Extant Water Research Articles

A new species of rail (Aves: Rallidae) from the Upper Pleistocene and Holocene of Eivissa (Pityusic Islands, western Mediterranean)

A new species of rail is described from a Pleistocene and Holocene cave deposit on the island of Eivissa, Pityusic Islands (western Mediterranean Sea). Rallus eivissensis sp. nov. was an insular relative of the European Water Rail Rallus aquaticus. Compared with the extant Water Rail, the new species was smaller and stouter, had shorter and more robust hind limbs and shorter wings, with probably reduced flight ability. The Pityusics were the only Mediterranean islands with a vertebrate Quaternary fauna lacking terrestrial mammals, and this absence is no doubt related to the Eivissan rail evolution. The chronology of the Rallus eivissensis sp. nov. extinction overlaps broadly with a period of uncertainty for the arrival of humans at Eivissa, suggesting a relationship between the two events.

Completeness of a fossil record: the Pleistocene echinoids of the Antilles

Diversity of Pleistocene marine invertebrates with single component, robust, easily identifiable skeletons shows a good correspondence to that of the Recent when compared between similar environments in the same region. Such comparisons are less easily made for multi-element skeletons. In the Antilles there are 24 extant species of echinoids in 0–30 m water depth. Considering all available fossils - complete tests, disarticulated spines, and test fragments and ossicles - the Pleistocene echinoids of the Antillean region have a high similarity with the extant shallow water fauna (c. 63% specific and 72% generic similarity). Many of the extant, shallow water, regular echinoid taxa are known from the Pleistocene, although irregular echinoids are less well represented. These results are comparable with those determined for coeval benthic invertebrates from this and other geographic regions, and indicate a high degree of similarity from a survey which is so far limited to only a few of the islands. Not all Pleistocene units considered herein were deposited in shallow water, but they include autochthonous specimens of taxa whose depth range extends beyond shallow water at the present day or presumed allochthonous specimens derived by downslope transport from shallower water, or both.

Is the Pungwe water supply project a solution to water accessibility and sanitation problems for the households of Sakubva, Zimbabwe?

Following the severe drought of 1991–92, the City of Mutare embarked upon a concerted search for a secure water supply. This search culminated in the decision to transfer water from the Pungwe River via pipeline to the City of Mutare. This project was heralded as bringing ‘purity, security, and prosperity’ to the people of Mutare. Once again, and as is typical of Southern Africa today, a new ‘supply’ was presented as the ‘solution’ to the city’s water problems. In this paper, we challenge this claim by presenting the case of Sakubva, a low income, and high-density suburb of Mutare, Zimbabwe. Residents of Sakubva face many problems relating to water supply and sanitation. Has the Pungwe-Mutare Water Project ‘solved’ these problems? In short, we argue that while the Pungwe project has ensured a steady supply of clean water to Sakubva, this water inadvertently worsens many of Sakubva’s extant water and sanitation problems. In the absence of appropriate water demand management measures, supply alone is as much burden as it is blessing.In terms of methodology, between July 2000 and July 2001, members of the research team made several visits to the study area. This included a two-week home stay for two of the researchers––one in a private home in New Dangare, one in a shack in Muchena. Aside from direct participation and informal observation, a variety of methods were used: formal, semi-/structured interviews with key informants; informal, semi-structured interviews and focus group discussions with a cross-section of residents in Sakubva; transect walks where interviews were carried out both on formal and informal bases. Two peer educators from the Voices of Concerned Youth, City Health Department, Mutare assisted researchers. In addition, primary and secondary data were consulted.

Phylogeny, Classification and Floral Evolution of Water Lilies (Nymphaeaceae; Nymphaeales): A Synthesis of Non-molecular, rbcL, matK, and 18S rDNA Data

The water lilies (Nymphaeaceae) have been investigated systematically for decades because they are believed to represent an early group of angiosperms with relatively unspecialized floral organization. Although this group is small taxonomically, the relationships among genera of water lilies have eluded clarification and no single classification has become widely accepted. We present a well-corroborated phy- logeny of water lily genera that is based on agreement between non-molecular data and DNA sequences obtained from both organellar and nuclear genomes. For specific portions of the resulting phylogeny, we evaluate the support conferred by each separate data set in comparison to various combinations. This ap- proach enabled us to assess the potential benefits of further data acquisition, and also allowed us to evaluate the fundamental advantages and disadvantages of each data partition. Every data set contributed differently to the overall phylogenetic analysis and resolution of the cladogram. The 18S rDNA performed the most poorly, with homoplasious sites confounding some topological assessments in comparisons of closely related genera. However, as taxonomic distance increased, phylogenetic signal in the 18S rDNA data increased due to the expression of sequence variation in highly conserved sites. Even the 18S rDNA data were relatively congruent with the other data evaluated, and the resulting combined data analysis rendered a single maxi- mum parsimony tree with strong nodal support throughout. When floral features were evaluated using this well-corroborated phylogeny, the pleiomerous condition of water lily flowers showed several instances of secondary derivations. Although the actual morphological details of the first water lily flowers remain un- certain, it is clear that the flowers of extant water lilies do not necessarily depict the ancestral organization. Results of the phylogenetic analysis are used to encourage the adoption of an evolutionarily based classifi- cation system for water lilies.

Lithification and porosity evolution in Permian periplatform limestones, Midland basin, Texas

Carbonate debris flows and turbidites in Lower Permian strata in the subsurface Midland basin (Texas) underwent a long, complex period of diagenesis. Prior to redeposition into toe-of-slope and proximal basin settings platform-margin reef and associated grainstones were pervasively cemented by radiaxial-fibrous calcite (RFC). The former high-Mg calcite mineralogy of these inferred marine cements is suggested by the presence of microdolomite inclusions, relatively high residual MgCO3 contents (1.8 mole %), and mean δ18O (−2.3 o/oo) and δ13C (3.0 o/oo) compositions which approach those of extant sea water. Platform-margin strata subsequently underwent a period of dissolution, accompanied and followed by equant calcite cementation. Evidence of vadose cements in some rocks, the depleted δ18O (−2.6 to −6.6 o/oo) and δ13C (0.3 to 2.7 o/oo) isotopic compositions of these cements relative to RFC and extant sea water, and regional evidence of sea level fluctuations during the Early Leonardian suggest that dissolution and cementation resulted from subaerial exposure and meteoric influx during at least one period of sea-level lowstand. Redeposition transported platform, margin-derived carbonates basinward into water depths of about 500 m, where they were lithified presumably by high-Mg calcite cements. Lithification occurred in the subbottom burial environment, in contact with circulating marine fluids, down to maximum depths of at least 300 m. Chemical compaction and multiple periods of, silicification, fracture formation and occlusion of fractures by calcite occurred during progressively deeper burial. A period of intense dissolution along fractures, probably in the Triassic, resulted in extensive mesogenetic porosity in some of these wells, and likely was coincident with hydrocarbon maturation in associated thermally mature shales.

Chemical and microscopic characterization of outer seed coats of fossil and extant water plants

Sclerotic outer seed coat layers (testae) of three fossil and two extant water plant species were analyzed using scanning electron and light microscopy in addition to Curie-point pyrolysis, solid state 13C NMR, and CuO oxidation. Comparison between the chemical results from the fossil and extant samples reveals that the original resistant constituents in the sclerotic testae are native lignin-celluloses which are transformed to polyphenol macromolecules recognized in the fossil samples. The combination of microscopic and chemical data provides new insights regarding the early diagenetic processes by which lignin-cellulose-containing plant remains may have been transformed. In particular, the unaltered morphology in combination with major chemical modifications is used as the basis to postulate the timing and nature of lignin transformations. The combination of pyrolysis, solid state 13C NMR, and CuO oxidation is shown to be a powerful tool to characterize the chemical structure of testae of fossil and extant water plants.