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Habitat requirements of Elodea canadensis Michx. in Polish rivers

Cegłowska A., Jusik S., Samecka-Cymerman A., Klink A., Szoszkiewicz K.

Oceanological and Hydrobiological Studies

2017

Vol. 46, No. 4

363--378

The main objectives of this work were to investigate the range of habitat conditions (in terms of water chemistry and hydromorphological parameters) at sites colonized by Elodea canadensis and to analyze the species composition of communities with this plant species. We analyzed physicochemical, hydromorphological and biological data from 1135 sites located in Polish rivers to identify environmental factors that determine the occurrence of Elodea canadensis. Canadian waterweed was present at 18.1% of the analyzed river sites, located mainly in the lowlands (26.2% of all lowland sites).The results show that Elodea canadensis prefers moderately mineralized water (545 ± 329 μS cm−1), rich in calcium and magnesium carbonates (174 ± 63 mg CaCO3 |−1, 84.1 ± 31.4 mg Ca2+ |−1 and 11.1 ± 6.4 mg Mg2+ |−1), with moderate concentrations of chlorides and sulfates (38.9 ± 59.1 mg Cl−|−1 and 62.3 ± 50.9 mg SO42- |−1) and in terms of nutrients, it prefers water from moderately rich to mesotrophic and eutrophic. This plant has high light requirements and grows mainly in unshaded sections of shallow rivers. The studied species avoids sections of rivers strongly transformed and those with reinforced banks and bottoms. Canadian waterweed occurs mostly in the company of vascular macrophytes associated with slow-flowing rivers with sandy bottom material, indicating mesotrophic and eutrophic water.

Distribution pattern of epiphytic microcrustaceans in relation to different macrophyte microhabitats in a shallow wetland (Upo wetlands, South Korea)

Choi J.-Y., Kim S.-K., Jeong K.-S., Joo G.-J.

Oceanological and Hydrobiological Studies

2015

Vol. 44, No. 2

151--163

Macrophytes determine the physical complexity of aquatic environments and provide a suitable habitat for colonization by microcrustaceans. We evaluated the effects of a seasonal growth pattern and structure of macrophyte species on epiphytic microcrustaceans collected from macrophyte surfaces (stems and leaves) in shallow wetlands from May 2011 to October 2012. In 2011, epiphytic microcrustaceans that preferred free-floating macrophytes (Spirodela polyrhiza and Salvinia natans) and submerged macrophytes (Potamogeton crispus and Ceratophyllum demersum) were affected by the seasonal growth of these species. Epiphytic microcrustaceans were abundant on the surface of Spirodela polyrhiza in June and August and on Salvinia natans in September and October. In 2012, epiphytic microcrustaceans preferred submerged macrophyte species over the free-floating ones. The results of stable isotope analysis showed that epiphytic microcrustaceans depend on epiphytic particulate organic matter (EPOM) from each macrophyte species rather than on suspended particulate organic matter. Small species (Coronatella rectangula, Pleuroxus laevis, and Chydorus sphaericus) used EPOM (dominated by epiphytic algae) on free-floating and submerged macrophyte species; however, relatively larger species (Ilyocryptus spinifer and Macrothrix rosea) used EPOM only from submerged macrophytes. Based on these findings, we conclude that the distribution of epiphytic microcrustaceans is determined by seasonal characteristics, morphology of macrophyte species, and abundance of food resources.