 mg l−1 (DO8), 4 mg l−1 (DO4) and 2 mg l−1 (DO2) conditions. Differentially expressed genes (DEGs) screening with the NOISeq method identified 51, 59 and 61 DEGs according to the criteria of fold change ≥2 and divergence probability ≥0.8 in the comparisons of DO2 vs DO4, DO2 vs DO8 and DO4 vs DO8, respectively. Gene ontology analysis showed that ‘cellular process’ and ‘binding’ had the most enriched DEGs in the categories of ‘biological process’ and ‘molecular function’, respectively (catalytic activity also had the most enriched DEGs in the category of ‘molecular function’ based on the comparison of DO2 vs DO8), while ‘cell’ and ‘cell part’ had the most enriched DEGs in the category of ‘cellular component’. The DEGs were mapped to 79, 81 and 104 pathways in the KEGG database, and 8, 29 and 16 pathways were significantly enriched, respectively. The DO-specific DEGs identified in this study of the respiratory tree are important targets for further research into the biochemical mechanisms involved in the response of the sea cucumber to changes in the DO concentration.

One of the lobsters kept in the tanks of the Plymouth Laboratory moulted on the night of 2 0 August 1940. This opportunity was taken to examine the changes in water content and osmotic pressure of the freshly moulted as compared with unmoulted lobsters. Though only one recently moulted individual has been examined, the results seem to be worthy of note since so far as we are aware no data are available on the subject in regard to Homarus. The biology of moulting among lobsters has received the attention of many investigators (vide Herrick (1895) and Drach (1939) for summary and literature).

The water content was determined by distilling the fresh lobster together with a known weight of sea water under xylol. This method is a modification of that of Dean and Stark which one of us (A. G. L.) has tried on a number of animals and found to give accurate results. The density was estimated by a modification of a method previously described (Lowndes, 1938). Osmotic pressure of blood and the external medium were measured by Baldes's (1934) modification of the Hill thermoelectric technique, as employed by one of us (N. K. P.) in the study of prawns and other crustaceans. The water content of the moulted skin was calculated from its dry weight taken after dehydrating in a hot air oven for 48 hr. at 105° C. Osmotic pressure was measured 17±6 hr. after moult; density and water content after 34±6hr. The temperature of sea water at which the density was estimated was 17° C.

The pink shrimp Dichelopandalus bonnieri Caullery, 1896, is widely distributed on North Atlantic coasts; it is recorded from the Bay of Biscay, south and west Norway, Scottish and Irish Coasts, South of Iceland and the east coast of North America on muddy substrates in depths ranging from 40 m to 1200 m (Kemp, 1910).

Food of Seriola lalandi was mainly composed of juveniles of horse mackerel (Trachurus lathami) (%IRI = 99.66) showing the species as carnivorous feeders predating on small pelagic organisms.

In making benthic surveys it is often difficult to extract all the animals from the various sediments in good condition. Even the IBP Handbook (Holme & Mclntyre, 1971) does not give comprehensive details of methods for extracting animals from the complete range of sediment types. The greatest difficulty is presented by clays and compacted silt. In recent work we have had very satisfactory results by using the following procedure. Core and grab samples taken in the field are stored in seal-tight buckets for processing in the laboratory. In the case of grab samples taken from boats, preliminary sieving is performed on site and only the resistant sediments returned to the laboratory. The samples are broken into pieces of approximately 100 cm3 or less and stored in 5 % formaldehyde solution using a volume about three times that of the sediment. This serves to fix and preserve the fauna and also helps in the breakdown of clays. At this stage samples may be stored for a long time. Wherever layers of soft mud are found among the resistant material they are washed off, sieved and the fauna preserved separately. The resistant samples are then frozen in a domestic freezer and left for 24 h before thawing. The freezing is very effective in breaking down resistant sediments into small particles, thus releasing the animals, which can readily be removed by elutriation. Normally, most animals seem to be adversely affected by freezing in much the same way as some vegetables lose their consistency when frozen (an exception to this are members of the polychaete family Phyllodocidae). However, the prior treatment with formalin seems to protect the tissues from damage by freezing.

1. For the preservation of ropes the importance of the preservative against bacterial decay being also an internal lubricant for the rope fibres must be remembered.

2. Tests have been carried out for one year in sea-water, which was much contaminated by sewage at times, under Plymouth Pier and in cleaner water of a tidal basin outside Plymouth Sound Breakwater for 10½ months, using 2-inch and 0-6-inch ropes respectively; the latter was manila, the former were manila, hemp, sisal and coir.

3. The preservatives included cutch, cutch bichromate, cutch ammonia copper sulphate, coal tar distillates, including those of the Coalite process, also hardwood and softwood tars. The tars and tar oils were tried alone and mixed with copper soaps, naphthenate (Cuprinol and Shell products), oleate and resinate, also zinc and iron naphthenates (Cuprinol). The naphthenates and oleate are good lubricants.

4. Very good results were obtained with green Cuprinol containing tar and with 10 per cent copper oleate in a light coal tar; slightly inferior were 10 per cent copper resinate in Coalite heavy oil or in creosote oil as now used largely in Plymouth; also 10 per cent copper oleate with 20 per cent of Coalite tar in Coalite neutral oil, b.p. 100–245° C, which i s a very cheap solvent. All these maintained the thin manila rope at or above 70 per cent of its initial strength after 10½ months; the untreated control was down to 13 per cent.

The response of the shore crab Gaetice depressus to predation risk stimuli of either the octopus Octopus vulgaris or crushed conspecifics was examined at two different time phases in the activity rhythm (active and inactive period) by laboratory experiments. When octopus chemical stimuli were introduced to the experimental aquarium, the crab activity decreased in the active period (night) but not in the inactive period (daytime). When the chemical stimuli of crushed G. depressus were introduced, the activity of the crabs increased in the inactive period although the stimuli decreased the activity in the active period. This indicates that G. depressus adjust their anti-predator response according to a combination of the type of predation risk and also the activity rhythm.

Vertical posture has been studied only in the scutellid sand dollar Dendraster excentricus although it has been reported in another Dendraster species and two species of laganid sand-dollars. The vertical posture has been associated with the posterior eccentric position of the apical system and petals of the test. We have discovered the scutellid sand dollar Encope michelini, which shows no eccentricity of the apical system and petals, also has the vertical posture in the population studied. Absence of eccentricity of the apical system and petals in living and fossil sand-dollars does not indicate absence of the vertical posture.

An ecologically unique cirripede, Octolasmis unguisiformis sp. nov. (Cirripedeia: Thoracica: Poecilasmatidae), was found to be ectosymbiotic with an ocypodid crab, Macrophthalmus milloti, on tidal flats of the Amami Islands, the Ryukyu Archipelago, Japan. The cirripedes were attached to the ventral side of the crab carapace, around the bases of the first and second ambulatory legs. The cirripedes resemble the chelipeds of male host crabs. Adult cirripedes were found only on female crabs, whereas juvenile cirripedes were present on crabs of both sexes, suggesting that the survival rate of the cirripedes on female crabs was higher than that of those on male crabs. The cheliped-like appearance and female-biased distribution of the cirripedes are discussed from the standpoint of mutualism between the crab and the epizoic cirripede.

The taxonomy of six species and one subspecies of Natatolana, which have previously been recorded from the north Atlantic Ocean and Mediterranean Sea, is reviewed. Natatolana caeca, N. gallica, N. gracilis and N. neglecta are redescribed from the type material. The location of possible type material of N. borealis is reported and a redescription of this species is provided, based on material from the type locality. Natatolana neglecta var. imicola is recognized as a valid species. Natatolana schtnidti is regarded as a junior synonym of N. imicola based on comparison of type material and this material is used to redescribe the species. Distribution records for these species are summarized from examination of material held in various collections and a key to separate these species is provided.

The comparative research programme on harpacticoid copepod assemblages of the west coast of Ireland and northern Finistere began in 1982. During 1981 in Galway, D. Jackson sampled three sandy beaches around Galway Bay (Figure 1), Grattan Road Strand, Silver Strand and An Poll Brean (on Mweenish Island) near Carna (simply called Carna in the following text) and was preparing his PhD thesis (Jackson, 1985). Between 1978 and 1984 in Brittany, P. Bodin had been conducting a long-term ecological survey (Bodin, 1988) of three sandy beaches polluted by the 'Amoco Cadiz' oil spill; Brouennou, Corn ar Gazel and Kersaint (Figure 2). As these six beaches shared common characteristics of granulometry, salinity, temperature and hydrodynamics, it was decided to undertake a comparative study of the systematics, ecology and biology of their harpacticoid copepod assemblages.

Stanley Kemp, Sc.D., F.R.S., Secretary of the Marine Biological Association of the United Kingdom and Director of the Plymouth Laboratory, died on 16 May 1945 at the age of 62. His death at the height of his power has come as a most grievous blow to both marine science and zoology in general.

The stage of development of the gametes of both male and female honeycomb worms Sabellaria alveolata (L.) was examined, using histology, over a 14-month period. Samples came from Howes Strand and Garrettstown, County Cork in south-west Ireland. A clear cycle of both male and female gametogenesis was evident, with a distinct peak in the summer (June–September) when the majority of them were ripe. During October–January a small proportion of males contained abundant spermatozoa, but no mature oocytes were found. Over the whole sampling period the ratio of males:females was 1.4:1. Further south in Roches de la Fosse in France at the centre of its range, two spawnings and an even sex-ratio have been reported.

The Lusitanian toadfish Halobatrachus didactylus is a demersal teleost and the only species of the family Batrachoididae that occurs along the continental Portuguese coast. It is a subtropical species that is more abundant in the south of Portugal, whereas along the western coast it is concentrated in discrete populations, located in estuaries and coastal recesses. The distinct features of these estuaries have revealed important changes in the respective Lusitanian toadfish populations, namely particularities in their distribution and population structure, and also in the morphology and breeding behaviour of the specimens. A survey covering 31 stations in the Tagus estuary, Portugal, and adjacent coastal waters sampled these stations over an 18 month period. This study characterized the distribution, abundance, population structure and activity of H. didactylus in this coastal zone. Toadfish showed a preferential distribution in the intermediate and lower estuarine stretches, and was more abundant in the Montijo Bay, a small bay within the Tagus estuary. Three length-groups were identified, with larger specimens more abundant in deeper areas. The specimens also revealed a preference for areas of higher water temperature, low water current and muddy substrates. Female specimens were slightly more abundant than males and type II males had a very low frequency of occurrence (3.2%). Captures of toadfish were high in spring and late summer and very low in winter.

This study determined the spatial and seasonal density, number of genera, genera composition, maturity index and trophic structure of free-living nematode assemblages in the subtidal waters of the northern Beibu Gulf, South China Sea, and explored whether these five biotic characteristics were related to various environmental variables. Based on the data derived from samples collected seasonally at nine stations, the mean densities of nematodes decreased from alongshore to offshore station in the northern Beibu Gulf. However, the number of nematode genera increased from alongshore to offshore station. Non-parametric multidimensional scaling analysis showed no clear seasonal changes for nematode assemblages in most sampling stations. Higher densities of the genera Elzalia and Tricoma were found in offshore sampling stations, and a higher density of the genus Cheironchus was found in alongshore sampling stations. The mean percentage of each feeding type compared to the total numbers was highest in epigrowth feeders (2A), second highest in non-selective deposit feeders (1B), third highest in predators (2B), and lowest in selective deposit feeders (1A). There were significant negative correlations between nematode density and water depth and temperature; significant positive correlations between the number of nematode genera and water depth and salinity; and significant negative correlation between the maturity index of the nematode assemblage and organic matter. BIOENV analysis indicated that water depth, salinity, pH, median sediment particle size and organic matter were the most correlated combination of environmental variables affecting the nematode assemblages.

The results of phosphate determinations in sea water by the Deniges method, using red light, in an absorptiometer, may be in error if the stannous chloride reagent has low HC1 concentration, and contains stannic tin.

The error is in the reagent blank determination, and seems to be caused by colloidal stannic compounds which increase the opacity of the solution. In sea water the effect may be smaller or immeasurable so that results are over-corrected.

When the stannous chloride solution contains about 5% hydrochloric acid, reagent blank figures are low, and independent of stannic tin concentration. This acidity is recommended.