A volcanic eruption over the weekend has taken a toll on the wildlife of the ecologically-fragile Galapagos Islands, causing the deaths of numerous fish and various sea lions, said officials on Thursday.

Dead wildlife was spotted in the Pacific Ocean waters off the famed island chain not long after the eruption Saturday of the La Cumbre volcano, officials at the nature preserve said.

Officials said a lava flow 10-meters (some 30-feet) wide poured into the Pacific Ocean waters after the eruption.

Saturday's eruption by the 1,500-meter- (4,500-foot-) tall La Cumbre was the first in four years, officials said.

Authorities stressed that the eruption was part of the Galapagos' ecosystem and said they were not inclined to intervene, other than to "monitor and document the changes" on the flora and fauna of the archipelago.

Located 1,000 kilometers (620 miles) west of Ecuador's coast, the Galapagos archipelago of 13 main islands and 17 islets is a UNESCO World Heritage Site.

In 2007, UNESCO declared the famous island chain's environment endangered due to the increase of tourism and the introduction of invasive species.

The pristine nature reserve was where Charles Darwin conducted his landmark research that led to his revolutionary theories on evolution.