A revised classification of the Gymnamoebia (Protozoa: Sarcodina)

A revised classification of the naked amoebae is proposed on the basis of a synthesis of many kinds of information presently available for taxonomic purposes above the species level. These amoebae, constituting the subclass Gymnamoebia within the class Lobosea, superclass Rhizopoda, include not only strictly lobose amoebae but also those with more or less filose subpseudopodia produced from a broader hyaline lobe. The subclass is divided into the orders Amoebida, Schizopyrenida, and Pelobiontida, and suborders are recognized within the order Amoebida. Although the Gymnamoebia are undoubtedly heterogeneous and polyphyletic and the proposed classification is intended chiefly as a practical system with a logical basis, there are a few suggestions of natural relationships.     

Observations of the heliozoean genera Pinaciophora and Acanthocystis (Heiliozoea,Sarcodina, Protozoa) from Ellis Fjord,Antarctica

Summary The heliozoeans Pinaciophora denticulata Thomsen, Acanthocystis perpusilla Petersen et Hansen, Acanthocystis turfacea Carter and Acanthocystis sp., collected from a marine location in Ellis Fjord, Antarctica and grown in saline culture, are pictured by scanning and transmission electron microscopy. P. denticulata has been reported from cold marine localities elsewhere in the world, but marine reports of Acanthocystis are rare, and both A. perpusilla and A. turfacea have been reported previously only from fresh waters.     

Diazotrophic Diversity and Distribution in the Tropical and Subtropical Atlantic Ocean

To understand the structure of marine diazotrophic communities in the tropical and subtropical Atlantic Ocean, the molecular diversity of the nifH gene was studied by nested PCR amplification using degenerate primers, followed by cloning and sequencing. Sequences of nifH genes were amplified from environmental DNA samples collected during three cruises (November-December 2000, March 2002, and October-November 2002) covering an area between 0 to 28.3°N and 56.6 to 18.5°W. A total of 170 unique sequences were recovered from 18 stations and 23 depths. Samples from the November-December 2000 cruise contained both unicellular and filamentous cyanobacterial nifH phylotypes, as well as γ-proteobacterial and cluster III sequences, so far only reported in the Pacific Ocean. In contrast, samples from the March 2002 cruise contained only phylotypes related to the uncultured group A unicellular cyanobacteria. The October-November 2002 cruise contained both filamentous and unicellular cyanobacterial and γ-proteobacterial sequences. Several sequences were identical at the nucleotide level to previously described environmental sequences from the Pacific Ocean, including group A sequences. The data suggest a community shift from filamentous cyanobacteria in surface waters to unicellular cyanobacteria and/or heterotrophic bacteria in deeper waters. With one exception, filamentous cyanobacterial nifH sequences were present within temperatures ranging between 26.5 and 30°C and where nitrate was undetectable. In contrast, nonfilamentous nifH sequences were found throughout a broader temperature range, 15 to 30°C, more often in waters with temperature of <26°C, and were sometimes recovered from waters with detectable nitrate concentrations.     

Discovery of Poromitra macrophthalma (Melamphaidae) in the Atlantic Ocean

Journal of Ichthyology - The occurrence of big-eyed rhinofish Poromitra macrophthalma in the central part of the Atlantic Ocean is reported for the first time. This species was previously known...     

Molecular phylogeny and morphological evolution of the Acantharia (Radiolaria)

Acantharia are ubiquitous and abundant rhizarian protists in the world ocean. The skeleton made of strontium sulphate and the fact that certain harbour microalgal endosymbionts make them key planktonic players for the ecology of marine ecosystems. Based on morphological criteria, the current taxonomy of Acantharia was established by W.T. Schewiakoff in 1926, since when no major revision has been undertaken. Here, we established the first comprehensive molecular phylogeny from single morphologically-identified acantharian cells, isolated from various oceans. Our phylogenetic analyses based on 78 18S rDNA and 107 partial 28S rDNA revealed the existence of 6 main clades, sub-divided into 13 sub-clades. The polyphyletic nature of acantharian families and genera demonstrates the need for revision of the current taxonomy. This molecular phylogeny, which highlights the taxonomic relevance of specific morphological criteria, such as the presence of a shell and the organisation of the central junction, provides a robust phylogenetic framework for future taxonomic emendation. Finally, mapping all the existing environmental sequences available to date from different marine ecosystems onto our reference phylogeny unveiled another 3 clades and improved the understanding of the biogeography and ecology of Acantharia.     

Bloom of Emiliania huxleyi (Prymnesiophyceae) in the western South Atlantic Ocean

A monospecific bloom of the coccolithophorid Emiliania huxleyi(Lohmann) Hay & Mohler (Prymnesiophyceae) was detected offRio de La Plata at 36°S and 54°W in November 1989. Thecell densities observed were up to 6x10⁵ cells I^–1. Thisis the first record of a bloom of E.huxleyi in the area.     

Early juvenile development of deep-sea asteroids of the NE Atlantic Ocean, with notes on juvenile bathymetric distributions

The postmetamorphic ontogenesis of 11 deep‐sea asteroid species is described. Juvenile bathymetric distributions are compared to adults. The deep‐sea juvenile asteroids of the NE Atlantic could be distinguished to species level from a very early stage of development. In all species, except Porcellanaster ceruleus and Plinthaster dentatus, the arms grow faster than the body. In Porcellanaster ceruleus and Plinthaster dentatus, early growth is nearly isometric. In the appearance of the epiproctal cone, the change in form of the furrow and apical spines, the early development of the cribriform organ adjacent to the madreporite and the appearance of sediment in the stomach indicate that Porcellanaster ceruleus is likely to undergo a shift in habitat and diet during the juvenile phase. Porcellanaster ceruleus is probably a predator on meiofauna and small macrofauna during the early stages of life, changing to a burrowing lifestyle ingesting sediment particles. Juvenile sea stars showed wider bathymetric distributions than their adult counterparts, suggesting that events occurring during the early stages of life are important for the maintenance of the local population structure and diversity in the deep NE Atlantic.     

Genetic Structure of Capelin (Mallotus villosus) in the Northwest Atlantic Ocean

Capelin (Mallotus villosus) is a commercially exploited, key forage-fish species found in the boreal waters of the North Pacific and North Atlantic Oceans. We examined the population structure of capelin throughout their range in the Canadian northwest Atlantic Ocean using genetic-based methods. Capelin collected at ten beach and five demersal spawning locations over the period 2002 through 2008 (N = 3,433 fish) were genotyped using six polymorphic microsatellite loci. Temporally distinct samples were identified at three beach spawning locations: Chance Cove, Little Lawn and Straitsview, Newfoundland. Four capelin stocks are assumed for fisheries management in the northwest Atlantic Ocean based on meristics, morphometrics, tag returns, and seasonal distribution patterns. Our results suggested groupings that were somewhat different than the assumed structure, and indicate at least seven genetically defined populations arising from two ancestral populations. The spatial mosaic of capelin from each of the two basal cluster groups explains much of the observed geographic variability amongst neighbouring samples. The genetic-defined populations were resolved at Jost’s D _est ≥ 0.01 and were composed of fish collected 1) in the Gulf of St. Lawrence, 2) along the south and east coasts of Newfoundland, 3) along coastal northern Newfoundland and southern Labrador, 4) along coastal northern Labrador, 5) near the Saguenay River, and at two nearshore demersal spawning sites, 6) one at Grebes Nest off Bellevue Beach on the east coast of Newfoundland, and 7) one off the coast of Labrador at Domino Run. Moreover, the offshore demersal spawners on the Scotian Shelf and Southeast Shoal appeared to be related to the inshore demersal spawners at Grebes Nest and in Domino Run and to beach spawners from the Gulf of St. Lawrence.     

Distribution and species composition of juvenile and adult scombropids (Teleostei,Scombropidae) in Japanese coastal waters

Two scombropid fishes, Scombrops boops and Scombrops gilberti, are closely related and commercially important species in Japan. These species are often confused in commercial markets because of their morphological similarity. In this study, scombropid specimens collected from various Japanese coastal waters were subjected to polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) analysis and phylogenetic analysis of the 16S rRNA gene in mitochondrial DNA. These analyses showed that all the scombropid specimens collected from localities in the Sea of Japan were identified as S. boops, whereas those from the Pacific Ocean included two species, S. boops and S. gilberti. Almost all juvenile (<200 mm standard body length, S_L) S. gilberti originated from the Pacific coastal waters of the northern Japan, whereas adults (>400 mm S_L) were found only in deep water off the Izu Peninsula to the Izu Islands. This suggests that S. gilberti might migrate extensively during its life cycle. In addition, differences in the number of specimens and the distribution between the two species suggest that S. gilberti is less abundant than S. boops in Japanese waters.     

Gregarines of the Genus Lecudina (Protozoa,Apicomplexa) from Pacific Ocean Polychaetes*

The gregarine Lecudina longissima Hoshide, 1944 is described from the intestine of the marine polychaete Lumbrineris zonata (Johnson, 1901) from Santa Catalina Island, Calif. L. catalinensis n. sp. is described from the intestine of L. inflata Moore, 1911 from the same island. L. pherusae sp. n. and L. zimmeri sp. n. are described from the intestine of the marine polychaete Pherusa capulata (Moore, 1909) off Santa Catalina Island.     

Liver ultrastructure of juvenile Atlantic salmon (Salmo salar)

Light and transmission electron microscopy of the liver of juvenile Atlantic salmon (Salmo salar) reveals a tubular arrangement of parenchymal cells, with biliary passages typically located at the center of tubules. Hepatocytes generally contain a single nucleus surrounded by a cuff of rough endoplasmic reticulum (RER), with many round to elongate mitochondria associated with the perinuclear RER. Whereas glycogen deposits are common and usually lie at the cell periphery, parenchymal cells seldom contain lipid droplets. Golgi complexes and heterogeneous dense bodies also occur in many hepatocytes, often in close proximity to bile canaliculi. Numerous microvilli from hepatocytes extend into the subendothelial space of Disse, which is also the location of stellate fat-storing cells. Interhepatocytic macrophages, sometimes containing prominent phagolysosomes and residual bodies, are common in the liver. The intrahepatic biliary system consists of intercellular canaliculi, bile pre-ductules, ductules, and ducts. In contrast to some other teleosts, the liver of the Atlantic salmon contains no intracellular bile canaliculi or Kupffer cells. The hepatic endothelium, arterioles, and perivenous regions are also described.     

Fellodistomidae and Zoogonidae (Digenea) of deep-sea fishes of the NW Atlantic Ocean

The following species are described from fishes in deep-waters of the northwestern Atlantic Ocean: Fellodistomidae: Steringophorus furciger from Antimora rostrata, Coryphaenoides (Lionurus) carapinus, Lycenchelys paxillus, L. verrillii and Lycodes atlanticus; S. blackeri from Xenodermichthys copei, S. haedrichi n. sp. from Porogadus milesi, characterised by its lobate testes, sucker-ratio and long vitelline fields Megenteron crassum from Dicrolene intronigra; Zoogonidae: Brachyenteron rissoanum n. sp. from Polyacanthonotus rissoanus, characterised by the ovary position, the saccular seminal vesicle, the marginal genital pore and egg-size; Koiea notacanthi n. g., n. sp. from Notacanthus (?) chemnitzi, characterised by the Y-shaped excretory vesicle and the posteriorly placed testes.     

Ecology and Gametogenic Biology of the Genus Umbellula (Pennatulacea) in the North Atlantic Ocean

Four putative species of the seapen genus Umbellula, U. lindahli, U. thomsonii, U. durissima and U. monocephalus, are found at bathyal and abyssal depths in the Porcupine Seabight and Abyssal Plain in the NE Atlantic Ocean and at bathyal depths off the Bahamas. The most common species, U. lindahli, has a cosmopolitan distribution in the world ocean. In situ observations, from bathyal depths in the Bahamas, of the posture of U. lindahli show that the polyps are spread out to maximize particle capture from the water column. In addition, the individuals of U. lindahli from the Bahamas suggest that the tentacles are cropped by a predator, but there is no evidence of predation in the NE Atlantic specimens. Reproduction in U. lindahli is typical of that previously observed in pennatulids. Fecundity is high, although most of the oocytes present are previtellogenic with only a few developing through to maximum size at any one time. Some specimens of U. lindahli appear to be infested with a small flatworm.     

Abundance and biogeography of tintinnids (Ciliophora) and associated microzooplankton in the Southwestern Atlantic Ocean

Absolute abundances of foraminifers, polycystine and phaeodarian radiolarians, tintinnids, pteropods and early crustacean larvae and moults were assessed in a collection of 57 vertically stratified (0-100 m) net microplankton samples from 22 stations located between 34 and 58S (along 51-56°W), covered on 8-16 November 1994. Tintinnids were identified to species and measured in order to estimate their biomass from biovolume to carbon conversions. The distribution of the microzooplanktonic groups assessed was irregular and patchy, both geographically and vertically, and their abundances were characteristic of oceanic low to medium productivity environments. Tintinnid biomass was also generally low (0.05-0.40 g Cl^-1). With the exception of the tintinnids, associations between microzooplanktonic numbers and chlorophyll a were generally loose. Eighty-eight tintinnid taxa were recorded, yet only five accounted for 53% of the specimens identified. Multivariate (cluster) analysis of tintinnid specific distribution patterns clearly showed several distinct zones. From north to south, these are: Transition Zone (TZ), with three subzones, TZ north (34°S-38°S), TZ central (39°44S-44°S) and TZ south (46°S); Subantarctic Zone (SZ; 48-55°S); Polar Front Zone (55°30S); Antarctic Zone (AZ; 58-59°36S). Each of these was characterized by distinct tintinnid assemblages, abundance and biomass. With few exceptions, tintinnid cells were fairly evenly distributed throughout the upper 50 m. Taxonomic composition usually changed little with depth. Mean population depths were calculated for a subset of 35 tintinnids; 29 of these dwell preferably above 40 m. The spatial distribution of tintinnid species richness showed a more or less gradual decrease from north to south. Specific diversity and equitability generally increased with depth, and were higher in antarctic waters than the southern transitional and subantarctic ones; this trend is tentatively attributed to higher water column vertical stability south of the Polar Front.      

The deep-water pycnogonids (Arthropoda: Pycnogonida) of the northeastern Atlantic Ocean

Over 2000 specimens of pycnogonid from deep-sea collections made in the northeastern Atlantic Ocean by IOS and SMBA between 1971 and 1994 have been analysed. Thirty-five species were identified, two being new to science, viz Nymphon akanthochoeros and an unnamed Anoplodactylus species. The deep-sea Pycnogonida of the northeastern Atlantic are reviewed using these data and records from the literature. Keys are presented for the six families represented by more than one species. The pycnogonid fauna of this area is characterized particularly by Paranymphon spinosum and Colossendeis clavata , with other dominant species including Colossendeis species, notably C. macenima , and Nymphon laterospinum, Anoplodactylus typhlops and A. arnaudae. Of the 54 species recorded below 200 m in the northeastern Atlantic, available evidence suggests that nine are 'endemic'. Relative distributions of the other species are discussed. A distinct change in the pycnogonid fauna with depth was found at around 1400 m. There is latitudinal separation of species groupings, shown most conspicuously by the shallower water species.     

Distribution of spring phytoplankton (mainly diatoms) in the upper 50 m of the Southwestern Atlantic Ocean (30-61{degrees}S)

This is the first study on diatom spatial patterns in relationto major oceanographic features along a megascale transect inthe Southwestern Atlantic Ocean and provides a comparison withdiatom distribution in surface sediments. Absolute abundancesof diatoms, silicoflagellates and dinoflagellates (>10-µmfraction) were assessed in 80 bottle samples from 5 to 50 m,retrieved in November 1993 at 20 stations (30–61°S)along 53°W. Siliceous phytoplankton were scarce in the northernhalf of the transect and in the south of 57°S (100–150cells L^–1), with a strong peak in the vicinity of thePolar Front (200 000 cells L^–1), whereas dinoflagellateswere more abundant at the northern stations (up to 24 000 cellsL^–1). In the south of 50°S phytoplanktonic cell densitieswere loosely (but significantly, r = 0.54, P < 0.01) associatedwith chlorophyll a, whereas in the north of this latitude, thisrelationship disappeared (r = 0.018, P > 0.1). In total,191 diatoms and 4 silicoflagellates were recorded. Changes indiatom assemblage compositions along the transect allowed identificationof five discrete areas: Subtropical (29°S), Northern Transitional(34–41°S), Southern Transitional (43–48°S),Subantarctic (49–54°S) and Antarctic (55–59°S),each characterized by a set of typical species. Diversity changedlittle with latitude, but numbers of species were higher inthe north of 40°S. Comparison of diatom assemblage makeupin the plankton and in the surface sediments shows very strongdisagreements, whereby cold water species are very significantlyover-represented in the sedimentary record, suggesting enhancedpreservation and strong subsurface equatorward advection ofthe cold water taxa.     

Insights into the evolution of heliozoa (Protozoa, Sarcodina) as provided by ultrastructural studies on a new species of flagellate from the genus Pteridomonas

The fine structure of Pteridomonas danica , a new species of helioflagellate (protozoa), is described. The organism has a single apical flagellum which bears two rows of tripartite tubular hairs. There are two kinetosomes which are bound to each other and to the surface of the single nucleus by amorphous electron-dense material. The flagellum is surrounded by a wreath of fine arms, which are supported internally by triads of microtubules. The triads terminate on the nucleus. The mitochondria have tubular cristae which contain wisps of intracristal material. The dictyosomes are located in the posterior part of the cell, being clustered around the internal element of the contractile stalk. Extrusomes are present. Pteridomonas has substantial similarities with the colourless flagellate Ciliophrys and with the pedinellid algal flagellates. As Ciliophrys resembles the actinophryid heliozoa in several important respects, the evidence supports the contention that these heliozoa have a common ancestry with the heterokont algae and have evolved along a line involving the pedinellids and some colourless helioflagellates. If the perceived relationships are to be reflected in their taxonomy, then a substantial reclassification of these organisms is required.     

Distribution of Vibrio parahaemolyticus and Related Organisms in the Atlantic Ocean off South Carolina and Georgia

The distribution of Vibrio parahaemolyticus and related organisms in the Atlantic Ocean was determined during the summer of 1971 from samples collected at stations along four transects on the continental shelf off the South Carolina and Georgia coasts. No V. parahaemolyticus strains were isolated from any of the samples of seawater (surface and bottom), sediment, and plankton which were collected. A numerical taxonomy analysis of data on substrate utilization, including 154 organic compounds serving as single carbon sources, was carried out, and four groups of strains were observed. Each group showed well-separated distribution profiles from shore out to the continental shelf. That is, the groupings were observed to correspond to coastal, off-shore and intermediate distribution patterns for the strains. This study provides a useful example of the kind of ecological distributional analysis of bacteria which can be accomplished with numerical taxonomy.