title: Physiological and behavioural responses of Gammarus pulex exposed to acid stress.
abstract: Physiological and behavioural responses of the acid-sensitive amphipod Gammarus pulex exposed to a wide range of acid conditions (pH 4.1, 5.1, 6.0) under laboratory conditions were investigated. An exposure of 38 h to acid conditions caused significant decreases in survival rate, osmolality, haemolymph Na+ concentration, ventilatory and locomotor activity compared to organisms exposed to a circumneutral medium (pH 7.9). We highlighted the interest of using individual response distribution, since drastic effects can be detected in organisms exposed to pH 6.0, in particular for osmolality: The response can be divided into two groups, unimpacted and impacted organisms. Moreover this representation permitted to evaluate the health level of individual organisms through the determination of threshold values. Significant correlations between mean pH and mean physiological/behavioural responses were observed. The relationships between individual responses permitted not only to compare endpoints, but also to show that affected organisms were impacted by ionoregulation failure, hypoventilation and low locomotor activity. The energetic reallocation in favour of maintenance functions, such as osmoregulation, is discussed. The results of this study indicate that the values of haemolymph Na+ concentration, osmolality and locomotor activity in G. pulex could be effective ecophysiological/behavioural markers to monitor freshwater ecosystems and to assess the health of organisms or populations.
authors.affiliation: Laboratoire d'Ecotoxicologie, CEMAGREF, 3 bis quai Chauveau, CP 220, 69336 Lyon, Cedex 09, France. vincent.felten@univ-reims.fr
authors.forename: V
authors.initials: V
authors.lastname: Felten
authors.forename: G
authors.initials: G
authors.lastname: Charmantier
authors.forename: M
authors.initials: M
authors.lastname: Charmantier-Daures
authors.forename: F
authors.initials: F
authors.lastname: Aujoulat
authors.forename: J
authors.initials: J
authors.lastname: Garric
authors.forename: O
authors.initials: O
authors.lastname: Geffard
mesh_terms: D000143:Acids / Q000633:toxicity*; D033304:Amphipoda / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D006458:Hemolymph / Q000187:drug effects / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008124:Locomotion / Q000187:drug effects; D008136:Longevity / Q000187:drug effects; D012119:Respiration / Q000187:drug effects; D012964:Sodium / Q000097:blood; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000143:Acids; D014874:Water Pollutants, Chemical; D012964:Sodium