Effect of salmon carcasses on egg production of a freshwater amphipod, Jesogammarus jesoensis: a field observation

Abstract

The effect of salmon carcasses on egg production of a freshwater amphipod, Jesogammarus jesoensis, was examined by comparing populations with and without a supply of carcasses in Naibetsu River in Hokkaido, northern Japan. The female body length in the population with carcasses became larger in the years when carcasses were abundant, being significantly larger than that in the population without carcasses. No evidence, however, was found that carcasses influenced the ratio of brooding females to mature females. Every year, the clutch size in the population with carcasses was larger than the clutch size without carcasses. Because clutch size showed a significant correlation with female size, the larger clutch size was considered to be a result of the larger female size. In addition, however, comparison of clutch size using analysis of cavariance revealed that clutch size in the population with carcasses was larger than that without carcasses, even for the same body size. Egg size showed no difference between populations and for different years. These results indicate that salmon carcasses influence egg production of J. jesoensis by increasing female body size and by increasing the investment in each clutch per unit of body size.

Reproductive Biology and Adaptability of the Invasive Alien Freshwater AmphipodCrangonyx floridanus(Crustacea: Amphipoda, Crangonyctidae)

“…For example, when their habitat is rich in salmon carcasses, they tend to oviposit significantly more eggs (Kusano and Ito, 2005). Our research on the alien amphipod Crangonyx floridanus, however, showed no season-related fluctuations in batch or egg size.…”

Fish carcass deposition to suppress invasive lake trout through hypoxia causes limited, non‐target effects on benthic invertebrates in Yellowstone Lake

“…We observed amphipods, the dominant benthic invertebrate, on top of lake trout carcasses, suggesting potential for direct consumption. Amphipods consume many food resources, and high‐quality food resources such as carcass material can increase growth and fecundity (Cruz‐Rivera & Hay, 2000; Ito 2003; Kusano & Ito, 2005; MacNeil et al., 1997). Additionally, mobile taxa such as amphipods may immigrate to sites treated with carcass material and colonize the carcasses, which could cause increases in density and biomass evident at relatively short timescales (Chaloner et al., 2002).…”