Effects of fertilization and elevated CO<Subscript>2</Subscript> on larval food and butterfly nectar amino acid preference in<Emphasis Type="Italic"> Coenonympha pamphilus</Emphasis> L.

The effects of larval diet on the nutritional preferences of butterflies has rarely been examined. This study investigates whether alterations in the larval diet result in changes in adult preferences for nectar amino acids. Larvae of Coenonympha pamphilus were raised on fertilized or unfertilized Festuca rubra, grown under ambient (350 ppm) or elevated (750 ppm) atmospheric CO ₂environments. Fertilization led to marked increases in leaf nitrogen concentration. In plants grown under elevated CO ₂conditions, leaf water and nitrogen concentrations were significantly lower, and the C/N-ratio increased significantly. Fertilization of the host plant shortened the development time of C. pamphilus larvae, and pupal weight increased. In contrast, larvae of C. pamphilus developed significantly slower on F. rubra grown under elevated CO ₂, but adult emergence weight was not affected by CO ₂treatment of the plant. C. pamphilus females showed a clear preference for nectar mimics containing amino acids, whereas males, regardless of treatment, either preferred the nectar mimic void of amino acids or showed no preference for the different solutions. Female butterflies raised on fertilized plants showed a significant decline in their preference for nectar mimics containing amino acids. A slight, but not significant, trend towards increased nectar amino acid preference was found in females raised on plants grown under elevated CO ₂. We clearly demonstrate that alterations in larval host quality led to changes in butterfly nectar preferences. The ability of the butterfly to either rely less on nectar uptake or compensate for poor larval conditions represents a trade-off between larval and adult butterfly feeding.     

Interannual variation of ichthyoplankton density and species composition in the waters off northeastern Taiwan

The ichthyoplankton in the waters of northeastern Taiwan have been studied since 1989. Based on collections in August 1989 to 1991, this report treats primarily the annual variation of ichthyoplankton density, species composition and assemblage diversity among the waters of the East China Sea, the Kuroshio and the mixing zone. The ranges of average densities found for fish eggs were 7 to 3897 ind 1000 m^-3 and 0.02 to 1.43 g 1000 m^-3, for ichthyoplankton 154 to 1364 ind 1000 m^-3 and 0.33 to 3.23 g 1000 m^-3, and for zooplankton 52 to 532 g 1000 m^-3. An interannual comparison indicates a tendency towards a decrease in ichthyoplankton density from 1989 to 1991. In total, 5803 individuals assigned to at least 91 families and 254 taxa at species level were collected. Lantern fish form the most common species group (Benthosema pterotum: 12.1%; Diaphus pacificus: 4.2%). The other species in order of frequency are: gobies (5.8%); Callionymus sp. (3.4%); Auxis spp. (3.1%); Trachinocephalus myops (3.0%); Nibea sp. (2.8%); Synagrops philippinensis (2.3%); Priacanthus macracanthus (2.2%); and percophid (2.0%). The relative frequency of the ten most abundant taxa fluctuated annually. Neither interannual distinction nor interannual correlation was confirmed by statistical analysis, but intra-annual rank correlations were established among the water masses. A weak tendency towards increasing diversity from 1989 to 1990 and little diversity in the mixing zone were observed. We conclude that there is a complex inter-dependence of assemblages from the waters of northeastern Taiwan.     

Genetic differentiation in two sibling species of the brackish-water polychaete Hediste japonica complex (Nereididae)

Genetic divergence among ten populations of small- and large-egg forms of the brackish-water polychaete Hediste japonica complex was investigated on 14 isozyme loci by electrophoretic analysis. The two forms were distinguishable by complete allele substitutions at five loci, resulting in high genetic differentiation (Nei's D: 0.533 to 0.662). No genetic evidence of hybridization between the two forms was detected in sympatric populations in three rivers. These results indicate that the two forms are reproductively isolated, clearly showing that the two forms are distinct species. The genetic differentiation among populations was higher in the large-egg form (D: 0.005 to 0.111, G _ST: 0.435) than that in the small-egg form (D: 0.000 to 0.001, G _ST: 0.020). This genetic difference between the two forms seems to be attributable to a difference in their life histories. The average expected heterozygosity was low in populations of both the large-egg form (0.005 to 0.068) and the small-egg form (0.014 to 0.038) in comparison with other marine invertebrates. Received: 11 April 1997 / Accepted: 8 September 1997     

Time-dependent shifts between infanticidal and parental behavior in female burying beetles a mechanism of indirect mother-offspring recognition

Summary Female burying beetles Necrophorus vespilloides Herbst (Coleoptera: Silphidae) were allowed to lay eggs on a carcass and their subsequent behavior towards larvae added to the carcass was observed. Females did not discriminate against unrelated larvae if these were added within an hour after the females' own first larva had hatched (at the right time). Changing the spatial surroundings of the carcass had no effect on the females' readiness to exhibit care behavior. Neither did the age of the larvae added or the condition of the carcass affect the onset of maternal care. However, the females' response to larvae encountered was strongly time-dependent: most females killed and ate larvae that could not have hatched from their own eggs because they were added long before their own larvae hatched. The proportion of females accepting larvae added to early increased as the time their own larvae hatched approached. Larvae added to the carcass 2 or 3 days after the test females' own first larva had hatched were always accepted by females that had already started to feed larvae, but were often killed by females that were not feeding larvae. In the latter group of females, the tendency to kill larvae added was most pronounced if the females had already started to produce a second clutch of eggs at the time larvae were added. Offprint requests to: J.K. Müller     

Histological study of the effects of starvation on reared and wild-caught larval stone flounder,Kareius bicoloratus

Starvation tolerance of laboratory-reared larval stone flounder, Kareius bicoloratus, was examined at different temperatures and salinities during the winters of 1984, 1985 and 1986. Starvation tolerance decreased with increased temperature and exhibited low values with high salinities. The highest starvation tolerance observed at low salinity was just before the metamorphosis stage. Starvation tolerance showed little change until larvae were 11 d. It increased with age thereafter. Epithelial cell heights of the digestive tract and cell diameters of pancreas and liver were measured histologically in reared stone flounder during growth and starvation. These values decreased markedly in the starved condition. Aldehyde fuchsin positive granules in the rectal epithelium also disappeared during the short starved period. The nutitrional condition of wild-caught stone flounder larvae, collected in January and February 1986 from the Matsukawa-ura inlet, Fukushima, Japan, was also examined. Eighty percent of larvae were estimated to be in fed condition just before sampling. The changes in cell heights of digestive organs agreed with this estimate. These histological methods seem to be useful in assessing the nutritional condition of marine fish larvae.     

Determination of photosynthetic pigment composition in an individual phytoplankton cell in seas and lakes using fluorescence microscopy; properties of the fluorescence emitted from picophytoplankton cells

To develop a method for the determination of photosynthetic pigment species in individual phytoplankton cells, especially natural picophytoplankton cells, the fluorescence spectra of intact cells were studied with cultured phytoplankton. The study was made mainly with phycoerythrin-containing picophytoplankton collected off Japan in 1982 with reference to diatomal species and phycoerythrin-free cyanophycean species. The spectra were measured for cell suspensions with an ordinary spectrofluorometer, and for individual cells with a microscope spectrofluorometer, paying special attention to the effect of cell-fixation. Results indicated that: (1) the cell-fixation with the glutaraldehyde and paraformaldehyde mixture modified phycoerythrin emission from picophytoplankton markedly in its wavelength location and intensity, but (2) the emission from phycocyanin was affected far less, and (3) the emission from chlorophyll a was not altered. However, the phycoerythrin emission modified by the fixation was found to be easily distinguished from other emissions, and kept its intensity high enough for detection with a fluorescence microscope. The fluorescence properties after the fixation were kept unaltered for a long period of time. Based on the results, we propose a simple method for the determination of photosynthetic pigments in individual phytoplankton cells in seas and lakes using fluorescence microscopy. Results of our tests with natural samples of phytoplankton are presented, and problems for further improvement are also discussed.     

Siliceous sponge spicules in coral reef sediments

Experimental etching with hydrofluoric acid indicated that silica deposition occurs in a recognizable pattern in common sponge microscleres. The postdepositional alteration of these spicules has previously been generally unrecognized or misinterpreted in the literature. Early stages of postdepositional etching of sponge spicules were observed in the acid insoluble fraction of sediments from the West Atlantic barrier reef near Carrie Bow Cay, Belize. Preliminary data on silica distribution in the Belize barrier reef show that concentrations in fine sediment (<0.25 mm) increase landward of the main reef tract. Sponge spicules are the main component of particulate silica in sediments of the reef and fore-reef where sponge populations abound, whereas grains prevail in the back-reef lagoon deposits. Recycling of locally dissolved silica appears to be important for the growth of many off-shore reef sponges.     

Molecular taxonomy of vestimentiferans of the western Pacific,and their phylogenetic relationship to species of the eastern Pacific III. Alaysia-like vestimentiferans and relationships among families

The phylogenetic status of Alaysia-like vestimentiferans, which were collected at eight sites in the western Pacific, was analyzed on the basis of the nucleotide sequence of part of a mitochondrial gene for cytochrome oxidase I. The 123 individuals analyzed were tentatively classified into four species, which inhabit, respectively, seep areas off the central part of the Japanese mainland, hydrothermal vent fields in the Mid-Okinawa Trough, hydrothermal vent fields in the southern Okinawa Trough, and both seep and vent sites in the Bismarck Sea. From six additional lamellibrachiid specimens from two sites in the Bismarck Sea, two new tentative species were recognized, namely, one from a seep area off Papua New Guinea and another from the hydrothermal vent field at the DESMOS site in the Manus Basin. Phylogenetic analysis using all available sequences of six vestimentiferan families and Alaysia-like vestimentiferans revealed that vestimentiferans could be divided into three groups, namely, lamellibrachiids, escarpiids, and others, even though the monophyly of the third group was supported by only low bootstrap probabilities. Within the first group, the earliest divergence of a tentative lamellibrachiid species from the DESMOS site was apparent. All Alaysia-like vestimentiferans formed a monophyletic group with Arcovestia ivanovi from the Manus Basin, and it is suggested that this group might be derived from vestimentiferans that are endemic to the hydrothermal sites in the Eastern Pacific Rise.