Zinc bioaccumulation and ionoregulatory impacts in Fundulus heteroclitus exposed to sublethal waterborne zinc at different salinities

Exposure of Fundulus heteroclitus to an environmentally relevant Zn concentration (500μgL−1) at different salinities (0, 3.5, 10.5, and 35ppt) revealed the following effects: (i) plasma [Zn] doubled after exposure at 0ppt, a response which was eliminated at 35 ppt. Tissue [Zn] also increased in gill...
Ausführliche Beschreibung

Exposure of Fundulus heteroclitus to an environmentally relevant Zn concentration (500μgL−1) at different salinities (0, 3.5, 10.5, and 35ppt) revealed the following effects: (i) plasma [Zn] doubled after exposure at 0ppt, a response which was eliminated at 35 ppt. Tissue [Zn] also increased in gill, liver, intestine, and carcass at 0ppt. (ii) Both branchial and intestinal Ca2+ ATPase activities decreased in response to Zn at 0ppt and were elevated at 35 ppt. Plasma [Ca] decreased by 50% at 0ppt and by 30% at 3.5ppt and increased by 20% at 35ppt. Gill [Ca] decreased by 35% at 0ppt and increased by about 30% at all higher salinities. (iii) Branchial Na+,K+ ATPase activity decreased by 50% at 0ppt, increased by 30% and 90% at 10.5 and 35ppt respectively. Intestinal Na+,K+ ATPase activity was reduced by 30% at 0ppt. (iv) Plasma [Na] decreased by 30% at 0ppt in Zn-exposed. Zn exposure also disturbed the homeostasis of tissue cations (Na+, K+, Ca++, Mg++) in a tissue-specific and salinity-dependent manner. (v) Drinking rate was not altered by Zn exposure. In toxicity tests, acute Zn lethality (96-h LC50) increased in a close to linear fashion from 9.8mg L −1 at 0ppt to 75.0mgL −1 at 35ppt. We conclude that sublethal Zn exposure causes pathological changes in both Ca++ and Na+ homeostases, and that increasing salinity exerts protective effects against both sublethal and lethal Zn toxicities. Ausführliche Beschreibung