If a terrestrial ecosystem has a net primary production of 3,000 kcal/m2/yr and a cellular respiration rate of 2,000 kcal/m2/yr, what is the gross primary production for this ecosystem? 100 kcal/m2/yr 500 kcal/m2/yr 1,000 kcal/m2/yr 5,000 kcal/m2/yr

Answer (b) supersaturation;

The population of unionid mussels decreased after zebra mussels were introduced. zebra mussels competed with the unionid mussels for food. the zebra mussels were able to displace the unionid mussels, allowing the zebra mussel population to increase  over the years. the unionid mussel population decreased because  of lack of food.