The effect of fresh and aged Agarum fimbriatum and Nereocystis luetkeana diets on the population growth of Tigriopus californicus

Abstract

The study explores the effect of diets of fresh and aged Agarum fimbriatum and Nereocystis luetkeana on the population growth of Tigriopus californicus. Fresh diets were expected to increase abundance, and the two algal species were expected to produce different sized populations. Founding populations of 30 gravid females were fed weekly a piece of one of 4 diets (fresh / aged x A. fimbriatum / N. luetkeana) for 32 days. Fresh N. luetkeana resulted in the largest population growth (1845 +/-633.8) and fresh A. fimbriatum the smallest (521 +/-32.5). This trend was consistent for the nauplius, copepodite and adult life stages, as well as the gravid female populations. Hatching rates were studied and significant differences were found among the treatments. Gravid females fed fresh N. luetkeana diets hatched eggs the fastest (15.7 hrs +/- 12.4) and fresh A. fimbriatum the slowest (35.1 +/-21.6). Polyphenolic anti-herbivory compounds in A. fimbriatum are suggested as the primary cause for the findings.