Copula trials in Neptunea arthritica were conducted to provide possible hypotheses explaining the outcomes of reproductive interaction with regards to size differences and female resistance in the context of conflict over copula duration between the sexes. Size asymmetry predicted the outcome of copula duration to favour the largest individuals. Female resistance was expressed consistently and increased with consecutive copulas, generating variation in copula duration. When resistance was removed, copula duration increased in contrast with natural trials suggesting intense conflict. Overall, males showed a tendency to mate with large females, which represents higher rejection risk, indicating that benefits from mating with large females might offset the risk of failure against resistance. Conflict possibly stems from a ‘power asymmetry’ in which individuals of one sex could sequester control over some aspects of mating to the detriment of the opposite sex.

A new spionid polychaete, Malacoceros jennicus, is described from the crater of a hydrothermally active submarine volcano near Grenada in the Caribbean, Lesser Antilles Arc region. The new species is characterized by having prominent lateral frontal horns on the prostomium, paired eye spots, neurosetae that include simple capillaries, inferior sabre setae, numerous bidentate hooded hooks, and a pygidium bearing four digitiform anal cirri surrounding the anus. Worms were collected in regions of diffuse venting with a suction sampler deployed on an ROV. Specimens representing a range of sizes including sexually mature and reproductive individuals containing eggs and sperm were found. Stable isotope analysis of 13C and 15N indicate mixed feeding on photosynthetic and hydrothermal vent source material.

Germination of cysts serves as inoculum for the proliferation of some dinoflagellates, and cyst abundance in sediments represents crucial information to understand and possibly predict Harmful Algae Blooms (HABs). Cyst distribution is related to the physical characteristics of the sediments and the hydrodynamics (circulation) of a particular region. In the northern Gulf of California (nGC) several Gymnodinium catenatum HABs have been recorded. However, the presence of resting cysts and the effect of hydrodynamics on their distribution in the nGC have not been investigated. This study evaluated cyst abundance, distribution and their relation to local circulation in surface sediments during two periods that coincided with a non-bloom year condition (July 2016) and after a major HAB registered in the nGC that occurred in January 2017. Also, a numerical ocean model was implemented to characterize the transport and relocation of cysts and sediments in the region. Gymnodinium catenatum cysts were heterogeneously distributed with some areas of high accumulation (as high as 158 cyst g−1, and 27% of total cyst registered). Cysts seemed to be transported in an eastward direction after deposition and accumulated in an extensive area that probably is the seedbed responsible for the initiation of HABs in the region. The nGC is a retention area of cysts (and sediments) that permit the formation of seedbeds that could be important for G. catenatum HAB development. Our results provide key information to understand G. catenatum ecology and specifically, to understand the geographic and temporal appearance of HABs in the nGC.

Sea surface temperatures have been taken daily at Keppel Pier, Millport (55° 44‘ 55“ N. lat.; 4° 54’ 20” W. long.), for the past 10 years (1949–58), the data being included in returns to the Meteorological Office. The records are not given in their standard publication and they are, therefore, presented here to supplement those of Cooper (1958) for inshore waters at Plymouth some 400 miles farther to the south. For some years the samples were drawn in a specially constructed container fitted with a Fahrenheit thermometer which was read to the nearest whole degree; more recently the bucket method has been used, and a centigrade thermometer graduated in degrees and read to an estimated tenth of a degree. The two methods were checked against each other before the change was made and the results found to be consistent. All readings were taken at 09.00 h G.M.T., irrespective of the state of the tide. The results are shown in Table 1.

The survivorship of marine invertebrates that have a life span of less than 2 years is usually assessed by observing the decrease in abundance of animals from samples taken frequently throughout the life of an identifiable cohort or generation (e.g. Crisp, 1971). This method is only suitable for species with approximately simultaneous recruitment so that the animals can be aged with reasonable accuracy and the mortality before the end of the recruitment period can safely be ignored. Such age-specific survivorship data can be used to calculate secondary production by revealing the number of animals that reach successive weights (= Allen curves) (Crisp, 1971).

It has previously been shown (Ford, 1, p. 284) that herrings with fully ripened roes or milts form a considerable proportion of the landings by commercial drifters at Plymouth during December and January. Although naturally-deposited spawn has rarely been obtained from the sea-bottom in the district, the fact that newly-hatched larvæ occur in abundance provides evidence that actual spawning occurs locally. It has also been shown that from the end of September onwards, ripe fishes may be taken in stop-nets in Plymouth Sound, and even in sprat-seines in the estuarine waters of the River Tamar. A number of interesting and important questions is suggested by these observations. For example, do the ripe herrings which frequent the River Tamar actually spawn there, and if so, are they morphologically identical with those which spawn at sea, or are they of a different character? Would eggs deposited in the river be successfully fertilised and able to endure the periodic freshening of the water? Are the morphological characters of the offspring in any way dependent upon the environmental conditions under which they are developed?

Here we present a comparison of saddle and eye patch patterns of killer whales from Norwegian, Icelandic, British, Spanish and Greenlandic waters. We found only a small amount of variation in saddle patch shapes, which may reflect a recent phylogenetic divergence from the most recent common ancestor. Eye patch shapes were more variable than saddle patches in small details. Most individuals had eye patches with parallel orientation, with the exception of a small group of killer whales from the Hebrides, which, as previously reported, had sloping eye patches that sloped downward at the posterior end. This differentiation in pigmentation patterns of the Hebridean killer whales from neighbouring populations could reflect one or more of several evolutionary processes, including a deeper phylogenetic divergence, low gene flow with other local populations and drift.

Water, carbon, and nitrogen contents were analysed in both juvenile and adult specimens of Diaphus theta, Stenobrachius leucopsarus, and S. nannochir, which are the dominant myctophid species in the subarctic and transition waters of the North Pacific. The relationship between body length and dry weight, carbon content, and nitrogen content of these three species were expressed as double logarithmic equations. The differences in chemical content among the different size-classes of each species may be associated with reproductive biology.

A simple aquarium system was used to keep large ormers collected from the wild and to rear juveniles from fertilization up to age one year. Spawning was induced by exposure to u.v. irradiated sea water and counts made of gamete production. Repeated spawning was observed in males and from egg counts it was inferred that females also undergo repeat spawning in the wild.

Juvenile ormers were reared on simple collectors up to 4 mm shell length and later in open mesh cages. There was large variation in growth rate between individuals among the juvenile ormers. After one year shell lengths varied in the range 6·2–21·o mm.

Twenty-three adult ormers (shell length 40·4–93·6 mm) were reared for eight months in a tank with a concrete shelter. The smaller ormers remained under the shelter much more than the larger ones, some of which adopted a permanent position outside the shelter. In the study period growth was greater in the smaller specimens (less than 70 mm shell length) than in the larger ones.

The heart-body in Neoamphitrite figulus (Dalyell) forms a mass of tissue within the supra-oesophageal vessel almost occluding the lumen. The tissue forms a much-infolded cylinder enclosed by a basal lamina consisting of a fibrous reticulum through which the assembled haemoglobin molecules are discharged into the plasma (Dales & Pell, 1970). A function of both the heart-body and the extravasal (‘chloragogen’) tissue in polychaetes without a heart-body was established by biochemical analysis (Kennedy & Dales, 1958; Dales, 1963, 1965) to be the synthesis of plasma haemoglobin (erythrocruorin) or chlorocruorin. This was confirmed by electron microscopy (TEM) by Breton-Gorius (1963) in Arenicola, Potswald (1969) in Spirorbis, Dales & Pell (1970) in Neoamphitrite, Lattice, Myxicola, Megalomma and Sabella, and by Friedmann & Weiss (1980) in Amphitrite. It would appear that the same tissues also sequester phagocytosed materials (Braunbeck & Dales, 1984). Re-examination of this tissue by trans-mission electron microscopy (TEM) has extended our knowledge of the ultra-structure. Here we discuss these results in relation to the function of these tissues in the production of the respiratory pigments found in the plasma. Some heart-bodies of Terebella lapidaria L., Lattice conchilega (Pallas) and Cirriformia tentaculata (Montagu) have also been examined by TEM for comparison with that of Neoamphitrite figulus.

Spirobolbolaimus undulatus sp. nov. is described in intertidal sandy sediment from the East China Sea. The new species is characterized by six jointed outer labial setae much thicker and longer than the four slender cephalic setae, anterior and posterior pharynx bulbs, sclerotized multispiral amphid fovea, eight longitudinal rows of postamphideal setae, gubernaculum apophysis and many precloacal supplements. The new species differs distinctly from the type species Spirobolbolaimus bathyalis in the presence (vs absence) of jointed outer labial setae, eight additional small teeth, gubernaculum apophysis and many precloacal supplements and eight (vs six) rows of postamphideal setae. It differs from the other known congener Spirobolbolaimus boucherorum in the jointed outer labial setae (vs setae with smooth outline), three main teeth with eight additional small teeth (vs only three main teeth) and many distinct precloacal supplements (vs seven tiny papillate ones). We emend the diagnosis of the genus Spirobolbolaimus based on the description. Microlaimus pecticauda and Microlaimus spirifer possess two opposed reflexed ovaries, and thus are transferred from the family Microlaimidae to Molgolaimus of the family Desmodoridae: Molgolaimus pecticauda comb. nov. and Molgolaimus spirifer comb. nov.

The effect of temperature on the rate of reaction catalysed by crude muscle AMP-aminohydrolase from two species of elasmobranch and two species of teleost fish has been investigated at low substrate concentration in the range of temperature 5–50 °C.

The enzyme from teleost fish shows a very broad temperature optimum around 30 °C. The reaction rate of the enzyme from elasmobranch fish is strongly dependent on temperature. The optimum temperature for the enzyme from thornback ray lies around 40 °C. Both crude and 500-fold purified AMP-aminohydrolase from thornback ray show the same temperature-dependence.

Microphytobenthos need photoadaptive strategies to survive the highly dynamic light environment in which they reside. Xanthophyll pigments can provide photoprotection by cycling electrons between epoxide and de-epoxide forms, dissipating excess light energy as heat. This study examined the xanthophyll cycle in microphytobenthos on a tidally exposed substrate at Browns River, Tasmania. Fv/Fm decreased from 0.52±0.01 to 0.47±0.01 at noon in surface samples and a decrease in the diadinoxanthin:chlorophyll-a ratio from 0.022±0.003 to 0.015±0.005 also suggests that the microphytobenthos was under physiological stress at noon. The results indicate that the cells exposed to light at the surface migrated deeper into the sediments and replenished the epoxide form of their xanthophylls. The results suggest that micrphytobenthos utilizes both behavioural and physiological strategies to survive in the dynamic intertidal environment.

The ventricle of the heart of the plaice (Pleuronectes platessa L.) was examined in histological sections stained with Aniline blue. The ventricles from hearts from two age groups (from 3–5 years and 9–16 years as judged from otolith examination) of plaice were studied in histological section. In younger fish (3–5 years) epicardial collagen bundles form a thin (< 24–0 μm) layer and only the superficial trabeculae are partially invested with collagen bundles, those deeper trabeculae not having collagen bundles associated with them. In older fish epicardial connective tissue had increased greatly (> 120.0 μm) in thickness and endocardial collagen is much more abundant, and was observed throughout all ventricular trabeculae. Secondly, in the hearts of older fish only, an extensive epicardial vascular system was observed, as revealed by arterial and venous profiles. This vascular system was confined to the epicardium and did not penetrate the myocardium to form a vascular bed, nor was it derived from extracardiac vessels.

The investigation of the trawling-grounds in Start Bay, Torbay, and Teignmouth Bay, which had been previously investigated in 1895–8 by Messrs. Stead and Holt, was resumed by the Marine Biological Association in 1901, under authority from the Devon Sea Fisheries Committee.

It is well known that vision is the main physical factor governing the formation and maintenance offish shoals, and that, in general, shoals break up when the light intensity falls below a certain level. Breder (1929, 1942), Newman (1876), Parr (1927, 1931), and others, have shown this by laboratory experiment.

During a commercial fishing voyage to the Barents Sea it became possible, by means of a recording echo-sounder, to study the shoaling behaviour of cod in deep water relative to light intensity. The observations were made aboard the Hull trawler Lancella whilst fishing in a depth of 110 fathoms at Skolpen Bank in September 1955. For this a Kelvin and Hughes recording echosounder type MS. 24J was used, the depth range across the chart being 55 fathoms. The scale was phased so that the region between 80 and 135 fathoms deep was displayed.

The bibliography concerning the Mediterranean Sipuncula is reviewed, particularly that from the eastern Mediterranean. Additional data are provided from macrobenthic samples collected between 1974 and 1997 in the Hellenic waters. A total of 17 species are recorded, five of which (Sipunculus norvegicus, Golfingia elongata, Nephasoma lilljeborgi, Thysanocardiacatharinae and Aspidosiphon (Akrikos) mexicanus) are reported for the first time in Hellenic waters. Three more species (Onchnesoma squamatum squamatum, Aspidosiphon (Aspidosiphon) elegans, Apionsoma (Apionsoma) trichocephalus) which are found exclusively in the extreme eastern basin (Israel, Egypt) raises the number of eastern Mediterranean Sipuncula species to twenty.

The chromosome number and karyotype of amphioxus Branchiostoma belcheri tsingtauense were studied using embryonic cells. The diploid chromosome number (2n) of B. belcheri tsingtauense is 36, and its karyotype 2n=36, 2st+34t, FN=36. This is the first report on the karyotype of the cephalochordate. Evidence suggesting the possible presence of a pair of sex-chromosomes in the amphioxus has been provided.

New values for the extinction coefficient of red light in distilled water require that published results for this coefficient in waters from the Tamar Estuary shall be increased by o.1, 1.3 and 2.0 at 610, 720 and 750 mμ respectively. Earlier deductions as to the favourable transmission of red light in turbid estuarine waters apply only up to about 680 mμ. That part of the extinction coefficient due to suspensoids and colouring matter was inversely proportional to the first power of the wave-length. Other conclusions remain unaffected.

Antarctic krill, Euphausia superba, normally live in social aggregations (schools) but rarely aggregate in laboratory tanks. In order to study the effect of stress on solitary living we tethered krill to wooden skewers and measured heart rate both when they were held isolated from conspecifics and when they were held at normal schooling distances (∼1 body length). Heart rate did not differ significantly with sex or body size. However, intermoult krill had a significantly lower heart rate than postmoult animals. When two individuals were held at schooling distance, with one slightly higher in the water column than the other, the heart rate of the higher individual slowed significantly (106–98 beats min−1), while that of the lower individual remained the same. We interpret these results to mean that krill living solitarily are stressed but will respond to neighbouring individuals by decreasing their metabolic rate and saving energy.