By Steve Gelsi

Energy shares started out August with gains in early action Monday as oil reclaimed the $71-a-barrel mark and the broad market jumped in the face of optimism about an economic rebound.

The NYSE Arca Oil Index rose 1.8% to 978. The NYSE Arca Natural Gas Index moved up 2.9% to 461. The Philadelphia Oil Service Index advanced 3.2% to 176.

Marathon Oil Corp. (MRO) was up 1.7% to $32.80 after it reported that second-quarter income fell 47%.

Other names in the oil sector also posted solid gains, with Anadarko Petroleum Corp. (APC) rising 3.2% to $49.78 and Hess Corp. (HES) up 3% to $56.90.

Among stocks in the spotlight, Chesapeake Corp. (CHK) increased 3% to $22.08 as natural gas prices rallied. The natural gas giant is expected to report earnings of 53 cents a share when it reports its second-quarter results after the closing bell on Monday.

Crude-oil futures rose $1.84 to $71.29 a barrel on the New York Mercantile Exchange. Natural gas futures rose 24 cents to $3.89 per thousand BTUs.

Meanwhile, the Dow Jones Industrial Average was up about 62 points, or 0.7%, on optimism about the economy.

-By Steve Gelsi; 415-439-6400; AskNewswires@dowjones.com