The sea-grass borer Zachsia zenkewitschi belongs to a group of economically and ecologically important bivalves, commonly referred to as shipworms. The sole recognized representative of the genus Zachsia, this species displays an unusual life history and reproductive strategy that is now understood to include: environmental sex determination of free swimming larvae, extreme sexual and size dimorphism between males and females, internal fertilization, maintenance of often large harems of male dwarfs within a specialized cavity of the female mantle, and complex maternal care of larvae in specialized brood pouches within the gill. It is also the only shipworm species known to burrow in sea grass rhizomes rather than terrestrial wood. Although Z. zenkewitschi is rare and little studied, understanding of its biology and anatomy has evolved substantially, rendering some aspects of its original description inaccurate. Moreover, no existing type specimens are known for this species. In light of these facts, we designate a neotype from among specimens recently collected at the type location, and undertake a re-description of this species, accounting for recent reinterpretation of its life history and functional anatomy.

Clam gardens are ancient mariculture features developed by Indigenous Peoples of the Northwest Coast of North America that create shallow sloping intertidal shelves where clam productivity is enhanced. We quantify the area of clam habitat created by constructing rock-walled clam gardens terraces in northern Quadra Island, British Columbia, Canada. We combined modelling, high-resolution mapping, beach sampling, and a comprehensive survey of the shoreline to document the location and areal extent of clam habitat in clam gardens today. We divided our analysis into three classes of clam gardens, which differ in substrate and thus the amount of clam habitat created. We found that Indigenous People built clam garden walls on 35% of the shoreline and that about 112,979 m2 of flat beach terrace were created by clam garden construction. Collectively, the three classes of clam gardens increased clam habitat area between 26 and 36%. About 35% of the area of clam habitat in clam gardens was constructed de novo on bedrock shelves and rocky slopes where no clam habitat existed previously. Furthermore, about 12.0% of clam gardens are smaller than 30 m2, reflecting the effort put into creating enhanced food production wherever possible. Our analysis demonstrates that clam management in the form of clam gardens was extensive prior to colonization and that these features still have a significant impact on today’s intertidal ecosystems. Clam habitat expansion facilitated by clam garden construction encouraged a sustainable and abundant food source in the past and could do so again in today’s changing environmental conditions.