There were only some studies on the interactions between climate change and other effects (Wilby, 1996, Durance and Ormerod, 2007). Potential interactions between global and local climate changes and acid-base variations may be important. In a long-term 25-year study of small watersheds in Wales, Durance and Ormerod (2007) found that the larger changes in community structure were related to climate change in streams with neutral chemistry than in acidified streams. There were two possibilities for this apparent inconsistency. First, this does not imply that the faster winter runoff has no effect on the acidified freshwater ecosystem, but rather the annual resolution of their study was unable to detect the short-term episodic events (Durance and Ormerod, 2007).