In New England saltmarshes, mummichogs (Fundulus heteroclitus) connect the vegetated marsh and creek food webs by opportunistically foraging on the invertebrate communities of the marsh surface when access is permitted by tidal flooding and marsh-edge geomorphology. Via their movements, mummichog represent a critical food web node, as they can potentially transport energy from the marsh surface food web to creek food web and exert top-down control on the communities of the vegetated marsh surface. Here, we demonstrate that access to the marsh surface (afforded by marsh-edge geomorphology) did not impact mummichog distribution across the marsh platform and exhibited no evidence of top-down control on their invertebrate prey. Thus, mummichogs function as initial nodes in the trophic relay, unidirectionally moving energy from the vegetated marsh to the creek food web. Reduced marsh surface access via altered marsh-edge geomorphology results in a 50% to 66% reduction in total energy available to aquatic predators via this route. Estuarine systems are intimately connected to coastal and offshore systems via consumer mediated flows of energy; thus, disruptions to the trophic relay from the marsh surface at the tidal creek scale can have far reaching impacts on secondary productivity in multiple disparate systems and must be accounted for in considerations of impacts to future food-web function.
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Habitat decoupling via saltmarsh creek geomorphology alters connection between spatially- coupled food webs
Consumer-mediated movement can couple food webs in distinct habitats and facilitate energy flow between them. In New England saltmarshes, mummichogs (Fundulus heteroclitus) connect the vegetated marsh and creek food webs by opportunistically foraging on the invertebrate communities of the marsh surface when access is permitted by tidal flooding and marsh-edge geomorphology. Via their movements, mummichog represent a critical food web node, as they can potentially transport energy from the marsh surface food web to creek food web and exert top-down control on the communities of the vegetated marsh surface. Here, I use gut content analysis, calorimetric analysis, and field surveys to demonstrate that access to the marsh surface (afforded by marsh-edge geomorphology) impacts the trophic relay of marsh production to creek food webs. Fish populations in creeks with greater connectivity had a higher total biomass of terrestrial invertebrates in their guts. However, bomb calorimetry showed no difference in the average caloric content of mummichog individuals from creeks with different creek edge geomorphology. Access also did not impact mummichog distribution across the marsh platform and exhibited no evidence of top-down control on their invertebrate prey. Thus, mummichogs function as initial nodes in the trophic relay, unidirectionally moving energy from the vegetated marsh to the creek food web. Reduced marsh surface access via altered marsh-edge geomorphology results in a 50 % to 66 % reduction in total energy available to aquatic predators via this route. Estuarine systems are intimately connected to coastal and offshore systems via consumer mediated flows of energy; thus, disruptions to the trophic relay from the marsh surface at the tidal creek scale can have far reaching impacts on secondary productivity in multiple disparate systems and must be accounted for in considerations of impacts to future food-web function.
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- Award ID(s):
- 1902704
- PAR ID:
- 10325251
- Date Published:
- Journal Name:
- Food webs
- Volume:
- 29
- Issue:
- e00206
- ISSN:
- 2352-2496
- Page Range / eLocation ID:
- 1-9
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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At PIE, mummichog (Fundulus heteroclitus) use the spring-cycle high tides to access the flooded high marsh platform and consume invertebrate prey. Invertebrate surveys were conducted before and after spring tides that flooded the high marsh area to determine the effect of mummichog predation that occurs on the high marsh during the flood events and to assess the impact of low marsh geomorphology on top-down control by mummichog. These data were included in part of the study "Cross-habitat access modifies the ‘trophic relay’ in New England saltmarsh ecosystems” (Lesser et al. 2021) as well as a part of a NEU Three Seas Master's thesis.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/https://doi.org/10.1016/j.ecss.2020.106825
