Particulate amino acids in the sea: Effects of primary productivity and biological decomposition

Abstract

We measured the flux of amino acids associated with sinking particles collected by sediment traps at two Pacific Ocean sites. These results were compared with results from six other sites where we and others have measured amino acid fluxes. This comparison shows that the flux of amino acids on sinking particles is related to primary productivity. This relationship exists in spite of differences in the oceanic regimes sampled and in the sediment traps, bactericides, and amino acid analysis techniques used. The amount of particulate amino acids leaving the euphotic zone in areas of higher productivity is a higher proportion of the primary production than in less productive areas. And, a larger amount of particulate amino acids reaches deeper waters in more productive areas. However, the particulate amino acids leaving the euphotic zone decompose faster with depth in more productive areas. Faster decomposition below the surface waters in areas of high productivity suggests that (I) decomposition of particulate organic matter may be mediated more by zooplankton and less by microbial processes than in areas of lower productivity, or (2) phytoplankton growing in more productive areas are more easily remineralized than those growing in less productive areas.

Preservation of organic matter in mound-forming coral skeletons

“…The contribution of these amino acids in marine particles and sediments usually increases with degradation, except for glutamic acid, which decreases with degradation (Lee and Cronin, 1984;Müller et al, 1986;Burdige and Martens, 1988;Lee et al, 2000). In the Florida Keys coral, mole % aspartic acid and glutamic acid in THAA increase with age, while mole % glycine and alanine decrease with age (Fig.…”

Linking diagenetic alteration of amino acids and bulk organic matter reactivity

“…The preferential accumulation of glycine and threonine is probably due to their concentration in cell walls (Hecky et al 1973) that are preserved during sinking and decomposition (Siezen and Mague 1978;Lee and Cronin 1984;Müller et al 1986), whereas amino acids that are concentrated in cell plasma (tyrosine, phenylalanine, and glutamic acid) (Hecky et al 1973) tend to be depleted during degradation. Sediment-trap studies sampling POM at increasing depth in the water column confirm these compositional changes of amino acids during decay ( Table 1.…”

“…3B), demonstrates the consistency of the DI with well-established indicators of diagenetic alteration. The microbial production of GABA and BALA from their protein precursors and their subsequent preservation in sedimentary deposits has been proposed as a degradation state indicator of marine sediments (Lee and Cronin 1984;Cowie and Hedges 1994). Similarly, hexosamines are generally incorporated into structural biopolymer matrices such as bacterial cell walls and chitinous material (de Leeuw and Largeau 1993) and are enriched in more refractory materials (Dauwe and Middelburg 1998).…”

Solubilization of particles in sediment traps: revising the stoichiometry of mixed layer export

“…A number of studies have reported solubilization/degradation of organic carbon (Gardner et al, 1983;Noji et al, 1999;Honjo et al, 1995), and nitrogen (Hansell and Newton, 1994;Kähler and Bauerfeind, 2001) amino acids (Lee and Cronin, 1984;Lee et al, 1992), fatty acids (Körtzinger et al, 1994), phosphate (Knauer et al, 1984;von Bodungen et al, 1991), dissolved inorganic nitrogen (primarily ammonium, Knauer et al, 1990;von Bodungen et al, 1991), silica (von Bodungen et al, 1991Bauerfeind et al, 1997;Antia et al, 1999), metals (Knauer et al, 1984;Pohl et al, 2004) and particulate barium (Dymond and Collier, 1996). Despite finding that solubilization can account for a substantial proportion of the measured particulate flux, to date there has been no systematic analysis of the corrections that may need to be applied to arrive at values of the entire flux arriving in the trap.…”