Seasonal species composition and distribution of barnacle larvae in Avacha Inlet (Kamchatka)

The annual dynamics of the numbers and distribution of barnaclelarvae in Avacha Inlet were studied. Planktonic cirripede larvaewere found in the area studied from late March at a temperatureof –1–0°C until October. The highest densityof 18 000 m^–3 was observed in mid-April. Balanus crenatusand Semibalanus cariosus were the dominant species, Chthamalusdalli and Balanus balanus larvae being less abundant. Naupliardensity was maximal at 0–5 m and decreased with depth.Maximum densities of B.crenatus larvae were observed in RakovayaBay, where there are many ships and a seawater-cooled powerstation. Most nauplii of the intertidal barnacle S.cariosus,which prefers wave-exposed open coast, were taken in the AvachaInlet narrows Settling on artificial substrata was most intensivefrom late May to early June     

Larval development of Balanus reticulatus Utinomi, 1967 (Cirripedia, Thoracica) and a comparison with other barnacle larvae

The morphological features of the cephalic shield, labrum, abdominalprocess, antennules, antennae and mandibles of Balanus reticulatusare described and illustrated. The size and setation formulaeof the larvae are given at each stage. The trilobed labrum andlateral margin of the cephalic shield with numerous small spinesare diagnostic features for all the subsequent nauplius stages.Numerous small denticulate processes on the surface of the cypridcarapace are major morphological characteristics not found inother balanomorph species. We have constructed keys from stageII to stage VI for the predominant barnacle nauplii of Koreancoastal waters, based on morphological traits such as totallength, shield width, labrum shape, the presence or absenceof posterior shield spines and dorsal shield spines in stagesIV, V and VI, the specific setal type in the fourth segmentof the antennal endopodite, and setation formulae of Pollicipesmitella, Chthamalus challengeri, Megabalanus rosa, B.reticulatus,Balanus amphitrite and Balanus albicostatus.     

Taphonomy and systematics of a new Late Cretaceous verrucid barnacle (Cirripedia,Thoracica) from Canterbury,New Zealand

Abstract: Cirripede remains (Thoracica, Verrucomorpha), found associated with the mosasaur Prognathodon waiparaensis  Welles and Gregg, 1971 in glauconitic sands of the Late Cretaceous Conway Formation exposed along the Waipara River bank (mid‐Canterbury, New Zealand), are identified as a new species, Verruca sauria sp. nov. On the basis of taphonomy, it is deduced that these verrucids grew on a postmortem accumulation of mosasaur bones under very quiescent conditions. The current amphitropical distribution of the earliest known verrucids, i.e. V. sauria sp. nov., V. prisca  Bosquet, 1854 , V. pusilla  Bosquet, 1857 and V. tasmanica  Buckeridge, 1983 , is rationalized in the light of Tethyan palaeogeography.     

The fine structure of the frontal filament complex of barnacle larvae (Crustacea: Cirripedia)

Cell and Tissue Research - The frontal filaments comprise two regions, the internal vesicles and the external filaments. Dendrites of extra-optic protocerebral origin pass ventrally from the brain,...     

Barnacles (Cirripedia: Thoracica) from the equatorial East Pacific

Previously unidentified barnacles (Cirripedia: Thoracica) that were collected during the ninth cruise of the R/V Akademik Mstislav Keldysh in the equatorial zone of the East Pacific Ocean from depths of 1422–1490 m are examined. The following species were found in two samples we studied: Amigdoscalpellum costellatum, A. elegans, Arcoscalpellum michelottianum, Annandaleum gruvelii gruvelii, Cristallinaverruca allisoni, and Metaverruca recta. These species are described, illustrated, and compared to the published data. This study extends the previously known areas of distribution of some species and adds further data on their morphology.     

The ectoparasitic barnacle Anelasma (Cirripedia,Thoracica, Lepadomorpha) on the shark Centroscyllium nigrum (Chondrichthyes,Squalidae) from the Pacific sub-Antarctic

We report the occurrence of the ectoparasitic lepadomorph barnacle Anelasma sp. on the deep-sea squaloid shark Centroscyllium nigrum from the Pacific sub-Antarctic off southern Chile. Anelasma has previously been documented only from the northeast Atlantic on the squaloid shark Etmopterus spinax; this new record extends the known range of Anelasma into the Pacific Ocean and into the Southern Hemisphere, and documents a new host for this parasitic barnacle.     

The cypris larvae of the parasitic barnacle Heterosaccus lunatus (Crustacea, Cirripedia, Rhizocephala): some laboratory observations

Heterosaccus lunatus parasitizes the portunid crab, Charybdis callianassa in Moreton Bay, Australia. With the host crabs maintained at 22.5 degrees C this sacculinid rhizocephalan released larval broods every 6-7 days. During July-August 1996 and particularly August 1999 such broods showed the change-over from male only larvae in the early broods to females only in the later broods. As the host crabs were maintained under similar aquarium conditions in both years it is concluded that the light/dark cycle is the principal cue triggering this larval sex reversal. Oogenesis in the parasite externa is somehow controlled to produce two different sized ova - male larvae develop from large ova and females from small ova. A working hypothesis outlining how sex is probably determined for the larvae of sacculinids is erected. H. lunatus is considered the ideal sacculinid for the further experimental work necessary to verify the proposed sex-determining mechanism and its control processes. Measurements of the maximum swimming speeds of H. lunatus male and female cyprids showed the larger males to be the faster in absolute terms (27.95 compared with 17.60 mm s(-1), respectively), however, the calculated relative speeds were almost identical at approximately 90 body lengths s(-1). Settlement experiments confirmed that female H. lunatus cyprids settle only on the gills of C. callianassa; these cyprids needed to be at least 2 days old before they were able to settle.     

Ctenophore-zooplankton-phytoplankton interactions in Narragansett Bay, Rhode Island, USA, during 1972-1977

Plankton dynamics at a station in lower Narragansett Bay, RIare compared for six summer and fall seasons, 1972–1977.In four of these years, initiation of the summer pulse of thectenophore Mnemiopsis leidyi was accompanied by a rapid declinein zooplankton abundance and a summer phytoplankton bloom. Terminationof the phytoplankton bloom coincided with depleted ctenophoreabundance and increased zooplankton biomass in two of the years.Yearly variations in the summer abundance of the diatom Skeletonemacostatum were positively related to the magnitude of the ctenophorepulse. The magnitude of ctenophore population was related tothe zooplankton biomass present at the start of the pulse. Theserelationships, the timing and magnitude of the plankton eventssuggest that M. leidyi regulated summer zooplankton and phytoplanktondynamics. Ctenophores may control phytoplankton blooms indirectlythrough their predation on herbivorous zooplankton and directlyby the nutrient excretion accompanying such grazing. This evidencethat a planktonic carnivore two trophic steps removed from thephytoplankton regulates the latter's dynamics in NarragansettBay is analogous to reported regulation of benthic algal (kelp)dynamics by the sea otter, lobster and various crabs throughtheir predation on herbivorous sea urchins. The factors responsiblefor the seasonal decrease in ctenophores remain unresolved;ctenophore predators on Mnemiopsis are absent in NarragansettBay. Infection by the vermiform larval anemone, Edwardsia lineata,grazing by the butterfish, Peprilus triacanthus, and changesin food availability, temperature and salinity likewise do notexplain this disappearance.     

Larvae of Barnacles (Cirripedia: Thoracica) in the White Sea Plankton

The barnacle fauna of the White Sea is briefly described. The morphology of barnacle larvae in this water body is comparatively analyzed. The characters important for the larvae identification are given particular attention. A classification key for the naupliar and cyprid larvae of White Sea barnacles is proposed.     

Relationship between cyprid energy reserves and metamorphosis in the barnacle Balanus amphitrite Darwin (Cirripedia; Thoracica)

Nauplii batch cultures of Balanus amphitrite were reared with four different diatoms (Skeletonema costatum, Thalassiosira pseudonana, Chaetoceros gracilis, silicate-limited C. gracilis) at three different cells concentrations: 1×10⁵, 5×10⁵, and 1×10⁶ cells ml⁻¹. The cyprid energy reserves were quantified as the ratio of triacylglycerols (TAG) to DNA. Energy reserves of larvae fed on different diatoms at a concentration of 1×10⁶ cells ml⁻¹ were ranked in the order: silicate-limited C. gracilis>C. gracilis>T. pseudonana>S. costatum. There was a significant linear relationship between the TAG content of the diet and cyprid energy reserves. The effect of cyprid energy reserves on metamorphosis to polystyrene surface in the presence and the absence of conspecific settlement factor (SF) was studied after 12, 24, and 48 h of incubation. A strong positive correlation between energy reserves and percent metamorphosis was observed in the absence of SF (r_{12 h}=0.88, r_{24 h}=0.82, r_{48 h}=0.68, P<0.05). A weak positive correlation was observed in the presence of SF (r_{12 h}=0.43, r_{24 h}=0.48, r_{48 h}=0.50, P<0.05). In both treatments, more than 80% of the cyprids with high energy reserves metamorphosed within 24 h. In contrast, a high proportion of cyprids with low energy reserves metamorphosed in response to SF in 24 h. Our results indicate that discriminatory metamorphic behavior of cyprids is closely linked to their TAG/DNA ratio, a proxy for energy reserve.     

Littoral barnacles of The Snares islands,southern New Zealand (Cirripedia: Thoracica)

Abstract

Ibla idiotica, Lepas australis, Calantica villosa, Chamaesipho columna, Tetraclitella purpurascens, Notobalanus vestitus, and Notomegabalanus campbelli are reported for the first time from The Snares. The occurrence of Calantica spinosa and Epopella plicata is confirmed. Habitat information and recorded distribution in New Zealand are given for each species. The Snares barnacle fauna is restricted both in diversity and in numbers of individuals. This may be due to high wave energies, strong winds which aid desiccation, and counter-flow of currents, which might disrupt larval dispersal from the north and north-west.     

The distribution of cirripede larvae (Cirripedia: Thoracica) in the Amursky and Ussuriisky bays of the Sea of Japan

Based on data from plankton surveys that were carried out in the waters of the Amursky and Ussuriisky bays of the Sea of Japan from May to October 2007 and 2008, the species composition, time of occurrence, density, and distribution of cirripede larvae (Cirripedia: Thoracica) were studied. The larvae of five species of this group were revealed. Their average density does not exceed 400 ind./m3 and their proportion in the total meroplankton does not exceed 22%. In the summer season, the larvae of Amphibalanus improvisus prevailed and in the autumn season the nauplii of Balanus rostratus prevailed. The number of larvae of barnacles was higher in Amursky Bay, with deep-sea species nauplii being concentrated in its central part and shallow water ones in the northern and central parts, in the zones of costal gyres. In Ussuriisky Bay, the density of larvae of most species decreased seaward from the coast. The abundance of larvae of invasive species A. improvisus show that it has successfully become naturalized in Amursky Bay and is gradually replacing the native species Chthamalus dalli and Balanus crenatus in the lower littoral and upper sublittoral zones.     

The functional morphology of the alimentary tract of barnacles (Cirripedia: Thoracica)

The alimentary tract of barnacles is made up of cuticle-lined foregut and hindgut with an intervening U-shaped midgut associated anteriorly with a pair of pancreatic glands and perhaps midgut caeca. Epithelial salivary glands secrete acid mucopolysaccharide, glycoprotein or both. Cells of all the midgut regions are capable of absorption which is carried out mainly by the anterior midgut and caeca. Midgut cells of Balanus balanoides (L.) show a seasonal variation in the distribution of intracellular lipid droplets. Midgut cells rest on an elastic basal lamina and secrete a peritrophic membrane which contains mucopolysaccharide and protein. Cells of the stratum perintestinale connect with the midgut epithelial cells via cell processes which probably translocate absorbed materials. Glycoprotein globules and lipid droplets accumulate in the body parenchyma of B. balanoides and are transported to the ovaries to form yolk (glycolipovitellin). The pancreatic gland cells of all barnacles are active secretory cells secreting proteinaceous material (probably digestive enzymes).     

Molecular phylogeny and character evolution of the chthamaloid barnacles (Cirripedia: Thoracica)

The Chthamaloidea (Balanomorpha) present the most plesiomorphic characters in shell plates and cirri, mouthparts, and oral cone within the acorn barnacles (Thoracica: Sessilia). Due to their importance in understanding both the origin and diversification of the Balanomorpha, the evolution of the Chthamaloidea has been debated since Darwin's seminal monographs. Theories of morphological and ontogenetic evolution suggest that the group could have evolved multiple times from pedunculated relatives and that shell plate number diminished gradually (8→6→4) from an ancestral state with eight wall plates surrounded by whorls of small imbricating plates; but this hypothesis has never been subjected to a rigorous phylogenetic test. Here we used multilocus sequence data and extensive taxon sampling to build a comprehensive phylogeny of the Chthamaloidea as a basis for understanding their morphological evolution. Our maximum likelihood and Bayesian analyses separate the Catophragmidae (eight shell plates and imbricating plates) from the Chthamalidae (8-4 shell plates and no imbricating plates), but do no support a gradual reduction in shell plates (8→6→4). This suggests that evolution at the base of the Balanomorpha involved a considerable amount of homoplasy.     

Seasonal variation of pelagic invertebrate larvae in the shallow antarctic waters of Admiralty Bay (King George Island)

Recent studies have revealed increasing numbers of benthic invertebrate species producing pelagic larvae in Antarctic waters. This paper investigates temporal changes in larval abundance in shallow areas of Admiralty Bay. Plankton was collected from December to May of 2000/2001 and 2001/2002. Air and water temperature and solar radiation were significantly higher during the second year, characterising three seasonal periods early summer, late summer and early winter. Mean meroplankton abundance was 160 and 1,548 in d.100 m⁻³ for the first and second years, respectively. Mollusc veligers were dominant in both years. Analysis of variance showed that in 2001 veligers were present in the early winter and in 2002 they were synchronous with the late summer phytoplankton bloom; polychaetes and trochophors were concentrated in the early winter, while echinoderms and nemerteans were abundant in early summer. These results showed the importance of seasonality (i.e. a combination of air and water temperature, solar radiation and food supply) to the reproductive events of an Antarctic coastal nearshore environment.     

Synaptonemal polycomplexes in spermatocytes of the gooseneck barnacle,Pollicipes polymerus Sowerby (Crustacea: Cirripedia)

Polycomplexes are described for the first time in spermatocytes of a cirripede crustacean, Pollicipes polymerus Sowerby. Synaptonemal complexes of regular tripartite construction are seen from zygotene to mid-pachytene. Although some of the synaptonemal complexes are disrupted at late pachytene and may degenerate at this stage, some persist and by diplotene may form polycomplexes by the bending and self-fusion of their lateral elements. These polycomplexes are still encompassed by chromosomes and consist of four dense plates and intercalated central elements and transverse fibers. Other polycomplexes with five or six dense plates, all of which are considerably wider than lateral elements of mid-pachytene synaptonemal complexes, are also seen in diplotene nuclei. These may be attached to a chromosome at only one end or may be in the nucleoplasm, free of chromosomal involvement except for fine fibrous connectives. No polycomplexes are seen in meiotic cells after diplotene and their fate is unknown. It is suggested that poly-complexes serve as sequestra for synaptonemal material which could prevent normal chromosomal disjunction.     

Seasonal variations of tintinnids (Ciliophora: Oligotrichida) in Narragansett Bay, Rhode Island, U.S.A.

Tintinnids exhibit a bimodal peak of abundance in NarragansettBay, with a minimum in late spring and a lesser peak in latesummer-early autumn, depending on location. Thirty-three speciesin eight genera were identified, with the fauna dominated bythe genus Tintinnopsis. Tintinnid abundance was not obviouslycorrelated with salinity, temperature, or nanoplankton chlorophyllconcentration. Patterns of change in seasonal abundance canserve as a framework for posing additional questions of therole tintinnids play in marine food webs.