The present study enhances knowledge of the biodiversity of diatoms in Chuuk, Micronesia following our 2018 study on the seaweed-associated diatoms. We collected planktonic samples of diatoms from five sites of reef flats using a 20 μm mesh net, and two samples of seaweeds with epiphytes by hand from an islet on the barrier reef. In addition, the seaweed-associated diatoms from our 2018 study were analysed using scanning electron microscopy. A total of 109 diatom taxa are documented in the present study. Of these, 70 species were from net samples, and 39 species from the seaweed-associated diatoms. Thirty-one species are newly recorded from Micronesian waters. Most taxa are benthic or tychoplanktonic; euplanktonic diatoms were rare. The occurrence of benthic diatoms from the water column might be related to the Chuuk environmental conditions which include shallow water, strong light intensity and high grazing pressure, to which benthic diatoms seem to be able to better adapt than planktonic diatoms.

Balanus balanoides (L.) is a cross-fertilizing hermaphrodite. The spermatozoa which are inseminated into the mantle cavity are initially inactive. Eggs are laid into the two elastic sacs of the oviducal glands (see Walley, 1965), which expand into the mantle cavity as more eggs are laid. The discharge of eggs into the elastic sacs also forces fluid out of the oviducal glands into the mantle cavity where the spermatozoa have been deposited. The fluid activates the inseminated spermatozoa (Walley, White & Brander, 1971; Walker, 1977).

In order to effect fertilization of the eggs activated spermatozoa must pass across the oviducal gland sac wall. How the spermatozoa accomplish this is the subject of the present investigation.

From works on the anatomy and ecology of dorid nudibranchs it has been assumed that they were capable of cutaneous respiration through their dorsal mantle. The present work has shown how the oxygen uptake is depressed when the dorids Onchidoris bilamellata and Archidoris pseudoargus are exposed to air and the gills collapsed into the body surface. The effect of ligaturing the gills of A. pseudoargus into the branchial pocket has enabled direct measurements to be made of the mantle respiration.

The effect of temperature on respiration was examined.

Here we report on a previously undocumented facultative symbiosis involving the wrasses Labroides dimidiatus and Thallasoma amblycephalum living in association with two species of sea anemones, on coral reefs in the north-western Pacific. By SCUBA diving we observed juvenile L. dimidiatus occurring in Entacmaea quadricolor (solitary type) cleaning the anemonefish Amphiprion frenatus and in Heteractis magnifica cleaning the anemonefish Dascyllus trimaculatus. Thallasoma amblycephalum co-existed in H. magnifica with the anemonefish D. trimaculatus, A. ocellaris and L. dimidiatus.

A new species of the corophiidean amphipod genus Corophium (sensu stricto) from the estuary of the Oka River (Basque Country, northern Iberian Peninsula) is presented. Data on the ecology and distribution of the species are included, which is comparable to other species of the genus, but has several differences. Two amendments to the diagnosis of the genus are proposed. A key of the European species of the genus is also included.

The astigmatid mite species, Tyrophagus putrescentiae, was found to occur in meiobenthic collections from the Mdloti Estuary on the eastern seaboard of southern Africa. To examine whether these mites are actually components of estuarine systems or the result of contamination of collecting and laboratory materials, special sterilization procedures were incorporated into the collection protocol. Samples employing sterilization procedures still yielded Tyrophagus mites, providing evidence for their existence in the estuarine sediments. The origination of these mites in estuarine and fringe marine systems, in general, is discussed. These findings are significant in terms of the potential trophic importance of Tyrophagus mites.

Corophium bonnellii (Milne-Edwards) has been suspected of being parthenogenetic for more than fifty years (see Crawford, 1937) and this suggestion has been supported by recent breeding experiments (Moore, 1981). Many thousands of specimens have been examined by taxonomists and ecologists from a wide geographical area in both hemispheres, yet only Toulmond & Truchot (1964) have claimed to have found a male. No description or figures were presented by Toulmond & Touchot (1964) to support their contention.

The following piece of research has been undertaken at the suggestion of the Conway Fisheries Eesearch Station of the Ministry of Agriculture and Fisheries.

For some years experiments have been in progress at Conway in connection with oyster breeding. During the oyster season, from May to August, when the tanks of the Kesearch Station are not being used for mussel cleansing, cultural work on the oyster (Ostrea edulis) has been carried out. One of the greatest difficulties is the feeding of the larvae in the free swimming state and this problem affects both tank culture and culture on a smaller scale. In some years a settlement of spat has taken place, but it is not known what conditions made that phenomenon possible. It has been suggested that the available food supply might be of importance, since both detritus on the one hand, and seaweed spores and gametes on the other, have been regarded as constituting the food of larvae (Martin, 1923). As nothing over 10μ can be ingested by the larvae, there is a limit to the spores and gametes which may be used.

The aquarium or tank room, to which visitors are admitted on payment of a small charge, was not designed primarily for public display, but was intended principally to facilitate scientific observations on the habits and life histories of marine animals. This original purpose it has never lost, but of recent years it has increasingly catered also for the steadily growing number of people interested in natural history, and for numerous classes of school-children brought by their teachers. Since the aquarium was re-opened in November 1946 attendances have shown a big increase over comparable pre-war figures.

Surface characteristics including wettability, thickness and adhesive potential of the pedal mucus produced by Patella vulgata and Littorina littorea were measured, to determine their effects on the settlement of marine organisms. The pedal mucus produced by P. vulgata was less wettable than that produced by L. littorea. For organisms that prefer to settle on hydrophobic substrata the pedal mucus produced by P. vulgata would be their preferred settlement site. The pedal mucus produced by stationary P. vulgata was thicker (mean thickness±SE=0·37±0·004 mm) than the pedal mucus produced by mobile P. vulgata and/or that produced by L. littorea, neither of which differed in their thickness (mean thickness±SE =0·10±0·01 mm).  The pedal mucus produced by P. vulgata had a greater adhesive potential (mean force of adhesion for the size range of mimics examined=3715–5380 Nm2) than the pedal mucus produced by L. littorea (mean force of adhesion for the size range of mimics examined=2846–3361 Nm2). Comparison of the adhesive potential of the pedal mucuses with a pedal mucus analogue, silicon grease, suggests that the pedal mucuses function as a Stefan (1874) adhesive when adhering organisms.

This study described the myliobatids caught in artisanal beach seine fisheries in southern Brazil. Fieldwork was carried out from spring 2012 to winter 2014 in Cassino Beach (Rio Grande, Brazil). Both retained and discarded specimens were identified to species level, and sex, maturity and disc width (DW in cm) were recorded. A total 359 specimens of Myliobatis spp. were recorded, of which 43.4% were from fishery discards, 31.5% from beach seine and 25.1% from drifting gill-net (‘lance de praia’, a fishery that has developed recently in the study area). Catches of myliobatids were higher in the spring and autumn. A total of 94 Myliobatis goodei (24 males, 69 females (eight pregnant) and one unsexed), and 179 Myliobatis ridens were recorded (24 males, 148 females (17 pregnant) and seven unsexed). Myliobatis goodei ranged in size from 45.0–65.0 cm DW (males) and 43.3–115.0 cm DW (females). Myliobatis ridens were 45.0–59.0 cm DW (males) and 41.2–98.0 cm DW (females). Both beach seine and gill-net fisheries operated in potential nursery areas for these myliobatid rays, as indicated by the proportionally high number of mature females (including pregnant females) and juveniles found in this study. The rays probably feed and give birth during the warmer seasons of the year (spring and summer) in these areas.

The strontium-to-calcium ratio (Sr/Ca) in aragonitic shells and statoliths often depends on temperature, and has been investigated for its potential availability as a sclerochronological record of the temperatures experienced during the life of the animal. Only a few cephalopod species have been subjected to rearing experiments to validate the temperature dependence of statolith Sr/Ca despite the strong demand for estimating their historical ecology, particularly of migratory squid populations. In this context, we examined the relationship between temperature and statolith Sr/Ca in the spear squid, Heterololigo bleekeri, by maintaining wild-caught immature individuals at one of three constant temperatures: 12, 14 or 16°C. A portion of statolith precipitated during the experiment was optically identified by daily increment analysis, and then subjected to Sr/Ca measurement using an electron probe micro-analyser. Regression analysis (N = 29) demonstrated the dependence of statolith Sr/Ca on temperature and the relationship was estimated as an equation Y = 9.93 (±0.29) − 0.11 (±0.02) X. However, ~90% of the total residual variance was accounted for by the among-individual variation of statolith Sr/Ca within each temperature group. Consequently, the 95% confidence interval ranged over ± 7.85°C when the temperature was estimated by inserting a Sr/Ca value into this equation. The statolith Sr/Ca values are unlikely to provide reliable estimates for absolute temperatures, but it may allow reconstruction of a time-series of relative temperatures experienced by a particular individual.

I. Introduction.

Some eighteen months ago the Director of the Plymouth Laboratory of the Marine Biological Association decided to carry out a series of investigations concerning the surface currents of the English Channel at different seasons of the year, and for a series of years, by means of properly devised floating bodies which would attract attention when standed on the shore, and the recovery of which could without difficulty be recorded. At the commencement of the investigation Mr. Allen communicated his scheme to the editors of the west-country Press, and these gentlemen kindly gave publicity to the plan, the success of which depended very largely upon the co-operation of residents and visitors frequenting the sea-shore. Mr. Allen's letter expresses so clearly the object and method of the investigation, that I cannot do better than reproduce it here:—

Very little information is available on bottlenose dolphin (Tursiops truncatus) habitat use in the South-western Atlantic. It is, however, essential in understanding their ecology and to improve conservation management. In this study, habitat use of bottlenose dolphins was examined in Bahía San Antonio, an area frequented by the species. Given the large tidal amplitude and extended intertidal zone in this bay, special focus was given to the intertidal vs subtidal habitat use patterns. Bottlenose dolphins were observed in only half of the surveyed area, with on average 1 dolphin group encountered per 100 km surveyed. All dolphin groups were seen in shallow waters <10 m deep. GLM analyses showed that especially during high tide, depth had an important effect on the dolphin encounter rate, with most dolphin groups encountered in the intertidal zone. While in the intertidal zone, most dolphin groups were observed to be engaged in surface feeding activities. The presented data indicate dolphins remained in shallow waters, and moved to the intertidal zone during high tide where they appear to find feeding opportunities. This information is believed to be of high value in understanding this population's ecological needs, and essential when aiming to improve marine conservation efforts at times of increased anthropogenic pressures in the area.

Introduction

Monthly samples of Argentina sphyraena L. taken in the Clyde Sea Area over 2 years were used to describe age, growth, length-weight relationship, annual cycle in condition, and mortality. Results indicate that one transparent ring is laid down in the otoliths each year between November and May, providing a means of ageing this species.

The heteronemertean species Micrura dellechiajei is thus far only known from its type locality in the Gulf of Naples (Italy) and has not been recorded in 120 years. During two oceanographic surveys conducted in Spanish Mediterranean waters, several nemertean specimens were collected, and thorough morphological examination indicated that some of these pertained to the species M. dellechiajei, suggesting that populations may be more widespread than previously thought. Because of the rarity of this species coupled with the fact that its last morphological narrative was given 120 years ago, we here provide a redescription of the species based on the new specimens, complete with illustrations and new data concerning its morphology, and we also place some of the collected specimens in a molecular phylogenetic framework.

Previous morphological studies of Illex coindetii from the Mediterranean have shown both juvenile and mature individuals all year round suggesting an homogeneous population pattern, however, seasonal spawning variation seems to exist varying with geographical area. Present work analysed 240 individuals from the northern Tyrrhenian and Atlantic Iberian waters at the four year-round seasons using 33 presumptive enzyme-coding loci to compare geographical and temporal variances. Genetic variability was low (Ho=0·02–0·04). Moderate variation at some loci was found due to both temporal and geographical factors (12% of total genetic variance) and to temporal variance (FST=0·004–0·015). Unweighted pair-group method using arithmetric averages (UPGMA) and Multidimensional scaling–minimum spanning tree (MDS–MST) analyses after Cavalli-Sforza & Edwards (1967) chord genetic distances showed the summer Italian and the spring Atlantic samples as the most divergent among the whole.

So few data are available concerning polychaete fecundity that recent speculation about the relative advantages of different life-history ‘strategies’, and about the relative value of protected and unprotected larval development, has been almost completely abstract. The dangers of this approach have been clearly indicated by Stearns (1976) in his recent review. Until quantitative studies are made of the number and weight of gametes produced in relation to the weight of individuals for a range of species, there seems little basis for discussion of the problems mentioned above.

Two new Mycalina (Porifera: Poecilosclerida) are described from the south-western Atlantic, collected during Programme REVIZEE (1996–2002)—South Score, off the São Paulo State coast, Brazil. Esperiopsis bathyalis sp. nov. is characterized by the possession of two well differentiated categories of sigmas, the smaller ones being sigmancistras. Hamacantha microxifera sp. nov. is set apart by its possession of abundant small microxea-like raphides, diancistras 100–150 μm long, and absence of sigmas.