That is a great thing to reflect on. So life finds a way. So I've got this right. If a shipwrecks on a seagrass bed does it affect the areas around it. I would think that sea grass grows in a stable predictable area. With an obstruction it would create currents and eddy's that would be inconsistent with even flow. Disrupt and wash away seagrass. The most resilient seagrass would fill in the earlier disrupted areas. Along the shipwreck itself I think it would still rip too much to put roots down. The shipwreck itself would start growing things. Life grows on structure. The higher the watermark I think the surrounding the sooner the surroundings would encompass it. Personal observation not knowledge from academia