Linking habitat interactions and biodiversity within seascapes

Abstract

Habitat interactions play key roles in regulating biodiversity and ecosystem functions. This is particularly important in aquatic ecosystems, where the flow of water facilitates exchanges of energy and matter. Oyster reefs, a highly degraded habitat globally and a key focus for restoration efforts, can reduce water movement and facilitate the deposition of particles around them, affecting nutrient cycling in surrounding sediments. The effects of these reefs on sediment infauna taxonomic and functional biodiversity, however, remain unknown. We sampled sediments at increasing distances from reefs at three estuaries to evaluate the relationships between proximity to oyster reefs and composition and functionality of infaunal communities and explored the potential mechanisms behind those relationships. Sediments close to oyster reefs had consistently greater amounts of labile organic matter, which in turn was positively related to the number of taxa and total abundance of infauna. Also, the functional traits of infauna, such as bioturbation and feeding modes, were related to proximity to reefs, but they were variable between estuaries indicating the importance of background estuarine environmental conditions. These results suggest that habitat linkages between oyster reefs and sediments are important in regulating taxonomic biodiversity, while functional biodiversity seems to be driven by processes operating at larger scales. Given burgeoning restoration initiatives worldwide, particularly those of oyster reefs, incorporating seascape interactions can help inform recovery of biodiversity and functions beyond the target habitat at the seascape level, which is often overlooked.

Oyster Reefs Are Reservoirs for Potential Pathogens in a Highly Disturbed Subtropical Estuary

“…Likely of greater concern is the potential for oyster reefs to function as hot spots for PPM by condensing pathogens onto the benthos [202], where they can both infect reef inhabitants and be moved through the ecosystem via trophic transfer. Oyster reefs are homes to diverse assemblages of polychaetes, crustaceans, molluscs, and other animals [203][204][205][206] that can be infected by contacting or consuming the pathogens potentially found in the biodeposit samples investigated in this study [114,120,135]. Infected animals often die, but they can also spread pathogens to higher-level predators such as wading birds [207] and several commercially and recreationally important fishery species, including juvenile groupers, snappers and flounders, and adult drum and sheepshead [179,208].…”

Reversing functional extinction: successful restoration of eradicated oyster reefs

“…larvae and carbon transport), and how emerging ecological services influence the structure and function of surrounding communities (e.g. sediment infauna, seagrass, and fish; Bugnot et al 2022, Martinez‐Baena et al 2023), is vital to understand the extent to which these restorations modify seascape processes.…”

A deep dive into the ecology of Gamay (Botany Bay, Australia): current knowledge and future priorities for this highly modified coastal waterway

“…Infaunal communities in sandy beaches are dominated by peracarid crustaceans, with biodiversity being greatest at the lower intertidal and in areas protected from wave action (Dexter 1984(Dexter , 1985. At Quibray Bay, infaunal communities in sandy flats are more diverse that those from sandy beach habitats, likely owing to reduced wave action in this area of the bay (Rossi and Underwood 2002;Bugnot et al 2022). By-catch data from prawn trawling represents the only information on demersal fish and macrobenthic communities in Gamay, finding 137 taxa associated with sediment habitats, including 115 finfish taxa, 11 crustaceans, 10 molluscs and 1 echinoderm (Liggins et al 1996).…”

“…However, censuses from other NSW estuaries have found a five-fold greater density, biomass and productivity of macroinvertebrates on oyster reefs than on adjacent sediments (McLeod et al 2020), suggesting that a similar habitat value may be expected in Gamay. Oysters have also been shown to influence nearby communities in Gamay, enhancing invertebrate abundances and richness in surrounding unvegetated sediments and mangroves (Minchinton and Ross 1999;Bishop et al 2009Bishop et al , 2012Hughes et al 2014;Bugnot et al 2022).…”

“…This information will be necessary if we are to understand the degree to which bay resilience depends on this, both now and into the future. The configuration of habitats, such as proximity to habitat-forming species and rocky reefs, and the connectivity among these habitats will be likely to influence sediment infauna biodiversity and functioning; however, little is known about this in Gamay (but see, Bugnot et al 2022). Similarly, it remains largely unknown how the productivity of mudflats at Ramsar-listed Towra Point and nearby soft-sediment habitats are influenced by adjacent oyster reefs, despite this area being important foraging ground for endangered and migratory shorebirds.…”