DOI: 10.5061/dryad.547d7wmh9
title: Data from: Age-based δ15N and δ13C values of otolith organic matter reveal trophic ecology in marine fishes

description: Fish inhabiting a similar environment confront space and resource sharing
 and thus develop diverse feeding strategies to adjust their trophic niches
 during the ontogeny to avoid competition. To explore the topic, we
 reconstructed the trophic trajectory of five Sciaenidae species by
 sequentially analysing the δ13C and δ15N values of otolith organic matter
 along the growth axis of the otolith. The isotope values were aligned to
 the age based on growth ring counting and 3D scanning of otolith
 morphology during organic matter extraction. The δ13C and δ15N values
 revealed the habitat shift and trophic levels of prey items, respectively.
 Sciaenidae fish use the benthic resources during their whole life and may
 move close to the estuary around 1.5-3 years old. They mainly prey on
 herbivores/zooplankton at the larval and early juvenile stage, but when
 they grow, there is minimisation of competition among age groups and
 species.
description: For the age-based trophic niche using stable isotope values
 recorded in otolith OM, we first adopted the ultrafiltration method
 because two stable isotope systems provide more trophic information. Then,
 we dissolve one of the paired otoliths layer by layer, extract the otolith
 OM in each layer and apply a 3D scanning technique to track the
 morphological change of each dissolution. Second, we estimate the fish age
 corresponding to each dissolved layer by image analysis. Third, we
 evaluate the habitat uses and trophic level of Sciaenidae fishes by
 comparing the stable isotope values of the particulate organic matter
 (POM). Thirty-three fish samples of five Sciaenid
 species (<em>Atrobucca nibe, Chrysochir aureus, Nibea albiflora,
 Pennahia macrocephalus, </em>and<em> Protonibea
 diacanthus</em>) were collected off the western coast of Taiwan in
 2020-2023. Muscle tissues and otoliths were collected from each sample.
 Muscle tissues were freeze-dried in which 0.7 mg dry powder was packed
 into tin capsules for further isotope analyses. The otoliths were washed
 with 0.2M NaOH, cleaned with ultrapure water three times, and dried in an
 oven at 50 ºC for 48 hrs. The packed muscle and otolith organic matter
 samples were analysed using Isotope Ratio Mass Spectrometry (Delta V
 Advantage, ThermoFisher Scientiﬁc, Germany) equipped with Elemental
 Analyser (Flash EA2000, ThermoFisher Scientiﬁc, Germany).
 The otolith organic matter extraction follows the ultrafiltration
 using Amicon ultrafilters (Merck Millipore Ltd., Tullagreen,
 Carrigtwohill, Co.Cork, IRL).  3D scanned with GOM Scan 1 MV100 (Carl
 Zeiss GOM Metrology GmbH, Braunschweig, Germany) to monitor the
 morphological changes. The 3D images in a series of otolith dissolutions
 were overlaid to evaluate in which direction, the otolith shape changed
 the most using a compatible software (GOM Software 2021_Hotfix_1 Rev.
 142421). The right otoliths from the second batch of samples were embedded
 in Epoxy Resin (Struers, Denmark), cut through the frontal plane using a
 low-speed diamond saw (IsoMet, Buelher, US), ground and polished until the
 core was observed at the surface.
description: # Age-based δ15N and δ13C values of otolith organic matter reveal the
 inter- and intraspecific trophic partitioning in marine fishes
 [https://doi.org/10.5061/dryad.547d7wmh9](https://doi.org/10.5061/dryad.547d7wmh9) This study aims to investigate the trophic trajectory of five commercially important Sciaenidae species inhabiting coastal and estuarine environments, where they experience spatial and resource competition. To achieve this, we conducted a comprehensive analysis of their trophic ecology. The study comprises three datasets: (1) Baseline stable isotope values, (2) Isotopic niche derived from stable isotope values of muscle tissue and otolith organic matter, and (3) Stable isotope values of otolith organic matter ## Description of the data and file structure Baseline: The stable carbon and nitrogen isotope values of particulate organic matter (POM) were collected from inshore and offshore seawater. These samples represent the pelagic ecosystem and are compared to published data on benthic ecosystems. | **Column name** | **Description** | **Units** | **Data format** | **Missing data code** | | :-------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | :-------- | :-------------- | :------------------------------------------------------- | | Location | The sampling location of particulate organic matter. | - | Category | - | | Latitude | The latitude of the sampling location. | degree | Number | - | | Longitude | The longitude of the sampling location. | degree | Number | - | | Ecosystem | Categories as pelagic and benthic ecosystems. | - | Category | - | | Environment | Categories as inshore and offshore. | - | Category | - | | Year | The sampling years. | - | Category | - | | Month | The sampling months. | - | Category | - | | Temperature | The temperature of the sampling location. | °C | Number | NA: Temperature was not recorded during sampling. | | Salinity | The salinity of the sampling location. | PSU | Number | NA: Salinity was not recorded during sampling. | | d15N | Stable nitrogen isotope value of particulate organic matter. The number in the bracket symbol represents one standard deviation. | ‰ | Number | NA: The sample amount was under the detected limit. | | d15N.sd | The standard deviation of stable nitrogen isotope value of particulate organic matter. | ‰ | Number | NA: A single estimation is without a standard deviation. | | d13C | Stable carbon isotope value of particulate organic matter. | ‰ | Number | NA: The sample amount was saturated. | | d13C.sd | The standard deviation of stable carbon isotope value of particulate organic matter. | ‰ | Number | NA: A single estimation is without a standard deviation. | | Source | The data was obtained by this study or Nazir et al. (2024). Nazir et al. "Anthropogenic nitrogen pollution inferred by stable isotope records of crustose coralline algae." Marine Pollution Bulletin 198 (2024): 115839. | - | Category | - | Isotope niche: Basic fish information—such as age, length, weight, and sampling locations—is provided. δ¹³C and δ¹⁵N values were measured in the otolith core, otolith edge, and muscle tissue to facilitate comparative analysis. | **Column name** | **Description** | **Units** | **Data format** | **Missing data code** | | :---------------- | :---------------------------------------------------------------------------- | :-------- | :-------------- | :------------------------------------------------- | | Species | Five fish species analysed in this study. | - | Category | - | | Location | The sampling location of particulate organic matter. | - | Category | - | | SampleID | Fish individual ID number. | - | Category | - | | Age | The age of the individual sample. | year | Number | NA: The age was not estimated during the analyses. | | Length | The total length of the individual sample. | cm | Number | - | | Weight | The total weight of the individual sample. | g | Number | - | | Muscle.d15N | Stable nitrogen isotope value of muscle tissue. | ‰ | Number | - | | Muscle.d13C | Stable carbon isotope value of muscle tissue. | ‰ | Number | - | | Otolith.core.d15N | Stable nitrogen isotope value of the organic matter in the otolith core area. | ‰ | Number | - | | Otolith.edge.d15N | Stable nitrogen isotope value of the organic matter in the otolith edge area. | ‰ | Number | - | | Otolith.core.d13C | Stable carbon isotope value of the organic matter in the otolith core area. | ‰ | Number | NA: The sample amount was saturated. | | Otolith.edge.d13C | Stable carbon isotope value of the organic matter in the otolith edge area. | ‰ | Number | NA: The sample amount was saturated. | Otolith organic matter: Stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope data were obtained from each layer of otolith dissolution in individual fish. These values were aligned with age estimates derived from growth ring counting and 3D scanning of otolith morphology during organic matter extraction. The dataset includes maximum, minimum, and median age estimates from both methods. | **Column name** | **Description** | **Units** | **Data format** | **Missing data code** | | :-------------- | :------------------------------------------------------------------------------------------------------------------------- | :-------- | :-------------- | :------------------------------------------------- | | Species | Five fish species analysed in this study. | - | Category | - | | ID | Fish individual ID number. | - | Category | - | | Layer | The otolith dissolution sequence. Number 1 represents the otolith core. | - | Category | - | | LayerID | The otolith dissolution layers were categorised as the core, edge and the layers between the core and edge. | - | Category | NA: The layers between the core and edge | | d15N | Stable nitrogen isotope value of otolith organic matter. Deviation. | ‰ | Number | - | | d13C | Stable carbon isotope value of otolith organic matter. | ‰ | Number | NA: The sample amount was saturated. | | Age.min | The minimum age assigned to the dissolution layer of otolith organic matter. | year | Category | NA: The age was not estimated during the analyses. | | Age.max | The maximum age assigned to the dissolution layer of otolith organic matter. | year | Number | NA: The age was not estimated during the analyses. | | Age.median | The median age assigned to the dissolution layer of otolith organic matter, which is based on the minimum and maximum age. | year | Number | NA: The age was not estimated during the analyses. |