GARDEN CITY — As the Labor Day weekend approaches, Long Island motorists are filling up their cars in anticipation of a rise in gas prices which analysts say will go into effect after Hurricane Isaac. Dr. Martin Cantor of the Long Island Center for Socio-Economic Policy said Isaac caused the shut down of major refineries in the Gulf of Mexico which in turn lead to a reduction in the production of gasoline. Despite its minimal impact, gas stations throughout the country will feel the effects of Isaac, added Robert Sinclair of AAA. Adding fuel to the fire, an explosion at Venezuela's biggest oil refinery, Amuay, will also generate problems to international consumers.