Non-native pink salmon Oncorhynchus gorbuscha carcasses benefit native benthic macroinvertebrates

Area of Science:

• Ecology
• Invasive Species Biology
• Nutrient Cycling

Background:

• Pink salmon (Oncorhynchus gorbuscha) invasion in the North Atlantic raises ecological concerns.
• Impacts of invasive salmon on non-native ecosystems are poorly understood.
• Marine-derived nutrients from salmon are crucial in native ranges but unknown in invaded ones.

Purpose of the Study:

• Investigate the ecological consequences of invasive pink salmon carcasses on benthic macroinvertebrate density and community structure.
• Determine if nutrients from carcasses are assimilated by native biota using stable isotopes.
• Assess the short-term effects of nutrient subsidies from invasive salmon.

Main Methods:

• Experimental channels were used with three treatment levels: control, low carcass addition, and high carcass addition.
• Pink salmon carcasses were added for 60 days to assess impacts on macroinvertebrates.
• Stable isotopes of carbon (δ13C) and nitrogen (δ15N) were employed to trace nutrient incorporation into native organisms.

Main Results:

• Macroinvertebrate density increased near carcasses in the high-addition treatment, indicating aggregation.
• Higher δ15N values in macroinvertebrates and willow moss near carcasses demonstrated nutrient uptake from decomposing salmon.
• Increased density of small macroinvertebrates was observed, but community composition did not significantly change within the 60-day experiment.

Conclusions:

• Native biota, including primary producers and macroinvertebrates, can assimilate marine-derived nutrients from invasive pink salmon carcasses.
• Invasive salmon may provide a nutrient subsidy to invaded stream ecosystems.
• Further research is needed to understand the long-term ecological effects of these nutrient subsidies.