Application of trophic transfer efficiency and age structure in the trophic analysis of fossil assemblages

We evaluate onshore-offshore trends in age-frequency distributions and trop hic transfer efficiencies using 11 modern death assemblages off the Texas c oast. Trophic transfer efficiencies-within trophic levels offer little insi ght over that achieved by a size-frequency distribution. Production/biomass ratios will always be 1 in the fossil record. Within trophic-level estimat es of paleogrowth efficiency, the ratio of paleoproduction to paleoingestio n (P-glt(i)/I-lt(i) where i indicates the i(th) trophic level and lt indica tes the time-averaged value) follow the expected ecological trend precisely in that paleogrowth efficiency is consistently higher in primary consumers than in predators in all 11 death assemblages. Paleoutilization efficiency , the ratio of predator paleoingestion to prey paleoproduction, I(lt)(2)deg rees /P(glt)(1)degrees, may provide information on the degree of bias in th e reservation of primary (1) and secondary (2) consumer trophic groups. I(l t)(2)degrees /P(glt)(1)degrees, fell below 0.1 in most cold-seep and bay as semblages, indicating a large surplus of primary consumers. In sharp contra st, I(lt)(2)degrees /P(glt)(1)degrees was above 10.0 in most heterotrophic continental slope and inner continental shelf assemblages, indicating an ov errepresentation of predators. In the classic food web, predator life span should exceed prey life span (DeltaL(lt): L(lt)(2)degrees > L(lt)(1)degrees ). Predators should be more insulated from fluctuations in food supply than their prey and the degree of this insulation should control DeltaL(lt). Of the 11 death assemblages covering the bay-to-continental slope transect, p redators' life spans were longer than their prey only on the continental sh elf and slope, indicating a requirement for a stable enough environmental r egime to permit biological processes rather than physical factors to contro l life spans. Paleoproduction transfer efficiency, the ratio of paleoproduc tion between two consecutive trophic levels, P(glt)(2)degrees /P(glt)(1)deg rees, is the most accurately estimated trophic transfer efficiency in paleo ecology because it does not require an estimate of age-at-death. The relati onships of paleoutilization efficiency and paleoproduction transfer efficie ncy are nearly identical among the 11 death assemblages. Although theoretic ally this need not be the case, these assemblages suggest that predator ove rrepresentation might be identified from a ratio dependent solely upon size -at-death.