Relationship between Water Chemistry and the Distribution of the Endangered Aquatic QuillwortIsoetes sinensisPalmer in China

Abstract

The progressive decline in populations of Isoetes sinensis Palmer in China has been attributed to deteriorating water quality; however, no data have been adduced to support this assumption. In this study we identified locations in China that presently have populations of I. sinensis and locations where the species has been extirpated. We measured various water chemistry parameters at these sites, as well as at similar sites within the distribution range of I. sinensis but from where the species has never been recorded. The results indicate that distribution and occurrence of I. sinensis are closely correlated with water chemistry. Water samples drawn from habitats from where I. sinensis has been extirpated had higher concentrations of heavy metal ions, particularly chr;, dum VI (cr63. In addition, these samples consistently yielded higher readings for dissolved carbon dioxide, water hardness, and concentration of nitrates."uthor for correspondence (wangqf97@public.wh.hb.cn)

Estimating influence of environmental quality and management of channels on survival of a threatened endemic quillwort

“…Similarly nutrient content in the sediment suggests conditions of medium-low fertility if compared to the typical agricultural soils of the surrounding plain. Therefore it seems likely that the nutrient increase, especially in the sediments, leadsIsoëtes to faster plant growth and increased biomass, rather than "disrupting" the metabolic activity as suggestively hypothesized for other Isoëtes species ( Wen et al, 2003). This result suggests that I. malinverniana can be considered relatively tolerant of eutrophication as already reported for other aquatic quillworts Brettum, 1989 andBallestreros, 1993) and is capable of phenotypic adaptations in size as a response to habitat variations, like other congenerics ( Rorslett and Brettum, 1989) and other macrophytes adapted to nutrient poor, acidic water, like Juncus bulbosus (Schneider et al, 2013) and Littorella uniflora ( Bagger and Madsen, 2004).…”

“…Isoëtes species and, to a wider extent, isoetids are reported to have morphological and metabolic strategies evolved as adaptations to unproductive oligotrophic environments ( Hutchinson, 1975, Chapin, 1980and Vitousek, 1982. Consequently, water pollution and eutrophication by contamination with domestic, agricultural or industrial effluents is generally regarded as the main predictor of Isoëtesand isoetid decline ( Smolders et al, 2002, Arts, 2002, Wen et al, 2003and Pedersen et al, 2006. Therefore, we expected that more viable populations would be found in the most nutrient poor channels with characteristics similar to those reported for most Isoëtes and isoetid natural habitats, and thus with higher conservation values.…”

Current status and conservation strategies for Isoetes in China: a case study for the conservation of threatened aquatic plants

“…The habitats of extirpated populations (Appendix 2) were exploited for tourism, fish farming and cultivation. Pollution and eutrophication of these habitats have generally raised values of pH, dissolved carbon dioxide, water hardness, and nitrates (Wen et al, 2003). Our study indicates that there are four main factors contributing to the decline and extirpation of Isoetes in China: habitat degradation or loss, water pollution and eutrophication, competitive exclusion by associated plants, and human disturbance.…”

“…Following preliminary reports on Isoetes in China (Palmer, 1927;Diao, 1990;Fu & Jin, 1992;Chen et al, 1998;Ding & Zeng, 2001;Xue & Huang, 2002), the genus has recently received more attention Wang et al, 2002;Liu et al, 2003;Pang et al, 2003;Wen et al, 2003). There are four known species of Isoetes from China: I. hypsophila Hand.-Mazz (Handel-Mazzetti, 1923), I. sinensis Palmer (Palmer, 1927) and I. yunguiensis on the mainland, and I. taiwanensis on Taiwan (DeVol, 1972).…”

Development of expressed sequence tag-based microsatellite markers for the critically endangered Isoëtes sinensis (Isoetaceae) based on transcriptome analysis

“…I. sinensis provides environmental services such as air purification, and is a good bioremediation agent. The continuous reduction of its population has been associated with water quality deterioration in regions where it has ceased to grow (Wen et al, 2003). Therefore, appropriate means of conservation should be formulated to save this species from extinction, and to achieve this, proper molecular analysis is essential.…”