Occurrence and abundance of three larval codlet species (Bregmacerotidae, Teleostei) in the Southwest Atlantic Ocean (12–22°S)

There are still only a few studies related to Bregmacerotidae larvae in Brazil, although these larvae are frequently collected in oceanic ichthyoplankton samples. Thus this study analyzes the occurrence and abundance of Bregmaceros larvae along the Brazilian central coast and describes larval characteristics. During three oceanographic cruises samples were collected between the Real River (12°S) and the São Tomé Cape (22°S). Oblique hauls were conducted from a maximum depth of 200 m, using bongo nets of 330‐ and 500‐μm mesh size. Among the 951 bregmacerotids collected, three species were identified corresponding to 89%Bregmaceros atlanticus, 8%Bregmaceros cantori and 3%Bregmaceros n. sp. B. atlanticus was widely distributed along the study area and was more frequent in stations situated beyond the 200‐m isobath; this species was more abundant during the winter, showing a peak of density between Vitória and the São Tomé Cape (355 larvae per 10 m²). Bregmaceros cantori densities were very similar during the three cruises; the highest value (25.6 larvae per 10 m²) was recorded during the winter and higher concentrations were observed in neritic stations along the 200‐m isobath. Bregmaceros n. sp. was rare in collections made during the three cruises; it was concentrated along the Bahia coast (12–18°S), and was more frequent in stations situated in the oceanic region. Bregmaceros atlanticus varying from 2.0 to 6.0 mm and Bregmaceros n. sp. larvae varying from 3.0 to 6.0 mm were present in all cruises, indicating that they spawn year‐round. Bregmaceros cantori did not show a distribution pattern among the different length classes, probably associated with the fact that this species has a coastal distribution.     

Larvae of uncommon caridean decapods in the German Bight: Species composition,distribution and abundance

Typically, the most abundant group of shrimp larvae in the German Bight is formed by representatives of the family Crangonidae. Larvae of the remaining species have been largely ignored, and only scarce information concerning their ecology is available. Thus, the purpose of the present study was to determine the species composition, distribution and abundance of noncrangonid shrimp larvae in the German Bight in July 1990, after the mildest winter of the century. The material is based upon plankton samples collected at 77 stations, covering the entire German Bight. Eight species were identified, as well as larvae of Palaemonidae andProcessa-juveniles.Processa nouveli holthuisi (53.0%) andP. modica (31.3%) were predominant in the collection. The distribution of the two species was clearly separated: the main concentration ofP. nouveli holthuisi (peak concentration of 1.94 larvae per m³) was confined to the northwest corner of the German Bight, while a majority ofP. modica larvae (peak concentration of 0.54 larvae per m³) occurred at the southwesterly stations. The spatial distribution ofCaridion steveni andEualus occultus around Helgoland indicates the presence of an adult population at the only rocky island in the study area. Other taxa, such as larvae of Palaemonidae and juvenilePandalina brevirostris were collected exclusively in estuarine habitats. Based upon both the results of the present study and comparable data, we conclude that developmental stages of ten non-crangonid species, as well as representatives of Palaemonidae, can be expected to occur in the plankton of the German Bight. The extremely mild temperatures of the preceding winter may have been, in part, responsible for the relatively high densities of some taxa encountered during our plankton survey. We assume that warm winter temperatures favour the immigration, reproduction and survival of cold-sensitive species.     

Larval settlement of the bivalvesMya arenaria andM. uzenensis on scallop collectors in Vostok Bay, Sea of Japan

This paper discusses data on the horizontal and vertical distribution of the spat ofMya arenaria andM. uzenensis on collectors for the cultivation of the scallopMizuhopecten yessoensis in Vostok Bay. The maximum settlement of the mollusks on scallop collectors occurred in the innermost part of the bay. The spat density ofM. arenaria on collectors was 2.6 times that ofM. uzenensis. M. arenaria larvae preferred settling on the upper portions of collectors, while the distribution ofM. uzenensis was random. The time of collector placement in the sea influenced spat numbers.     

The period of occurrence,density, and distribution of larvae of three commercial crab species in Peter the Great Bay,Sea of Japan

Based on materials from plankton surveys carried out in 2004–2009, the period of occurrence, density, and distribution of larvae of three commercial species of crabs in the Peter the Great bay and adjacent areas of Sea of Japan were studied. The larvae of the horsehair crab Erimacrus isenbeckii (Brandt, 1848) occurred in the plankton from mid-March to early June, within the range of water temperature from −1 to 10.8°C. The larvae of the helmet crab Telmessus cheiragonus (Tilesius, 1812) appeared in the plankton in mid-April and occurred to the end of June within the temperature range from 2.8 to 13.0°C. The larvae of the snow crab Chionoecetes opilio (O. Fabricius, 1788) appeared in the plankton in mid-April as well, but some individuals sporadically occurred until early August. All the species of crabs produced one generation of larvae for their reproduction season. The terms of larval stay in plankton depended on water temperature and the duration of the pelagic period increased in colder years. In that area, the larvae of C. opilio were the most abundant (up to 41 ind./m³) and the zoea density of horsehair and helmet crabs was significantly lower (no more than 2 ind./m³). The larvae of C. opilio occurred over the entire area of the Peter the Great bay; the greatest aggregations of their early stages were observed in its southwestern open part. The maximum density of E. isenbeckii zoea was recorded in the south of the Amursky bay and in the Posyet bay. Individual larvae of T. cheiragonus occurred in the Posyet bay and in the southern part of the Amursky and Ussuriisky bays. The late-stage larvae of all crab species were concentrated in areas of the coastal circulation.     

Population growth rates forAmblyomma americanum (Acari: Ixodidae) onBos indicus,B. taurus andB. indicus x B. taurus cattle

Densities ofAmblyomma americanum (L.) onBos indicus, B. taurus andB. indicus x B. taurus cattle are compared over a 3-year period, and the growth rate (rate of increase or decrease) of parasitic tick populations on each cattle genotype is estimated.Average log₁₀ densities of parasiticA. americanum larvae are significantly (P=0.05) lower onB. indicus cattle than onB. taurus andB. indicus x B. taurus cattle. Average log densities of nymphal and adult ticks onB. taurus cattle are significantly higher than onB. indicus cattle but neither cattle genotype differs in this regard fromB. indicus x B. taurus cattle.Estimated annual tick population growth rates (log₁₀) for parasiticA. americanum are positive onB. taurus cattle (+0.84 larvae, +0.09 nymphs, +0.22 adults calf^–1 year^–1), but are negative onB. indicus (–0.18 nymphs, –0.14 adults calf^–1 year^–1) andB. indicus x B. taurus cattle (–0.45 larvae, –0.24 nymphs, –0.14 adults calf^–1 year^–1). Populations of parasitic larvae were not detected onB. indicus cattle.     

A new species of Hormathia (Actiniaria, Hormathiidae) from the eastern Weddell Sea, Antarctica

A new species of sea anemone in the genus Hormathia, is described and illustrated based on forty-two specimens collected during the Polarstern cruises ANT XV/3 and ANT XVII/3 in the Weddell Sea. The main features of the new taxon are the crown of flattened and hooked tubercles at the distal end of the scapus, the regular arrangement of pointed tubercles along the column and the cnidom. The new species shares the pointed tubercles, at least in the upper part of the scapus, with two other species of Hormathia in the southern hemisphere: Hormathia spinosa Hertwig 1882 and H. pectinata Hertwig 1882 Received in revised form: 27 December 2000 Electronic Publication     

Pelagic larvae of bivalve mollusks of Amursky Bay,Sea of Japan

Larvae of 63 Bivalvia taxa were found in Amursky Bay. Of these, 47 were identified to the species level. Larvae of 55 taxa were found throughout the bay. The highest species diversity was recorded in the northeastern part and in the center of the southern part of the bay, as well as at the exit from it. Larvae of Mactra chinensis, Mytilus coruscus, Crassostrea gigas, Teredo navalis, Mya japonica, and Mysella ventricosa were widely distributed in the bay. The maximum numbers of species were observed in July and September. A comparison of species lists using the set-theory method showed that the species complexes typical of different parts of Amursky Bay are formed under the influence of the Razdolnaya River runoff flow from the north and marine waters coming from the south. The mean density of larvae during the observation period was 1100 specimens/m³ in the northern and 735 specimens/m³ in the southern part of the bay. The highest density of larvae in Amursky Bay was observed at the end of June, the beginning of July, and in September; the minimal larval density occurred in April, May, and August. While the species diversity was similarly high, the density of larvae was significantly higher in Amursky Bay than in the nearby Ussuriisky Bay.     

The early life history of kurosoi,Sebastes schlegeli (Scorpaenidae), in the Sea of Japan

Larval and juvenile stages of kurosoi,Sebastes schlegeli, are described and illustrated from wild specimens. Some ecological aspects of larvae and juveniles are also described. Notochord flexion occurred between 5.6–7.5 mm SL. Transformation occurred between 13–20 mm SL. Preflexion and flexion larvae ofS. schlegeli can be distinguished from similar larvae by the pigmentation of the dorsal and ventral midlines of the tail and absence of pigmentation on the ventral portion of the rectum. After notochord flexion, the dorsal and lateral regions in both larvae and pelagic juveniles were heavily pigmented, suggesting adaptation for neustonic life style. Larvae and juveniles were caught at many coastal stations, but did not occur in cooler offshore waters. Larvae smaller than 20 mm SL inhabited surface waters. Until ca. 40 mm SL, juveniles inhabited mainly surface waters (without drifting seaweed), but also used other habitats, such as the drifting seaweed, and near the sea bed. Small larvae (<7 mm SL) fed mainly on copepod nauplii. Larger larvae fed on calanoid copepodites andEvadne nordmanni. Pelagic juveniles fed mainly on fish eggs, with fish larvae also being important food items for some individuals. Most food items taken by juveniles that were associated with drifting seaweed were eggs with attaching filaments (Cololabis saira andHyporhamphus sajori), suggesting that the high density of such food items both attracts and keeps juveniles around drifting seaweed.     

Aeromonas species in stabilization ponds in the arid region of Marrakesh,Morocco, and relation to fecal-pollution and climatic factors

During the period 12 July 1985 to 23 December 1987, water samples were collected in two-week intervals for estimates ofAeromonas species in a waste treatment system located in the arid region of Marrakech, Morocco. Fecal coliforms, temperature, and chemical oxygen demand were measured simultaneously withAeromonas species densities. Statistical methods were utilized to analyze the significance of average differences and temporal patterns ofAeromonas species numbers. Removal ofAeromonas in the whole system did not exceed 1.14 log.Aeromonas densities showed significantly higher resistance to the treatment process when compared with fecal coliforms; however, abundance of the two groups presented a similar seasonal change. The highest numbers occurred during the cold months, while the lowest appeared in the warm months. Statistical time-series analyses of the densities data showed the seasonal and cyclic distribution ofAeromonas in this treatment plant. These temporal changes were simultaneously observed in all the stations investigated and were negatively correlated with water temperature values. Aeromonas populations were dominated byA. caviae andA. hydrophila in the inlet samples. These two species were rapidly eliminated in the treatment plant. The temporal distribution ofA. caviae was similar to the change in densities ofAeromonas and fecal coliforms. The seasonal fluctuations of abundance ofAeromonas were probably related to this species, which dominated in the winter samples but dropped during the summer. Meanwhile,A. sobria dominated all the final effluent samples. This greater survival ofA. sobria and its known pathogenicity may limit the re-use of treated water for irrigation of fodder plants.     

Intra-tree foraging behavior ofDacus dorsalis flies in relation to host fruit quantity, quality and type

Promising diets were screened and the most successful modified with additives used in artificial diets for other entomophagous insects. Two suitable diets were obtained, one for adults and one for larvae ofChilocorus nigritus (Fabricius) (Coleoptera: Coccinellidae). They were still inferior to natural prey and not adequate as the sole food source for rearing consecutive generations. They are valuable as substitute food in the insectary during shortages of natural prey. Oleander scaleAspidiotus nerii Bouché andAsterolecanium miliaris (Boisduval) were evaluated as natural prey forC. nigritus and two other potential biocontrol agents in southern Africa,C. bipustulatus (Linnaeus) andC. infernalis Mulsant.A. nerii andA. miliaris were suitable for all life stages ofC. nigritus and adults ofC. bipustulatus andC. infernalis. A. miliaris was inadequate for larvae ofC. bipustulatus andC. infernalis.     

SEASONAL GROWTH,BIOMASS, AND REPRODUCTIVE BEHAVIOR OF THREE SPECIES OF RED ALGAE IN GODAVARI ESTUARY,INDIA1

Growth and different phases in the life histories of Bos-trychia tenella (Vohl.) J. Ag., Caloglossa leprieurii (Mont.) J. Ag., and Catenella impudica (Mont.) J. Ag. were estimated for 23 months from January 1986 to December 1987 in the Gautami Godavari estuary of lndia. Seasonal data on hydrographical conditions, biomass, and plant length were collected from three stations in this estuary. Biomass was minimum in August and September and maximum in January and February, as was frond length of tetrasporic and vegetative plants. Temperatures of 24°–27°C and salinities of 5–20 ppt coincided with optimal growth for all three algae. In all three species, tetrasporophytes were present in all months of the year without any seasonal periodicity, and nearly 50% of the plants were tetrasporophytes. The gametophytes of B. tenella and C. leprieurii and cystocarpic plants of C. impudica occurred from October to May, with greatest abundance in January. The abundance of spermatangial and cystocarpic plants in the populations of B. tenella and C. leprieurii ranged from 3 to 15%. Spermatangial plants of Catenella impudica could not be identified, and the abundance of cystocarpic plants was very low.     

Isozyme variation inBulnesia retama,B. schickendantzii andB. foliosa (Zygophyllaceae)

The genetic variation between two allopatric populations ofBulnesia retama and that ofB. schickendantzii andB. foliosa was investigated. The Peruvian population ofB. retama showed low values of P (0.117) and He (0.057) compared to those in the Argentine population with P = 0.59 and He = 0.269;B. schickendantzii showed P = 0.54 andB. foliosa P = 0.17. Genetic identity between the latter was 0.836 and between the allopatric populations ofB. retama was 0.89; the Peruvian population had reduced allelic variation per locus (A = 1.176) in comparison to the Argentine population (A = 1.955). The values of A, P, He andWright's fixation indices suggest that the Peruvian population could have originated from a single or very few migrants from southern latitudes (founder effect).     

Habitat preferences as patch selection of larval and emerging chironomids (Diptera) in a gravel brook

Four common species of larval and emerging chironomids were investigated during 1981 and between 1984/1985 in an alpine gravel brook. The emergence patterns ofN. dubius, O. rivulorum andH. ornaticollis were significantly affected by fluctuations of the water level, while rises in water temperature tended to trigger the peaks in emergence of the same species and ofO. frigidus. N. dubius exhibited its main emergence activity over areas of bed sediment which had a lower mean water velocity or were discontinuously flooded. On the other hand, the imagines ofO. frigidus, O. rivulorum andH. ornaticollis reached peak densities in zones of the main current channel in the Seebach. The larvae of these species inhabited horizontally and vertically different areas of bed sediment depending on the developmental stage. Early instars ofN. dubius andH. ornaticollis preferred zones near the banks and reached their maximum densities in sediment depths of 10 to 20 cm and 20 to 30 cm, respectively. In contrast, the larvae ofO. frigidus andO. rivulorum reached their highest densities in the first 10 cm of the sediments with significant preferences for the zones of stronger water flow.     

Macrozooplankton studies in Kuwait Bay (Arabian Gulf). I: Distribution and composition of the ichthyoplankton

Fifty taxa of fish larvae were identified during a 12 monthstudy in Kuwait Bay. Dominants included ‘Sparidae-type’larvae, clupeids and gobies. Peak numbers and types of larvaeoccurred during late spring/early summer with the minimum duringwinter. The bay could be divided into three subareas based uponfaunal, sedimentary and hydrographic characteristics. Low larvalconcentrations were generally found in the vicinity of the Khoral Sabiya—an area of below average salinities. Westernbay stations had either the highest mean temperatures and/orsalinities and low larval densities. During spring and summer,only goby and clupeid larvae were more abundant here than inthe outer bay. Most of the dominants, particularly gobies, Bregmacerosand pomadasyids, occurred at above average concentrations atthe northeastern and outer bay stations.     

Laboratory investigations of Aphodius beetles (Scarabaeidae) as biological control agents of the Cattle Lungworm,Dictyocaulus viviparus (Nematoda: Dictyocaulidae)

The effect of Aphodius fossor, A. luridus and A. foetidus adults on Dictyocaulus viviparus larvae in cattle faeces was investigated. In chambers containing A. fossor and A. luridus, a significant decrease (at 5% level) in the median number of D. viviparus larvae occurred after 90 h at a density of one beetle per g of faeces. The possibility of using dung beetles as biocontrol agents for D. viviparus is discussed.     

Survival and behaviour of unfed stages of the ticksRhipicephalus appendiculatus,Boophilus decoloratus andB. microplus under field conditions in Zimbabwe

The survival and behaviour of the unfed stages ofRhipicephalus appendiculatus, Boophilus decoloratus andB. microplus in gauze columns were observed in long and short grass in the highveld of Zimbabwe. Ticks were exposed in the cool, hot and rainy seasons of 1980 and 1981. All species and stages survived longer in long grass than in short grass. Larvae from engorged female ticks released in the cool season hatched much later than incubator-reared controls. They were consequently not present during the cold weather and survived longer than larvae subjected to the low temperatures, in which the shortest survival-times were recorded. The survival of nymphs was insensitive to season. The longest survival-times were recorded in adults. Median survival-times of incubator-reared adults ranged from 165 to 375 days in short grass and from 333 to 493 days in long grass. These times were usually longer than those for adults which moulted in the field. Larvae of the three species and nymphs ofR. appendiculatus were active soon after hatching or moulting, irrespective of the season. In contrast, adults ofR. appendiculatus showed different patterns of activity in different seasons. Adults first appeared at the base of the columns in October/November and then gradually ascended to reach a maximum height in December/January. They remained high up in the columns until May/June when the weather became increasingly cold and dry. Larvae ofB. decoloratus climbed higher up in the columns in the long grass than did the larvae of the other two species.Larvae and nymphs ofR. appendiculatus and larvae ofB. microplus migrated up and down the columns daily, but larvae ofB. decoloratus and adults ofR. appendiculatus did not migrate.     

Lipiniella arenicola (Chironomidae) compared withChironomus muratensis andCh. nudiventris: Distribution patterns related to depth and sediment characteristics,diet, and behavioural response to reduced oxygen concentrations

Density patterns ofLipiniella arenicola andChironomus muratensis were studied in Lake Wolderwijd (The Netherlands) using geostatistics, and compared with patterns of depth and silt contents of the sediment.L. arenicola was restricted to shallow (depth <1 m), sandy silt (silt content <5%), wind-exposed sediments.Ch. muratensis occurred all over the lake, but the highest densities were found in the sheltered silty North-West corner. Gut analyses of IV-instar larvae from the Ventjagers flats (Haringvliet, Lower Rhine-Meuse) showed thatL. arenicola fed by selectively grazing on benthic algae,Ch. muratensis by filtering and non-selective grazing, andCh. nudiventris by non-selective grazing. In the laboratory, behavioural responses to reduced oxygen concentrations were tested with the impedance conversion technique.L. arenicola was more sensitive to low oxygen concentrations (<3 mg l^–1) than bothChironomus species. It is argued that the differences in resistance to hypoxia and feeding behaviour are in accordance with the differences in distribution patterns. The restriction ofL. arenicola to the pure sand habitats is not attributable to an especially high sensitivity to low dissolved oxygen concentrations alone. Several behavioural adaptations enableL. arenicola larvae to live in the shallow, wind-exposed pure-sand habitats: the ability to select food items, tube strength, and site selection of ovipositing females or planktonic larvae.     

Field evaluation of insect resistance in a wild tomato and its effects on insect parasitoids

Populations ofHelicoverpa (=Heliothis) zea (Boddie),Heliothis virescens (F.),Manduca sexta (L.) andM. quinquemaculata (Haw.) and their egg and larval parasitoids were sampled in field plots of the: insect-resistant wild tomato,Lycopersicon hirsutum f. glabratum C. H. Mull, accession PI 134417; susceptible commercial tomato cultivar ‘Better Boy’; F₁ hybrid; and selected, moderately resistant backcross genotype. Densities ofH. zea andH. virescens eggs and small larvae were higher on resistant genotypes than on susceptible genotypes, but densities of large larvae were similar on all genotypes. Densities ofManduca spp. larvae were too low to permit similar analyses of the effects of plant genotype. Rates of egg parasitism byTrichogramma spp. andTelenomus sphingis (Ashmead) were reduced on insect-resistant genotypes. Rates of parasitism by the larval parasitoidsCampoletis sonorensis (Cameron) andCotesia congregata (Say) were reduced on resistant genotypes. No consistent effects on parasitism rates byCotesia marginiventris (Cresson) were observed and parasitism rates byCardiochiles nigriceps Viereck were unaffected.     

Seasonal variations in numbers,biomass and breeding patterns of dung beettles [Coleoptera: Scarabaeidae] in Southern France

Seasonal variations in numbers and biomass and breeding of 28 species ofScarabaeidae-Scarabaeinae andGeotrupidae were studied at 2 temperate sites and 2 mediterranean sites in southern France in 1978 and 1979, using cattle-dung baited pitfall traps. Maximum dung burial occurred when females were parous and ovipositiong (i.e. during spring at the mediterranean sites and summer at the temperate sites). Using biomass as a measure of dung burial the most important spring active beetles at the mediterranean sites were:Budas bison, B. bubalus, Scarabaeus laticollis, Onthophagus lemur andCopris hispanus, and at the temperate sites:C. lunaris, O. vacca, andO. ovatus. These results confirmed the previous choice ofC. hispanus, C. lunaris, B. bison andO. vacca for introduction into Australia. In addition it is suggested thatB. bubalus, S. laticollis andO. lemur be considered for introduction into mediterranean areas of south western Australia to complement those species already introduced for bush fly control.