Using community and population approaches to understand how contemporary and historical factors have shaped species distribution in river ecosystems

Aim To examine how the employment of both community‐ and population‐level approaches can provide a wider view of the importance of contemporary and historical factors on current species distribution. We posit that community ecology should provide more information about contemporary factors, whereas population genetics should provide better information about historical factors. Location Rivers of the western Mediterranean Basin, including four subregions differing in geological history: the Iberian Plate, Transitional, Betic and Rif. Methods For a community‐level approach, Trichoptera richness and community composition were compared between subregions using species accumulation curves and a correspondence analysis. For a population‐level approach, the mtDNA cytochrome C oxidase subunit I (COI) gene of specimens of the Trichoptera midstream‐lowland species Chimarra marginata (L.) was sequenced and analysed using phylogeographical methods. Results The community approach revealed that historical events had more influence on headwater communities than contemporary ecological factors, whereas historical events had negligible influence on midstream‐lowland communities. In midstream‐lowland sites, however, the population approach showed that the genetic structure of C. marginata differed significantly between subregions and revealed patterns of historical gene migration. In terms of species richness, the Rif subregion had the lowest value per basin due to local climatic features and isolation. Main conclusions Both community‐ and population‐level approaches yielded information about the effects of historical factors on species distribution. However, the importance of historical events on current Trichoptera communities depends on the river zonation. Unlike headwater sites, midstream‐lowland sites showed signs of historical events at the population level but not at the community level at the scale used, indicating that both approaches should be employed together in biogeographical studies. Lack of detection of historical events at the community level does not necessarily mean that they are negligible. Most likely, the organizational level used is not appropriate. We also stress the importance of implementing conservation measures for rivers in the western Mediterranean, especially under future scenarios of climate change and human disturbances in the Mediterranean Basin.     

Trace Metal Fractionation by the Sequential Extraction Method in Sediments from the Lis River (Portugal)

The extractable contents of Zn, Pb, Cu, Cr, Mn, Ni, Fe and Al were evaluated in sediments from the Lis River (Portugal) using the three-step sequential extraction procedure described by Community Bureau of Reference (BCR, now the Standards, Measurement and Testing Programme) of the European Union. The distribution of trace metals among the exchangeable, water and acid soluble, reducible, oxidizable and residual fractions was determined. The highest metal concentrations were observed in samples collected at the most polluted river sites (animal husbandry, domestic, industrial and agricultural wastes). Pb, Cu, Cr, Ni, Fe and Al were found mainly associated with the residual and organic fractions. High concentrations of Zn and Mn were found in the exchangeable/acid soluble fraction.     

Occurrence and densities of bacteriophages proposed as indicators and bacterial indicators in river waters from Europe and South America

AIMS: To evaluate the feasibility of bacteriophages as a complementary tool for water quality assessment in surface waters from different parts of the globe. METHODS AND RESULTS: Faecal coliform bacteria, enterococci, spores of sulphite-reducing clostridia, somatic coliphages, F-specific RNA bacteriophages and bacteriophages infecting Bacteroides fragilis were determined by standardized methods in raw sewage and in 392 samples of river water from 22 sampling sites in 10 rivers in Argentina, Colombia, France and Spain, which represent very different climatic and socio-economic conditions. The results showed that the indicators studied maintained the same relative densities in the raw sewage from the different areas. Classifying the river water samples according to the content of faecal coliform bacteria, it can be observed that the relative densities of the different bacterial indicators and bacteriophages changed according to the concentration of faecal coliform bacteria. There was a relative increase in the densities of all groups of bacteriophages and sulphite-reducing clostridia with respect to faecal coliforms and enterococci in the samples with low counts of faecal coliform bacteria. CONCLUSIONS: The numbers of bacterial indicators and bacteriophages were similar in the different geographical areas studied. Once released in rivers, the persistence of the different micro-organisms differed significantly. Bacteriophages and spores of sulphite-reducing clostridia persisted longer than faecal coliforms and enterococci. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacteriophages in river water samples provide additional information to that provided by bacteria about the fate of faecal micro-organisms in river water. The easy, fast and cheap methods for phage determination are feasible both in industrialized and developing countries.     

The carbon dioxide system in the Elbe estuary

The pCO₂ distribution in thesurface waters of the Elbe estuary and German Bight was investigated during high river discharge in April 1997. pCO₂ values of about 1100 atm foundin the upper part of the estuary are, comparedto other European rivers, only moderate. In theouter estuary, the enhanced river dischargecreates a pronounced river plume reflected in decreased surface salinity.However, pCO₂ in this area(250 atm) is below atmospheric values dueto primary production. Comparison with resultswe obtained during other measuringcampaigns shows that in the outer estuarysupersaturation of CO₂ with respect to theatmosphere occurs only in early spring duringthe time of highest river discharge. In latespring and summer, intensive primary productionwithin the surface layer leads to a pronouncedundersaturation (141 atm), despite atemperature increase of more than 20 °Cfrom winter to summer. Undersaturation isenforced by stable stratification of the watercolumn during the productive seasons thatdiminishes the entrainment of CO₂from below the thermocline into the surfacewater. In winter, CO₂ is close toequilibrium with the atmosphere and controlledby physical processes. Our data suggest thatthe Elbe estuary represents a sink foratmospheric CO₂ over the investigatedseasons and that carbon cycling in this areais dominated by biological processes.     

MHC-DRB exon 2 allele polymorphism in Indian river buffalo (Bubalus bubalis)

The polymorphism of the major histocompatibility complex (MHC) class II DRB gene of riverine buffalo (Bubalus bubalis) was studied. Second exon sequences from the buffalo DRB locus, homologous to the cattle DRB3 gene, were amplified and characterized. A combination of single strand conformation polymorphism (SSCP) and heteroduplex analysis (HA) in a non-denaturing gel was used to identify new DRB second exon sequences. SSCP, HA and finally sequencing allowed the identification of 22 MHC-DRB exon 2 alleles from 25 unrelated Indian river buffalo. These are the first river buffalo DRB second exon sequences reported. A high degree of polymorphism in the sequences encoding the peptide binding regions was observed and some amino acid substitutions were found unique to the river buffalo.     

Populus nigra L. in the Garonne valley: legacy of the past and present constraints

This study used documents from archives and historical maps to follow the simultaneous change of the riparian woodlands (where Populus nigra is dominant) and the poplar plantations. Results showed that the riparian woodland decreased by 81% over the two last centuries. Each period was characterised by the dominance of only a few number of clones. The risk of introgression due to the massive presence of such a restricted genetic material around P. nigra was discussed. The impact of river management on poplar regeneration was examined as well.     

Spawning time and early life history of Murray cod, <Emphasis Type="Italic">Maccullochella peelii</Emphasis> (Mitchell) in an Australian river

Synopsis I investigated aspects of the early life history of Murray cod in the Broken River, southern Murray-Darling Basin, Australia. I documented patterns in abundance, length, age and the amount of yolk of drifting free embryos and estimated spawning periods for adult Murray cod in two reaches throughout each breeding season between mid-October and mid-December from 1997 to 2001. Free embryos began drifting in late-October and continued until mid- to late-December. Abundances of drifting free embryos showed no obvious peak in most years and were unrelated to discharge. Length, amount of yolk and age typically varied with sampling date, but only age showed strong and negative correlations with temperature. Thus, it appears that temperature affected rates of development, and that developmental stage, not length or age, was likely to be the determinant for when free embryos left the paternal nest. Most free embryos were estimated to have spent between 5 and 7 days drifting. Spawning of Murray cod in the Broken River usually commenced in mid-October and continued until at least early December. Initiation of spawning was associated with temperatures of 15°C and above, but discharge was highly variable, and no other environmental variables were consistent across years. The mid-point of spawning – usually in the first week of November – is considered a more significant time, because it likely coincides with peak spawning, and conditions during and immediately after this time are expected to be optimal for the survival of eggs and free embryos.     

Ontogenetic Behavior and Dispersal of Sacramento River White Sturgeon, <Emphasis Type="BoldItalic">Acipenser Transmontanus</Emphasis>, with a Note on Body Color

Synopsis We studied Sacramento River white sturgeon, Acipenser transmontanus, in the laboratory to develop a conceptual model of ontogenetic behavior and provide insight into probable behavior of wild sturgeon. After hatching, free embryos initiated a low intensity, brief downstream dispersal during which fish swam near the bottom and were photonegative. The weak, short dispersal style and behavior of white sturgeon free embryos contrasts greatly with the intense, long dispersal style and behavior (photopositive and swimming far above the bottom) of dispersing free embryos of other sturgeon species. If spawned eggs are concentrated within a few kilometers downstream of a spawning site, the adaptive significance of the free embryo dispersal is likely to move fish away from the egg deposition site to avoid predation and reduce fish density prior to feeding. Larvae foraged on the open bottom, swam <1 m above the bottom, aggregated, but did not disperse. Early juveniles initiated a strong dispersal with fish strongly vigorously swimming downstream. Duration of the juvenile dispersal is unknown, but the strong swimming likely disperses fish many kilometers. Recruitment failure in white sturgeon populations may be a mis-match between the innate fish dispersal and post-dispersal rearing habitat, which is now highly altered by damming and reservoirs. Sacramento River white sturgeon has a two-step downstream dispersal by the free embryo and juvenile life intervals. Diel activity of all life intervals peaked at night, whether fish were dispersing or foraging. Nocturnal behavior is likely a response to predation, which occurs during both activities. An intense black-tail body color was present on foraging larvae, but was weak or absent on the two life intervals that disperse. Black-tail color may be an adaptation for avoiding predation, signaling among aggregated larvae, or both, but not for dispersal.     

Ecological restoration and revegetation works in Korea

Korea established foundations for rapid economic growth and national development within a short period of time, but not without incidental problems of degradation to the natural environment. Problems include destruction of ecosystems and reduction of forest area. Nowadays, environment-friendly construction projects are required in Korea for efficient use and preservation of national land. In an effort to protect natural land four types of restoration and preservation plans have been proposed recently. This paper explores the status and value of these efforts and the problems of re-vegetation works on disturbed land in Korea. Korea still gives insufficient attention to species selection for re-vegetation in terms of ecological soundness. In restoring damaged areas, Korea still uses mainly exotic species. As a result, the Ministry of Construction and Transportation is revising design criteria for road slopes in consideration of climate and topography. The Ministry of Environment revised the Natural Environment Conservation Law and uses natural ecological restoration engineers and natural environment management operators as environment restoration specialists. These engineers and sectors specialize in the area of nature in reviews and ecological restoration works. The first national qualifying examination to select natural ecological restoration engineers and natural environment management operators took place in 2004. In an effort to seek systematic conservation for an eco-network, there have been attempts to designate the Baekdu Daegan, which runs south to north along the Korean Peninsula, and the Demilitarised Zone, which traverses east to west, as ecological axes. Efforts to survey the damaged habitats found in the Baekdu Daegan and to develop a restoration plan after designating restoration areas are being made. Moreover, in 2004, the National Assembly passed an Act on the Protection of the Baekdu Daegan Mountain System which will facilitate the designation of Baekdu Daegan into core and buffer areas and therefore its designation as a protected area. The Seoul Metropolitan Government is planning to increase green space in urban areas. In the case of the Cheonggyecheon stream restoration project, which was initiated as part of efforts to restore urban ecosystems, the removal of existing structures is nearing completion. Once it is finished, a highly diverse urban green corridor biosphere reserve will be created along with rooftop re-vegetation. The Seoul Metropolitan government plans to introduce programs to support rooftop re-vegetation projects. Various options are still under consideration or at a pilot stage, but once these efforts become more visible, they are likely to play a positive role in developing and preserving national land in Korea.     

Prevalence, quantification and typing of adenoviruses detected in river and treated drinking water in South Africa

AIMS: Human adenoviruses (HAds), of which there are 51 serotypes, are associated with gastrointestinal, respiratory, urinary tract and eye infections. The importance of water in the transmission of HAds and the potential health risks constituted by HAds in these environments are widely recognized. Adenoviruses have not previously been quantified in river and treated drinking water samples. In this study, HAds in river water and treated drinking water sources in South Africa were detected, quantified and typed. METHODS AND RESULTS: Adenoviruses were recovered from the water samples using a glass wool adsorption-elution method followed by polyethylene glycol/NaCl precipitation for secondary concentration. The sensitivity and specificity of two nested PCR methods were compared for detection of HAds in the water samples. Over a 1-year period (June 2002 to July 2003), HAds were detected in 5.32% (10/188) of the treated drinking water and 22.22% (10/45) of river water samples using the conventional nested PCR method. The HAds detected in the water samples were quantified using a real-time PCR method. The original treated drinking water and river water samples had an estimate of less than one copy per litre of HAd DNA present. The hexon-PCR products used for typing HAds were directly sequenced or cloned into plasmids before sequencing. In treated drinking water samples, species D HAds predominated. In addition, adenovirus serotypes 2, 40 and 41 were each detected in three different treated drinking water samples. Most (70%) of the HAds detected in river water samples analysed were enteric HAds (serotypes 40 and 41). One HAd serotype 2 and two species D HAds were detected in the river water. CONCLUSIONS: Adenoviruses detected in river and treated drinking water samples were successfully quantified and typed. The detection of HAds in drinking water supplies treated and disinfected by internationally recommended methods, and which conform to quality limits for indicator bacteria, warrants an investigation of the risk of infection constituted by these viruses. The risk of infection may have implications for the management of drinking water quality. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is unique as it is the first report on the quantification and typing of HAds in treated drinking water and river water. This baseline data is necessary for the meaningful assessment of the potential risk of infection constituted by these viruses.