Ocean Biology Studied from Space

Abstract

Visible spectral radiometric measurements from space, commonly referred to as ocean-colour measurements, provide a rich stream of information on ocean biota as well as on biological and ecosystem processes. The strength of the ocean-colour technology for observing marine life lies in its global reach, combined with its ability to sample the field at a variety of spatial and temporal scales that match the scales of the processes themselves. Another advantage lies in the growing length of the time series of ocean-colour-derived products, enabiling investigations into any long-term changes, if present. This paper presents an overview of the principles and applications of ocean-colour data. The concentration of chlorophyll-a, the major pigment present in phytoplankton–single-celled, free-floating plants that are present in the sunlit layers of the ocean–was the first, and remains the most common, biological variable derived from ocean-colour data. Over the years, the list of ocean-colour products have grown to encompass many measures of the marine ecosystem and its functions, including primary production, phenology and ecosystem structure. Applications that exploit the data are many and varied, and include ecosystem-based fisheries management, biogeochemical cycles in the ocean, ecosystem health and climate change. An integrated approach, incorporating other modes of ocean observations and models with satellite observations, is needed to investigate the mysteries of the marine ecosystem.

The link between surface and sub-surface chlorophyll-a in the centre of the Atlantic subtropical gyres: a comparison of observations and models

“…In this paper, we focus on the use of chlorophyll as an indicator of phytoplankton biomass. This follows standard biological oceanography practice, as it is an easily recorded consistent measure with global standards (see Table 1 of Sathyendranath et al, 2023) and is also one of the currencies used by most biological models, including the two that we had access to for this paper. However, a number of factors do affect the reliability of this measure of plankton biomass along the vertical dimension, including changes in plankton community structure and photoacclimation, viz.…”

“…Throughout this paper we have used estimates of chlorophyll as an indicator of biomass. Although widely used for pragmatic reasons (see Table 1 of Sathyendranath et al, 2023), there are potential biases arising from assuming a simple correspondence between chlorophyll and biomass.…”

Superyachts could support satellite ocean colour validation

“…Methods are also available to infer phytoplankton community structure from ocean-colour data, by exploiting spectral differences in the optical signatures of different types of phytoplankton, as well as other important optically-active constituents, such as the types of coloured dissolved organic matter (CDOM) in the water and non-algal particles. Recognised as an Essential Climate Variable, ocean-colour data helps to address many important issues, such as changing ocean biogeochemical cycles, collapsing fisheries, climate change, and shifts in waterborne diseases (Sathyendranath et al, 2023).…”