Community structure and spatiotemporal dynamics of the zooplankton in the South Brazilian Bight: A review

Abstract

The South Brazilian Bight (23-28.5°S; SBB) is a typical western boundary current system with a wide shelf and which has high ecologic and economic importance, supporting nationally important fishing grounds. Away from the coastal areas, the planktonic production is mostly controlled by regenerative processes prevailing in the oligotrophic Tropical Water (TW) of the Brazil Current, enriched by the advection of the nutrient-rich South Atlantic Central Water (SACW). About 790 zooplanktonic invertebrate species have been recorded, what is an underestimate considering that most meroplanktonic and some holoplanktonic taxa are largely unstudied. An inshore-offshore gradient is clear. Zooplankton abundance and biomass are typically higher in more coastal areas, diminishing offshore as the influence of the oligotrophic TW increases, while the diversity has the inverse tendency. The cold and nutrient-rich SACW intrusions certainly are the most relevant mesoscale physical feature over the shelf of the SBB, increasing considerably the primary production and subsequently zooplankton abundance and production. Indeed, available data suggest that the intrusions of the SACW and their strength are an important factor influencing both seasonal and interannual variability in zooplankton diversity, biomass, abundance, production, and sizespectra. While the distributional patterns of most of the dominant groups in relation to the main water masses are relatively well-known, little is known about the life strategy, trophic interactions, physiological responses, and the impact of the main physical processes on these populations. In this review, we also emphasize the need for process-oriented studies along SBB with spatiotemporal scales relevant to the main physical events in order to better understand the zooplankton dynamics and their role in the regional fishery production.