title: Sea water acidification affects osmotic swelling, regulatory volume decrease and discharge in nematocytes of the jellyfish Pelagia noctiluca.
abstract: BACKGROUND
  Increased acidification/PCO2 of sea water is a threat to the environment and affects the homeostasis of marine animals. In this study, the effect of sea water pH changes on the osmotic phase (OP), regulatory volume decrease (RVD) and discharge of the jellyfish Pelagia noctiluca (Cnidaria, Scyphozoa) nematocytes, collected from the Strait of Messina (Italy), was assessed.
  
  
  METHODS
  Isolated nematocytes, suspended in artificial sea water (ASW) with pH 7.65, 6.5 and 4.5, were exposed to hyposmotic ASW of the same pH values and their osmotic response and RVD measured optically in a special flow through chamber. Nematocyte discharge was analyzed in situ in ASW at all three pH values.
  
  
  RESULTS
  At normal pH (7.65), nematocytes subjected to hyposmotic shock first expanded osmotically and then regulated their cell volume within 15 min. Exposure to hyposmotic ASW pH 6.5 and 4.5 compromised the OP and reduced or totally abrogated the ensuing RVD, respectively. Acidic pH also significantly reduced the nematocyte discharge response.
  
  
  CONCLUSIONS
  Data indicate that the homeostasis and function of Cnidarians may be altered by environmental changes such as sea water acidification, thereby validating their use as novel bioindicators for the quality of the marine environment.
authors.affiliation: Dept. of Human and Social Sciences, University of Messina, Messina, Italy.
authors.forename: Rossana
authors.initials: R
authors.lastname: Morabito
authors.forename: Angela
authors.initials: A
authors.lastname: Marino
authors.forename: Peter K
authors.initials: PK
authors.lastname: Lauf
authors.forename: Norma C
authors.initials: NC
authors.lastname: Adragna
authors.forename: Giuseppa
authors.initials: G
authors.lastname: La Spada
mesh_terms: D000143:Acids / Q000633:toxicity; D000818:Animals; D048429:Cell Size / Q000187:drug effects; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D058894:Nematocyst / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D009997:Osmotic Pressure / Q000187:drug effects; D037401:Scyphozoa / Q000187:drug effects*; D012623:Seawater / Q000737:chemistry*
chemical_list: D000143:Acids