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The biomass of mesopelagic fishes is estimated to be on the order of or to exceed that of fishes in the epipelagic. Despite their abundance and importance as an ecological link between surface and deep ocean habitats, there is a dearth of basic life history data for mesopelagic fishes. Reproductive biology data are critical for understanding population dynamics and estimating production of a species, particularly when age and growth data are lacking. Between July 2018 and August 2022, collections were made in the western North Atlantic utilizing multiple net types to capture a broad size-range of mesopelagic fishes. Histological analysis of gonad tissue from four numerically dominant species—Argyropelecus aculeatus(Sternoptychidae),Benthosema glaciale(Myctophidae),Scopelogadus beanii(Melamphaidae), andSigmops elongatus(Gonostomatidae)—were examined to describe aspects of reproduction. We determined thatA. aculeatusandB. glacialeare gonochoristic batch spawners with indeterminate fecundity, and the standard length at which 50% of females were mature (L₅₀) was 39.45 and 33.77 mm, respectively.S. beaniiwere found to be gonochoristic, iteroparous, and likely have multi-year oocyte development with an L₅₀of 90.38 mm.S. elongatuswas confirmed as a protandrous hermaphrodite, iteroparous, and had an L₅₀of 200.45 mm. This study is the first to present regional maturity ogives for all four species and to describe detailed reproductive patterns inA. aculeatus, S. beanii, andS. elongatus.These results contribute to the data necessary for quantifying the role of mesopelagic fishes in global biogeochemical cycles and for ensuring responsible use of mesopelagic resources. 

This package provides a concatenated table of events recorded on seasonal Transect cruises for Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER) and other opportunistic cruises within the transect region. Events were recorded onboard with Rolling Deck to Repository (R2R) event logger (elog) software. Event listings include date, time, ship's position, instrument, and action for over the side operations, underway data collection, and other miscellaneous events during the cruise. The event log is used post-cruise in physical sample cataloging and data integration. Cruises are seasonal and include NES-LTER dedicated voyages, spring and fall cruises in collaboration with the Ocean Observatories Initiative (OOI), and additional opportunistic cruises. 

Particulate organic carbon and nitrogen are measured from discrete bottle samples collected during CTD-rosette casts on Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER) Transect cruises (ongoing since 2017). Sampling frequency is approximately seasonal. Samples were filtered and collected on combusted glass fiber filters, pelletized using ultra clean tin disks, and combusted using a Flash EA1112 CHN analyzer to calculate concentrations of particulate organic carbon and particulate organic nitrogen in micromoles per liter. Values are also reported as concentrations in micrograms per liter and carbon to nitrogen molar ratio. 

Dissolved organic carbon and dissolved total nitrogen are measured from discrete bottle samples collected during CTD rosette casts on Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER) transect cruises (ongoing since 2022). Sampling frequency is approximately seasonal. Sample collection is paired with particulate organic carbon at surface, subsurface chlorophyll max, and sometimes a third depth. Samples are filtered directly from the CTD rosette and acidified in the field, then analyzed using a Shimadzu TOC-LCPH total organic carbon analyzer coupled to a TNM-L analyzer for total nitrogen. Values are reported in micromoles per liter. 

Dissolved inorganic nutrients are measured from water column bottle samples taken on NES-LTER Transect cruises (ongoing since 2017) and include nitrate + nitrite, ammonium, silicate, and phosphate. Sampling frequency is approximately seasonal. Samples were filtered, frozen, then processed at the Woods Hole Oceanographic Institution's Nutrient Analytical Facility. Each sample may have up to 2 replicates, indicated by a or b in the data table. These macro-nutrients are analyzed in seawater using a colorimetric assay in which light absorbance is measured versus known standards, and final concentrations are calculated in micromole per liter. Some of the data are from cruises in collaboration with the Ocean Observatories Initiative (OOI). 

This package provides a table of cruises to the Martha's Vineyard Coastal Observatory for Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER). The majority of events are single day cruises, however, samples missing an MVCO Event Number were collected on multi-day NES-LTER transect cruises aboard larger research vessels. The same sampling protocols for CTD and bongo collection are used on both cruise types. Sampling frequency is approximately monthly, with NES-LTER sampling ongoing since 2017. Cruises involve collection of water column bottle samples, surface bucket samples, and zooplankton net tow samples, as well as ship-provided data. NES-LTER transect cruises will have more extensive underway and acoustic data which can be found by searching by cruise at https://www.rvdata.us/data. The event number for each cruise is provided, along with date, vessel name, cruise identifier where applicable, link to data location (for CTD, ADCP, and other underway data), and checklist of six data types. 

This data package provides abundance data for zooplankton collected during seasonal transect cruises conducted as part of the Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER) program, ongoing since 2018. Zooplankton are collected at standard NES-LTER transect stations (L1–L11) and the Martha’s Vineyard Coastal Observatory (MVCO) via oblique tows, using a 61-cm Bongo net with two mesh sizes (335 µm and 150 µm). The transect extends southward from near Martha’s Vineyard, Massachusetts, reaching approximately 150 km offshore along longitude 70 deg 53 min W, covering the continental shelf from nearshore to the shelf break, with sampling depths between 20 and 200 meters. Only the 335-µm mesh data is included here, as samples from this net are preserved on board and shipped to Morski Instytut Rybacki in Szczecin, Poland, where they are counted and identified to the lowest possible taxonomic level. Counts of taxa identified are provided by the NOAA’s Northeast Fisheries Science Center. Samples from the 150 um are preserved for other purposes and will be published as a separate data package. This second version of the data package includes staged and unstaged abundance data in volumetric (100 m³) and aerial (10 m²) units from the 335-µm net. Supplemental tables provide metadata for the cruises and stations. 

Abstract Phytoplankton community size structure influences the production and fate of organic carbon in marine food webs and can undergo strong seasonal shifts in temperate regions. As part of the Northeast US Shelf (NES) Long‐Term Ecological Research program, we measured net primary production (NPP) rates and chlorophylla(Chla) concentrations in three phytoplankton size classes (< 5, 5–20, and > 20 μm) during winter and summer for 3 yr along a coastal‐to‐offshore transect. Mean depth‐integrated NPP was 37% higher in summer than winter, with limited cross‐shelf differences because of significant interannual variability. When averaged across the shelf, depth‐integrated NPP was dominated by the > 20 μm size class in winter and generated equally by the three size fractions in summer because of substantial contributions from cells > 20 μm at the Chlamaximum depth. Furthermore, the relationship between Chlaand NPP, in terms of relative contributions, varied by size class. Variations in this relationship have implications for models of primary productivity on the NES and beyond. In comparison to historical NPP data, we identified equivalent levels of winter NPP but observed a 25% decrease in summer NPP, suggesting a potential reduction in the seasonality of NPP on the NES. Together, our results highlight seasonal shifts in NPP rates of different phytoplankton size classes, with implications for food web structure and export production. These data emphasize the importance of quantifying size‐fractionated NPP over time to constrain its variability and better predict the fate of organic carbon in coastal systems under environmental change. 

Phytoplankton communities in the open ocean are high‐dimensional, sparse, and spatiotemporally heterogeneous. The advent of automated imaging systems has enabled high‐resolution observation of these communities, but the amounts of data and their statistical properties make analysis with traditional approaches challenging. Spatiotemporal topic models offer an unsupervised and interpretable approach to dimensionality reduction of sparse, high‐dimensional categorical data. Here we use topic modeling to analyze neural‐network‐classified phytoplankton imagery taken in and around a retentive eddy during the 2021 North Atlantic EXport Processes in the Ocean from Remote Sensing (EXPORTS) field campaign. We investigate the role physical‐biological interactions play in altering plankton community composition within the eddy. Analysis of a water mass mixing framework suggests that storm‐driven surface advection and stirring were major drivers of the progression of the eddy plankton community away from a diatom bloom over the course of the cruise.