Secular Increase in Nutrient Levels through the Phanerozoic: Implications for Productivity, Biomass, and Diversity of the Marine Biosphere

Abstract

Approximately three decades ago, Helen Tappan began a series of classic papers on the interaction of the marine and terrestrial realms, and their influence on nutrient input to the oceans, marine productivity, and plankton evolution and extinction. Unfortunately, many of her assertions conflicted with the fossil record, and her papers have been treated in recent accounts as being largely of historical interest only. Based on recent 13C, lithologic, and paleontologic evidence (including a reinterpretation of plankton diversity patterns), I reassess the role of nutrients and productivity in the evolution of the biosphere through the Phanerozoic. Cambrian-to-Devonian seas were characterized by extremely low nutrient ("superoligotrophic") conditions. By the Permo-Carboniferous, nutrient levels and marine productivity had increased toward intermediate ("submesotrophic") concentrations via glaciation, sea level fall, and enhanced deep-ocean overturn and continental weathering. Following end-Permian extinctions, bioturbation rates increased above Paleozoic levels, thereby recycling nutrients back to surface waters (fully "mesotrophic" conditions) and enhancing marine productivity as pelagic habitats expanded (via sea level rise). Increased rates of ocean circulation, continental erosion, and bioturbation further heightened nutrient levels ("eutrophic" conditions) and productivity in the Neogene. Rising nutrient levels and marine productivity may have fueled a secular increase in marine biomass and diversity, and the accompanying decline in background extinction rates, through the Phanerozoic. CAMBRO-DEVONIAN SEAS: PUNCTUATED "SUPEROLIGOTROPHY" Stable Isotope Evidence Surface nutrient levels may have been far lower during much of the Cambro-Devonian than those of oligotrophic waters today (e.g., oceanic gyres; Worsley et al., 1986), and

Tintinnid ciliate diversity in the Mediterranean Sea: longitudinal patterns related to water column structure in late spring-early summer

“…For example, relationships between resource availability and diversity vary with scale. On a geological time scale, plankton diversity has been positively associated with increases in 'trophic state' of seas from an oligotrophic Devonian to the eutrophic Paleozoic (Martin 1996). In comparing different systems, among present-day freshwater communities, there is a strong negative relationship between nutrient concentrations and diversity of both phytoplankton and zooplankton (e.g., Liebold 1999).…”

Phanerozoic diversity and neutral theory

“…Three decades of paleobiological research have documented a rich array of trends in marine systems through the Phanerozoic, including increases in global richness Sepkoski et al 1981), local richness (Bambach 1977;Powell and Kowalewski 2002;Bush and Bambach 2004;Kowalewski et al 2006), local evenness (Powell and Kowalewski 2002), abundance (Kidwell and Brenchley 1994;Li and Droser 1999;Martin 2003;Finnegan and Droser 2008;Smith and McGowan 2008;Pruss et al 2010), and body size (Bambach 1993;Finnegan et al 2011;Payne et al 2014). Understanding and demonstrating the causal connections among these patterns has been elusive, but the recognition of a Phanerozoic increase in θ provides that causal link.…”

“…The area of shallow-marine ecosystems has waxed and waned over the Phanerozoic, it has not shown any long-term trend, and shallow-marine area is lower in the Neogene than in the Ordovician (Hannisdal and Peters 2011), opposite to the trend needed to generate increasing θ. Although absolute abundance of organisms is difficult to infer from the fossil record, a growing body of evidence suggests that the abundance of marine organisms has increased over the Phanerozoic (Kidwell and Brenchley 1994;Martin 2003;Finnegan and Droser 2008;Smith and McGowan 2008;Pruss et al 2010;Li and Droser 1999).…”

Sampling-standardized expansion and collapse of reef building in the Phanerozoic

“…Sealevel changes and tectonic factors that lead to the formation and destruction of marine habitats are currently discussed as the "common cause" scenario, which would affect sampling regimes, biodiversity and ecosystems simultaneously (Peters 2005(Peters , 2006. Evolutionary or ecological changes influencing the durability of shells or productivity are also of major interest in paleobiology (Martin 1995(Martin , 1996Kershaw & Brunton 1999;Kidwell 2005). These factors are sacrificed when departures between sampling and the fossil record of an ecosystem are analyzed.…”