Minecraft fails to initialize when both these mods are enabled.
I tested this with OptiFine HD Ultimate D, and with OptiFine HD Standard D.
I also tested this on the latest Forge build, 1119, and also on Forge 1088.

Here is the crash report: http://pastebin.com/AfQDjED2

To clarify, Minecraft runs just fine when I remove Enchiridion and Mariculture from the load list; conversely, Minecraft will run when I keep these two and remove OptiFine.
This error report was submitted on a BugMeNot account. I hope you don't mind.

Not a bug.