Figure 1: The Island Mass Effect. | Nature Communications

Figure 1: The Island Mass Effect.

From: Near-island biological hotspots in barren ocean basins

Figure 1

Localized increases in phytoplankton biomass near island- and atoll-reef ecosystems—Island Mass Effect—may be the result of several causative mechanisms that enhance nearshore nutrient concentrations, including coral reef ecosystem processes, such as nitrogen fixation or decomposition, and animal waste products, such as reef-associated fishes; current-bathymetric interactions that can drive vertical transport of water masses via upwelling, downstream mixing and eddies, and internal waves; island-associated inputs, such as submarine groundwater discharge and outflow from rivers, which can mobilize and transport sediment and other terrigenous material laden with nutrients; the flushing and associated outflow of lagoonal waters from atoll environments; human-derived runoff of agricultural production, urban development and wastewater input. Enhanced nearshore phytoplankton can influence food-web dynamics and elicit a biological response in higher trophic groups, for example: horizontal and vertical migration patterns in squids, fishes and other micronekton (collectively referred to as the ‘mesopelagic boundary layer community’) that move nearshore at night to feed on increased food resources; inshore migration of pelagic predators, such as tuna, to feed on the island-associated micronekton community; greater reef fish biomass and increased cover of calcifying benthic organisms in coral reef ecosystems.

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