Seagrass meadows improve inflowing water quality in aquaculture ponds

Abstract

Water quality is critical for fish health in aquaculture production. In flow-through systems, the inflowing water normally requires quality controls and treatments for being supplied from coastal water bodies that can be polluted by nutrients, suspended solids, and microorganisms. Here we assess how seagrass meadows benefit aquaculture systems through the provision of ecosystem services (water filtration, biological control, and regulation of dissolved gasses) in the water reservoir that supplies earthen ponds in an aquaculture system in southern Portugal. In the 1.45-ha reservoir, seagrasses retained daily an estimate of 0.8-1.8 kg d-1 of nitrogen, 0.04-0.07 kg d-1 of phosphorus in their biomass, and 0.7-1.1 kg dw d-1 of suspended total particulate matter, bringing benefits in terms of nutrient and particle removal from the water column. Diel and spatial variation in faecal coliforms levels (Escherichia coli) in the reservoir suggested that seagrasses, in combination with light exposure, may reduce the levels of this pathogen. Furthermore, the seagrassdominated system oxygenated the water through photosynthesis at a faster rate than the respiratory oxygen consumption, maintaining the system above the aquaculture minimum oxygen. This study demonstrates that seagrasses can be used as a nature-based solution to overcome water quality challenges in flow-through aquaculture ponds.

Seagrasses provide a novel ecosystem service by trapping marine plastics

“…Seagrass meadows are widespread in shallow coastal waters 19 and provide important ecosystem services and benefits, such as water quality improvement 20 , CO 2 absorption 21 , climate change mitigation 22 , sediment production for seafloor and beach stabilization 23 , coastal protection 24 , nursery and refuge areas for many species 25 , and support in fisheries production 26 . We have investigated microplastics and larger plastic debris washed ashore together with natural debris of the seagrass Posidonia oceanica, a Mediterranean endemic seagrass forming lush, extensive meadows from 0.5 to 40 m of water depth.…”

A simple prediction of time-mean and wave orbital velocities in submerged canopy

“…For example, these canopies provide shelter, nursery habitat and food sources for fish (Costanza et al 1997;Waycott, Longstaff & Mellors 2005;Whitfield 2017). They improve water quality by filtering nutrients (De Los Santos et al 2020) and capturing suspended sediments (Palmer et al 2004). The canopy resistance reduces current and waves, which reduces bed erosion and enhances coastal stability (Gedan et al 2011).…”

A field experiment exploring disturbance‐and‐recovery, and restoration methodology of Zostera capensis to support its role as a coastal protector

“…Seagrasses are submerged marine flowering plants that provide a wide range of ecosystem services (UNEP 2020), such as coastal protection, promoting water filtration, sediment retention, current dampening and are among the most effective natural ecosystem for carbon sequestration (Ondiviela et al 2014, Marbá et al 2015, Donatelli et al 2018, de los Santos et al 2020. They also have the ability to reconfigure water flow and influence nutrient cycling, as well as providing critical nurseries and habitats for a wide array of fish and invertebrate species (Hughes et al 2009).…”