Post-disturbance differences in litter decomposition and macroinvertebrate communities in a Texas saltmarsh-mangrove ecotone

As a result of climate change induced stressors, such as changing weather patterns and frequency and intensity of disturbance, many ecosystems are experiencing regime shifts. Coastal saltmarshes along parts of the Gulf of Mexico are being encroached upon and associated plant species are outcompeted as populations of Avicennia germinans (L) L, the black mangrove, expand due to a decrease in freeze events. This study has two main goals: to investigate the difference in macroinvertebrate community composition, diversity, richness, and abundance in litter habitat between two dominant vascular plant species – the marsh forb Batis maritima L and the mangrove A. germinans – across a temperature and salinity gradient, and to investigate the effect of macroinvertebrate colonization on litter decomposition rates across a temperature and salinity gradient. We also aim to determine individual species that are key contributors to litter decomposition. We hypothesize that community composition, diversity, richness, and abundance will vary among litter type and sites, with the greatest difference between sites at each end of a thermal gradient. Additionally, we hypothesize that macroinvertebrate colonization will increase decomposition rates in high salinity areas. To test this, we will deploy mesh bags containing leaf and stem litter at multiple sites of varying temperatures and salinities along the Texas Gulf coast. Bags will be placed near the waters’ edge of the intertidal zone and will be retrieved at different time intervals and returned to the lab where litter dry mass loss will be determined, and macroinvertebrates sorted and identified to the lowest practicable taxonomic level. This study will take place from March 2022 – January 2023 and is significant due to the limited number of studies on shallow water macroinvertebrate communities in saltmarsh-mangrove ecotones as well as understanding the impact of regime shifts on macroinvertebrate communities