Egg production and early development of the subarctic copepods Neocalanus cristatus,N. plumchrus and N. flemingeri

Reproduction and early development of the large subarctic copepods Neocalanus cristatus, N. plumchrus and N. flemingeri were investigated in the laboratory. All three species produced eggs at intervals of 5.0 to 14.7 days, depending on species and temperature. The females of N. flemingeri released the fewest clutches of the three species, but with the largest clutch size. Clutch size of N. cristatus was smallest with longest intervals between clutches. Mean±1 S.E. of total fecundities were 386±116 eggs for N. cristatus, 840±214 eggs for N. plumchrus, and 924±346 eggs for N. flemingeri. The egg laying period of a female at 2°C was estimated to be 91 days for N. cristatus, 60 days for N. plumchrus and 47 days for N. flemingeri. The color and outer characteristics of eggs and nauplii of these species were quite different. C : N ratios of the eggs were 9.3–10.5, which were slightly higher than that of females or CV. Egg hatching times for each species were 4.6–5.7 days at 2°C and decreased with increasing temperature at a Q₁₀ of 2.8–3.0. N. cristatus nauplii developed to copepodid stage I (CI) without feeding, and the developmental time in days from hatching to CI was expressed as a Bělehrádek equation, D_CI=17068×(T+14.7)^−2.05. Reproduction strategies of the three species of Neocalanus are discussed with reference to their life history strategies.     

Different effects of increased water temperature on egg production of Calanus finmarchicus and C. glacialis

Two copepod species, Calanus finmarchicus (a widespread North Atlantic species) and C. glacialis (an Arctic species), are dominant in the zooplankton of Arctic seas. We hypothesized that the anticipated warming in the Arctic might have different effects on the arctic and boreal species. The effect of temperature on egg production rate (EPR) in these species at temperatures of 0, 2.5, 5, 7.5, and 10°C under contrasting feeding conditions was assessed in 5-day-long experiments. The EPR of the fed C. finmarchicus increased with temperature over the entire tested range. On the contrary, the EPR of C. glacialis increased only in the range of 0–5°C and dropped with further temperature growth. The difference in the influence of temperature on reproduction of these two species is statistically significant. Feeding conditions have a considerable effect on the C. finmarchicus EPR. The EPRs of the female C. glacialis that fed or starved for 5 days displayed no significant difference. These results suggest that the C. finmarchicus EPR increases with temperature under favorable feeding conditions, whereas the C. glacialis EPR decreases at a temperature over 5°C independently of the feeding conditions. This allows for prediction of the shift in abundances of these two species in pelagic communities of Arctic seas in the case of a warming scenario.     

Abundance of epiphytic dinoflagellates from coastal waters off Jeju Island,Korea During Autumn 2009

The occurrence of harmful epiphytic dinoflagellates is of concern to scientists, the aquaculture industry, and government due to their toxicity not only to marine organisms but also to humans. There have been no studies on the abundance of the epiphytic dinoflagellates in Korean waters. We explored the presence of epiphytic dinoflagellates in the coastal waters off Jeju Island, southwestern Korea. Furthermore, we measured the abundance of epiphytic dinoflagellates on the thalli of 24 different macroalgae, collected from five different locations in October 2009. Five epiphytic dinoflagellate genera Amphidinium, Coolia, Gambierdiscus, Ostreopsis, and Prorocentrum were found. These five genera were observed on the thalli of the macroalgae Chordaria flagelliformis, Martensia sp., Padina arborescens, and Sargassum sp., while none were observed exceptionally on Codium fragile. The abundance of Ostreopsis spp. was highest on Derbesia sp. (8,660 cells/g wet weight), while that of Gambierdiscus spp. was highest on Martensia sp. (4,870 cells/g-ww). The maximum abundances of Amphidinium spp., Coolia spp., and Prorocentrum spp. were 410, 710, and 300 cells/g-ww, respectively. The maximum abundance of Coolia spp., Gambierdiscus spp., and Ostreopsis spp. obtained in the present study was lower than for other locations reported in literature. The results of the present study suggest that the presence and abundance of epiphytic dinoflagellates may be related to the macroalgal species of the coastal waters of Jeju Island.     

Molecular phylogeny of the genus <Emphasis Type="Italic">Chondracanthus</Emphasis> (Rhodophyta), focusing on the resurrection of <Emphasis Type="Italic">C. okamurae</Emphasis> and the description of <Emphasis Type="Italic">C. cincinnus</Emphasis> sp. nov.

Determining the taxonomic status of the red algal genus Chondracanthus based on morphological characters is challenging due to the similarity and high degree of plasticity of the thallus. Since the taxonomic history of several Chondracanthus species remains unclear, we analyzed the plastid rbcL and mitochondrial COI genes of the specimens from Korea and Japan, in combination with morphological observations, to examine their phylogenetic relationships. Our results confirmed the distinction of C. okamurae, which is separated from C. intermedius, and identified a novel species, C. cincinnus sp. nov. Three species (C. okamurae, C. intermedius and C. cincinnus) formed a monophyletic clade with C. tenellus. C. okamurae is distinguished by linear, narrow, cylindrical to compressed, slightly recurved axes, and a high-intertidal to subtidal distribution. It was collected from Korea and Japan, while C. intermedius was identified from Japan only. A new species, Chondracanthus cincinnus sp. nov., is characterized by linear, compressed, strongly recurved axes, and a low-intertidal to subtidal distiribution. Based on the molecular phylogeny using rbcL and COI data, we herein resurrect C. okamurae as a distinct species and identify C. cincinnus as a new species.     

Comparison between amphipod assemblages associated with Caulerpa racemosa var. cylindracea and those of other Mediterranean habitats on soft substrate

The spread of the invasive alga Caulerpa racemosa var. cylindracea in shallow-water habitats can present different faunal assemblage composition. We compared the amphipod assemblages associated with C. racemosa and natural habitats found on shallow-water Mediterranean soft substrata. Four vegetated habitats were compared: C. racemosa, Caulerpa prolifera, Cymodocea nodosa and Posidonia oceanica with unvegetated substrata. Samples were collected during two sampling periods (September 2004 and March 2005). A total of 63 amphipod species were recorded. The results showed that the vegetated habitats sampled, including C. racemosa stands, supported a higher abundance and species richness of amphipods. Furthermore, the assemblage structure differed between the different habitats, while the abundance of some species was significantly different, depending on habitat. For example, Microdeutopus obtusatus was favoured by C. racemosa habitat; Ampelisca diadema was associated with C. prolifera beds; and Hyale schmidti was more abundant in P. oceanica meadows. Habitat invasion by C. racemosa can exert an important influence on biotic assemblages, modifying habitat structure and associated fauna.     

Food Selection in Two Corallivorous Butterflyfishes, Chaetodon austriacus and C. trifascialis, in the Northern Red Sea

Abstract. Using an in situ observational approach, the food preferences among hard corals were examined for the two obligate coral‐feeding butterflyfishes Chaetodon austriacus and C. trifascialis in the Northern Red Sea, Gulf of Aqaba, Egypt. Chaetodon austriacus is a generalist coral feeder that feeds mainly on three genera of abundant hard corals (Acropora, Porites and Pocillopora). In contrast, C. trifascialis is a specialist coral feeder on Acropora spp. and Pocillopora verrucosa. In general, C. austriacus had a lower feeding rate than C. trifascialis (both species in the Northern Red Sea reefs had high feeding rates compared with other reefs). Ivlev's electivity index was calculated for the two species. This index shows that C. austriacus prefers Montipora and Pocillopora, and avoids Lobophyllia and Favites. On the other hand, C. trifascialis prefers Acropora valida and avoids Porites solida. Thus, the feeding preference and avoidance of these chaetodontids depend on both biting rate and food availability in the environment rather than on biting rate alone.     

The biology and ecology of Centropages typicus: An introduction

We briefly introduce the different chapters of this special issue which review the current knowledge and understanding of the biology and ecology of Centropages typicus obtained over the last 30 years. The papers are grouped into two major theme areas: the first five papers review behaviour, feeding, metabolism, growth and development, and reproduction, and the four following papers have a regional focus dealing with temporal and spatial distribution in the Mediterranean Sea and in the North Atlantic shelf areas. The findings reviewed in the two groups of papers converge to explain why C. typicus is such a very successful copepod species in these coastal areas. In the different chapters, similarities and differences with congeneric species (C. velificatus, C. hamatus, C. brachiatus, C. chierchiae, C. furcatus, and C. abdominalis) have been explored where these are known.     

Fish faunal and habitat analyses using trawls,camera sleds and submersibles in benthic deep-sea habitats off central California

Beam trawl, camera sled and submersible data from 2 000–3 300 m off central California produced similar fish faunal composition, but different density estimates. All species caught in trawls were observed in camera-sled and submersible observations. However, some rare species that were observed were not caught in trawls. The fish fauna was dominated by the families Macrouridae, Zoarcidae, Moridae, and Rajidae. Fishes both trawled and observed were the macrourids Coryphaenoides armatus, C. filifer and C. leptolepis; the zoarcids Bothrocara spp., Pachycara lepinium and Lycenchelys spp.; the morid Antimora microlepis; the rajid Bathyraja trachura, the ophidiid Spectrunculus grandis, and the liparidid Careproctus ovigerum. One unidentified liparidid (Paraliparis sp.) and two unidentified Lycenchelys spp. were trawled and may have been seen but also could not be identified to species from photographs. Observed only in photographs were the liparidids Paraliparis rosaceus and Careproctus melanurus, synodontid Bathysaurus mollis, and notocanthid Notacanthus chemnitzii. These three techniques differed in their ability to provide specimens for accurate identification, counts, and later life history (feeding habit, age and growth, and reproduction) studies, and to provide information on dispersion, habitat utilization, behavior and interactions. Accurate density estimates were undoubtedly hampered by trawl and camera sled avoidance, escape, and uncertainties concerning the area trawled. Camera sleds produced higher (and perhaps better) estimates of density. Submersible observations from the DSV Alvin produced a similar species list but little additional, quantitative information. Both visual techniques allowed habitat characterization, but no strong faunal associations with habitat types were observed.     

Chemical induction of settlement and metamorphosis in two Babylonia (Gastropoda) larvae

INTRODUCTIONStudiesonchemicalinductionofsettlementandmetamorphosisinmarineGastropodalarvaehaveadvancedconsiderablyoverdecades,manyofwhichfocusonHalionsrufescensandPhestillasibogae.AccordingtotheavailabledataItheeffectivefactorswhichcaninduceGastropodalarvaetosettleandmetamorphose,includenatureinducers,neurotransmittersandtheirstructuralanalogs,inorganicion(K )andorganicsolvents.Sincethemechanismofmetamorphosisingastropodlarvaediffersmarkedlyamongvariousspecies,itisnecessarytoexamineandc…     

Fine-scale vertical distribution of coastal and offshore copepods in the Golfo de Arauco, central Chile, during the upwelling season

In order to understand the mechanism by which zooplankters from different origins co-occur during the upwelling season within Golfo de Arauco, one of the most productive areas in central Chile, we assessed short term variations in the vertical distribution of the most abundant copepod species. Fine-scale, day and night vertical zooplankton sampling was done with a pump over 12 days in summer. The water column in the gulf consisted of three layers: Equatorial Subsurface Water of low dissolved oxygen content in the deeper part of the water column, strong temperature and oxygen gradients at mid-depth (15-25 m), and a layer of warmer, more oxygenated, less saline water at the surface. Copepods within the gulf originated from offshore, from the continental shelf, and from the coastal area. Most taxa showed distinctive vertical distributions. Three copepod groups were identified by their mean weighted depths of residence. One group included shallow residents found above the thermocline/oxycline (Acartia tonsa, Centropages brachiatus, Corycaeus sp., Paracalanus parvus, Oncaea sp.). A second group was comprised by species distributed at or below the thermocline/oxycline (Oithona sp., Oncaea conifera, Lucicutia sp., Metridia sp., Heterorhabdus papilliger). The third group was composed of vertical migrators that crossed the thermocline/oxycline (Calanus chilensis, Calanoides patagoniensis, Aetideus armatus, Pleuromamma piseki). In spite of their different vertical distribution ranges, the most abundant and frequent copepod species (P. parvus, C. chilensis, C. patagoniensis, C. brachiatus) share a common capacity to withstand wide ranges of oxygen concentration and temperature. This characteristic, along with the capacity to vary their life strategies under different environmental conditions, seems to facilitate the maintenance of large numbers of copepods in coastal waters along the Humboldt Current.     

Composition,abundance, distribution and seasonality of larval fishes in the shallow nearshore of the proposed Greater Addo Marine Reserve,Algoa Bay,South Africa

The larval fish assemblage was investigated in the shallow, nearshore region of a proposed marine protected area in eastern Algoa Bay, temperate South Africa, prior to proclamation. Sampling was conducted at six sites along two different depth contours at ∼5 m and ∼15 m to assess shore association. Larvae were collected by means of stepped oblique bongo net tows deployed off a ski-boat, twice per season for 2 years between 2005 and 2007. In total, 6045 larval fishes were collected representing 32 families and 78 species. The Gobiidae, Cynoglossidae, Clupeidae, Engraulidae and Sparidae were the dominant fish families. Catches varied significantly among seasons peaking in spring with a mean of ∼200 larvae/100 m³. Mean overall larval density was higher along the deeper contour, at ∼15 m (40 larvae/100 m³). The preflexion stage of development dominated catches at the ∼5 m (80%) and ∼15 m (73%) depth contours. Body lengths of Argyrosomus thorpei, Caffrogobius gilchristi, Diplodus capensis, Heteromycteris capensis and Solea turbynei, all estuary associated species, were larger at the shallow sites nearer to shore. Larvae of coastal species that produce benthic eggs dominated catches (75%) in the shallow sites (∼5 m) but were less abundant (32%) farther from shore at the deeper (∼15 m) sites. All developmental stages of D. capensis, Engraulis capensis, H. capensis, Sardinops sagax and two Pomadasys species were found in the study area. It appears that some species use the shallow nearshore as a nursery area.     

Two new records of Valenciennea helsdingenii (Perciformes: Gobiidae) and Chromis margaritifer (Perciformes: Pomacentridae) from Jeju Island,Korea

Two specimens of Valenciennea helsdingenii and one specimen of Chromis margaritifer were collected on scuba in October 2011 from Jeju Island, Korea. V. helsdingenii is characterized by a body with two dark stripes that connect the head and caudal fin, and a large dark spot between the third and sixth dorsal fin spines. C. margaritifer is characterized by a body that is dark brown anteriorly but white posteriorly at the boundary between the fifth dorsal fin soft ray and the ninth anal fin soft ray. The Korean name ‘Bok-gi-mang-duk-sok’ is proposed for the genus Valenciennea, the name ‘Du-jul-bok-gi-mang-duk’ is proposed for the species V. helsdingenii, and the name ‘Huinggo-ri-ja-ri-dom’ is proposed for C. margaritifer.     

Zooplankton distribution across the Lomonosov Ridge,Arctic Ocean: species inventory,biomass and vertical structure

On a transect across the Lomonosov Ridge stratified zooplankton tows were made to the bottom at seven stations. A species inventory was established and compared with earlier observations in the Arctic Ocean. Differences between the Amundsen and Makarov basins are relatively small and correspond well with the general circulation patterns for Atlantic, Pacific, and neritic waters, suggesting slow mixing rates for the different basins. There were no remarkable differences in the species composition or their vertical distribution between the two sides of the Lomonosov Ridge. This indicates effective faunistic exchange across the ridge, although several bathy-pelagic species were almost or completely absent on top of the Ridge. Biomass showed a strong gradient along the transect, with a pronounced peak (9.5 g dry weight m⁻²) in the core of Atlantic water over the ridge, and minima over the deep basins. These differences were related to the effect of bottom topography for deep-living species, and the dynamics of the Atlantic layer for the meso- and epipelagic species. The maximum was formed mainly by the copepods Calanus hyperboreus and Metridia longa together with chaetognaths and ostracods. The presence of young developmental stages in some of the abundant species (C. hyperboreus, M. longa) suggests successful reproduction at all stations but C. finmarchicus was almost exclusively represented as old stages and adults. Comparison with earlier data on abundance and biomass from the Canada Basin (Russian Drift station “North Pole-22”) shows a pronounced difference with respect to both absolute quantities and relative composition. The copepod C. finmarchicus is completely absent in the central Canada Basin, and the portion of non-copepod zooplankton is dramatically decreased. This points to a reduced advection of Atlantic water or more severe food conditions in this basin.     

Temporal and spatial distribution of the two closely related Acartia species A. omorii and A. hudsonica (Copepoda,Calanoida) in a small inlet water of Japan

Temporal and spatial distributions of Acartia omorii and Acartia hudsonica were investigated in Maizuru Bay, middle Japan, from 1977 to 1978. In both years, adults of the two species appeared synchronously 17 days after the bottom temperature cell to 20°C in November; the numbers of both species sharply decreased when the bottom temperature rose to 20°C in late June and disappeared in early or mid-July. These facts indicate that a bottom temperature of 20°C is critical for the recruitment of the populations of these species. Acartia hudsonica was more limited to the inner position of the bay than A. omorii; spatial segregation may be explained not only by preference for different hydrographic conditions, but also by interspecific competition between the two species. In temperate waters, co-existing Acartia species belonging to the same subgenus appear to be segregated only in space while those of different subgenera usually exhibit a seasonal segregation. Pacific populations of A. hudsonica appear to be more restricted to inlet waters and estuaries than Atlantic populations, probably owing to the presence of the closely related sympatric species in the Pacific.     

Seasonal and spatial dynamics of Centropages typicus and C. hamatus in the western North Atlantic

Centropages typicus and Centropages hamatus are two of the most abundant copepods on the continental shelf in the mid-Atlantic region of the western North Atlantic. Their range extends from the Scotian Shelf (C. typicus) and the Grand Banks (C. hamatus) in the north to Cape Hatteras in the south. South of Cape Hatteras they have only been observed in inshore waters of North and South Carolina and not offshore on the continental shelf or in coastal waters of eastern Florida. However, C. hamatus has been observed in western Florida. Abundances of both species are greatest in inshore regions in the mid-Atlantic Bight with C. hamatus tending to have a more coastal distribution. In this region seasonal variability is low with high abundances from late fall through mid-summer. In the north year-round presence of both species is confined to inshore areas and offshore banks such as Georges Bank, and Browns Bank, Emerald Bank and Western Bank on the Scotian Shelf. In this northern region there is a pronounced seasonal cycle in abundance with high abundances during late summer and fall. Periods of high reproductive rates are closely linked to blooms of large phytoplankton and food availability rather than temperature appears to be controlling population abundances.     

漳州西施舌线粒体基因组全序列:腔蛤蜊属存在新种的证据

利用长PCR扩增漳州西施舌线粒体DNA(ZZ-mtDNA),用引物步移法测序,获得线粒体基因组DNA全序列,研究其基因组特点。结合双壳类49个物种线粒体全基因组,分析基因间核苷酸和蛋白质氨基酸序列的差异,构建系统进化树,探讨漳州西施舌系统演化地位。研究结果表明:漳州西施舌线粒体基因组DNA全长17 199 bp,A+T含量为64.2%,编码36个基因,其中12个蛋白质编码基因,22个转运RNA基因(tRNAs),2个核糖体RNA基因(lrRNA 和srRNA),全部基因均位于重链上,tRNASer为单拷贝,tRNAMet为双拷贝;非编码区占10.9%(1 882 bp/17 199 bp),其中,主非编码区为882 bp,与RZ-mtDNA主非编码区差异明显,另有一个较大(400 bp)的非编码区为漳州西施舌特异性非编码区;以双壳纲帘蛤目文蛤属3种贝类、贻贝目贻贝属4种贝类、珍珠贝目牡蛎科的6种贝类为参照,对编码基因的核苷酸序列和蛋白质氨基酸序列进行差异分析显示,漳州西施舌与日照西施舌达到了种间差异水平。线粒体基因组编码的基因、tRNA组成、非编码区均揭示漳州西施舌是腔蛤蜊属的一个新种。     

Deep-water stands of Cystoseira zosteroides C. Agardh (Fucales,Ochrophyta) in the Northwestern Mediterranean: Insights into assemblage structure and population dynamics

Populations dominated by Cystoseira zosteroides, an endemic and threatened Mediterranean seaweed, colonize deep-water rocky habitats down to more than 50 m depth. Assemblages dominated by this species display high algal and invertebrate species richness. Algal biomass averages 1134 g dw m⁻². Erect and turf algae account for only 25% of total algal dry weight, while encrusting corallines are responsible for the remaining 75%. Sponges, bryozoans and ascidians constitute the dominant sessile macrofauna. Cystoseira zosteroides is the dominant erect algae, with a mean biomass of 60.6 g dw m⁻², and densities ranging from 4 to 7 plants m⁻². The alien turf alga Womersleyella setacea has a biomass of 104.2 g dw m⁻² and covers most of the understory substrate. The size-frequency distribution of C. zosteroides populations shows differences over time. Mean annual growth of the main axis is around 0.5 cm and mean annual mortality rate is lower than 2%. Recruitment was almost nil during the studied period of time (10 years). Processes structuring these deep-water Cystoseira stands must be driven by episodic disturbances, after-disturbance recruitment pulses, and long periods of steady growth that last at least 10 years. However, it is also possible that recruitment is irreversibly inhibited by the alien alga W. setacea in which case these old-growth stands are faced with extinction. The highly diversified assemblages and the low growth and low mortality rates of C. zosteroides indicate high vulnerability to natural and anthropogenic disturbances, and call for effective measures to ensure their conservation.     

海南万宁小海近岸表层海水弧菌组成及其变化

于2006年冬至2007年秋分四个季度对海南万宁小海近岸表层海水的弧菌种类分布及数量变化进行了调查.共分离到27种弧菌属细菌,其中副溶血弧菌、创伤弧菌、溶藻弧菌、霍乱弧菌、河流弧菌和拟态弧菌6种弧菌为主要弧菌.在6种主要弧菌中,溶藻弧菌、副溶血弧菌和霍乱弧菌在夏季和秋季检出率较高;河流弧菌在春季和夏季的检出率较高;拟态...     

Germination of phytoplankton resting cells from surface sediments in two areas of the Southern Chinese coastal waters

To understand the role of phytoplankton resting cells in the outbreak of algal blooms, particularly harmful algal blooms, surface sediments were collected monthly from April 2007 to March 2008 from two bays near the international ports in the Southern Chinese coastal waters. Sieved sediments were incubated for 20 and 40 days, and germinated vegetative cells were observed. Altogether, 97 taxa were recorded, of which 50 were diatoms and 35 dinoflagellates. Vegetative cells of cyanobacteria, chlorophytes, dictyophytes, euglenophytes, haptophytes, and raphidophytes were also observed. Centric diatoms such as Chaetoceros, Melosira, Skeletonema, and Thalassiosira dominated. Scrippsiella, Gymnodinium, and Alexandrium were common dinoflagellate taxa. Diatom spores germinated in samples from all seasons but were abundant in the autumn and winter samples. Low numbers of dinoflagellate cells germinated in the winter samples. The nanophytoplankton taxa, Gymnodinium corii and Chrysochromulina sp., which have not been recorded in the previous phytoplankton surveys, were abundant, suggesting either their new appearance in the water column or perhaps that they were overlooked in routine phytoplankton monitoring due to their small sizes. Vegetative cells of harmful or potentially harmful taxa were germinated, and some of them such as Amphidinium, Gambierdiscus, Ostreopsis, and Coolia have not previously been reported in the study area. Based on the results of the incubation of sediments from the two bays near the international ports, it is suggested that international shipping increases the risk of the introduction of new phytoplankton species and thus promotes the incidence of harmful algal blooms.