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Seabirds vector selenium (Se) into terrestrial ecosystems in Antarctica and on tropical coral islands, but factors controlling distribution within affected soils are unknown, especially in temperate regions. At a Westland petrel (Procellaria westlandica) breeding colony on mainland New Zealand, the concentration of Se in petrel guano (3.6mg [kg.sup.-1]) exceeded soil parent material (0.8mg[kg.sup.-1]) and in all but two soil samples (range 1.2-4.2mg[kg.sup.-1]; n=52). External Se (Se not derived from parent material) accounted for 645 ± 9% (mean ± s.d.) of soil Se. Measurements were also made at a former seabird breeding site, and at a site with no Holocene seabird breeding. Median surface-soil Se concentrations (mg [kg.sup.-1]) were in the order burrow soil (2.6)> adjacent forest floor (2.2)> former breeding site (1.0) > control site (0.2), with significant differences between burrow soil and (1) the former breeding site and (2) the control site. In a linear regression model, soil pH, and [δ.sup.15]N were the only significant predictors of external Se in colony soil. The correlations are consistent with seabird input driving both the Se supply and increased sorptive uptake in an environment acidified by seabird guano. Despite the enhanced Se in colony soil, median foliage concentrations (tree fern 0.05 mg[kg.sup.-1], nikau 0.08 mg[kg.sup.-1]) were close to the accepted minimum for herbivore nutrition. Seabirds therefore contribute significant Se to breeding colony soils in temperate areas, but this is not necessarily transferred to plant foliage. Additional keywords: allochthonous, burrowing seabird, nutrient subsidy, seabird soil, trace element., Introduction Selenium (Se) is a trace element with an unusually narrow boundary between deficiency and toxicity (Fordyce 2007). It is often deficient in soils, but can be found at toxic [...]

Guano from breeding seabirds provides a large external source of nutrients to the soils of breeding colonies. However, little is known of guano P retention relative to N or the relative importance of guano and soil parent material as P sources. Soil profile N and P inventories (0-0.60 m, n = 4; 0-.36m, n = 1) and guano N and P concentrations were measured at a Westland petrel colony, and the parent material contributions of P were calculated using Ca, Al, Fe, Ti, and Zr as reference elements. Median inventories (0-0.60 m) were 1.49 kg N/[m.sup.2] and 332 x [10.sup.-3] kg P/[m.sup.2], the N result being similar to that from a seabird colony on peat soil where N retention was very low. Calculated parent material contributions were smallest (32-66% of soil P) when based on Ca and largest (47-102% of soil P) when based on Zr. Contributions were similar for Al, Fe, and Ti; Al (41-87% soil P) was selected for subsequent calculations. Regardless of the reference element, parent material therefore contributed a large part of soil P. Phosphorus in excess of parent material supply ([P.sub.excess]) was significantly correlated with soil C, implying that guano P is held primarily in organic form. The median soil N : P molar ratios were 9.6:1 based on total P and 11.2:1 based on [P.sub.excess], compared with ratios for Westland petrel guano of 4.1:1 (when birds were consuming fisheries waste) and 16.4:1 (when fisheries waste was replaced by fish). The similarity between soil and guano N : P ratios implies that both N and P are lost from soil at similar rates, although volatilisation of N would enrich soil drainage water in P. Calculations using guano deposition rates from the literature yielded P residence times of 4-15 years ([P.sub.excess]) and 11-41 years (total P), consistent with a highly dynamic soil system. Additional keywords: ecological stoichiometry, nutrient cycles, New Zealand, nutrient limitation, stable isotope, Westland petrel., Introduction Nitrogen (N) and phosphorus (P) are essential plant nutrients with contrasting biogeochemical behaviours. Although N can be fixed from the atmosphere, P comes mostly from soil parent material. Consequently, [...]

Stable isotope analysis (SIA) is widely used in ecology, but samples are usually analysed in specialist facilities. Like any complex process, SIA is susceptible to human error. Despite the best efforts of the SIA laboratory, errors may occasionally remain in results released to clients.We used our experiences as ecologists and laboratory analysts to identify human error scenarios to which SIA performed anywhere might be susceptible. These scenarios ran from sample selection and submission by the ecologist, to the final results report from the SIA laboratory. Several scenarios involved errors hard to find by visual examination, by either ecologist or analyst.The ecologist can prevent pre‐submission errors by formalising their sample submission process, and can best perform a final results quality check by submitting their own quality control material with a matrix similar to that of the samples. Prevention of laboratory errors is best accomplished by a comprehensive risk‐based quality management system and a continual improvement, no‐blame laboratory culture.We recommend that the ecologist views the entire sample selection, submission and laboratory analysis as an integrated whole, establishing their own quality management processes to run alongside those of the SIA facility. This recommendation applies to any ecological methodology where samples are sent to a specialist facility for analysis. [ABSTRACT FROM AUTHOR]

Stable isotope studies have repeatedly shown marine nutrient incorporation from seabirds, anadromous fish and tidal wrack into terrestrial and freshwater ecosystems. However, little is known about the physiological consequences of marine-derived nutrient subsidies. Protein content and lipid storage are important physiologically, and the C : N ratio is a widely used proxy that reflects changes in these quantities. In this study we tested the response of C : N ratios in stream biota to the presence of marine-derived nutrients from Westland petrels, a forest breeding seabird. Samples of different stream invertebrate functional feeding groups, predatory freshwater fish, coarse particulate organic matter and riparian soil and vegetation came from four reference streams and four streams with a wide range of seabird densities. Samples were analysed for percentage C, percentage N and δ15N using isotope ratio mass spectrometry. The data were tested against petrel colony size, stream size and distance from colony to sampling site. Despite increased δ15N accompanying petrel presence (as reported previously), Westland petrels had no effect on stream biota C : N ratios, regardless of colony presence or absence or colony size. Despite the nutrients provided by petrels, we conclude that petrel N replaced rather than enhanced non-marine N in these stream ecosystems. Studies have shown that nutrients from marine ecosystems can be incorporated into terrestrial and freshwater ecosystems through vectors such as salmon and seabirds. However, little is known about the physiological consequences of these marine nutrients. Despite detecting seabird-derived nutrient in the streams in this study, we found that seabird nitrogen replaced existing nitrogen rather than making stream biota more nitrogen rich. [ABSTRACT FROM AUTHOR]

Endemic Westland petrels ( Procellaria westlandica ) are a remnant of extensive seabird populations that occupied the forested hill country of prehuman New Zealand. Because seabird guano is rich in Se, an often-deficient essential element, we proposed that Westland petrels enhance Se concentrations in ecosystems associated with their breeding grounds. We sampled terrestrial (soil, plants, riparian spiders) and freshwater (benthic invertebrates, fish) components from Westland petrel-enriched and non-seabird forests on the western coast of New Zealand's South Island, an area characterised by highly leached, nutrient-poor soils. Median seabird soil Se was an order of magnitude higher than soil from non-seabird sites (2.2 mg kg − 1 compared to 0.2 mg kg − 1 ), but corresponding plant foliage concentrations (0.06 mg kg − 1 ; 0.05 mg kg − 1 ) showed no difference between seabird and non-seabird sites. In streams, Se ranged from 0.05 mg kg − 1 (riparian foliage) to 3.1 mg kg − 1 (riparian spiders and freshwater mussels). However, there was no difference between seabird and non-seabird streams. Stoichiometric ratios (N:Se, P:Se) showed Se loss across all ecosystem components relative to seabird guano, except in seabird colony soil where N was lost preferentially. Seabirds therefore did not enrich the terrestrial plants and associated stream ecosystems in Se. We conclude that incorporation of trace elements brought ashore by seabirds cannot be assumed, even though seabirds are a significant source of marine-derived nutrients and trace elements to coastal ecosystems world-wide. [ABSTRACT FROM AUTHOR]

The paucity of leaf litter in seabird forest is usually explained by litter burial in burrows, but burial by itself fails to address the processes controlling decomposition. We measured soil microbial C in samples from a Westland petrel ( Procellaria westlandica ) colony both within and outside the breeding season, and compared the results with two non-seabird forests. From the few studies of seabird soil microbial C, we initially hypothesised a soil microbial C concentration sequence of occupied burrows > unoccupied burrows > adjacent forest floor > non-seabird forest. Instead, the highest values came from non-seabird forest, a pattern consistent with published meta-analyses on the effects of N addition. Within the colony, highest concentrations were in forest floor soil and there was no burrow occupation effect. However, seabird forest soil microbial C followed a strong inverse relationship with soil δ 13 C ( r = −0.58; P < 0.001) as well as the expected relationship with total soil C ( r = 0.75); the relationship with soil δ 13 C in non-seabird forest was not significant ( P = 0.29). We propose that soil microbes in seabird forest repeatedly process a single pool of increasingly refractory terrestrial soil C, facilitated by seabird guano priming of organic matter mineralisation. In this context, the paucity of leaf litter in seabird forest can be seen as a consequence of microbial C limitation in a nutrient-saturated system, an explanation consistent with recent theory. [ABSTRACT FROM AUTHOR]

Stable isotope analysis ( SIA) is widely used in ecology but is usually performed by specialist facilities. Consequently, the reliability of SIA data depends completely on the facility's quality systems unless ecologists take steps themselves. Although widely recommended, practical advice on how to do this is lacking., Here, we outline preparation of 150 vials of an in-house quality control material ( QCM) based on air-dried soil as an exemplar and describe methods of data analysis applicable to any QCM matrix. Homogeneity testing of the candidate material involves duplicate analysis of 10 randomly chosen vials, a Cochran test for outliers and 1-way anova. Given that many ecologists find SIA expensive, we propose that an ecologist preparing a soil QCM pretest for homogeneity using a simple colorimetric analysis of a soil quantity (bicarbonate-extractable P) sensitive to inhomogeneity., Once pretest homogeneity has been established, homogeneity under SIA can be tested. We obtained a 1-way anova P value of 0·824 in our laboratory pretest, then 0·782 ( δ13C) and 0·125 ( δ15N). QCM stability should also be confirmed., Submission of each batch of samples for SIA should be accompanied by a vial of the QCM, labelled as a normal sample. Control charting of the results then allows detection of within-batch issues encompassing any component of the analytical process (transport to the laboratory, sample preparation and subsampling, sample analysis, results calculation and reporting) and assessment of long-term analytical control. Any issue thus identified can form the basis of a conversation with the SIA laboratory about the affected batch of samples. [ABSTRACT FROM AUTHOR]

The remaining five Coenocorypha snipes are restricted to remote islands in the New Zealand archipelago, so their ecology is difficult to study directly. To ascertain habitat types and ecological interactions across the different taxa and locations, we measured the Δ13C and Δ15N of feathers from known individual Auckland Island snipe C. aucklandica aucklandica (Adams I., n = 12; Enderby I., n = 4; Rose I., n = 8), Chatham Island snipe C. pusilla (Rangatira, n = 10), and Campbell Island snipe (Coenocorypha undescribed sp.; n = 1). Data for Snares snipe C. a. huegeli (North East I., n = 1) came from the literature. Developmental stage (nestling, juvenile, adult) and sex were statistically indistinguishable. Although significant differences in Δ13C occurred between islands, the overall range was small (mean ± standard deviation, -22.7 ± 0.9‰). The restricted Δ13C show that the snipe we sampled occupied a consistent habitat regardless of taxa, island size, and disturbance history. Conversely, the range in Δ15N was large at c. 18.5‰ and implied occupation of sites with a wide range of nutrient status. The δ15N from Adams I. (mean 5.9 ± 1.7‰) was much lower than the other islands (mean 19.2 ± 2.0‰) and could only be explained by including a 15N-depleted site not affected by seabirds or seals. Auckland Island snipe therefore integrate seabird breeding and nonbreeding areas as well as inhabiting locations with seals and high seabird densities. Consequently, Coenocorypha snipes provide connectances between marine animals on land and the wider terrestrial environment and so may be considered for (re)-introduction to predator-proof mainland New Zealand restoration sites. [ABSTRACT FROM AUTHOR]

Marine nitrogen (N) has been traced into terrestrial and freshwater food chains at petrel (Aves: Procellariiformes) colonies on the South Island of New Zealand, but the effects of N or other marine-derived nutrients on the productivity of mainland forests are unknown. Mean ring widths in matai (Prumnopitys taxifolia; n = 3) and rimu (Dacrydium cupressinum; n = 2) trees growing in a Westland petrel (Procellaria westlandica) colony were 0.9-1.4 mm yr-1, similar to ring widths reported elsewhere. However, series of much wider rings in cores showed that trees in a petrel colony can experience periods of accelerated growth. δ15N values of whole wood were, at 3.2-11.1‰, significantly enriched in comparison to other temperate forest trees. The highest δ15N values were at the cambial and pith ends of different cores, so isotopic fractionation during N remobilisation is unlikely to have been significant. The radial extent of 15N enrichment suggests that petrels have bred at the site since at least the mid 18th century. [ABSTRACT FROM AUTHOR]

1. Stable isotope ratios of aquatic invertebrates, aquatic mosses and leaves of riparian plants were used to determine whether marine-derived nutrients from breeding colonies of the Westland petrel (Procellaria westlandica) were incorporated into the food webs of small streams in New Zealand. 2. The δ15N signatures of all plants and animals examined were higher by 3.6-4.6‰ in small streams draining catchments with petrel colonies than in nearby streams where petrels were absent. δ13C values of leaves from terrestrial plants were also enriched by about 2‰ where petrels were present, but the carbon ratios of aquatic species were depleted in 13C, rather than enriched, suggesting that any marine signal was over-ridden by isotopic shifts related to photosynthetic fractionation. 3. A high marine-nitrogen signal was maintained along the 3 km length of Scotchman Creek with the δ15N values of leptophlebiid mayflies and predatory insects ranging from 7.4-9.5 and 9.2-11.9‰, respectively. 4. Most nutrients derived from petrels are likely to be translocated to streams via the soil, which they enter in the form of excreta, spilled food, feathers, dead chicks, and abandoned eggs. However, because changes in δ15N values are brought about by soil processes such as volatilisation of ammonia, nitrification and denitrification, it is difficult to predict the exact isotope signature of nitrogen entering a stream. Tentative estimates of the proportion of marine-derived nitrogen in stream biota, calculated using a mass-balance approach, ranged from 28-38%. 5. Our findings indicate that marine nutrients transported inland by seabirds can be incorporated into the food webs of streams. In pre-human times when there were many more seabird colonies on mainland New Zealand than exist today, marine-derived nutrients introduced by birds may have had significant effects on nitrogen cycling and the productivity of New Zealand streams. [ABSTRACT FROM AUTHOR]