Dam-regulated nutrient inputs control the inter-annual variation of net primary production in the central Bohai Sea

Yao, Yuan 1 ; Yu, Guirui2 3; Han, Lang1; Chen, Zhi2 3; Li, Pan1; Yan, Zhifeng1; Liu, Congqiang1

Published May 11, 2026 on Dryad. https://doi.org/10.5061/dryad.2280gb63b

Data files

May 11, 2026 version files 39.62 KB

README.md

8.49 KB
Yao_et_al._2025.xlsx

31.13 KB

Abstract

Net primary production (NPP) is the foundation of marine food webs and the biological carbon pump. River damming significantly impacts NPP in marginal sea by changing nutrient concentrations and ratios in the coastal zone. Clarifying the impacts of river damming on NPP in marginal seas can help improve the management of living marine resources. We combined data collection with field surveys to investigate the seasonal and inter-annual variability of NPP in the central Bohai Sea, with a particular focus on the effects of dam-regulated nutrient inputs (the Water Sediment Regulation Scheme of Yellow River (WSRS)) on NPP. Our findings revealed that the most significant factor influencing the seasonal variations in NPP in the central Bohai Sea was SST, but NPP was nutrient-limited under favorable SST conditions in summer. Large nutrient inputs resulting from the implementation of WSRS significantly increased chlorophyll-a concentration and NPP in the central Bohai Sea during summer. The coupling of nutrient input and suitable temperature and light could maximize the stimulation of NPP elevation. Furthermore, the substantial nutrient inputs with high N/P ratio from the Yellow River led to a significant increase in the DIN/PO₄-P ratio, thus promoting the diatom/dinoflagellate ratios and picoeukaryotes abundance. The growth of picoeukaryotes contributed to an increase in chlorophyll-a, thereby exerting control over changes in NPP. This study offers valuable insights into the effects of dam regulation on offshore NPP, and help in our understanding of how marine ecosystems are influenced by giant dam construction.

Dataset DOI: 10.5061/dryad.2280gb63b

Description of the data and file structure

This dataset accompanies the study “Dam-regulated nutrient inputs control the inter-annual variation of net primary production in the central Bohai Sea”.
It includes inter-annual and seasonal measurements of environmental parameters, nutrient concentrations, net primary production (NPP), and phytoplankton community composition, collected from field surveys, remote sensing/model outputs, and literature.

Files and variables

File: Yao_et_al._2025.xlsx

Description:

Sheet name / file	Contents
Inter-annual variations	Yearly data of CAFE-model NPP, SST, PAR, DIN, PO₄-P, N*, diatom/dinoflagellate ratio, phytoplankton abundance, Yellow River discharge and nutrient inputs during WSRS summer events
Seasonal variations	Seasonal measurements including sample time, location (longitude, latitude), SST, PAR, Chl-a, DIN, PO₄-P, SiO₃-Si, DIN/PO₄-P ratio, N*, CAFE-model NPP, SDD, and wind speed
Field surveys	In situ measurements from two cruises (pre- and post-WSRS) including Chl-a, Synechococcus, picoeukaryotes, nanoeukaryotes, NO₃⁻, NO₂⁻, NH₄⁺, DIN, PO₄-P, DIN/PO₄-P, and CAFE NPP

3. Variables and Units

3.1 Inter-annual variations

Variable	Unit	Description
`year`	YYYY	Calendar year
`CAFE_NPP`	mg C m⁻² day⁻¹	Net primary production estimated from the CAFE model
`diatom/dino_ratio`	—	Diatom to dinoflagellate abundance ratio
`DIN_summer`	μmol/L	Dissolved inorganic nitrogen in summer
`PO4-P_summer`	μmol/L	Phosphate concentration in summer
`N/P_summer`	molar ratio	DIN/PO₄-P ratio in summer
`phytoplankton_abundance`	10³ cells/L	Net-collected phytoplankton abundance
`SST`	°C	Sea surface temperature
`PAR`	mol m⁻² day⁻¹	Photosynthetically active radiation
`Chl-a`	μg/L	Chlorophyll-a concentration
`YellowRiver_discharge`	10⁸ m³	Freshwater discharge during WSRS summer
`DIN_input`	G mol	DIN input from Yellow River during WSRS summer
`PO4-P_input`	G mol	PO₄-P input from Yellow River during WSRS summer
`N*`	μmol/L	Terrestrial DIN not involved in internal N:P transformations

3.2 Seasonal variations

Variable	Unit	Description
`sample_time`	YYYY-MM-DD	Date of sampling
`longitude`	°	Longitude of sampling site
`latitude`	°	Latitude of sampling site
`SST`	°C	Sea surface temperature
`PAR`	mol m⁻² day⁻¹	Photosynthetically active radiation
`Chl-a`	μg/L	Chlorophyll-a concentration
`DIN`	μmol/L	Dissolved inorganic nitrogen
`PO4-P`	μmol/L	Phosphate concentration
`SiO3-Si`	μmol/L	Silicate concentration
`DIN/PO4-P`	molar ratio	DIN/PO₄-P ratio
`N*`	μmol/L	Terrestrial DIN not involved in internal transformations
`CAFE_NPP`	mg C m⁻² day⁻¹	CAFE-model NPP estimate
`SDD`	m	Secchi disk depth
`Wind`	m/s	Surface wind speed

3.3 Field surveys

Variable	Unit	Description
`sample_time`	YYYY-MM-DD	Date of sampling
`longitude`	°	Longitude
`latitude`	°	Latitude
`Chl-a`	μg/L	Chlorophyll-a concentration
`Synechococcus`	cells/mL	Synechococcus abundance
`picoeukaryotes`	cells/mL	Picoeukaryotes abundance
`nanoeukaryotes`	cells/mL	Nanoeukaryotes abundance
`NO3-N`	mg/L	Nitrate
`NO2-N`	mg/L	Nitrite
`NH4-N`	mg/L	Ammonium
`DIN`	mg/L	Dissolved inorganic nitrogen (sum of NO₃⁻, NO₂⁻, NH₄⁺)
`PO4-P`	mg/L	Phosphate
`DIN/PO4-P`	molar ratio	DIN/PO₄-P ratio
`CAFE_NPP`	mg C m⁻² day⁻¹	CAFE-model NPP estimate

4. Missing Data

All missing or unavailable values are labeled as null.
null indicates that the data were either not measured or not applicable for that observation.
For example, diatom/dinoflagellate ratio may be missing for certain years or stations if plankton net samples were not collected.

5. Notes and Limitations

Phytoplankton ratios derived from 20-μm mesh net samples may underestimate small-celled taxa, particularly picoeukaryotes.
Seasonal and inter-annual patterns may be influenced by multiple interacting factors (e.g., nutrients, SST, PAR), so correlations should be interpreted with caution.
Units and variable definitions are provided to facilitate reanalysis by other researchers.

6. References

CAFE model: Oregon State University, http://www.science.oregonstate.edu/ocean.productivity/
MODIS Level-3 SST, PAR, Chl-a: NASA Ocean Color, https://oceancolor.gsfc.nasa.gov/
Field surveys: This study, 2023
Yellow River discharge and nutrient data: Yang et al., 2024; Jiang et al., 2020

Access information

Other publicly accessible locations of the data:

National Earth System Science Data Center (https://www.geodata.cn)

Data was derived from the following sources:

CAFE model: Oregon State University, http://www.science.oregonstate.edu/ocean.productivity/
MODIS Level-3 SST, PAR, Chl-a: NASA Ocean Color, https://oceancolor.gsfc.nasa.gov/