Buried in https://blog.nationalgeographic.org/2015/03/22/sailing-into-starvation-island-70-years-after-the-end-of-world-war-ii-peace-boat-visits-guadalcanal/ one finds:
“In Japan, Guadalcanal is known as ‘Starvation Island,’ where some 22,000 Japanese and 7000 Americans died in land, sea, and air battles, and of malaria, dysentery and starvation. . .”
Here, https://warfarehistorynetwork.com/2016/10/27/abandoning-the-island-of-death/, you find
“A communiqué from Lt. Gen. Harukichi Hyakutake, the commander of the Japanese Seventeenth Army on Guadalcanal, seemed to bring the matter to a head. On December 23, Hyakutake informed Tokyo of the desperation on Guadalcanal. ‘No food available and we can no longer send out scouts. We can do nothing to withstand the enemy’s offensive. Seventeenth Army now requests permission to break into the enemy’s positions and die an honorable death rather than die of hunger in our own dugouts.’
“The General Staff finally faced the reality of what the men on Guadalcanal were suffering on a daily basis. Hyakutake’s men had drawn up their own method of determining how long a man might survive on Starvation Island:
“He who can rise to his feet—30 days left to live
“He who can sit up—20 days left to live
“He who must urinate while lying down—3 days left to live
“He who cannot speak—2 days left to live
“He who cannot blink his eyes—dead at dawn.”
So, was there edible flora & fauna . . . yes . . . was there edible flora and fauna to support the needs of the US personnel ashore?
No more than to support the needs of the Japanese.
My father was on Guadalcanal in the spring and summer of 1943. He said they never ate anything that was not canned and drank no water that had not been boiled and still dysentery was rampant . . . he spent two weeks in the ACORN hospital with same. Somewhere in my files I have a report detailing the weight loss per pilot in his squadron.