What Controls the Availability to Animals of Detritus Derived from Vascular Plants: Organic Nitrogen Enrichment or Caloric Availability?

Abstract

ABSTRACT: Detritus derived from marsh grass with high available caloric content was mineralized and incorporated by the polychaete Capitella capitata at a significantly higher rate than detritus from marsh grass with available caloric content more typical of naturally-occurring Spartina altemiflora. Detritus derived from vascular plant material is usually low in nitrogen content, so nitrogen enrichment via microbial activity may increase nitrogen content over time. Detritus research has emphasized the microbial role in protein enrichment. However, such detritus is also composed mostly of structural material not generally assimilable by macroconsumers. Microbial decomposition results in transformation products whose energy content is available to macroconsumers. Our results suggest that available energy and not necessarily nitrogen content, can limit the utilization of marsh grass detritus to the macroconsumer.