Marine reserve site selection along the Abel Tasman National Park coast, New Zealand: Consideration of subtidal rocky communities

Abstract

AbstractAt present, marine reserves do not represent the full range of community types throughout New Zealand.To assist with the placement of a marine reserve along the Abel Tasman National Park coast (northern South Island), dominant subtidal laminarian and fucoid algae, echinoids and herbivorous molluscs were quantitatively investigated. Results from 100 quadrats collected from 19 random transects at six selected sites showed that algae and grazer assemblages varied between granite and limestone substrata.Granite had a high percentage cover of crustose coralline algae (mean 82%–90%), a sublittoral fringe of brown macroalgae and no Ecklonia radiata or red foliose algae. Limestone sites were distinguished by a relatively low percentage cover of coralline algae (mean 13%) and high cover of foliose red algae and E. radiata (2%–36% cover and 0.2–13.9 stipes m−2, respectively).On limestone, molluscs Turbo smaragdus and Cookia sulcata, and the echinoid Evechinus chloroticus were larger than those on granite. On limestone sites with little macroalgae, herbivore size was intermediate. Grazers were more abundant on granite than limestone (mean 34.6 m−2, and 10.8 m−2 respectively).Differences in herbivore composition were recorded between granite substrata, while both algal and herbivore composition varied between limestone sites.We suggest that a variety of environmental factors including substratum influence algal and herbivore assemblages along the Abel Tasman coast.It is recommended that selection of a marine reserve site or sites along the coast of Abel Tasman National Park recognizes differences in community structure both between and within limestone and granite substrata.