Complex sentence: This disease was known as Withering Syndrome because the abalones starved to death even when food was plentiful because the parasite infested the digestive tract and prevented digestion and absorption of kelp, the abalone's primary food source.
Split into simpler sentences: This disease was known as "Withering Syndrome" because the abalones starved to death even when food was plentiful. This was because the parasite infested the digestive tract of the abalones and prevented digestion and absorption of kelp, the abalone's primary food source.