DOI: 10.5061/dryad.b8gtht7m4
title: Data from: Seabird presence and seasonality influence nutrient dynamics of atoll habitats

description: In this study, we investigate nutrient dynamics linked to seabird presence
 and seasonality. We compare seabird colonies of different taxa nesting on
 separate islands of Farquhar Atoll, Seychelles. We first quantify guano
 nutrient input and guano nitrogen isotopes for each seabird species. We
 assess the transfer of seabird-derived nutrients in terrestrial and marine
 habitats by comparing nitrogen isotope values in soil, plants, and
 seagrass on each seabird island and a control island, during the wet and
 dry seasons. We then assess the influence of seabirds by comparing
 nutrient levels in soil, plants, and seagrass on each seabird island and a
 control island, during the wet and dry seasons. For plants and seagrass,
 we also assess and compare nutrient ratios and carbon stable isotope
 ratios on each seabird island and a control island, during the wet and dry
 seasons.
description: This dataset was collected on Farquhar Atoll (Seychelles) between
 March and August 2022. Details for each dataset are
 provided in the README file.
description: # Seabird presence and seasonality influence nutrient dynamics of atoll
 habitats
 [https://doi.org/10.5061/dryad.b8gtht7m4](https://doi.org/10.5061/dryad.b8gtht7m4) The dataset contains the following raw data : Seabird guano nutrients (2 files), soil and plant nitrogen isotopes (1 file), soil nutrient levels (1 file), coastal plant nutrient levels (1 file) and seagrass nutrient levels (1 file). ## Description of the data and file structure Raw data files: 1. Seabird guano nutrients: * seabird_nutrient_metrics.csv: guano nutrient quantity (nitrogen [N] and phosphorus [P]) and population metrics (number of breeding pairs, number of days of breeding period, proportion of time spent on nests, productivity [proportion of fledged chicks per breeding pair], defecation rate) for red-footed boobies, brown noddies and sooty terns. Nutrient quantities are in g/kg dry weight, defecation rates are in g/bird/day. * guano_nitrogen_isotope.csv: guano nitrogen isotope ratios (d15N, **‰**) for red-footed boobies, brown noddies and sooty terns from samples collected in nests. 2. Soil and plant nitrogen isotope: * soil_plant_nitrogen_isotope.csv: nitrogen isotope ratios (d15N, **‰**) and total nitrogen (TN, %) for soil, terrestrial plants and seagrass. Samples collected during two seasons (dry, wet), at three islands (Goelettes, South, North). Seabirds indicate seabird presence or not for each island and species indicate which seabird taxa. Terrestrial sampling (soil & plants) was done at 6 sites (S1-S6, two sites for each island) and along three transect at each site (T1-T3). Habitat indicate habitat type along transects and taxa indicate plant species. Marine sampling (seagrass) was done at 6 locations at each site (01-06). Missing data code: na 3. Soil nutrient levels: * soil_nutrient.csv: nutrient concentrations for soil samples collected during two seasons (dry, wet), at three islands (Goelettes, South, North). Seabirds indicate seabird presence or not for each island and species indicate which seabird taxa. Terrestrial sampling was done at 6 sites (S1-S6, two sites for each island) and along three transect at each site (T1-T3). Habitat indicate habitat type along transects. Variables measured include pH, electrical conductivity (EC, mS/cm), nitrogen (N_dumas, g/kg), nitrate (N-NO3, mg/kg), ammonium (N-NH4, mg/kg), organic carbon (C_orga, g/100g), total carbon (C_tot, g/100g), phosphorus (P_dabin, g/kg), cationic exchange capacity (CEC, cmol(+)/kg), calcium (Ca, cmol(+)/kg), magnesium (Mg, cmol(+)/kg), potassium(k, cmol(+)/kg) and sodium (Na, cmol(+)/kg). 4. Coastal plant nutrient levels: * coastalplant_nutrient.csv: nutrient concentrations for coastal plant samples collected during two seasons (dry, wet), at three islands (Goelettes, South, North). Seabirds indicate seabird presence or not for each island and species indicate which seabird taxa. Terrestrial sampling was done at 6 sites (S1-S6, two sites for each island) and along three transect at each site (T1-T3). Habitat indicate habitat type along transects. Variables measured include nitrogen (N_dumas, g/kg), total carbon (C_tot, g/100g), phosphorus (P_tot, g/kg), nitrogen isotopic ratios (d15N, **‰**), carbon isotopic ratios (d13C, **‰**). 5. Seagrass nutrient levels * seagrass_nutrient.csv: nutrient concentrations for seagrass samples collected during two seasons (dry, wet), at three islands (Goelettes, South, North). Seabirds indicate seabird presence or not for each island and species indicate which seabird taxa. Sampling was done at 6 locations at each site (sample 01-06). Variables measured include nitrogen (N_dumas, g/kg), organic carbon (C_orga, g/100g), total carbon (C_tot, g/100g), phosphorus (P_tot, g/kg), nitrogen isotopic ratios (d15N, **‰**), carbon isotopic ratios (d13C, **‰**)