A fiddler crab reduces plant growth in its expanded range

Area of Science:

• Ecology
• Climate Change Biology
• Marine Biology

Background:

• Climate change is driving species range expansions globally.
• Ecosystem engineers, like burrowing crabs, can significantly alter recipient habitats.
• The Atlantic marsh fiddler crab (Minuca pugnax) has expanded its range northward.

Purpose of the Study:

• To investigate the ecological impacts of the invasive Atlantic marsh fiddler crab (Minuca pugnax) in its expanded range.
• To compare the effects of M. pugnax on Spartina alterniflora in its new range versus its historical range.
• To assess how M. pugnax influences foundational salt marsh primary producers.

Main Methods:

• A control-impact study design was employed.
• Spartina alterniflora aboveground and belowground biomass were measured.
• Benthic microalgal biomass was quantified in the presence and absence of M. pugnax.

Main Results:

• Spartina alterniflora aboveground biomass was 40% lower in areas with M. pugnax.
• Spartina alterniflora belowground biomass was 30% lower with M. pugnax presence.
• Benthic microalgal biomass decreased by 45% where M. pugnax was present, indicating grazing effects.

Conclusions:

• The ecological impact of M. pugnax on Spartina alterniflora is reversed in its expanded range compared to its historical range.
• M. pugnax acts as a significant regulator of primary producers in invaded salt marshes.
• Range-expanding species, particularly ecosystem engineers, can have inverse and profound impacts on new ecosystems, affecting functions like carbon storage and accretion.