Discarded appendicularian houses as sources of food, surface habitats, and particulate organic matter in planktonic environments

Observations using SCUBA reveal that macroscopic organic aggregates produced by appendicularians reached densities of 44 to 1,130 m −3 in the Gulf of California. Though these aggregates constituted less than 5% of total particulate carbon, their carbon : nitrogen ratio was twice that of particles in the surrounding seawater. The C : N ratio of the total particulate matter increased directly with the density of appendicularian produced aggregates. Aggregates were utilized extensively as food by euphausiid larvae, copepods, and planktivorous fish. Such aggregates affect the adaptive strategies and distribution of the plankton by introducing spatial heterogeneity and physical structure into an environment previously considered unstructured and may substantially alter the chemical composition of particulate organic matter.