It has been shown (1, 2) that the capacity for building up visual conditioned responses is common to many types of fish when the unconditioned stimulus used as the basis for the “conditioning” is food. Preliminary work at Plymouth, using the fish Blennius gattorugine, showed that was possible that a knowledge of wave-length discrimination in that species might be acquired by the now familiar method of “conditioning” to an electric shock. This work was continued when I came to Cullercoats, and six specimens were used which were sent from Plymouth in 1929. All of these died within a short space of time during the succeeding winter months, owing to the intense cold. It was therefore necessary to restrict the investigation to Blennius pholis L., which is both plentiful and hardy at Cullercoats. Some progress had already been made and in Part II (2) it was intimated that an analysis would be made of the capacity for wavelength discrimination in Blennius pholis using an electric shock as the unconditioned stimulus. The present paper gives the results of that enquiry as far as it was taken.

Citadel Hill, Plymouth (Plates I–II) The sexual display and mating of the dragonet (Callionymus lyra L.) were well described by Holt in 1898 from observations of the behaviour in a relatively small tank in the Plymouth aquarium. When in 1959 numerous dragonets werekept in a much larger tank mature males established territories within which they displayed tofemales. The more pugnacious males maintained larger territories than less pugnacious males. Maintenance was mainly by display against rivals without physical contact, but occasionally there were direct attacks in which minor damage was inflicted.

In his long and detailed account of the sexual display and mating of the dragonet (Callionymus lyra L.), based on observations in the Association's aquarium at Plymouth, Holt (1898) makes no mention of males defending specific areas and states that there was 'no evidence of serious combat among mature males' (p. 312). 'Occasionally the two males meet in full splendour. Then one lowers his colours and flies ingloriously; but I have never seen anything in the shape of a fight, and have never found wounds that might have been inflicted when I was not watching' (p. 288). Holt records (p. 286) that his dragonets inhabited a tank on the south side of the aquarium and it was in that tank that breeding displays took place. He also put large males into a very much larger tank, though only to watch their reactions in the presence of large turbot (p. 295): one was eaten, others disappeared not to be seen again.

Sagittal otolith morphology and otolith shape of two megrim species, Lepidorhombus boscii and Lepidorhombus whiffiagonis, were compared using descriptive morphological characters and Wavelet shape coefficients. Differences in otolith shape were examined by linear discriminant analysis (LDA). The first discriminant axis explained 66.6% of the variation between the groups, and the second axis 28.5%. Otolith classification based on LDA showed that in 79.5% of cases an otolith can be correctly classified based only on its shape. Relationships between otolith morphometric parameters (length and width) and fish size (total length) were described by fitting simple linear regression models. For L. boscii the highest positive correlation was found between right otolith width and total body length (R2 = 0.82), and for L. whiffiagonis between left otolith length and total body length (R2 = 0.39).

Ports have long been considered ‘high-risk’ areas for the introduction of non-native species (NNS) and should therefore be a focus of NNS monitoring. The industrial nature of active ports can, however, provide various problems when attempting to carry out monitoring programmes. Current methodologies designed to identify NNS and to describe fouling communities have not been developed specifically for use in active ports and can encounter a number of issues when used in these environments. Here, two surveys were developed and trialled within an active port in South Wales, UK, designed to describe fouling communities, identify NNS and overcome some of the major limitations to conducting surveys within ports. Over a 6-month period, fouling communities dominated by solitary ascidians developed in each survey. Seven NNS were identified, mostly species already recorded in the 1950s, including the Mediterranean crab Brachynotus sexdentatus, and the more recently introduced Japanese skeleton shrimp Caprella mutica. Each survey was evaluated independently with respect to key factors, including the ability to detect NNS and practical aspects of using these survey methods in an applied context. We conclude that whilst each survey can function independently, the use of both survey types in conjunction offers the most robust solution to identifying NNS and describing wider fouling communities within active ports. This research has implications for the future monitoring and management of NNS within UK ports.

In the process of calcification in the coralline algae, Clathromorphum and Corallina, the energy is derived from photosynthesis; the outer surface evolves carbon dioxide while calcium carbonate is deposited between the algal filaments. Evidence suggests that calcification may be brought about essentially by separation of acid and base followed by preferential removal of an acid component in the form of carbon dioxide.

These algae show strong oxidase, catalase and carbonic anhydrase activity, consistent with the processes postulated. The calcified algal thallus is normally reducing. Platinum electrode potentials, Eh, measured on and immediately below the outer surface of fresh and healthy Clathromorphum crust following abrasion ranged from 50 to 100 mV, some 150–370 mV negative to that of the surrounding water at the time. These potentials in the alga were most reducing after the material had been exposed to strong sunlight. Eh potentials, measured by electrodes of platinum foil attached to the outer surface of Clathromorphum in such a way as to shield it from light and from gaseous exchange from the sea water, reached values between 113 and -182 mV, or up to 480 mV negative to the Eh of the surrounding sea water.

Oxidation of crude suspensions of crushed fresh material showing reducing activity resulted in the production of base by removal of hydrogen ions. The amount of base so formed was greater when suspensions were first incubated out of contact with air for periods of up to several days, reducing conditions being enhanced by respiration of the alga alone or in conjunction with bacterial growth.

During the present year tow-netting has been carried on with such continuity as the weather permitted, and the fish-ova and larvæ thereby obtained have been studied by Mr. S. D. Scott during the winter months, and by myself since the spring. While reserving a general account of the results until the close of the season, it seems advisable to deal now, in however preliminary a manner, with a few species, an addition to the existing knowledge of which may be found of immediate use by workers in the same field. I take this opportunity of expressing my indebtedness to Mr. Scott for observing certain eggs which I was obliged to leave at the Laboratory at a stage too little advanced for specific determination.

Estuaries in Brazil are highly threatened environments and habitat loss is the main influential factor for the increase in the number of strandings of Antillean manatee (Trichechus manatus) calves in the north-eastern region of the country. The aim of the present study was to analyse and quantify the spatiotemporal dynamics of mangroves in the state of Paraíba and the association with manatee calf stranding events. The study area encompassed 10 remaining mangroves along the coast of the state, four of which were located within protected areas. Information on the mangrove forests was obtained from satellite images from the last four decades. Data on stranded Antillean manatee calves were obtained from a databank with records from 1980 to 2019. The data were analysed using geoprocessing techniques and statistical analyses. The results demonstrated changes in the mangrove forest over time, with larger areas existing during the 1980s, reductions in the following periods but a slight increase in the last decade. The number of stranded Antillean manatee calves increased over the years, with stranding events concentrated mainly on the northern coast of the state. The smallest number of stranding events occurred in the 1980s, when the mangrove forests were larger. Our findings confirm that the integrity of mangroves is of extreme importance to the maintenance and sustainability of Antillean manatee populations.

Rapid fixing of skeletal muscle by a ‘freeze-clamp’ technique results in up to a 3-fold lower lactate, a slightly higher pyruvate concentration and a 2- to 4-fold decrease in lactate/pyruvate ratio, to the lowest value yet recorded for fish muscle, when compared with the more usual method of direct immersion in liquid nitrogen. This is attributed to the faster cooling rate of freeze-clamped muscle minimizing ‘sampling anoxia’. Immobilizing fish either by anaesthetic or stunning produces no significant change in metabolite levels. It is concluded that it is relatively easy to handle quiescent flatfish, but light anaesthesia ensures no muscular activity.

The taxonomy of pedunculate cirripedes belonging to the genus Pollicipes has essentially remained unchanged since Charles Darwin described them in his exhaustive work on the Cirripedia. This genus includes three species of stalked barnacles: Pollicipes pollicipes in the north-eastern Atlantic, P. polymerus in the north-eastern Pacific and P. elegans in the central-eastern Pacific. However, a population genetics analysis of P. pollicipes suggested the presence of a putative cryptic species collected from the Cape Verde Islands in the central-eastern Atlantic. This study examines the morphology of these genetically divergent specimens and compares them with that of representative Atlantic samples of the biogeographically closely related P. pollicipes and with the poorly described P. elegans. Molecular data, including mitochondrial COX1 and nuclear ribosomal interspaces sequences, were obtained for all species of the genus Pollicipes. Morphological distinctiveness, diagnostic characters, congruent divergence level and monophyletic clustering, at both nuclear and mitochondrial loci support the taxonomic status of this new species, Pollicipes darwini.

Cholorophyll a, primary production and the patterns of 14C assimilation into the major end-products of photosynthesis were determined for phytoplankton in the coastal waters off Plymouth, in order to study their physiological ecology during spring conditions. At the end of the study period, a diatom bloom occurred after the development of a slight thermocline. Throughout the pre-bloom period, the majority of the label was found in storage products, and phytoplankton growth was not nutrient-limited. During the development of the bloom, however, an increase in protein synthesis was found, which is interpreted as a result of an active phytoplankton growth. Both synthesis ratios for protein to storage products, i.e. lipid and polysaccharide, (P/L+S) and protein to low molecular weight metabolites (P/M), summarize the variations in the physiological state of phytoplankton during this study. Comparison of the P/M synthesis ratio and different estimations of phytoplankton growth rate shows the usefulness of this index for characterising natural populations.

Archinome storchi sp. nov. is described as the second species of the family Archinomidae. The specimens were collected from a hydrothermal vent site in 2212 m depth on the Pacific–Antarctic Ridge at 37° S. It differs from Archinome rosacea mainly in the position of the anus, the first appearance of branchiae and the length of the nuchal cirrus. Additional specimens of A. rosacea collected from hydrothermal vent locations in the North Fiji Basin and on the Mid-Atlantic Ridge were used for morphological comparison. A synoptic table of characters is given for A. rosacea and A. storchi sp. nov. together with a list of records for Archinomidae compiled from the literature.

Thirty ‘rock-populations’ of the intertidal isopod, Jaera albifrons (Isopoda: Asellota), from South Wales area were found to display a significant and persistent sex ratio bias, with females outnumbering males by up to 12 to 1. This thelygeny was not mirrored in broods that were isolated in aquaria after insemination, nor in broods that developed under various temperature and light regimes. Such a discrepancy suggests that the mechanism generating sex ratio biases in natural populations is not innate, nor is influenced by cytoplasmic or environmental factors. The possible causes of thelygeny in natural populations are discussed.

A new final fish host (Stromateus brasiliensis) for the digenean parasite Monascus filiformis from the continental shelf of Patagonia Argentina in the South-western Atlantic Ocean is reported. This demersal-pelagic fish (commonly denominated pampanito) is exclusively a jellyfish consumer. It is well known that larval stages of Monascus filiformis mostly use medusae as secondary hosts. Therefore, the pampanito likely acquires this parasite when it predates upon some species of parasitized medusae in the area. This work improves the knowledge about the final hosts of this parasite and infers which species of medusa may be involved in their life cycle.

The increasing market demand for Glyptocidaris crenularis shapes its great potential for aquaculture. Temperature is an important factor affecting gonad production and quality of sea urchins. Therefore, it is essential and valuable to carry out an evaluation of the temperature effects on gonad production and quality in G. crenularis before potential aquaculture. Here, we investigated the long-term effects of temperature on gonad production, colour and flavour in G. crenularis. There was no significant difference of test diameter, height and body weight between the sea urchins in high (16–23°C) and low (12–16°C) temperatures (P > 0.05). Glyptocidaris crenularis showed significantly higher gonad production and index in high temperature and in low temperature (P < 0.05). L*, a*, b* readings were slightly higher in the low temperature groups, although no significant difference was found (P > 0.05). Subjective colour and flavour ratings found that G. crenularis in the low temperature group showed significantly better colour (P = 0.003) and flavour (P < 0.001) than those in the high temperature group. The present study provides valuable and insightful information into the establishing G. crenularis aquaculture.

Three new species of Iberian cheilostomate bryozoans are described from material held in our own collection as well as in the bryozoan collection in the Museo Nacional de Ciencias Naturales, Madrid. Chaperiopsis hirsuta sp. nov., from the Mediterranean, is the second species of this genus in European waters. Metroperiella gay sp. nov. and Schizoporella artabra sp. nov. are described from material collected in Galicia (north-western Spain).

It was observed during the summer of 1920 that specimens of the Long legged Spider-crab, Stenorhynchus phalangium Penn., which happened to be in the crowded tanks of the Roscoff Laboratory, were always to be found in the neighbourhood of specimens of Anemonia sulcata Penn. (Anthea cereus Ellis). That this was not merely accidental was shown when crabs, removed to a distance of over three feet, returned time after time to an Anemonia, passing on the way anemones of various species, as well as all manner of objects which might conceivably afford shelter. Of fifteen healthy crabs of this species observed during the past three summers, every one showed this tendency in greater or less degree. At least two of these crabs were found clinging to anemones of this species on the shore, between tide marks; but the subsequent behaviour of crabs dredged from deeper water was in no way different.

Seven species of chirostyloid and galatheoid crustaceans, including three new species, are reported from the eastern Arabian Sea and Bay of Bengal, India, based on material from depths ranging from 32–1420 metres. Trapezionida samudrika sp. nov. appears close to T. munin (Komai, 2011), but is distinguished by the shape of the carapace and fourth thoracic sternite, the armature of the third maxilliped merus, the length and armature of the cheliped, and the armature of the ambulatory legs. Paramunida travancorica sp. nov. differs from its closest species P. bineeshi Macpherson, Chan, Kumar & Rodriguez-Flores, 2020, P. mozambica Cabezas, Macpherson & Machordom, 2010, and P. stichas Macpherson, 1993 in the morphology of the carapace and antennular and antennal peduncles. Munidopsis bhavasagara sp. nov. is similar to M. dentifalx Osawa, Lin & Chan, 2007, but distinguishable by the absence of a pair of elevated, short ridges on the epigastric carapace region and the proportionally shorter chelipeds and ambulatory legs. The present material of Munidopsis unguifera Alcock & Anderson, 1894 represents only the third record of the species in India and a detailed description and illustrations are provided to supplement the previous descriptions. The remaining three species, Eumunida multispina Komai, Chakraborty, Paramasivam & Gidda, 2019, Munidopsis scobina Alcock, 1894, and M. stylirostris Wood-Mason in Wood-Mason & Alcock, 1891, are recorded from additional localities within their known geographic regions.

The present study undertaken in the largest coastal lagoon of Asia, Chilika, deals with monthly monitoring of benthic foraminifera assemblages in terms of distribution pattern, diversity and variations in taxonomic composition spanning over a period of 20 months. In total, 13 species of benthic foraminifera represented by eight families were identified in the lagoon. The stations in the Southern sector of the lagoon showed relatively low foraminifera abundance yet high diversity whereas higher abundance and lower diversity were observed in stations located in the Central sector which indicates the spatial patterning of the assemblage. Live foraminifera abundance was sparse in the study area indicating the stressed nature of the lagoon environment. The dissolved nutrient concentration of bottom water reflected significant seasonal variation. The stressed nature of the lagoon is further indicated by the dominance of the genus Ammonia across the inner sectors of the lagoon, a genus known to inhabit impacted habitats. Overall these data can serve as a baseline proxy for understanding palaeontological assemblages of foraminifera in similar shallow-water settings globally.

A trade waterproofing of sisal rope had still some effect after 3 days in sea water, the untreated being four-fifths saturated in 1 hr.

Treating manila, sisal and coir rope with Cuprinol or tar increases the wet weight at the most only slightly as less water is taken up than without preservative.

Water equilibrium is not attained till long after the B.S.I, specification test period for waterproofing sisal rope, but some effect of waterproofing may be distinguished up to perhaps 3 days.

On cotton netting copper naphthenate preservatives were most durable in a clean sea-water basin, but Dr Olie's method with cutch and ammoniacal copper sulphate ran them close and is cheaper. The best lasted 9 months as against untreated 5½ months.

On trawl twines the British Columbia grade of Cuprinol, a proprietary mixture containing copper naphthenate, was the best of those tried, and the twines lasted 16 months as against almost 9 for untreated manila.

On thin sisal rope six copper preparations are still under test.

The genus Prymnesium includes several species that produce toxins with cytotoxic, ichthyotoxic, neurotoxic and haemolytic activity. Bloom episodes of Prymnesium species have been reported from several parts of the world (North America, Europe, Africa, Asia and Australia), especially from temperate and subtropical regions and most of them from brackish waters. Blooms cause great economic losses to aquaculture and fisheries around the world. The ichthyotoxic and allelopathic effects of Prymnesium have been linked to the presence of Haemolysin 1, Prymnesins 1 and 2 and, more recently, fatty acids and fatty acid amides. The toxicology of this genus with regard to different growth conditions such as light, nutrients and other parameters has been well documented. It is unknown, however, whether different species and strains from the Prymnesium genus all produce the same types and level of toxins. In this study, we have determined the haemolytic activity of eight different strains from the genus Prymnesium in both exponential and stationary phases of growth. We have also evaluated the efficiency of the extraction solvent.