Effects of novel, non-native detritus on decomposition and invertebrate community assemblage

Abstract

When non-native primary producers become successful, the structure and function of native detrital food webs can be fundamentally altered. Salt marsh estuaries of the southeastern USA are in part detritus-based ecosystems and rely on the annual production of detritus from a single native species, the smooth cordgrass Spartina alterniflora. Over the last several decades, the success of a novel primary producer, the red macroalga Agarophyton vermiculophyllum (formerly Gracilaria vermiculophylla), in a system historically devoid of macroalgae provides the opportunity to measure the effect of non-native basal resources on native detrital pathways. We conducted 2 in situ experiments to compare (1) decomposition rates of A. vermiculophyllum and S. alterniflora and (2) invertebrate colonization rates onto dead A. vermiculophyllum and S. alterniflora. Relative to S. alterniflora, we found that A. vermiculophyllum decomposes more rapidly, losing 80% or more of its biomass within 3 wk, while S. alterniflora lost ~50%. Experimental litterbags with decomposed A. vermiculophyllum and S. alterniflora harbored similar highly abundant invertebrate communities that differed greatly from denuded areas. Our results demonstrate that A. vermiculophyllum provides a complementary source of labile organic matter relative to S. alterniflora, boosting the amount of food and available habitat for small invertebrates of intertidal salt marshes and mudflats. Thus, non-native macrophytes may differentially affect community and ecosystem properties just as much when dead as alive, especially when they are biologically distinct from native species.

Invasive Seaweeds in the Iberian Peninsula: A Contribution for Food Supply

“…Since then, this species is well established in the Iberian Peninsula because they can tolerate abiotic parameters variation such as temperature (11–25 °C) and salinity (10–30 PSU) [ 50 ]. Due to this species resilience, they are recognized by their environmental and ecological impact on fauna and flora [ 4 , 52 , 53 ].…”

“…Algae play a pivotal regulatory role in the aquatic environment, being sources of primary and secondary production, providing protection to coastal zones, and as nursery areas [ 3 ]. Moreover, seaweeds are a food source for many aquatic organisms, supporting provisioning services for a wide range of invertebrates [ 4 ]. Furthermore, seaweeds are part of cultural heritage and distinctiveness in each area, presenting economic value for society [ 5 ].…”

Whole System Analysis Is Required To Determine The Fate Of Macroalgal Carbon: A Systematic Review

“…2019, Haram et al. 2020). These types of experiments are conducted mostly on sandy shore ecosystems, but similar degradation experiments have been conducted in benthic subtidal habitats (de Bettignies et al.…”

“…2013, Dufour et al 2012, Eereveld et al 2013, Lastra et al 2014, G omez et al 2018, Rodil et al 2019, Haram et al 2020. These types of experiments are conducted mostly on sandy shore ecosystems, but similar degradation experiments have been conducted in benthic subtidal habitats (de Bettignies et al 2020, estuarine sandflats (Gladstone-Gallagher et al 2016), and in specific seabed hollows where algal blades are known to accumulate (Norkko et al 2004).…”

Non-native red alga Gracilaria vermiculophylla compensates for seagrass loss as blue crab nursery habitat in the emerging Chesapeake Bay ecosystem

“…tomentosoides increased recruitment of native Mediterranean mussels ( Mytilus galloprovincialis ) in the Adriatic Sea [ 10 ]. In previously unvegetated intertidal flats along the southeastern Atlantic Coast of North America, the red macroalga Gracilaria vermiculophylla (synonym Agarophyton vermiculophyllum ) attracted epifaunal colonizers by adding structure when facilitated by the polychaete Diopatra cuprea [ 11 – 13 ], increased epifaunal abundance and richness [ 14 ], and provided similar detrital habitat as native smooth cordgrass Spartina alterniflora wrack for invertebrates [ 15 ]. In Europe, G. vermiculophylla increased epifaunal species richness when entangled in seagrass beds (eelgrass Zostera marina ) in Denmark [ 16 ] and increased macrofaunal richness and both macrofaunal and meiofaunal density in intertidal mudflats in France [ 17 ].…”