title: Cylindrospermopsis raciborskii exudate-Cu complexes: impact on copper dynamics and bioavailability in an aquatic food chain.
abstract: BACKGROUND
  The increasing contamination of aquatic environments motivates studies on the interactions among natural dissolved organic matter, metals, and the biota. This investigation focused on the organic exudates of the toxic cyanobacteria Cylindrospermopsis raciborskii as a Cu carrier through a three-level aquatic trophic chain (bacteria, protozoa, and copepod).
  
  
  CONCLUSIONS
  The effects of bacteria activity and growth on the metal-organic complexes were evaluated through changes in free Cu(2+) ions, total dissolved, and total particulate Cu. To be sure that the added copper would be complexed to the exudates, its complexing properties were previously determined. The cyanobacteria exudate-Cu complexes were furnished to bacteria that were further used as a food source to the protozoan Paramercium caudatum. This was then furnished as food to the copepod Mesocyclops sp. The results showed that, in general, the cyanobacterial exudates decreased Cu bioavailability and toxicity to the first trophic level (bacteria), but because the heterotrophic bacteria accumulated Cu, they were responsible for the transference for the otherwise low availability metal form. Both the bacteria and protozoan organisms accumulated Cu, but no metal accumulation was detected in the copepods.
authors.affiliation: Departamento de Botânica, Universidade Federal de São Carlos, Rodovia Washington Luis, km 235. Caixa Postal 676, CEP 13565-905 São Carlos, São Paulo, Brazil. pmayrink1@yahoo.com.br
authors.forename: P F M
authors.initials: PF
authors.lastname: Nogueira
authors.forename: A T
authors.initials: AT
authors.lastname: Lombardi
authors.forename: M M
authors.initials: MM
authors.lastname: Nogueira
mesh_terms: D000818:Animals; D001682:Biological Availability; D002412:Cations; D033342:Copepoda / Q000187:drug effects / Q000378:metabolism; D003300:Copper / Q000493:pharmacokinetics* / Q000633:toxicity*; D046891:Cylindrospermopsis / Q000187:drug effects / Q000378:metabolism*; D020387:Food Chain; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology / Q000469:parasitology; D010247:Paramecium / Q000187:drug effects / Q000378:metabolism; D013054:Spectrophotometry, Atomic
chemical_list: D002412:Cations; D003300:Copper
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