Data

Data and code for: Decadal change in seabird-driven isotopes on islands with differing invasion histories

Name: Data and code for: Decadal change in seabird-driven isotopes on islands with differing invasion histories
Published: 2024

Australian Ocean Data Network

Pascoe, Penelope ; Jones, Holly

Viewed: [[ro.stat.viewed]] Cited: [[ro.stat.cited]] Accessed: [[ro.stat.accessed]]

ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/9cd2434b-fbc3-4efa-9631-9850a72be2ec&rft.title=Data and code for: Decadal change in seabird-driven isotopes on islands with differing invasion histories&rft.identifier=https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/9cd2434b-fbc3-4efa-9631-9850a72be2ec&rft.description=Invasive mammal eradications are commonplace in island conservation. However, post-eradication monitoring beyond the confirmation of target species removal is rarer. Seabirds are ecosystem engineers on islands and are negatively affected by invasive mammals. Following an invasive mammal eradication, the recovery of seabird populations can be necessary for wider ecosystem recovery. Seabirds fertilise islands with isotopically heavy nitrogen, which means nitrogen stable isotope analysis (δ15N) could provide a useful means for assessing corresponding change in ecosystem function. We quantified decadal changes in δ15N on eight temperate New Zealand islands subject in pairs to distinct mammal invasion and seabird restoration histories: invaded, never-invaded, invader-eradicated and undergoing active seabird restoration. First, we investigated long-term changes in δ15N values on individual islands. Second, we used a space for time analysis to determine if δ15N levels on islands from which invaders had been removed eventually recovered to values typical of never-invaded islands. On each island soil, plants (Coprosma repens, C. robust and Myrsine australis) and spiders (Porrhothelidae) were sampled in 2006/07 and 2022 allowing δ15N change on individual islands over 16 years to be assessed. Combined, the samples from invader-eradicated islands provided a 7 – 32 year post-eradication dataset. Change in δ15N was only detected on one island across the study period, following the unexpected recolonisation of seabirds to an invaded island. Invader-eradicated islands generally had higher δ15N values than invaded islands however, they were still lower than never-invaded islands and there was no trend in δ15N with time since eradication. This, and the measurable increase in δ15N following seabird recolonisation on one island, may suggest that δ15N change occurs rapidly following invader-eradication, but then slows, with δ15N values staying relatively constant in the time period studied here. Isotope and seabird population studies need to be coupled to ascertain if plateauing in δ15N reflects a slowing of seabird population growth and subsequent basal nutrient input, or if the baseline nutrients are entering the ecosystem but then not propagating up the food web.Maintenance and Update Frequency: notPlannedStatement: We selected eight geographically proximate and environmentally similar islands in Cook Strait, New Zealand to investigate long-term changes in nitrogen stable isotopes levels across islands with different restoration treatments: never-invaded islands - Takapourewa/Stephens and Kuru Pongi/ Middle Trio, invaded islands - Moutiti/Victory and Tawhitinui, eradicated islands - Wakaterepapanui and Nukuwaiata, and actively seabird restored islands - Te Hoiere/Maud and Mana. Each island was originally sampled for a stable isotope study in 2006/07 by Jones (2010b) and we re-visited each island in 2022 for this study. Soil, plant (taupata - Coprosma repens, karamu - C. robusta, and māpou - Myrsine australis) and spider (family Porrhothelidae) samples were collected from inside and outside seabird colonies (no burrows found within a 3m radius of the sampling location) at between 9 and 47 sampling locations on each island. At each sampling location soil and as many of the three plant species as were present were collected. Plants were sampled by picking three new growth leaves from separate individuals of the same species, if available. Soil was sampled by scraping back the litter layer and collecting approximately 100 g using a small hand trowel down to 10 cm depth. Up to three spiders were collected from inside and three from outside seabird colonies opportunistically on each island (because spider tunnels were not always present in each sampling locale) by digging up their tunnels. On each island with a seabird colony, we also collected three seabird guano samples. Spider samples were stored in 70% ethanol for transportation off the island. All samples were then washed in distilled water and oven dried at 60°C for 48 hours to prevent decomposition and in preparation for stable isotope analysis. Dried soil samples were passed through a 0.5 mm sieve, then all samples were hand ground to a fine powder using a mortar and pestle. Stable isotope analysis was conducted using an Elemental Combustion System (ECS 4010, Costech Instruments) coupled to the Delta Plus Advantage IRMS (Thermo Fisher Scientific) mass spectrometer at Northern Illinois University using USGS-25 and IAEA-N1 international standards.&rft.creator=Pascoe, Penelope &rft.creator=Jones, Holly &rft.date=2024&rft.coverage=westlimit=172.423099; southlimit=-41.404298; eastlimit=175.129228; northlimit=-40.187028&rft.coverage=westlimit=172.423099; southlimit=-41.404298; eastlimit=175.129228; northlimit=-40.187028&rft_rights=This dataset is the intellectual property of the University of Tasmania (UTAS) through the Institute for Marine and Antarctic Studies (IMAS).&rft_rights=Creative Commons Attribution 4.0 International License https://creativecommons.org/licenses/by/4.0/&rft_rights=Cite data as: Pascoe, P., & Jones, H. (2024). Data and code for: Decadal change in seabird-driven isotopes on islands with differing invasion histories [Data set]. Institute for Marine and Antarctic Studies. https://doi.org/10.25959/VDN6-R115&rft_rights=Data, products and services from IMAS are provided as is without any warranty as to fitness for a particular purpose.&rft_rights=Please contact the authors prior to use&rft_subject=biota&rft_subject=seabirds&rft_subject=Marlborough Sounds&rft_subject=ISLANDS&rft_subject=EARTH SCIENCE&rft_subject=BIOSPHERE&rft_subject=TERRESTRIAL ECOSYSTEMS&rft_subject=INVASIVE SPECIES&rft_subject=ECOLOGICAL DYNAMICS&rft_subject=COMMUNITY DYNAMICS&rft_subject=NITROGEN ISOTOPES&rft_subject=CLIMATE INDICATORS&rft_subject=PALEOCLIMATE INDICATORS&rft_subject=ICE CORE RECORDS&rft_subject=ISOTOPES&rft_subject=ISOTOPIC ANALYSIS&rft_subject=BIOLOGICAL RECORDS&rft_subject=TREE RINGS&rft_subject=Countries | Countries | New Zealand&rft.type=dataset&rft.language=English Access the data

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Creative Commons Attribution 4.0 International License
https://creativecommons.org/licenses/by/4.0/

This dataset is the intellectual property of the University of Tasmania (UTAS) through the Institute for Marine and Antarctic Studies (IMAS).

Cite data as: Pascoe, P., & Jones, H. (2024). Data and code for: Decadal change in seabird-driven isotopes on islands with differing invasion histories [Data set]. Institute for Marine and Antarctic Studies. https://doi.org/10.25959/VDN6-R115

Data, products and services from IMAS are provided "as is" without any warranty as to fitness for a particular purpose.

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Brief description

Invasive mammal eradications are commonplace in island conservation. However, post-eradication monitoring beyond the confirmation of target species removal is rarer. Seabirds are ecosystem engineers on islands and are negatively affected by invasive mammals. Following an invasive mammal eradication, the recovery of seabird populations can be necessary for wider ecosystem recovery. Seabirds fertilise islands with isotopically heavy nitrogen, which means nitrogen stable isotope analysis (δ15N) could provide a useful means for assessing corresponding change in ecosystem function. We quantified decadal changes in δ15N on eight temperate New Zealand islands subject in pairs to distinct mammal invasion and seabird restoration histories: invaded, never-invaded, invader-eradicated and undergoing active seabird restoration. First, we investigated long-term changes in δ15N values on individual islands. Second, we used a space for time analysis to determine if δ15N levels on islands from which invaders had been removed eventually recovered to values typical of never-invaded islands. On each island soil, plants (Coprosma repens, C. robust and Myrsine australis) and spiders (Porrhothelidae) were sampled in 2006/07 and 2022 allowing δ15N change on individual islands over 16 years to be assessed. Combined, the samples from invader-eradicated islands provided a 7 – 32 year post-eradication dataset. Change in δ15N was only detected on one island across the study period, following the unexpected recolonisation of seabirds to an invaded island. Invader-eradicated islands generally had higher δ15N values than invaded islands however, they were still lower than never-invaded islands and there was no trend in δ15N with time since eradication. This, and the measurable increase in δ15N following seabird recolonisation on one island, may suggest that δ15N change occurs rapidly following invader-eradication, but then slows, with δ15N values staying relatively constant in the time period studied here. Isotope and seabird population studies need to be coupled to ascertain if plateauing in δ15N reflects a slowing of seabird population growth and subsequent basal nutrient input, or if the baseline nutrients are entering the ecosystem but then not propagating up the food web.

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Maintenance and Update Frequency: notPlanned

Statement: We selected eight geographically proximate and environmentally similar islands in Cook Strait, New Zealand to investigate long-term changes in nitrogen stable isotopes levels across islands with different restoration treatments: never-invaded islands - Takapourewa/Stephens and Kuru Pongi/ Middle Trio, invaded islands - Moutiti/Victory and Tawhitinui, eradicated islands - Wakaterepapanui and Nukuwaiata, and actively seabird restored islands - Te Hoiere/Maud and Mana. Each island was originally sampled for a stable isotope study in 2006/07 by Jones (2010b) and we re-visited each island in 2022 for this study. Soil, plant (taupata - Coprosma repens, karamu - C. robusta, and māpou - Myrsine australis) and spider (family Porrhothelidae) samples were collected from inside and outside seabird colonies (no burrows found within a 3m radius of the sampling location) at between 9 and 47 sampling locations on each island. At each sampling location soil and as many of the three plant species as were present were collected. Plants were sampled by picking three new growth leaves from separate individuals of the same species, if available. Soil was sampled by scraping back the litter layer and collecting approximately 100 g using a small hand trowel down to 10 cm depth. Up to three spiders were collected from inside and three from outside seabird colonies opportunistically on each island (because spider tunnels were not always present in each sampling locale) by digging up their tunnels. On each island with a seabird colony, we also collected three seabird guano samples. Spider samples were stored in 70% ethanol for transportation off the island. All samples were then washed in distilled water and oven dried at 60°C for 48 hours to prevent decomposition and in preparation for stable isotope analysis. Dried soil samples were passed through a 0.5 mm sieve, then all samples were hand ground to a fine powder using a mortar and pestle. Stable isotope analysis was conducted using an Elemental Combustion System (ECS 4010, Costech Instruments) coupled to the Delta Plus Advantage IRMS (Thermo Fisher Scientific) mass spectrometer at Northern Illinois University using USGS-25 and IAEA-N1 international standards.

Issued: 27 08 2024

Data time period: 2006-10-01 to 2022-04-30

This dataset is part of a larger collection

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text: westlimit=172.423099; southlimit=-41.404298; eastlimit=175.129228; northlimit=-40.187028

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