This is an original study on a on a coastal ecosystem, combining environmental data with data on phytoplankton functional groups. Such a time series on flow cytometry in combination with environmental data at high temporal resolution over multiple years is relatively rare and can give a detailed view into the variability of the phytoplankton community over the last decade. This is the first pluri-annual study of the whole size-range of the phytoplankton community characterized by one unique method.

The use of neural networks to emulate the dynamics of the Earth system (ocean, atmosphere) is of critical importance since it enables efficient and operational forecast, data assimilation, and affordable uncertainty quantification. This field has been very productive in numerical weather forecasts but relatively fewer results were demonstrated in the oceans. This paper could be a reference for mesoscale ocean dynamics emulation.

This is an important contribution to the science surrounding the Atlantic Meridional Overturning Circulation (known as AMOC), in particular with regard to observations and methods. This work may have strategic relevance for planning observations in the future. It also represents an interesting effort at incorporating artificial intelligence (AI) technology into obtaining optimal results from observational data analysis.

This paper in the Ocean Science Jubilee Special Issue is a multidisciplinary review of silicon in the ocean (and in fact also in the earth system). It presents "everything you ever wanted to know about silicates but were afraid to ask". In addition to its scientific excellence and thoroughness as a review, it is also noteworthy for being entirely conceived and written by a group of early career researchers who decided to work together on this topic. We commend their initiative!

This paper is of high quality, it exemplifies the complexity of detecting ocean eddies (eulerian versus lagrangian, importance of the code parameters of the regions considered), it acknowledges the fact that not all ocean eddies are the same (dynamically talking), and that their effect on plankton is complex. The method presented is well-described, powerful and would allow digging into these biophysical interactions in many different oceanographic settings. It shows that the common view following seminal papers by e.g. McGillicuddy and D. Chelton that consists of "cyclonic eddies -> isopycnals shaoling -> increase phytoplankton biomass" versus "anticyclonic eddies -> isopycnal deepening -> decreased phytoplankton biomass" is too simplistic and needed to be updated.

The article provides critical observations relating to the Thwaites Eastern Ice Shelf and the modified Circumpolar Deep Water. The observed warming has important consequences for implied basal melting and can impact the stability of the ice shelf, with notable subsequent impacts, such as addition of mass into the ocean and thus implied sea level rise. The work calls for further efforts in constraining the uncertainties via a combination of observations, modelling and mechanistic understanding.

Marine heatwaves are of particular interest globally currently, both scientifically and for their impact on communities. While much work has been done on surface expressions of marine heatwaves, their subsurface expressions have been less well studied. This is particularly the case in the Southwest Indian Ocean. This region is climatically important and the ecological impacts of marine heatwaves (both surface and subsurface) in this area could be significant, with consequential negative socio-economic outcomes.

The authors present the first synoptic characterisation of an oceanic mesoscale eddy’s full life cycle using groundbreaking SWOT satellite altimetry. This unprecedented view challenges the long-standing perception of eddies as simple, elliptical structures, revealing the crucial role of mesoscale interactions in their evolution. The SWOT results capture intense submesoscale turbulence at the eddy’s rim, exposing secondary instabilities that likely drive its dissipation. These findings not only validate decades of vortex theory but also open new frontiers in our understanding of oceanic turbulence.

The study introduces an innovative method for estimating meridional heat transport (MHT) across latitudes. By combining diverse oceanographic approaches, including remote sensing (gravimetry, altimetry), in-situ observations, and advanced statistical modeling, the study bridges several domains of ocean science. It opens the door for things such as an improved estimation of ocean heat content, surface fluxes, sea level variability, currents and enhanced error characterization in satellite observations. The new method could serve as the foundation for alternative estimates of both MHT and the Atlantic Meriodional Circulation (AMOC) that do not depend on costly, geographically limited in-situ observing arrays, which is especially beneficial if it allows the AMOC to be observed across a range of latitudes.

Oxygen is fundamental to ocean biogeochemical processes, with deoxygenation potentially reducing biodiversity, and disrupting biogeochemical cycles. This paper develops and implements a new inverse method to decompose oxygen change into its constituent parts by linking each process to concomitant changes in temperature and dissolved inorganic carbon (DIC). They apply this method to a GO-SHIP repeated section of the North Atlantic Ocean. They find that alterations in remineralisation, either local or upstream, are responsible for up to half of the total oxygen decrease seen in the upper 2000 m between 1992 and 2015. This method could be repeated on any dataset, observations or model, that includes temperature, DIC, and oxygen concentration data.

This paper highlights a new implementation of density co-ordinate functionality within an adjoint ocean model, the MITgcm ECCO adjoint. This is illustrated accordingly with a science application investigating the variability of Subantarctic Mode Water. The use of adjoints helps to trace causal links within the ocean, and the density-following feature is of particular interest for the ocean community with many possible further applications.

The paper contributes to our knowledge of the impact of marine heat waves on ecosystems, a subject that is topical and that we know little of. The impact on coccolithophores is important for carbon uptake. The impact of MHW more generally on algal blooms is also important for higher trophic levels, the wider ecosystem, and for commercial interests such as aquaculture. The study gives useful confirmation that the environmental ranges defined by O’Brien et al for coccolithophore blooms do seem to apply even in these anomalous MHW conditions and in two separate regions.