Simplify the following text for a Grade 7 native English-speaking person.
Original: The majority of these spawn gametes , breeding in mass spawning events that are triggered by the rising sea temperatures of spring and summer , the lunar cycle , and the diurnal cycle .
Simplified: This spawning is controlled by the rising sea temperatures . This happens in spring and summer , as part of the moons lunar cycle , and the day\/night diurnal cycle .