Physiological and Biochemical Effects of Simulated Acid Rain on Phaseolus Vulgaris Var. HUR-15

Pot experiments were performed to determine the effects of simulated acid rain on Phaseolus vulgaris var. HUR-15. Seeds of Phaseolus vulgaris var. HUR-15 were exposed to simulated acid rain at pH values of 5.1, 4.1, 3.1, 2.1 and 1.1 and a control level of pH 6.8. Plants were harvested at three stages, i.e. pre, peak and post-flowering stages. Seedlings succumbed at pH 1.1. Necrosis developed on the leaves of plants treated with water of pH 2.1, resulting in adverse effect on chlorophyll content. They died after peak-flowering. Root and shoot length and dry weight were reduced with the lowering in pH. Carbohydrate, nitrogen and protein contents decreased with the decrease in pH level, adversely affecting their nutrient value.     

Effect of Grazing and Climatic Changes on Alpine Vegetation of Tungnath,Garhwal Himalaya,India

Effect of grazing and changing climate on vegetation composition of alpine pasture at Tungnath, Garhwal Himalaya was observed. Growth form pattern and phytosociological attributes were analyzed during 1988 under grazed (exposed to extensive grazing) and ungrazed (protected from grazing) conditions. These observations were repeated during 1998. It was observed that number of early growing species and long vegetative growth cycle species had increased at both sites in 1998 in comparison to 1988. Further, some species, viz., Poa alpina, Polygonum spp., Ranunculus hirtellus, Anemone spp., are predominantly found near the timberline-subalpine region. These species are less palatable and were present at both sites with higher dominance (TBC) and niche width in 1998 indicating wide distribution of the species along an altitudinal gradient. These observations indicated the migration of these species towards upper slopes of alpine. Species diversity was also higher after ten years. However, it is clear that climatic changes alone are not responsible for these vegetational shifts. In fact, human-induced changes are the main reason for habitat destruction and changes in vegetation composition of the alpine region of Garhwal Himalaya. Before final conclusions can be made, long-term studies on vegetation composition and changes are needed, especially in Himalayan region.     

Aquatic Macroinvertebrate Diversity in Nanda Devi Biosphere Reserve,India

Aquatic macroinvertebrate diversity in the Nanda Devi Biosphere Reserve (NDBR) was monitored for a period of twelve months (September 2000 to August 2001). All the important hydrological attributes were measured monthly for one year. Macroinvertebrates were sampled from three sites (S¹$, S²$, & S³$) of the headwater stream Dhauliganga of NDBR. The present study revealed that the velocity of the water current, hydromedian depth, turbidity and dissolved oxygen in addition to nature and size of the bottom substrates have their significant impact on benthic invertebrate diversity. The ecological relevance of the measured hydrological attributes was investigated by comparing their degree of correlation with invertebrate density and diversity. Macroinvertebrate diversity was found to be highest (3.096 ± 0.03) in winter months (November–January) and lowest (2.816 ± 0.02) in monsoon months (July–August). The high diversity of macroinvertebrates may be due to low turbidity, high water transparency, optimum water temperature, high dissolved oxygen, low water velocity and suitable composition of the bottom substrates.     

Using Sediment Budgets to Investigate the Pathogen Flux Through Catchments

We demonstrate a materials budget approach to identify the main source areas and fluxes of pathogens through a landscape by using the flux of fine sediments as a proxy for pathogens. Sediment budgets were created for three subcatchment tributaries of the Googong Reservoir in southeastern New South Wales, Australia. Major inputs, sources, stores, and transport zones were estimated using sediment sampling, dam trap efficiency measures, and radionuclide tracing. Particle size analyses were used to quantify the fine-sediment component of the total sediment flux, from which the pathogen flux was inferred by considering the differences between the mobility and transportation of fine sediments and pathogens. Gullies were identified as important sources of fine sediment, and therefore of pathogens, with the pathogen risk compounded when cattle shelter in them during wet periods. The results also indicate that the degree of landscape modification influences both sediment and pathogen mobilization. Farm dams, swampy meadows and glades along drainage paths lower the flux of fine sediment, and therefore pathogens, in this landscape during low-flow periods. However, high-rainfall and high-flow events are likely to transport most of the fine sediment, and therefore pathogen, flux from the Googong landscape to the reservoir. Materials budgets are a repeatable and comparatively low-cost method for investigating the pathogen flux through a landscape.     

Anatomical and experimental evidence for particulate feeding in<Emphasis Type="Italic"> Lucinoma aequizonata</Emphasis> and<Emphasis Type="Italic"> Parvilucina tenuisculpta</Emphasis> (Bivalvia: Lucinidae) from the Santa Barbara Basin

Previous nutritional models for adults of the lucinid bivalve Lucinoma aequizonata contend that symbiotic chemoautotrophic bacteria provide most of the organic carbon for the host. The existence of this symbiosis, coupled with the hosts distinctive anatomical features, shaped the impression that particulate feeding was not a significant part of L. aequizonata nutrition. Here, we use several techniques to show that particulate feeding is a consistent and important part of the L. aequizonata nutritional strategy. Histological and scanning electron microscopy observations reveal that the gills of L. aequizonata, like those of the lucinid Parvilucina tenuisculpta, have functional mucociliary epithelia, able to transport captured particles to the mouth. Observations of gut content and radiolabeled feeding experiments indicate that L. aequizonata does ingest and assimilate carbon from particulate organic matter. Furthermore, molecular identification of a broad spectrum of organisms in the guts of native adult specimens demonstrates that L. aequizonata is non-selective when ingesting organic material, and has a mixotrophic diet.Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by P.W. Sammarco, Chauvin     

Patterns in swimming by a scyphomedusa: a novel approach to quantifying behavior in individuals

Behavior is commonly studied at the group level using several individuals, but there is increasing evidence that the behavior of a few individuals often has a disproportionate effect on the response of a population to its environment. The present study used a suite of statistical techniques, random series analysis, analysis of variance, spectral analysis, and goodness-of-fit tests of frequency histograms, to quantitatively describe the time-dependent changes in individual behavior. Each technique reveals a different facet of the behavior and, when simultaneously applied to the data, distinguishes significant differences among the behaviors of several individuals. The approach was developed and tested on the swimming behavior of four specimens of the scyphomedusa Aurelia aurita (Linnaeus, 1758), which were observed for 19 days, beginning 16 January 1998, and videotaped under identical environmental conditions during that period. The analyses showed that each medusa swam in a unique pattern, varying swimming at characteristic frequencies. Application of the approach to individual-based numerical modeling, to the role of endogenous stimuli in the behavioral repertoire, and to in situ studies of animal behavior is discussed.Communicated by J.P. Grassle, New Brunswick     

Evolution of coral reef fish<Emphasis Type="Italic"> Thalassoma</Emphasis> spp. (Labridae). 1. Molecular phylogeny and biogeography

Wrasses in the genus Thalassoma comprise 27 recognized species that occur predominantly on coral reefs and subtropical rocky reefs worldwide. The phylogenetic relationships for 26 species were examined based on two mitochondrial genes (cytochrome b and 16S rRNA) and one nuclear intron (the first intron of the ribosomal protein S7). Two closely related species, the bird-wrasses (Gomphosus varius Lacepède, 1801 and G. caerulaeus Lacepède, 1801), were also included in the analysis. These species grouped within the genus Thalassoma. Thalassoma newtoni (Osório, 1891) from Sao Tome, which is generally synonymized with the Atlantic/Mediterranean Thalassoma pavo (Linnaeus, 1758) appears to be a valid species. Using a molecular clock, the genus was estimated to have originally diverged 8–13 million years ago, with Thalassoma ballieui (Vaillant and Sauvage, 1875) from Hawaii and Thalassoma septemfasciata Scott, 1959 from Western Australia as the ancestral species. Approximately 5–10 million years ago, a sudden burst of speciation resulted in seven clades, which were resolved with the sequence data. The terminal Tethyan event and the closing of the Isthmus of Panama were probably the major historical factors shaping the evolution of species in the genus Thalassoma. These data on the spatio-temporal pattern of speciation in the Indo-Pacific indicate that peripheral species have been generated at various times throughout the history of the genus, and that none of the widespread species are relatively young. Thus, there is no clear support for centrifugal (youngest at the periphery) versus centripetal (oldest at the periphery) modes of generation of species, two theories which have been used to account for geographic gradients in species diversity.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00227-003-1199-0.An erratum to this article can be found at Communicated by J.P. Grassle, New Brunswick     

Non-random mating and population genetic subdivision of two broadcasting corals at Ningaloo Reef,Western Australia

Allozyme electrophoresis of two corals was used to assess whether populations at Ningaloo Reef, Western Australia are primarily self-seeding or whether recruitment is from a broader geographic pool. Significant genetic subdivision across a range of spatial scales (between 6.5 km and 155 km) was found for both Acropora digitifera and A. aspera, with mean F _ST values of 0.010 and 0.067 respectively. Large departures from Hardy-Weinberg expectations were found for both species. Without exception these were due to deficits of heterozygotes; mean D values were –0.341 for A. digitifera and –0.455 for A. aspera. The magnitude of the deficits was consistent both across loci for all sites and across all sites for each locus. Some loci were found to be in linkage disequilibrium but no consistent pattern was observed. Also, multi-locus genotypic diversity values were generally high (between 0.83 and 1.00) and so departures from equilibria cannot be attributed to asexual reproduction. The most plausible explanation for the patterns observed is restricted gene flow at both the planktonic and gametic stages, with mating between close relatives.Communicated by G.F. Humphrey, Sydney     

Juvenile–adult relationship in the gregarious ophiuroid<Emphasis Type="Italic"> Ophiothrix fragilis</Emphasis> (Echinodermata): a behavioral and morphological study

Ophiothrix fragilis forms dense beds in the North Sea–English Channel region, where juveniles are exclusively found on adults. The aim of this study was to see how the behavior and morphology of juveniles could help elucidate the close juvenile–adult relationship found in this species. Juveniles are found on the disk, arms and in the bursae of adult conspecifics, the ones on the disks being significantly larger. No clear advantage seems to be gained by the juveniles being in the bursae, and their presence there is most likely due to juvenile movement on adults and to and from adults. Hooked spines serve as anchory organs during the early life of the juvenile, but growth of the arms enhances its anchory capabilities and the hooked spines become secondary in that respect. They regress as ophiuroids become older, to the advantage of the other spines used in suspension feeding. Juveniles are attracted to conspecifics, and true gregarious behavior has been observed. The tip of each arm, the terminal tentacle, plays a major role in distance chemoattraction, with juveniles needing at least one intact terminal tentacle to be able to initiate a response. Electron microscope observations of the terminal tentacle permitted us to recognize two different potential receptor structures designated stäbchens. The first possesses one long projecting cilia and is mostly present around the base of the terminal tentacle, while the other has one to five short projecting cilia and is mostly found on the tip. No receptors are found on the shaft. Receptors are not associated with secretory structures. Juveniles and adults are closely associated with one another, and both the morphology and behavior of juveniles play an important role in that relationship.Communicated by O. Kinne, Oldendorf/Luhe     

A basidiomycete isolated from the skeleton of<Emphasis Type="Italic"> Pocillopora damicornis</Emphasis> (Scleractinia) selectively stimulates short-term survival of coral skeletogenic cells

Endolithic fungi bore through the extracellular calcium carbonate skeleton of reef-building scleractinian corals, both healthy and dead, and effect net erosion of coral reefs. Potential fungal interactions with coral tissue were investigated using an in vitro approach suggested by earlier observations of skeletal repair cones at the site of fungal perforation in Porites sp. A fungal strain was isolated from the skeleton of a long-term culture of healthy, tissue-covered, Pocillopora damicornis Linnaeus colonies maintained in a recirculating system in Monaco. As coral soft tissue spontaneously dissociated in vitro, the skeleton became exposed and hyaline hyphae emerged radially from 15% of the total clipped branches. In this study, which was performed between January 2001 and March 2003, 35 skeleton–hypha explants were embedded in agar-based solid medium, yielding 60% hyphal growth. A fungal strain (F19-3-1) of the dominant (80%) morphology was isolated and propagated in agar-based solid medium. The strain was identified by 18S and 26S rDNA gene sequence analysis as a basidiomycete in the genus Cryptococcus. Co-cultures were used to provide experimental exposure of coral soft tissue to the fungus. The fungus extended the survival of coral cells by 2 days, selectively maintaining skeletogenic cell types. This effect may be interpreted as stimulation by the fungus of a short-term coral defense response.Communicated by J.P. Grassle, New Brunswick