Data support analyses describing the potential for niche partitioning and complementarity in a guild of suspension-feeding rocky shore invertebrates. I focused on the mussels Perna canaliculus, Mytilus galloprovincialis, Aulacomya maoriana, and Xenostrobus pulex, all of which coexist along the coastline of the South Island of New Zealand. I quantified the mussel species’ distributions, both vertically on the shore and within the three-dimensional mussel bed matrix, and used carbon (delta¹³C) and nitrogen (delta¹⁵N) stable isotope ratios to compare species’ diets. Mussels exhibited niche partitioning along all resource axes, including patterns of tide-height zonation, depth in the mussel bed, and diet. Given the mussels’ use of different spatial and food resources, I evaluated the potential for complementarity with respect to mussels’ roles as mediators of carbon inputs into rocky-shore ecosystems. In these systems, mussels are basal species, capturing and consuming particulate organic matter in the nearshore ocean and making it available for local consumption within the benthic community. I found that mussels accumulated appreciable amounts of carbon via growth and that even the most productive species – Perna canaliculus – only contributed about half of the mussel-mediated carbon that accumulated over a year.

This dataset includes data from surveys of mussel beds, destructive sampling to quantify abundances, measurements of lengths and masses, measurements of annual growth rates, and carbon and nitrogen percentages and stable isotope values. Samples are from mussel beds at four sites on the South Island of New Zealand: Blue Duck (42.28º S, 173.75° E) and Box Thumb (43.58° S, 172.78° E) on the east coast and Nile River (41.90° S, 171.44° E) and Nine Mile (42.34° S, 171.26°E) on the west coast. Mussels were surveyed and sampled at each site at three tidal elevations: 1.0, 1.5, and 2.0 m above the lowest astronomical tide. Mussel species included Perna canaliculus, Mytilus galloprovincialis, Aulacomya maoriana, and Xenostrobus pulex, all of which coexist at these sites.

The dataset is described in the associated ReadMe file: BRACKEN_10-7280D1696J_Readme.txt. All data are in .csv files. Contact the author (m.bracken@uci.edu) for additional information.