DOI: 10.5061/dryad.0rxwdbs79
title: Seabird nutrient subsidies enrich mangrove ecosystems and are exported to nearby coastal habitats

description: In this study, we investigate how mangrove ecosystems respond to nutrient
 subsidies supplied by nesting seabirds. We first quantify seabird guano
 nutrient input and seabird guano nitrogen isotopes. We then assess the
 influence of seabirds on mangroves by comparing nitrogen, phosphorus,
 nutrient ratios and resoprtion efficiency in mangrove leaves sampled from
 sites with nestings seabirds versus sites without nesting seabirds. We
 trace the transfer of seabird-derived nutrients within the mangrove
 ecosystems by comparing nitrogen isotope values in sediment, mangrove
 leaves, gastropod and crabs at sites with nestings seabirds versus without
 nesting seabirds. Lastly, we assess the export of seabird-derived
 nutrients from mangrove ecosystems by comparing nitrate, nitrite and
 phosphate levels in seawater, and nitrogen isotope values of macroalgae,
 at sites with nestings seabirds versus without nesting seabirds.
description: This dataset was collected within the mangrove forests of Aldabra
 Atoll (Seychelles) between November 2022 and February 2023.
 Details for each dataset are provided in the README
 file.
description: # **Seabird nutrient subsidies enrich mangrove ecosystems and are exported
 to nearby coastal habitats**
 The dataset contains the
 following raw data : Seabird guano nutrients (3 files), Mangrove leaves
 nutrients (1 file), Mangrove foodweb nitrogen isotopes (1 file) and
 Seawater nutrient concentrations (1 file). The dataset also contains code
 for analyses (4 files). ## Description of the data and file structure Raw
 data files: 1. Seabird guano nutrients: *
 seabird_guano_nutrient_quantity.csv: nitrogen (N) and phosphorus (P)
 content of red-footed boobies and lesser frigatebird guano from samples
 collected in nests. N and P are in g/kg dry weight. *
 seabird_guano_nitrogen_isotope.csv: nitrogen isotope values (d15N) of
 red-footed boobies and lesser frigatebird guano from samples collected in
 nests. d15N values are in **‰.** * seabird_guano_nutrient_total.csv: guano
 nutrient quantity 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 and lesser frigatebird. Nutrient quantities
 are in g/kg dry weight, defecation rates are in g/bird/day. 2. Mangrove
 leaves nutrients: * mangrove_leaves_nutrients.csv: nitrogen isotope values
 (d15N), nitrogen (N), carbon (C) and phosphorus (P) concentration in green
 mangrove leaves (d15NG, NG, CG, PG) and senescent leaves (NB, CB, PB).
 Samples collected at 10 sites (5 seabird, 5 non-seabird sites) and within
 8 quadrats at each site (suffix A-H). N, C and P are expressed as %
 composition, d15N values are in **‰.** 3. Mangrove foodweb nitrogen
 isotope: * mangrove_foodweb_nitrogen_isotope.csv: nitrogen isotope values
 (d15N) of mangrove ecosystem compartments (leaves, sediment, littorinid
 gastropod, sesarmid crab, portunid crab, Halimeda macroalgae). Samples
 collected at 10 sites (5 seabird, 5 non-seabird sites) and within 8
 quadrats at each site (suffix A-H). d15N values are in **‰.** 4. Seawater
 nutrient concentrations: * seawater_nutrients_lagoon.csv: seawater
 nutrient concentrations (NOx and phosphate) collected at sites with
 seabird and without seabirds and during incoming and outgoing tide. NOx
 and phosphate are in µmol/L. ## Code/Software R scripts: 1. guano:
 Analyses for guano nutrients. Uses 'seabird guano nutrient' raw
 data files. 2. mangrove_nutrient: Analyses for mangrove nutrients,
 nutrient ratios and resorption efficiency. Uses 'mangrove leaves
 nutrients' raw data file. 3. foodweb_isotope: Analyses for mangrove
 foodweb isotopes. Uses 'mangrove foodweb nitrogen isotope' raw
 data file. 4. seawater: Analyses for seawater nutrient concentrations.
 Uses 'seawater nutrient concentrations' and 'mangrove
 foodweb nitrogen isotope' raw data file. All codes are run with R
 software (version 4.3.0). R packages used include: dplyr, ggplot2, nlme,
 car, MuMIn, ggeffects, emmeans.