Fish and invertebrate use of restored vs. natural oyster reefs in a shallow temperate latitude estuary

Abstract

Coastal marine habitats continue to be degraded, thereby compelling largescale restoration in many parts of the world. Whether restored habitats function similarly to natural habitats and fully recover lost ecosystem services is unclear. In estuaries, oyster reefs have been degraded by multiple anthropogenic activities including destructive fishing practices and reduced water quality, motivating restoration to maintain oyster fisheries and other ecosystem services, often at relatively high cost. We compared fish and invertebrate communities on recently restored (0-1 year post-restoration), older restored (3-4 years post-restoration), and natural oyster reefs to determine if and when restored reefs support functionally similar faunal communities. To test the influence of landscape setting on the faunal communities, the restored and natural reefs, as well as a control without reef present, were distributed among three landscapes (on the edge of salt marsh away from seagrass [salt marsh landscape], on mudflats [mudflat landscape], and near to seagrass and salt marsh [seagrass landscape]). Oyster density and biomass were greatest on restored reef habitat, as were those of non-oyster bivalve species. Total abundance of invertebrates was much greater on oyster reefs than in control plots, regardless of reef or landscape type, yet were frequently highest on older restored reefs. Meanwhile, juvenile fish densities were greatest on natural reefs, at intermediate densities on older restored reefs, and least abundant on controls. When comparing the effects of reef age and landscape setting, juvenile fish densities were greatest on younger reefs within the mudflat landscape. Collectively, these results indicate that oyster reefs harbor higher densities of resident invertebrate prey, which may explain why reef habitat is also important for juvenile fish. Laboratory and field experiments supported the notion that gag grouper (a predatory demersal fish) forage more effectively on oyster reefs than on unstructured mud bottom, whereas our experiments suggest that

Evidence of ontogenetic partitioning of restored coastal habitat by a generalist sportfish

“…Further, these data identified potential ontogenetic shifts in size structure and relative trophic position (via increased 15 N values) between and within habitats, where restored habitats provided foraging opportunities to all size classes. Thus, congruent with Grabowski et al (2022), this study suggests estuarine habitat quality and variety provide opportunities to facilitate fish foraging, growth, and development.…”

“…The random effect of season better captured temporal variation, where fall had highest body condition scores likely reflecting isotope turnover rates from energy storage following the productive summer (Lewis et al 2020); whereas the lower body condition in spring may reflect the lower productivity and prey abundance in winter months. Thus, restored habitat can provide more effective foraging opportunities for sportfish (Grabowski et al 2022; Troast et al 2022), which may facilitate sportfish survivorship during less biologically productive seasons. Body condition is an indicator of sportfish health, and the results here demonstrate it can be augmented by habitat restoration in a subtropical estuary, thus providing a good indicator for restoration success.…”

“…Furthermore, settlement of postlarval dispersal phases of fish (i.e. hereafter defined as “recruitment”) and post‐settlement survival of young‐of‐the year is influenced by habitat availability and quality (Nagelkerken et al 2015), which can be enhanced by habitat restoration (Peterson et al 2003; Grabowski et al 2022). However, relatively little is known about how fish use restored habitats across ontogeny.…”

“…The survival and successful conservation of coastal marine species and their related ecosystem services depends on the presence of suitable habitat (Grabowski et al 2022). In estuaries, benthic nursery habitat is critical for supporting early life stages of many fishes, which act as a source of recruits to adult populations (Nagelkerken et al 2015; Whitfield 2017; Fontoura et al 2022).…”

Introduction: Honoring the contribution of Charles H. Peterson (1946–2020) to the field of marine ecology

“…Butler et al (2021) reveal the role sponges play in helping to facilitate coral restoration. Grabowski et al (2022) and Powers and Grabowski (2023) revisit and extend our understanding of the role that habitat structure, location, and hydrodynamics play in successful oyster restoration efforts. Paxton et al (2022) provide a framework for better incorporating ecological principles, adaptive management, and experiments in the siting, design, construction, and evaluation of artificial reefs in the coastal ocean.…”