English Channel Off Research Articles

Redescription of Tripaphylus musteli (van Beneden, 1851) (Copepoda: Sphyriidae) and the relegation of Paeon Wilson, 1919 to synonymy with Tripaphylus Richiardi in Anonymous, 1878

Tripaphylus musteli (van Beneden, 1851) (Copepoda, Siphonostomatoida, Sphyriidae) is redescribed from an adult female collected from the branchial chamber of a starry smooth-hound, Mustelus asterias Cloquet (Carcharhiniformes, Triakidae), captured in the English Channel off Portland, UK. The new account of T. musteli is the first based on a complete adult female and highlighted the lack of a robust distinction separating Tripaphylus Richiardi, in Anonymous, 1878 and Paeon Wilson, 1919 prompting us to relegate Paeon to a junior subjective synonym of Tripaphylus. In the light of this synonymy the eight former species of Paeon are transferred to Tripaphylus as follows: T. ferox (Wilson, 1919) new combination, T. elongatus (Wilson, 1932) new combination, T. vassierei (Delamare Deboutteville & Nuñes-Ruivo, 1954) new combination, T. lobatus (Kirtisinghe, 1964) new combination, T. asymboli (Turner, Kyne & Bennett, 2003) new combination, T. versicolor (Wilson, 1919) new combination, T. australis (Kabata, 1993) new combination, and T. triakis (Castro Romero, 2001) new combination. Comparisons between terminology used in this report and that in the literature indicate that all transformed adult females of Tripaphylus probably possess a full complement of cephalic appendages and maxillipeds. All limbs, with the exception of the maxillae share a general morphological similarity to the corresponding appendages of conspecific males. The maxilla of the transformed adult female of Tripaphylus is a small digitiform protuberance associated with a swelling in some species.

Novel Ecosystems: Altering Fish Assemblages in Warming Waters

The effects of increasing sea temperatures extend far beyond changes in species' distributions. By altering local fish abundances, temperature changes will have profound effects on the structure, functioning and services of marine ecosystems.

Influence of diatoms on copepod reproduction. I. Field and laboratory observations related to Calanus helgolandicus egg production

ABSTRACT: Egg production rates (EPR) by Calanus helgolandicus females were investigated with specimens sampled weekly, from April to November 2003 and from March to October 2004, at a station located in the English Channel off Roscoff. Comparison of results between 1994, 2003 and 2004 showed that C. helgolandicus was a late spawner in 1994 and became an early spawner in 2003 and 2004. In all cases high variations in EPR were observed, which could not be correlated to phytoplankton biomass, expressed as diatom, chlorophyll a, particulate carbon and nitrogen concentrations in 2003 and 2004. Neither were they correlated to food quality, expressed as C/N ratio. To explain this mismatch between EPR and food concentration, a series of mixed phytoplankton species dominated by diatoms (≥11 μm filtrate representing natural diatom assemblages: NDA) and 7 single diatom species, all occurring during blooms in the field, were assayed as diets with C. helgolandicus females. Ingestion of diatoms by females was estimated by faecal pellet production rates and complementary scanning electron microscopy examinations of diatom remains in pellets. Depending on diatom species in diets, EPR was either increased or depressed 2 to 3 d after food uptake by females had started. The EPR decrease was reversible, when diatom diets were replaced by the dinoflagellate Prorocentrum minimum. This effect was also observed when females were transferred to natural phytoplankton populations from the English coast of the Channel close to Plymouth, where food composition in the field differed compared to that off Roscoff. EPR ceased completely when the concentration of NDA diets was artificially increased, but recovered after a shift to a dinoflagellate diet. These results indicate that phytoplankton dominated by diatoms can impair C. helgolandicus egg production in the field. This effect was not related to the production of polyunsaturated aldehydes by diatoms. Limitations due to unidentified essential compounds not provided by the metabolism of diatoms, or unknown diatom-derived toxins, were probably involved.

Population dynamics and metabolism of Aequipecten opercularis (L.) from the western English Channel (Roscoff, France)

Population dynamics of the queen scallop, Aequipecten opercularis, was investigated in the western English Channel off Roscoff. Annual formation of natural growth rings on the shell surface was validated by stable isotope (δ 18O and δ 13C) analysis. A von Bertalanffy growth function ( H t = 58.9 mm • (1-e −0.604• (t +0.235))) was fitted to size-at-age data of 249 individuals. Annual somatic and gonad production amounted to 19.74 kJ m −2 and 0.98 kJ m −2 y −1, respectively. Total mortality rate Z was estimated to be 1.716 y −1. Net growth efficiencies (ranging from 45% in 1-y-old to 11% in 6-y-old individuals) were in the same range as in other short-lived scallops. Individual growth, however, was distinctly slower in this population than in other A. opercularis populations from similar latitudes, most likely due to a more stressful environment.

Occurrence of ocean sunfish, Mola mola near fronts in the western English Channel

Surface occurrence of ocean sunfish (Mola mola) was recorded during summer (May–September) in the western English Channel off Plymouth over a six-year period between 1995 and 2001. Fifteen individuals of between 0.5–0.7 m estimated total length were sighted during 1651 hours of observation. Nearly all sightings (93%) occurred in June and July in water between 13 and 17°C. Sunfish were mostly associated with frontal and stratified water masses (86%) rather than in cooler, mixed water.

Temporal variability of viruses, bacteria, phytoplankton and zooplankton in the western English Channel off Plymouth

The temporal distribution of autotrophic and heterotrophic components of the planktonic community was studied from samples collected weekly at station L4, located to the south of Plymouth, UK, from October 1992 to January 1994. Phytoplankton succession followed the typical pattern of temperate waters, the development of a summer Gyrodinium aureolumbloom being the most prominent feature. Bacterial numbers were significantly correlated with temperature during autumn and winter, whereas resource availability and predation, including viruses, appear to be the most important controlling factors in spring and summer. High mesozooplankton densities, mainly copepods, were observed throughout most of the study associated with a series of diatom blooms, and also during autumn when low phytoplankton biomass was measured. This data set was analysed in order to build up conceptual trophodynamic models whereby the role of biological communities on the cycling of organic matter could be inferred. The results obtained in this study provide empirical evidence supporting the existence of a sucession of trophic organization patterns in a coastal temperate environment. Classical models (herbivorous or microbial webs) appeared episodically whereas transition models (multivorous web) dominated throughout most of the seasonal cycle.

A Perspective on the Application of Chemistry to Oil Spill Response

It might seem incongruous that a research focused organisation such as the International Union for Pure and Applied Chemistry would pay attention to an issue as pragmatic as oil spills. After all, an oil spill tends to be viewed as a very practical matter, its issues characterised by loss of a valuable commercial product, damage to the environment, high costs of clean up, high legal liabilities, and very much media attention. Oil spills are not generally considered a pure or even applied chemistry issue. However, this would be a very short-sighted interpretation. Effectively every element of an oil spill, whether environmental, physical, operational or legal, is related to the complex chemistry of the oil and its breakdown products released to the environment. Indeed, it would be safe to say that if petroleum were a simple chemical product, the difficulties inherent in clean up of an oil spill would be much reduced, no matter what the origin or cause of the spill.

Occurrence in the English Channel of a Warm-Water Cirripede, Solidobalanus Fallax

A species of balanomorph barnacle with solid plates and basis, Solidobalanus fallax, is recorded for the first time in the English Channel off Plymouth, at 44–56 m depth. It occurs exclusively on the valves of the queen scallop, Aequipecten opercularis. Only one out of 15 scallops carries the barnacle. Morphological details of the species are re-described in comparison with Balanus crenatus and B. spongicola, with which it co-occurs. Solidobalanus fallax ranges from Angola through West Africa and Morocco to Algeria but has not been reported previously from Europe. Some specimens were incubating embryos in late May, indicating a potential for local recruitment. Solidobalanus fallax is unlikely to be a recent immigrant but its abundance may have increased as a result of changing climate.

A comparative study of reproductive and nutritional periodicities in two populations of Asterias rubens (Echinodermata: Asteroidea) from the English Channel

Gonadial, pyloric caecal and somatic indices and oocyte size-frequencies are compared over a 3-year period for the starfish Asterias rubens from an intertidal nutritionally rich site and a subtidal impoverished site from the English Channel off south-west Britain. The intertidal population showed significantly higher values for all three indices over most of the study period compared with the subtidal population, and its spawning occurred later. The somatic index of the subtidal population showed a steeper rise than the intertidal population over that part of the cycle in which the gonads were undergoing enlargement, which gives further support to the suggestion that starfishes deprived of sufficient food may give priority to maintenance of the body-wall over enlargement of either the food-storage tissues of the pyloric caeca or the gonads.

Changes in Biological Conditions in the English Channel off Plymouth during the Last Half Century

COMPARABLE observations on chemical and biological conditions in the western English Channel off Plymouth have been made with varying regularity and intensity since 1921, and regular records of nutrient salts and the larger zooplankton were kept from 1924 to 1939. During that period a notable change took place: the herring fishery, which had been a regular winter feature at Plymouth, petered out in the early 1930s when young herring ceased to join the shoals1,2, and at the same time there was a decrease in the amount of nutrient salts present in the water in the winter3 and a very marked, decline in the quantity, of zooplankton including the planktonic stages of bottom-living fish. From 1935 pilchard seemed to take the place of herring4.

Some sections in the Lower Gault of the Weald

Sections in the dentatus Zone of the Lower Gault in the Weald are described. The presence of the eodentatus Subzone at the Coney Hill sand-pit, Barrow Green, is recorded and a comparison is made with deposits of this Subzone exposed at the Shere By-Pass and at Folkestone. The benettianus Subzone exposed at Shere and in the Sevenoaks Brick Works are described and correlated with other known or possible occurrences in the Weald. The expansion of deposits of the dentatus-spathi Subzone in the northern Weald when traced westwards from Folkestone is demonstrated. In Kent and east Surrey the deposits are greatly condensed. In west Surrey the degree of condensation becomes less, and in east Hampshire the dentatus-spathi Subzone is little condensed and forms the bulk of the Lower Gault. In the Selborne area it appears that the transgression during the cristatum and basal orbignyi Subzones has removed all Lower Gault sediments above the dentatus-spathi Subzone. In Sussex there is evidence of an easterly condensation within deposits of this Subzone, and the presence of a nodule bed, comparable to the dentatus nodule bed at Folkestone, is recorded in the English Channel off Beachy Head.

The Biomass of the Bottom Fauna in the English Channel off Plymouth

A survey has been made of the biomass of the macrobenthos at twenty stations in the English Channel off Plymouth. The object was to provide a basis for following long-term fluctuations in the fauna.A brief survey of physical conditions in the area is given, and a gradeanalysis of the soil at each station has been made.Core-samples show that the sediment is shallow in many places and rock has been taken at 36 cm. or less below the surface at a number of stations.Samples totalling ½m.2 were taken at each station with a modified 'scoopsampler', covering 1/10m.2, which is briefly described.Sources of error in sampling are considered in detail. Some species may evade the sampler and others live too deep in the sediment to be taken. A comparison against a Petersen grab and a new ' suction-corer' show that the scoop-sampler does take a reasonably quantitative sample. The number of species taken in successive hauls, when plotted against the log of the area sampled, approaches a straight-line relationship similar to that obtained by Williams (1950).A statistical analysis is made of a series of samples taken at one station, and the variance between the two samples in each haul and between successive hauls calculated. At this pàrticular station the fauna in successive samples is shown to be fairly random.A sieve of 2-2 mm. mesh was employed. Compared with a finer sieve losses in terms of numbers may be quite large, but the total weight taken is little affected.

Records of pilchard spawning in the English Channel

The pilchard, Clupea pilchardus Walbaum, is known to spawn in summer in the southern North Sea in the neighbourhood of the Sandettié Bank (Buchanan-Wollaston, 1911; Furnestin, 1939a, 1945) and in the eastern English Channel off Beachy Head (Furnestin, 1939a, 1945). Furnestin (1939b, 1945) concludes from these records that spawning is in all probability continuous throughout the Channel from the southern North Sea to the Celtic Sea. There appear, however, to be no previous references to pilchard spawning in the central part of the English Channel. The following records from the area are of interest therefore, and provide confirmation of Furnestin’s conclusion.

A cubical photometer for studying the angular distribution of submarine daylight

Preliminary observations have been made in the English Channel off Plymouth on the average obliquity of illumination under water, and on the relative intensity of light reflected upwards at various depths, the readings being made with a cubical photometer containing six “Electrocell” selenium rectifier cells mounted behind opal glasses and Jena VG 9 (green) filters. The cells measured the light of wave-lengths about 480–580 mμ falling on upward-and on downward-turned horizontal surfaces, and on four vertical surfaces i n rectangular azimuths.The average angle with the vertical or of obliquity was from 36 to 40°, and no significant difference could be detected between that for smooth sea and overcast sky, and that for rough sea and either high or low sun. Figures for smooth sea and sunlight are more difficult to obtain, as in the absence of drift due to wind the photometer may rotate.No decrease in average obliquity with depth was found, in some cases there was evidence of a slight increase. This is in accordance with our previous results, and accords well with the constancy of extinction coefficient so often found throughout a series. It is not, however, in agreement with the careful work of Johnson & Liljequist, so further determinations would seem to be desirable.The percentage of the light which was scattered back so as to fall on a downward-turned surface varied from 5.5 for comparatively opaque water (extinction coefficient 0.20) inside Plymouth breakwater, to 2.1 for very clear water (extinction coefficient 0.076) some miles off at sea. The presence or absence of sunlight had little effect, values close to 3.0 being obtained with and without sun for water having a coefficient close to 0.110.

On the Occurrence of the Siphonophores Muggiœa atlantica Cunningham and Muggiæa kochi (Will) in the English Channel

In 1892 Cunningham described a new species of Siphonophore, Muggiœa atlantica, which was first noticed by him in the waters of the English Channel off Plymouth in the autumn of 1891. Since then there have been records from time to time of the occurrence of this species at Plymouth (see Plymouth Marine Fauna, 1931, p. 84), and its distribution in the English Channel and Irish Sea in 1904 was worked out by Gough (1905).

Chemical Constituents of Biological Importance in the English Channel, November, 1930, to January, 1932. Part I. Phosphate, silicate, nitrate, nitrite, ammonia.

Determinations of phosphate, silicate, nitrate, nitrite and ammonia have been made at frequent intervals at two Stations, L4 and El, in the English Channel off Plymouth between the autumn of 1930 and January, 1932. Determinations were also made quarterly at E2 in mid-Channel.The year 1931 was an early one from the point of view of plankton production. The chemical data show that there was a small mid-winter outburst which gathered momentum during January and February. The main spring outburst started, however, early in March, carrying on fairly steadily until about the middle of May. The summer was characterised by exceptionally low phosphate and nitrate right through the water column due to very efficient utilisation in the spring and to the unusual hydrodynamical conditions. There was also a small autumn outburst.

On the Occurrence of Pelagic Tunicates (Thaliacea)]in the Waters of the English Channel off Plymouth

It is only occasionally that pelagic tunicates of the genera Doliolum and Salpa are recorded in numbers in the waters off Plymouth. In view of their possible use as indicators of the presence of Atlantic water (see Bowman, 1923; and Schmidt, 1909, p. 159), it is of value that their occurrence should be put on record. Regular weekly catches of plankton have been made since 1930 with half-hour oblique hauls with the two-metre stramin ring-trawl. During this period species of both genera have appeared in such numbers that it has seemed desirable to make a careful examination of the species occurring.

Photoelectric measurements (made during the summer of 1930) of the penetration of light (wave‐length 2,900 to 4,800 Ångström Units) in sea‐water, and the results of laboratory photoelectric measurements (made during the summer of 1931) of the absorption‐coefficient of sea‐water

Shelford and Gail on Paget Sound, Washington, and Poole and Atkins in the English Channel off Plymouth, England, determined quantitatively the penetration of light for various depths in sea‐water by the photoelectric cell method using electrical circuits with high sensitivity. Attempts to apply their data to another area, such as the Pacific Ocean near San Diego, California, could not be done, nor would the application of their figures to such an entirely different body of water be justified. Therefore, during the summer of 1930, an area seven miles off the coast of La Jolla (city of San Diego), California, was studied by submerging a Burt photoelectric sodium‐vacuum cell to various depth‐levels in the ocean.

A Note onBalanophyllia regia, the only Eupsammiid Coral in the British Fauna

TheEupsammiidé are one of the most interesting families of the Madjeporaria. They have an exceptionally wide range of distribution, being found alike in temperate and tropical seas. In the latter they were probably originally confined to deep water, where the majority of them still occur, but they have extended their vertical range (Yonge, 1930) and various species are now found on many of the coral reefs in the Indo-Pacific region. ThusDendrophyllia rameaoccurs in moderately deep water in the Mediterranean and has also been found in the English Channel off RoscofE (Lacaze-Duthiers, 1897), while other species of this genus are common near the surface on many of the Pacific coral reefs, the bright orange-coloured polyps ofDendrophyllia mannibeing, for example, very conspicuous on the fringing reefs at Kaneohe Bay on the Island of Oahu, Hawaii (Edmondson, 1929; Yonge, 1930).

Note on the Oxidisable Organic Matter of Sea Water

In a former paper (1922) it was shown that the pH value of stored sea water decreased owing to the production of carbonic acid by organisms in it, and the oxidisable matter as indicated by this biological method appeared to be higher than the result obtained by oxidation with permanganate, according to various analyses available for comparison. These, however, were not done on the same water, so an attempt was made to determine this quantity on water of the English Channel off Plymouth. As is well known the permanganate method gives results which vary appreciably, according to the conditions of the experiment.