Floating Wetland Islands Implementation and Biodiversity Assessment in a Port Marina

Abstract

Floating wetland islands (FWI) are considered nature-based solutions with great potential to promote several ecosystem services, such as biodiversity and water quality enhancement through phytoremediation processes. To our knowledge, the present work is the first to scientifically document the in-situ establishment of an FWI in a seawater port marina. The establishment and performance of a cork floating platform with a polyculture (Sarcocornia perennis, Juncus maritimus, Phragmites australis, Halimione portulacoides, Spartina maritima, Limonium vulgare) was evaluated. The diversity of organisms present in the FWI was undertaken based on the macrofauna assessment, taking into consideration marine water characterization, with a focus on hydrocarbons. Microbial communities were assessed based on metabarcoding approach to study 16S rRNA gene from environmental DNA retrieved from biofilm (from the planting media), marine biofouling (from the submerged platform) and surface marina water. S. perennis was the species with the highest survival rate and growth. The structure of the microbial community showed clear differences between those established in the FWI and those in the surrounding water, showing the presence of some bacterial groups that can be relevant for bioremediation processes (e.g., Saprospiraceae family). Concerning the macrofauna analysis, Mytilus sp. was the predominant taxa. To be of relevance, total petroleum hydrocarbons were detected at the marina up to ca. 6 mg/L. This study gives new insights into broadening FWI application to the saline environments of port marinas and to supporting a management strategy to promote several ecosystem services such biodiversity, species habitat, water quality enhancement and added aesthetic value to the marina landscape.

Ecosystem Service Assessments within the EU Water Framework Directive: Marine Mussel Cultivation as a Controversial Measure

“…However, floating islands could never realistically be that large due to the negative shading effect on submerged vegetation. More than their impact on nutrient regulation, the stakeholders appreciated their potential role as biodiversity hotspots and a habitat for birds, insects, and aquatic fauna [51,52]. Those aspects seem more promising than their use purely for nutrient removal in eutrophicated waters, where the size limits the efficiency.…”

Water Quality Assessment of Urban Ponds and Remediation Proposals

“…The FTW are considered a valuable phytoremediation tool and a nature-based solution that delivers a range of ecosystem services, such as biodiversity promotion and water quality enhancement, among others. They can be applied in different contexts dealing with fresh and saline water, and wastewater [42][43][44].…”

“…For example, the plants used in DC are halophytes, typically from saline and brackish environments, and have also been applied in FTW in port marina environment, although the establishment of H. portucaloides was not so successful as Sarcocornia spp. [42]. Another application of S. fruticosa, with phytoremediation purposes, was considered for highly saline wastewater treatment with constructed wetlands, where it has shown high resilience [46].…”

Screening Life Cycle Environmental Impacts and Assessing Economic Performance of Floating Wetlands for Marine Water Pollution Control

“…Currently, they are being used to treat hypertrophication, sewage and domestic wastewater, combined sewer overflow, contaminated groundwater, stormwater, acid mine drainage, poultry effluent, piggery effluent, boron-enriched water, polluted river water, and nutrients-enriched water [7]. However, the FWs technology in coastal and marine environments has been mainly used for erosion control, food web support, aesthetic improvement, and sediment trapping, but solid scientific documentation of these applications is limited [5,9]. Especially concerning the treatment of hydrocarbons and other marine contaminants with floating wetlands, a gap in scientific research and knowledge has been identified, and even the treatment of these contaminants with conventional constructed wetlands has been sparse [5,9,10], but with increasing research interest in recent years [11].…”

“…However, the FWs technology in coastal and marine environments has been mainly used for erosion control, food web support, aesthetic improvement, and sediment trapping, but solid scientific documentation of these applications is limited [5,9]. Especially concerning the treatment of hydrocarbons and other marine contaminants with floating wetlands, a gap in scientific research and knowledge has been identified, and even the treatment of these contaminants with conventional constructed wetlands has been sparse [5,9,10], but with increasing research interest in recent years [11].…”