This data package provides net community production (NCP) and gross oxygen production (GOP, a measure of gross primary production) for the winter and summer Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER) Transect cruises in 2022. Two tables are provided: a high-frequency table with NCP rates calculated from measurements of O2/Ar made continuously by an at-sea equilibrator inlet mass spectrometer (EIMS), and a low-frequency table with both NCP and GOP rates calculated for discrete samples measured post-cruise. The GOP rates were calculated from triple O2 isotopic (TOI) ratios. These data are derived from the EIMS and TOI data for the NES-LTER Transect cruises in EDI data package knb-lter-nes.6.3.
more »
« less
This content will become publicly available on March 13, 2025
Unusual Hemiaulus bloom influences ocean productivity in Northeastern US Shelf waters
Abstract. Because of its temperate location, high dynamic range of environmental conditions, and extensive human activity, the long-term ecological research site in the coastal Northeastern US Shelf (NES) of the northwestern Atlantic Ocean offers an ideal opportunity to understand how productivity shifts in response to changes in planktonic community composition. Ocean production and trophic transfer rates, including net community production (NCP), net primary production (NPP), gross oxygen production (GOP), and microzooplankton grazing rates, are key metrics for understanding marine ecosystem dynamics and associated impacts on biogeochemical cycles. Although small phytoplankton usually dominate phytoplankton community composition and Chl a concentration in the NES waters during the summer, in August 2019, a bloom of the large diatom genus Hemiaulus, with N2-fixing symbionts, was observed in the mid-shelf region. NCP was 2.5 to 9 times higher when Hemiaulus dominated phytoplankton carbon compared to NCP throughout the same geographic area during the summers of 2020–2022. The Hemiaulus bloom in summer 2019 also coincided with higher trophic transfer efficiency from phytoplankton to microzooplankton and higher GOP and NPP than in the summers 2020–2022. This study suggests that the dominance of an atypical phytoplankton community that alters the typical size distribution of primary producers can significantly influence productivity and trophic transfer, highlighting the dynamic nature of the coastal ocean. Notably, summer 2018 NCP levels were also high, although the size distribution of Chl a was typical and an atypical phytoplankton community was not observed. A better understanding of the dynamics of the NES in terms of biological productivity is of primary importance, especially in the context of changing environmental conditions due to climate processes.
more » « less- NSF-PAR ID:
- 10509324
- Publisher / Repository:
- Copernicus Publications
- Date Published:
- Journal Name:
- Biogeosciences
- Volume:
- 21
- Issue:
- 5
- ISSN:
- 1726-4189
- Page Range / eLocation ID:
- 1235 to 1257
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Phytoplankton growth and microzooplankton grazing rates were measured from incubation experiments using the dilution method in the framework of the Northeast U.S. Shelf Long-Term Ecological Research project. The data set includes plankton population dynamics rates obtained during 12 cruises from winter 2018 (EN608) to summer 2022 (EN687) along a north/south transect from Martha’s Vineyard to the shelf-break. Phytoplankton growth and microzooplankton grazing rates were measured for the total phytoplankton community (chl-a concentrations) and for size fractions (chl-a size fractionation) less than and greater than 10 µm. Phytoplankton growth and microzooplankton grazing rates, the first trophic interaction between primary producers and higher trophic levels, are essential parameters to assess the cycling and export of carbon in the ocean and to better understand marine food webs.more » « less
-
This data package provides net community production (NCP) and gross oxygen production (GOP, a measure of gross primary production) for the winter and summer Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER) Transect cruises in 2021. Two tables are provided: a high-frequency table with NCP rates calculated from measurements of O2/Ar made continuously by an at-sea equilibrator inlet mass spectrometer (EIMS), and a low-frequency table with both NCP and GOP rates calculated for discrete samples measured post-cruise. The GOP rates were calculated from triple O2 isotopic (TOI) ratios. These data are derived from the EIMS and TOI data for the NES-LTER Transect cruises in EDI data package knb-lter-nes.6.3.more » « less
-
This data package provides net community production (NCP) and gross oxygen production (GOP, a measure of gross primary production) for the winter, spring, and summer Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER) Transect cruises in 2020. Two tables are provided: a high-frequency table with NCP rates calculated from measurements of O2/Ar made continuously by an at-sea equilibrator inlet mass spectrometer (EIMS), and a low-frequency table with both NCP and GOP rates calculated for discrete samples measured post-cruise. The GOP rates were calculated from triple O2 isotopic (TOI) ratios. These data are derived from the EIMS and TOI data for the NES-LTER Transect cruises in EDI data package knb-lter-nes.6.3.more » « less
-
more » « less
Abstract Microzooplankton grazing is an essential parameter to predict the fate of organic matter production in planktonic food webs. To identify predictors of grazing, we leveraged a 6‐yr time series of coastal plankton growth and grazing rates across contrasting environmental conditions. Phytoplankton size–structure and trophic transfer were seasonally consistent with small phytoplankton cell dominance and low trophic transfer in summer, and large cell dominance and higher trophic transfer in winter. Departures from this pattern during two disruptive events revealed a critical link between phytoplankton size–structure and trophic transfer. An unusual summer bloom of large phytoplankton cells yielded high trophic transfer, and an atypical winter dominance of small phytoplankton resulted in seasonally atypical low trophic transfer. Environmental conditions during these events were neither seasonally atypical nor unique. Thus, phytoplankton size–structure rather than environmental conditions held a key‐role driving trophic transfer. Phytoplankton size–structure is easily measurable and could impart predictive power of food‐web structure and the fate of primary production in coastal ecosystems.
