Soil indicators of pre-European seabird breeding in New Zealand at sites identified by predator deposits

Soil samples (0-15 cm) from 2 sites identified by palaeontological methods as pre-European seabird breeding sites (Annandale, Ardenest) were compared with a control site (Ngarua; no seabird breeding). All sites had moderately calcareous soils developed on limestone or marble. Breeding site Kjeldahl nitrogen (range, 0.41-1.4% N) and total phosphorus (range, 1780-5285 mg/kg P) were comparable to present-day breeding sites and higher than the contro l (mean, 0.20% N, 520 mg/kg P). Total cadmium (Cd) results followed the sam e pattern, with results from Ardenest (mean, 0.49 mg/kg) and Annandale (0. 47 mg/kg) being similar to fertilised New Zealand pastoral soils. Contribut ions from extensive pre-European seabird breeding may therefore match super phosphate fertiliser as a Cd source. Results for delta(15)N and C : N were consistent with seabird breeding at both sites (Ardenest, delta(15)N = 8.4 parts per thousand, C : N = 10.6 g C/g N; Annandale, delta(15)N = 6.9 parts per thousand, C : N = 10.6). Results for delta(13)C were consistent with s eabird breeding at Ardenest (delta(13)C = -27.0 parts per thousand) but not at Annandale (delta(13)C = -27.0 parts per thousand), indicating dilution by organic matter derived from C-3 plants at Annandale. The Cd : P ratio wa s significantly lower (P = 0.05) at each of the seabird breeding sites (Ann andale, 6.5 +/- 1.5 x 10(-5) mol Cd/mol P; Ardenest, 2.5 +/- 0.7 x 10(-5)) than the control (mean 10.0 +/- 1.6 x 10(-5)).This ratio has the potential to complement delta(15)N, delta(13)C, and C : N in identifying and mapping pre-European seabird breeding sites, although more study is required.