Genetic evidence for the occurrence of a cryptic species with the littoral nemerteans Lineus ruber and L. viridis (Nemertea: Anopla)

Lineus ruber and L. viridis are common intertidal heteronemerteans found on the coasts of northern Europe and the east coast of North America. The two species resemble each other morphologically and were synonymised for many years prior to being separated on the basis of larval development. In this study, specimens of L. ruber and L. viridis were collected from sites along the west and southwest coast of Britain, northern France and the east coast of North America. The external morphology and allele frequencies of isozymes of the two species were compared from all sites. The external morphology of L. ruber and L. viridis was similar but they could generally be separated by colour. Allele frequencies for up to 13 enzyme loci between sympatric populations of L. ruber and L. viridis indicated that these two species are genetically very different (Nei's genetic identity=0.090 to 0.083). Allele-frequency data also indicated the presence of a third genetic type occurring sympatrically with populations of both L. ruber and L. viridis on the coasts of Britain and France but not on the coast of North America. Fixed differences in allele frequencies between populations of the third genetic type and sympatric populations of L. ruber and L. viridis were observed across multiple loci. Genetic identity between the third genetic type and sympatric populations of L. ruber and L. viridis were extremely low (Nei's genetic identity =<0.078). Such large genetic differences between populations indicate a barrier to gene flow and reproductive isolation. The aberrant type, which exhibits sufficient morphological variation to prevent individuals being distinguished from those of both L. ruber and L. viridis, therefore represents a separate species. The low genetic identities found in intrageneric comparisons of species found in this study have been found in other studies on nemerteans. They may indicate systematic problems within these groups or other phenomena such as morphological stasis.     

Some aspects of the ecology of the echiuran worm Bonellia viridis and associated infauna

In inshore waters around Malta, Bonellia viridis inhabit burrows with multiple exits in calcareous rocks, and are most abundant in areas bordering Posidonia oceanica meadows. The associated epiflora and fauna are typical of the Mediterranean hard-substrate infralittoral zone. The larger infaunal species associated with B. viridis include a poriferan, Cliona sp.; an unidentified nemertean worm; various polychaetes; the sipunculans Phascolosoma granulatum and Aspidosiphon muelleri; two species of molluscs-Lithophaga lithophaga and Lepidopleurus cajetanus; 8 species of decapod crustaceans; and the teleost Gobius geniporus. Four types of burrows are found in rocks containing B. viridis. The larger burrows (referred to herein as UBA burrows) contain 3 main species-the decapods Upogebia deltaura and Alpheus dentipes and B. viridis itself. Experimental evidence suggests that U. deltaura excavates the UBA burrows mechanically, although B. viridis may secondarily modify them by secretion of an acidic mucus and gentle mechanical action. There is a definite community of organisms living as commensals in the burrow of U. deltaura. The assemblage of organisms bears a striking parallelism to the assemblages inhabiting the burrows of species of Upogebia, Callianassa and the echiuran Urechis caupo of the Pacific coast of N. America. A food web for the UBA burrow community is suggested.     

Copper uptake by the sea anemoneAnemonia viridis and the role of zooxanthellae in metal regulation

Anemonia viridis (Forskäl) were collected from south-west Scotland and south-west England in October 1988. When exposed to 0.05 and 0.2mg 1^–1 copper in sea water, anemones did not take up the metal in proportion to external concentrations. Results suggested thatA. viridis regulated copper by expelling symbiotic algae (or zooxanthellae) which were shown to accumulate copper. The use of aposymbiotic (non-zooxanthellate) anemones in similar metal-uptake experiments indicated that other mechanisms may also be involved in metal regulation. Mucus was produced byA. viridis when the anemone was exposed to copper, and it is proposed that mucus may be involved in the regulation process. The implication of this work on the use of coelenterates as biological indicators of environmental metal levels is discussed.     

Distribution of lipids between the zooxanthellae and animal compartment in the symbiotic sea anemoneAnemonia viridis: Wax esters,triglycerides and fatty acids

The temperate sea anemoneAnemonia viridis (Forskäl) contained about 11% lipid on a dry weight basis when maintained at light levels of about 10µE m^–2 s^–1 and a temperature of 10°C. Aposymbiotic forms of the anemone had similar lipid levels. These values are very low compared with tropical symbiotic Anthozoa in which lipid levels constitute up to 50% of dry weight. In symbioticA. viridis, <6% of total lipid consisted of the storage lipids, wax esters and triglycerides. Most of the triglyceride was stored in the animal tissues rather than the zooxanthellae. Zooxanthellae contained only small amounts of wax esters. An analysis was made of the wax ester, triglyceride and fatty acid composition of symbiotic anemones, isolated zooxanthellae and aposymbiotic anemones. Wax ester composition was similar in symbiotic and aposymbiotic forms. However, triglyceride composition differed. In particular trimyristin (C42) was found only within the symbiotic association. Fatty acids showed a high degree of unsaturation, and acids with both even and odd numbers of carbon atoms were found. The most abundant fatty acid was 16:0 in all samples, except for the total lipids from zooxanthellae in which the major fatty acid wastrans-18:1.     

In vivo and in vitro differences in chloroplast functionality in the two north Atlantic sacoglossans (Gastropoda,Opisthobranchia) <Emphasis Type="Italic">Placida dendritica</Emphasis> and <Emphasis Type="Italic">Elysia viridis</Emphasis>

The photosynthetic functionality in chloroplasts in the two sacoglossan molluscs Placida dendritica and Elysia viridis from the Trondheim fjord in Norway was studied. P. dendritica and E. viridis with no functional chloroplasts in their digestive system were introduced to the green macroalgae Codium fragile. Our results showed that P. dendritica was not able to retain functional (photosynthetic) chloroplasts. Transmission electron microscopy (TEM) showed that chloroplasts were directly digested when phagocytosed into the digestive cells. Four stages of chloroplast degradation were observed. A corresponding operational quantum yield of chl a fluorescence (Φ_PSII ~ 0) indicated autofluorescence, and the presence of highly degraded chl a supported these observations. In contrast, E. viridis was able to retain functional chloroplasts. For this species it took only 1 week for the chloroplasts inside the digestive cells to acquire the same Φ_PSII and light utilisation coefficient (α) as C. fragile kept under the same light conditions. Data for 8 days showed a 2–6-fold increase in the maximum photosynthetic rate (P _max) and light saturation index (E _k) relative to C. fragile. This increase in available light was probably caused by a reduced package effect in the digestive gland of E. viridis relative to C. fragile, resulting in a partial photoacclimation response by reducing the turnover time of electrons (τ). Isolated pigments from C. fragile compared to E. viridis showed the same levels of photosynthetic pigments (chl a and b, neoxanthin, violaxanthin, siphonaxanthin, siphonein and β,ε-carotene) relative to μg chl a (w:w), indicating that the chloroplasts in E. viridis did not synthesise any new pigments. After 73 days of starvation, it was estimated that chloroplasts in E. viridis were able to stay photosynthetic 5–9 months relative to the size of the slugs, corresponding to an RFC of level 8 (a retention ability to retain functional chloroplasts (RFC) for more than 3 months). The reduction in Φ_PSII, P _max and α as a function of time was caused by a reduction in chloroplast health and number (chloroplast thylakoid membranes and PSII are degraded). These observations therefore conclude that chloroplasts from C. fragile cannot divide or synthesise new pigments when retained by E. viridis, but are able to partially photoacclimate by decreasing τ as a response to more light. This study also points to the importance of siphonaxanthin and siphonein as chemotaxonomic markers for the identification of algal sources of functional chloroplasts.     

Variation in protein patterns within and among polychaete sibling species of the genus<Emphasis Type="Italic"> Marenzelleria</Emphasis> (Spionidae): a preliminary survey

Differences in protein patterns of the soluble protein fraction among the sibling species Marenzelleria viridis (formerly type I) and M. neglecta (formerly type II) were investigated under common environmental conditions using two-dimensional gel electrophoresis (2D-PAGE). Protein expression was determined using general protein staining with Coomassie-blue and compared with radioactive labeling of proteins. In the well-resolved region of stained gels an average of 319 protein spots for M. viridis and 241 spots for M. neglecta could be detected. High sensitivity of radiolabeling allowed separation of an average of 517 and 496 spots for M. viridis and for M. neglecta, respectively. Differences in protein expression between both species could be attributed mainly to qualitative differences in protein patterns. Triplet pattern was used to calculate the genetic similarity of the two species. Thus, 373 protein spots were scored for this analysis; whereas 304 spots were invariant, 36 spots were specific for M. viridis, while 33 spots were specific for M. neglecta. The genetic similarity (F) of the two Marenzelleria sibling species was 0.815. Apart from presence and absence, differences between both species resulted either from slight changes in the isoelectric point or from molecular weight, but rarely from both. Genetic variability was found only among specimens of M. viridis. The experimental conditions to perform two-dimensional electrophoresis for these polychaete species were established for subsequent investigations on a proteomic level. Using 2D-PAGE we expect further insight into the evolutionary adaptation in Marenzelleria spp.Communicated by O. Kinne, Oldendorf/Luhe     

Cytogenetic studies in green mussel, Perna viridis (Mytiloida: Pteriomorphia), from West Coast of India

Chromosomes of Perna viridis were characterized by karyotype analysis, C-banding and nucleolus organizer regions (NORs). The diploid chromosome number was confirmed as 30 and the karyotype is composed of ten metacentric and five submetacentric chromosome pairs. Constitutive heterochromatin blocks were found on all chromosomal pairs except chromosomal pair 15, which showed uniform staining throughout the entire chromosomes. Silver staining revealed nucleolus organizer regions on telomeric region of four chromosomal pairs, viz. 1, 3, 7 and 11. This is the first comprehensive study undertaken on chromosomes of Perna viridis.     

Heterospecific call recognition and phonotaxis in the orientation behavior of the marbled newt,Triturus marmoratus

The role of acoustic cues as reference cues for orientation by amphibians has been demonstrated in anurans, the only amphibian group that engages in acoustic communication, but not in urodeles. Orientation responses of marbled newts, Triturus marmoratus, were studied to determine whether heterospecific calls elicited positive phonotaxis. The orientation tests consisted in presenting either a familiar acoustic stimulus, the advertisement calls of natterjack toads (Bufo calamita), or a control stimulus, the advertisement calls of European green toads (Bufo viridis) that the newts would not be expected to recognize. Marbled newts and natterjack toads occur in simpatry, but T. marmoratus and B. viridis are allopatric species. Thus, T. marmoratus is distributed over the northern half of the Iberian Peninsula, whereas B. viridis occurs in the Balearic Islands, but not over the Iberian Peninsula. Newts were released in a circular arena while a recorded chorus of natterjack toads or European green toads played outside the arena to determine whether they displayed positive phonotactic orientation. Our results show that marbled newts performed positive phonotaxis when exposed to the breeding calls of natterjack toads, but not to those of European green toads. Newts chose a compass course in the direction of the advertisement calls of B. calamita. Acoustic information might improve orientation accuracy. This study is the first to provide evidence of heterospecific call recognition and positive phonotactic response in urodeles.Communicated by W. Wiltschko     

Carbon budgets in temperate anthozoan-dinoflagellate symbioses

Carbon budgets were modelled for temperate anthozoan-dinoflagellate symbioses involving the sea anemones Cereus pedunculatus (Pennant), Anthopleura ballii (Cocks) and Anemonia viridis (Forskäl), and the zoanthid Isozoanthus sulcatus (Gosse). Irradiance regimes experienced at 1.5 and 9 m on sunny and cloudy days in summer were assumed. Photosynthetic capacity (P _max gross) and efficiency () were considerably higher in I. sulcatus than in the other Anthozoa. P _max gross and also differed in A. viridis from different localities. At 1.5 m on sunny days, zooxanthellae would require 1.80 to 5.89% of the carbon fixed in photosyn-thesis for respiration and growth, and translocate the remainder (94.11 to 98.20%) to the host. Productivity would decrease with increasing depth and cloud cover, resulting in a decrease in the potential availability of carbon for translocation. At 9 m on cloudy days, 37.82 to 87.84% of the carbon fixed in photosynthesis would be required for zooxanthella respiration and growth in C. pedunculatus, Anthopleura ballii and Anemonia viridis, leaving just 12.16 to 62.18% for translocation; the translocation rate would still exceed 95% in I. sulcatus. The potential contribution of zooxanthellae to the host's daily respiratory carbon requirements (CZAR) would be 72.6 and 72.1% in Anthopleura ballii and C. pedunculatus, respectively, at 1.5 m on sunny days, and would decrease to just 2.1 and 0.7%, respectively, at 9 m on cloudy days. These Anthozoa therefore require a heterotrophic source of carbon to survive. The CZAR in Anemonia viridis from different locations would be 140.6 to 142.9% at 1.5 m on sunny days, but would be <100% under the other assumed irradiance regimes. The CZAR in I. sulcatus would be 181.5% at 1.5 m on sunny days, and would only be <100% when at 9 m on cloudy days. Under favourable conditions, A. viridis and I. sulcatus are potentially autotrophic and may have surplus carbon available (15.69 to 43.89% of the gross photosynthetic production) for tissue biosynthesis, reproduction and storage. However, when field conditions are considered on an annual basis, the general need for heterotrophically-derived carbon in temperate Anthozoa is suggested.     

Observations in captivity of the activity patterns and resources utilization of the spider crab <Emphasis Type="Italic">Inachus phalangium</Emphasis> (Decapoda,Majidae)

The spider crab Inachus phalangium is common in the sublitoral fringe of the Mediterranean Sea and north-eastern Atlantic Ocean, where it can be found in association with the snakelocks sea anemone Anemonia viridis. Studies concerning its activity patterns and the role of the host sea anemone are lacking. Our study aimed at investigating activity rhythms and resources utilization of I. phalangium reared in captivity. The main behavioral traits exhibited by I. phalangium are performed mostly at night. Two experiments were designed, one examined the time budget of various behavioral acts and the degree of association with the sea anemone, the other analyzed the behavioral response to algae and anemones. We showed that algae have a crucial role in the biology of I. phalangium and that crabs are ready to leave the protection of their host to obtain them. Algae represent both the major component of the diet and one of the most utilized sources of masking material of I. phalangium, which provide, together with specialized cryptic behaviors, protection against predators. Although our data suggest that the association with A. viridis is not obligatory, but the role of the snakelocks sea anemone in the life of I. phalangium is still central, both as an anti-predatory defense and as a nutritional source. The association of I. phalangium with algae and the anemone is a facultative biotrophic commensalistic symbiosis.     

Hydrodynamic study of the functional morphology of the benthic suspension feeder Phoronopsis viridis (Phoronida)

Ambient water currents were altered by the morphology of an active suspension feeder, Phoronopsis viridis Hilton (phylum Phoronida), to produce a flow around its ciliated crown of feeding tentacles (lophophore). To test the effects of specific morphological characteristics on patterns of water movement, the morphology of model phoronids was varied and the resultant paths of water movement were compared to those around living phoronids. Living individuals were collected from the intertidal sandflats at Bodega Bay, California/USA, in the springs of 1984 and 1985. Although P. viridis actively produce a feeding current, use of various models demonstrated that the gross pattern of flow around a living phoronid was created by the physical interaction of its morphology with ambient currents. The important aspects of that morphology were the presence of a wide, porous crown of tentacles atop a cylindrically-shaped body. A hydrodynamic consequence of this morphology was that dye eroded off the substratum from a circular area around the base of the body and entrained upwards into the lophophore. In addition, rates of water movement were slowed at the lophophore and near the substratum adjacent to a phoronid, particles were slowed and diverted from horizontal paths immediately downstream of the lophophore, and the number of visible suspended particles within the wake per unit time increased with ambient velocity. Paths of water movement around a phoronid were also influenced by its angle and height relative to the substratum, indicating that P. viridis could behaviorally modify their local flow environment.     

Influence of habitat on abundance and size structure of a large temperate-reef fish, Achoerodus viridis (Pisces: Labridae)

The relationship between densities of Achoerodus viridis (Pisces: Labridae) and reef habitats at various localities within New South Wales (NSW), Australia was examined. Types of habitats were quantified at inner, mid and outer estuarine locations in each of two estuaries (Botany Bay and Port Jackson) to determine whether purported patterns of movement from estuaries could be related to differences in habitat. Although the same types of habitat were generally found at all locations, differences in the proportion of habitat types were found between shallow and deep reefs and among inner, mid and outer estuarine locations for both estuaries. Shallow habitats were usually dominated by Ecklonia radiata, turf and/or fringe habitat in Botany Bay, whereas deep sites were generally dominated by urchin-grazed barrens habitat and, sometimes, sponge- and ascidian-dominated deep reef. Shallow sites in Port Jackson were dominated by a mixture of habitats, as were deep reefs at mid-estuarine locations. Other deep reefs in Port Jackson were dominated by E. radiata (inner estuarine) or barrens (outer estuarine) habitat. Thus, patterns of habitat cover were not consistent between estuaries and numbers of fish could not be related to proportional representation of habitat on reefs along estuarine gradients. Univariate and multivariate analyses showed that there was little evidence that any size class of fish was correlated with the proportional representation of a particular habitat or group of habitats. Counts of fish that focused on barrens and E. radiata forest habitats over a period of 10 yr showed that similar numbers and all sizes of fish were found in the two types of habitat. Greater numbers of small fish were, however, found in the E. radiata forest habitat than in the barrens habitat. Estimates of abundance along the coast of NSW (100s to 1000 km) in a range of habitats (e.g. ascidian-dominated reef, kelp forest, urchin-grazed barrens) showed that there was no indication that a particular habitat consistently had greater numbers of A. viridis than other habitats. Therefore, A. viridis of a range of sizes appears to be flexible in its use of habitats on reefs. Received: 24 December 1997 / Accepted: 23 June 1998     

The systematic position of some boring sponges (Demospongiae,Hadromerida) studied by molecular analysis

A phylogenetic analysis of some bioeroding sponges of the family Clionaidae (Order Hadromerida) was performed to resolve some taxonomic problems both at the specific and the supraspecific level using the D2 and D3 regions of 28S rDNA. Species belonging to the genera Cliona, Cliothosa, Spheciospongia (fam. Clionaidae) and Diplastrella (fam. Spirastrellidae) from the Mediterranean Sea and Celebes Sea (Indonesia) were analysed. In the phylogenetic tree, the species clustered on two main branches, one comprising Cliona celata, C. rhodensis, C. utricularis, and Cliothosa hancocki, and the other made up of C. viridis, C. nigricans, C. schmidti, C. jullieni, Spheciospongia solida and S. vagabunda. Above the species level, data do not support the separation of the genus Cliothosa from Cliona, while they do support the inclusion of some massive boring species, previously assigned to the genus Spirastrella, in the family Clionaidae. At the species level, data demonstrated the genetic identity of taxa C. viridis and C. nigricans, in spite of their considerable morphological differences. In contrast, the yellow species commonly attributed to C. celata are probably to be considered as a complex of sibling species with a number of distinct taxa present in the Mediterranean. Data also showed the identity of the Mediterranean and Pacific populations of C. schmidti, suggesting the status of a Tethyan relict for this species.     

Metabolic responses to changing environmental conditions in the brackish water polychaetes Marenzelleria viridis and Hediste diversicolor

The metabolic strategies of the polychaete Marenzelleria viridis (Verrill 1873), a successful immigrant into Baltic shallow eutrophic coastal waters with meso-to oligohaline salinities since the 1980's, were determined by simultaneous calorimetry and respirometry. Resistance to oxygen deficiency under varying ecological conditions was also examined. The results of the studies with this immigrant were compared to those with the common indigeneous polychaete Nereis (Hediste) diversicolor (O.F. Müller). At 10 and 20 °C and the average habitat salinity of 5 M. viridis gradually reduced its metabolic activity with declining oxygen partial preessures (pO₂), whereas H. diversicolor maintained its metabolic activity. The metabolism of both species remained fully aerobic down to a pO₂ of 2 kPa. An additional hyposmotic stress of 0.5 salinity at a temperature of 20 °C led to a decrease in the rate of oxygen consumption in H. diversicolor below a pO₂ of 10 kPa, whereas metabolic heat dissipation remained constant. M. viridis, however, further reduced both, metabolic heat dissipation and oxygen consumption. The metabolic rates of both species under anoxia were similar, amounting to ca. 20% of the normoxic rate. The resistance of the two species to oxygen deficiency was also similar, ranging between 21 and 290 h (median survival time LT₅₀), depending on temperature and salinity. Specimens used in the present study were collected from the Southern Baltic coastal inlet of Darß-Zingster-Boddenkette during 1992 and 1993.     

Reproduction and larval development of Marenzelleria viridis (Polychaeta: Spionidae)

The pelagic larvae of the polychaete Marenzelleria viridis (Verrill, 1873) are newcomers among the meroplankton of the Baltic Sea, where they sometimes achieve an abundance of up to 21x10⁶ ind m^-3 near the coast, especially in late autumn and even in winter. Benthos samples were collected in the Darss-Zingst bodden chain from April 1992 to 1993 and used to ascertain the reproductive stages of individuals. Development from fertilized egg to benthic juvenile is described on the basis of field material. Details of the morphology of various pelagic stages and the young benthic worm are presented as drawings and scanning electron microscope photographs. In 1992, development of the gametes started in mid-May. The individuals reached maturity in late September after about 20 wk. The first planktonic stage was the fertilized egg. The larvae have initially one and later two pairs of black eyes and, in the 2nd segment, a ciliated pit. Gastrotrochs are present on the third and thereafter every alternate segment. Neuropodial setae develop once the 7-setiger stage is reached. Palps appear at the 10-setiger stage, and neuropodial bidentate hooks from the 10th to 11th setiger on. Metamorphosis into the juvenile benthic stage takes place at the earliest when the 15-setiger stage has been reached. The reproductive seasons of various populations of M. viridis and the developmental patterns of their larvae are discussed, and differences are compared with relevant findings for the spionids.     

Biochemical constituents and bioaccumulation as biomarkers in the green mussel Perna viridis with reference to silver and chromium toxicity

The sublethal effect of silver and chromium on some biochemical constituents was studied in the green mussel Perna viridis. The results revealed an overall reduction in total protein, total DNA, total RNA, glycogen, protein bound sugars and total lipid in the gill, hepatopancreas, and ovary of the mussels exposed to metals individually and in combination when compared with control. It was apparent that mussels exposed to mixtures of metals exhibited highly significant (P?P?P?相似文献   

Bacterial symbionts as an additional cytological marker for identification of sponges without a skeleton

Symbiotic bacteria from six Oscarella species (adults and embryos) collected in the Mediterranean Sea (O. lobularis, O. tuberculata, O. imperialis, O. microlobata, O. viridis) and the Sea of Japan (O. malakhovi) were investigated by scanning electron microscopy and transmission electron microscopy. In most cases, symbionts are rather numerous. Each sponge species has a definite set of bacterial morphological types. All bacteria are extracellular. Symbionts occupy the mesohyl of adult sponges or intercellular space in embryos and are often in contact with mesohylar filaments or cells. Bacteria of some morphotypes have characteristic blebs. Most symbionts are gram-negative, and two types of bacteria have traits of Archaea and one type of bacteria is similar to Planctomycetes. Data on morphology of bacterial symbionts can be a good additional character for identification of Oscarella species, which have no skeleton.     

Use of different soft tissues of Perna viridis a s biomonitors of bioavailability and contamination by heavy metals (Cd,Cu, Fe,Pb, Ni,and Zn) in a semi-enclosed intertidal water,the Johore Straits

Green-lipped mussels, Perna viridis, were collected from the eastern and western parts of the Johore Straits in September 2004 and January 2005. Based on the heavy metal concentrations in the different soft tissues (gonad, foot, mantle, gills, muscle, and remaining soft tissues) of these mussel samples, the eastern part of the Johore Straits (which is divided into two portions by a causeway), recorded higher levels of bioavailability and contamination by Cd, Cu, Fe, Ni, and Zn when compared to the western part, while Kg. Pasir Puteh in the eastern part was found to record the highest bioavailability and contamination by heavy metals. The use of different soft tissues of P. viridis as biomonitors of bioavailability and contamination by Cd, Cu, Fe, Pb, Ni, and Zn in the semi-enclosed Johore Straits is proposed, since erroneous results due to spawning and the problem of defecation before dissection could be overcome. Hence, a more accurate interpretation of the bioavailability and contamination by heavy metals in coastal waters could be obtained. To our knowledge, this is the most detailed study on the bioavailability and contamination of heavy metals in the Johore Straits on the Malaysian side of the waterway carried out by using the different soft tissues and metal distribution based on the Mussel Watch approach.     

A survey of antennal responses by five species of coniferophagous bark beetles (Coleoptera: Scolytidae) to bark volatiles of six species of angiosperm trees

Summary. Using Porapak Q traps, we collected the bark volatiles of six angiosperm trees native to British Columbia: black cottonwood, Populus trichocarpa Torr. & A. Gray (Salicaceae), trembling aspen, P. tremuloides Michx. (Salicaceae), paper birch, Betula papyrifera Marsh. (Betulaceae), bigleaf maple, Acer macrophyllum Pursh (Aceraceae), red alder, Alnus rubra Bong. (Betulaceae), and Sitka alder, A. viridis ssp. sinuata (Regel) á. L?ve & D. L?ve (Betulaceae). Utilising coupled gas chromatographic-electroantennographic detection analysis, the captured volatiles were assayed for antennal responses in five species of coniferophagous bark beetles (Coleoptera: Scolytidae), sympatric with most or all of the angiosperm trees: the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, the mountain pine beetle, D. ponderosae Hopkins, the spruce beetle, D. rufipennis (Kirby), the western balsam bark beetle, Dryocoetes confusus Swaine, and the pine engraver, Ips pini (Say). The identities of 25 antennally-active compounds were determined by coupled gas chromatographic-mass spectroscopic analysis, and co-chromatographic comparisons with authentic chemicals. The compounds identified were: hexanal, (E)-2-hexenal, (Z)-3-hexen-1-ol, 1-hexanol, heptanal, α-pinene, frontalin, benzaldehyde, β-pinene, 2-hydroxycyclohexanone, 3-carene, limonene, β-phellandrene, benzyl alcohol, (E)-ocimene, salicylaldehyde, conophthorin, guaiacol, nonanal, methyl salicylate, 4-allylanisole, decanal, thymol methyl ether, (E)-nerolidol, and dendrolasin. A number of these compounds are known semiochemicals that are active in the behaviour of other organisms, including bark beetles, suggesting a high degree of semiochemical parsimony. Antennally-active compounds ranged from seven in A. viridis to 17 in P. trichocarpa. The fewest number of compounds (9) were detected by I. pini and the largest number (24) were detected by D. pseudotsugae. Six compounds excited the antennae of all five species of bark beetles. The large number of antennally-active compounds detected in common by numerous bark beetles and present in common in numerous nonhost trees supports the hypothesis of olfaction-based recognition and avoidance of nonhost angiosperm trees during the process of host selection by coniferophagous bark beetles. Received 13 December 1999; accepted 14 March 2000     

Nutritional effect of five species of marine algae on the growth,development, and survival of the brine shrimp Artemia salina

Five species of unicellular algae of the same age, cultured bacteria-free under standard growth conditions, were analyzed for chemical composition and fed to different size classes of Artemia salina. The green algae Chlamydomonas sphagnicolo, Dunaliella viridis, Platymonas elliptica and Chlorella conductrix had significantly higher percentages of protein and lipid than did the diatom Nitzschia closterium. Total ash value was highest in populations of N. closterium. Shrimp fed Chlamydomonas sphagnicolo cells assimilated highest percentages of organic matter, while those fed Chlorella conductrix had lowest assimilation rate. Respiration rates were inversely proportional to animal size (weight) and algal cell volume. Growth, survival, rate of sexual maturtion, and sex ratio were dependent on the growth and assimilation efficiencies obtained from each respective algal food. Shrimp fed Chlamydomonas sphagnicolo, D. viridis, or P. elliptica cells displayed highest growth and assimilation efficiencies.