Assessing and conserving groundwater biodiversity: synthesis and perspectives

1. This paper is a synthesis of a special issue on groundwater biodiversity with a focus on obligate subterranean species, the stygobionts. The series of papers constitutes a great leap forward in assessing and understanding biodiversity patterns because of the use of large quantitative data sets obtained over a broad geographic scale. They also represent a conceptual shift, away from a purely taxonomic and phylogenetic focus to the analysis of whole groundwater assemblages.
2. The general patterns emerging for groundwater fauna are: very high levels of endemism, low local diversity relative to regional diversity, a limited number of lineages, occurrence of many relicts, and truncated food webs with very few predators.
3. β-Diversity is at least as important as α-diversity in determining total richness at different scales (aquifer, basin and region) and overall taxa richness increases across spatial scales.
4. Advances in understanding groundwater biodiversity patterns further include identification of several important factors related to geology and hydrology that determine the composition of European stygobiotic assemblages.
5. Important challenges for future research include improving sampling strategies, filling gaps in sampling coverage, intensifying research on theoretical and statistical models, and including functional and genetic diversity components in biodiversity assessments.
6. Strategies are proposed for protecting groundwater biodiversity and an argument is made to integrate biodiversity in groundwater management. Applying principles such as complementarity and flexibility for groundwater biodiversity conservation is a major step toward delineating a reserve network that maximise species representation at the European scale.     

VOLATILE FLAVOR COMPOUNDS AFFECTING CONSUMER ACCEPTABILITY OF KIWIFRUIT

Sensory research on kiwifruit has shown that specific sugars and acids, and volatile flavor compounds have causative effects on "sweet" and "acid" aroma and flavor attributes. New Zealand consumers (n = 162) assessed the perceived flavor intensity and acceptability of three volatile flavor compounds (ethyl butanoate, E-2-hexenal and hexanal) at varying levels in a model base solution. Increasing levels of ethyl butanoate positively affected all the acceptability attributes ("overall liking,""liking of aroma,""liking of flavor") as well as increased the perceived intensity of "kiwifruit aroma" and "kiwifruit flavor." Increasing levels of E-2-hexenal negatively affected all the acceptability attributes but increased the perceived intensity of "kiwifruit aroma" and "acid flavor." An increase in hexanal increased perceived intensity of "kiwifruit aroma." Ethyl butanoate and E-2-hexenel at the levels tested had the most prominent effects on consumer perceived intensity and acceptability of the "kiwifruit flavor."     

Environmental variability and the ecological effects of spawning Pacific salmon on stream biofilm

1. Variation in resource subsidies can create or reinforce heterogeneity in recipient ecosystems. Related activities of organisms delivering resource subsidies, such as ecosystem engineering by Pacific salmon spawners (Oncorhynchus spp.), also alter heterogeneity. We studied whether heterogeneity in stream environmental conditions and spawner abundances were reflected in the net ecological effects of salmon (i.e. enrichment by resource subsidies and disturbance by ecosystem engineering) on benthic biofilm. 2. We sampled seven Southeast Alaska streams over 3 years, both before and during the salmon run. In each stream and year, stream environmental characteristics and their influence on responses of benthic biofilm [mean and coefficient of variation of chlorophyll a (chl a), ash‐free dry mass (AFDM) and autotrophic index (AFDM:chl a)] to spawners were assessed. 3. Streams and periods before and during the salmon run were distinct based on their environmental characteristics. The responses of most biofilm metrics to spawners were stream‐ and year‐specific, suggesting that the ecological effect of spawners ranged from net enrichment to net disturbance depending on the stream or year studied. The environmental context, especially temperature, large wood, and sediment size, explained >50% of biofilm variability during the run, but <30% over the entire study, suggesting that salmon can alter environmental constraints. 4. Precision of biofilm estimates improved by increasing either the number of streams or the number of years sampled (i.e. spatial or temporal replication). However, combining data from different North Pacific Rim ecoregions inflated the confidence interval as compared with a single ecoregion, indicating the importance of regional environmental contexts for net salmon effects. 5. Our results suggest that biofilm responses to salmon can vary greatly, even within a single ecoregion, and that environmental conditions can modify net salmon effects. Consequently, generalisations about biofilm responses across the native range of salmon may be challenging.     

Nocodazole-Resistant Mutants in Paramecium

The effect of the microtubule inhibitor nocodazole was studied on Paramecium and shown to arrest cell multiplication, depolymerize the internal microtubule network, and block the development of macro- and micronuclear spindles and of the cytospindle (a cortical microtubule array assembled during division). After ultraviolet mutagenesis, three mutants resistant to nocodazole, that is capable of continued growth in the presence of the drug, were isolated and shown to correspond to three nonallelic single-gene nuclear mutations. One ( noc ^r- 1 ) is semidominant while the other two ( noc ^r- 2 and noc ^r- 3 ) are recessive. Cytological and physiological studies of nocodazole's effects on the mutants demonstrate that their resistance is due neither to a lack of drug penetration nor to its degradation since, in each mutant in the presence of the drug, some microtubule networks are normal or subnormal while others remain affected as in wild-type cells. These are the first mutants resistant to microtubule depolymerizing drugs obtained in ciliates that provide a new tool for studying the assembly and dynamics of the diverse microtubule arrays in this type of organism.     

Phylogenetic Position of Psalteriomonas lanterna Deduced from the SSU rDNA Sequence

ABSTRACT. The small subunit ribosomal DNA sequence (SSU rDNA) of the microaerophilic free-living amoeboflagellate Psalteriomonas lanterna has been sequenced and analyzed. The gene is 1,945 bp long and has a G + C content of 33.4%. Based upon ultrastructural studies, P. lanterna has been placed in the class Lyromonadea within the phylum Percolozoa Cavalier-Smith, 1991. However, based upon cytological characteristics, this microaerophilic free-living amoeboflagellate appears to be very primitive. It shares certain characteristics in common with some archezoans, i.e. it lacks mitochondria and dictyosomes but contains hydrogenosomes. Despite sharing these characteristics with the amitochondriate taxa, P. lanterna is not related to any of these taxa but instead to the Vahlkampfiidae. Therefore, we used primary sequence data and the secondary structure of the SSU rDNA gene to determine the placement P. lanterna in the phylogenetic tree. Our analyses showed that P. lanterna groups as a sister taxon to the Vahlkampfiidae but probably diverged from them quite early.