It is difficult to answer for the Ecosystem Game without seeing the full food pyramid. There are specific rules in the game for which animal eats first based on the calories provided, so you may have theoretically a baseline that provides sufficient calories, but, due to the order animals eat, it is still not sustainable.
In terms of the plant defense, I know candidates who had a similar performance as you had and passed. However that’s also linked to how many turns you lasted in the very first round and the performance in the Ecosystem Game.
If you have additional questions please feel free to PM me.