Marine and Freshwater Research, 2018, 69, 1508–1516 © CSIRO 2018 https://doi.org/10.1071/MF17301

Supplementary material

Forest stream biota carbon : nitrogen ratios are unaffected by nutrient subsidies from breeding Westland petrels (Procellaria westlandica)

Roseanna Gamlen-GreeneA,E, Jon S. HardingB, David J. HawkeC and Travis W. HortonD

ADepartment of Forest & Conservation Sciences, University of British Columbia, 3041–2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada.

BSchool of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, 8140, .

CDepartment of Science and Primary Industries, Ara Institute of Canterbury, PO Box 540, Christchurch, 8140, New Zealand.

DDepartment of Geological Sciences, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand.

ECorresponding author. Email: [email protected]

Page 1 of 5 Marine and Freshwater Research © CSIRO 2018 https://doi.org/10.1071/MF17301

50 --Seabird streams - - -Reference streams • CPOM; seabird • CPOM; reference 40 • Riparian plants; seabird • Riparian plants; reference • Riparian soil; seabird • Riparian soil; reference �30 • Algae; seab ird • Algae; reference --S • Deleatidium; seabird • Deleatidium; reference z I 0 C oloburiscus; seabird a Coloburiscus; reference 0 20 I 0 Potamopyrgus; seabird a Potamopyrgus; reference '■ 'I • • ; seabird • Megaloptera; reference 10 Stenoperla; seabird a Steno pe rla; refere nee , , • ♦ Gobiomorphus; seabird • Go bio morphu s; refe re nee • Dolomedes; seabird Dolomedes; reference 0 • -40 -35 -30 -25 -20 -15 • Spider spp. ; seabird • Spider spp.; reference o13CvPos (%0) 0 Echyride Ila; seab ird • Par eneph reps; reference

Fig. S1. δ13C and C : N convex hulls for seabird and reference streams, based on mean values of stream elements.

Page 2 of 5 Marine and Freshwater Research © CSIRO 2018 https://doi.org/10.1071/MF17301

50 -Seabird streams ■ CPOM 40 ■ Algae <> Deleati dium E + Potamopyrgus E3o ■ Coloburi scus ■ Echyridella ■ Megaloptera 2 20 • Stenoperla o Gobiomorphus ♦ Dolomedes 10 • Spider spp. • Riparian soil 0 ♦ Riparian plants -2 0 2 4 6 8 o15NAIR (%0)

50 - - -Reference streams B ■ CPOM ' ■ Algae 40 ' ' ' o Deleatidium ' ' + Potamopyrgus ' ' o Paraneph rops ' ' O Coloburiscus ' ' ' ' ■ Megaloptera ' ' ' • Stenoperla o Gobiomorphus ' ER ',.' ', o Dolomedes 10 ■ • Spider spp. --e- -• ♦ Riparian plants ◊�'o • Riparian soil 0 -2 0 2 4 6 8 <515NAIR (%0)

Fig. S2. Bi-plot of δ15N and C : N and associated convex hulls for seabird (A) and reference streams (B), focusing on the individual ecosystem components clustered at low C:N ratio. Red symbols, ecosystem components at the base of the stream food web; yellow symbols, collector–browsers; green symbols, filter feeders; blue symbols, predators; grey symbols, shredders; purple symbols, riparian source materials.

Page 3 of 5 Marine and Freshwater Research © CSIRO 2018 https://doi.org/10.1071/MF17301

9 X ■ Ecosystem component ffi CPOM A 6 • Riparian vegetation /::, Riparian soil .,. ♦ Algae t Ei:) Primary consumer z Secondary consumer � 3 ... lo e ■ Riparian predator t X Aquatic predator ♦ I Treatment $ t' 0 • R=No seabird subsidy • S=Seabird subsidy $ •

A s A s A s R s R s R $ R s R s Treatment

Fig. S3. Plot of mean δ15N (±standard error) against treatment for ecosystem components in West Coast streams. Soil, riparian top-soil; CPOM, in stream coarse particulate organic matter; primary consumer, Deleatidium spp.; secondary consumer, Megaloptera diversus; top predator, redfin bullies Gobiomorphus huttoni; riparian predator, spider Dolomedes spp.

Page 4 of 5 Marine and Freshwater Research © CSIRO 2018 https://doi.org/10.1071/MF17301

Bl Ecosystem component 50 Ill 8l Bl EB CPOM 8l •o Bl • Riparian vegetation 8l • 6 Riparian soil 30 Bl • • • ♦ Algae .. • Eii) Primary consumer 20 • � ...Secondary oonsumer • Riparian predator l:, I X Aquatic predator z t::, cj l:, 10 • • •

Fig. S4. Plot of log C : N against δ15N for all eight seabird and reference streams. Soil, riparian top-soil; CPOM, in stream coarse particulate organic matter; primary consumer, mayfly Deleatidium spp.; secondary consumer, Megaloptera Archichauliodes diversus; top predator, redfin bully Gobiomorphus huttoni; riparian predator, spider Dolomedes spp.

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