At PIE, mummichog (Fundulus heteroclitus) use the spring-cycle high tides to access the flooded high marsh platform and eat invertebrate prey, coupling the high marsh and aquatic creek food webs by gathering energy produced on the high marsh and making it available to the aquatic food web. Changes in the geomorphology of saltmarsh creek edges greatly influence the survival, biomass, and resource use of mummichog populations. Here we use gut content analysis assess the diet of mummichog on the high marsh platform during a flooding spring-cycle tide in July 2018 across 3 PIE creeks known to present different geomorphologic patterns in their low marsh zones. These data allow us to quantify the amount of terrestrial invertebrate prey mummichog consume on a single flooding tide and determine the impact altered low marsh geomorphology has on the trophic relationships in PIE food webs. These mummichog were captured in Breder traps; information about the consumer communities captured in these traps was recorded separately (LTE-TIDE-BrederTrap-Demographics). These data were included in part of the study “Habitat decoupling via saltmarsh creek geomorphology alters connection between spatially-coupled food webs” (Lesser et al. 2020) and were a portion of an MBL REU project.
Locations: Mud South (MS), West (WE), and Clubhead (CL)
In July of 2018, 8 stations of Breder traps were deployed per study creek, 4 stations in both the left and the right branch. Each station had 2 Breder traps: one was deployed in the low-marsh area, 1m from the TSA/SP boundary with the opening facing the creek in order to capture consumers as they moved onto the high-marsh area with the rising tide. The second was placed in the high-marsh area 1m from the TSA/SP boundary facing the marsh in order to capture consumers as they moved out of the high marsh as the tide receded. Breder traps were installed by clipping the grass and staking the trap into the ground to prevent any movement. The trap stations were placed with a minimum distance of 25m between them, ensuring independent samplings. Sampling was conducted over 2 nights, the 27th and 28th of July.
Sampling Collection and Processing
Traps were left out for 6 hours total, they were placed 3 hours before the incoming tide and collectred 3 hours after peak high tide. When traps were collected all captured consumers were collected and frozen for analysis. In the lab, consumers were measured to the nearest millimeter and weighed. All weights were measured to the nearest 0.0001g. For fishes total length (TL) was measured from the tip of the snout to the end of the caudal fin. Mummichog individuals of a length equal or greater than 40mm were dissected, and stomach and intestine mass (stmass) was weighed, stomach and intestine content was then extracted and weighted (ctmass). Stomach contents were identified to general taxonomic categories, and an estimated percentage of total stomach content was visually assessed for each item (grid was used to assist estimation if needed, Hyslop 1980). Individuals with no identifiable aquatic or terrrestrial food material were not considered for analysis.
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