Pacific herring spawn and macroalgae subsidize intertidal detritivores

摘要: Each year along the Pacific coast of North America, Pacific herring (Clupea pallasi) aggregate and spawn in the nearshore and intertidal. Although ephemeral, these spawn events often represent extremely large aggregations of biomass and energy, a portion of which is transferred to intertidal ecosystems. This input of herring resources, mainly in the form of eggs, represents a spatial subsidy to intertidal and possibly terrestrial ecosystems, but little is known of these relationships. Using fatty acids and stable isotopic signatures of carbon and nitrogen, we (1) traced the sources of production for detritivorous sand hoppers (Traskorchestia traskiana and T. georgiana) and (2) tested the hypothesis that herring resources subsidize sand hoppers. To this end, sand hoppers and potential sources of production (macroalgae, seagrass and herring eggs, when present) were collected from five mixed substrate beaches (two control, two high density and one low density spawn) before and after a herring spawn event in Quatsino Sound, British Columbia.