Larva fish assemblage structure in three-dimensional floating wetlands and non-floating wetlands in the Changjiang River estuary

Fish populations have declined in many estuarine and freshwater ecosystems in part due to the loss of habitat in recent decades.Reconstructing lost habitat for larvae fish is a potential method for recovering larvae fish populations.Three-dimensional artificial floating wetlands(AFWs)on which Phragmites australis was planted were experimentally deployed to recover the lost habitat in the Changjiang(Yangtze)River estuary from May to July 2018.The AFW area was characterized by slow velocity,high transparency,low dissolved oxygen,and relatively constant water temperature.The total individuals of larvae fish in the AFW area(12122 in total)was higher than that in the non-AFW area(1250 in total),and the densities of most larvae fish species were higher in the AFW habitat than in the non-AFW area.The distributions of larvae fish species were positively influenced by habitat type because they were strongly related to the negative part of the first axis of the redundancy analysis,and Cyprinus carpio and Cyprinus auratus were inclined to habitat in the slow velocity and high transparency AFW habitat area.These results indicate that larvae fish species are inclined to inhabit the AFW habitat.The use of three-dimensional P.australis AFWs would be a potential method for enhancing the habitat of larvae fish in the degraded habitats along the estuary.

Restoration or Rehabilitation of the Faleme River Affected by Mining Activities: What Methods?

The Faleme River, a West Africa long transboundary stream (625 km) and abundant flow (>1100 million m3) is affected by severe erosion because of mining activities that takes place throughout the riverbed. To preserve this important watercourse and ensure the sustainability of its services, selecting and implementing appropriates restorations techniques is vital. In this context, the purpose of this paper was to present an overview of the actions and techniques that can be implemented for the restoration/rehabilitation of the Faleme. The methodological approach includes field investigation, water sampling, literature review with cases studies and SWOT analysis of the four methods presented: river dredging, constructed wetlands, floating treatment wetlands and chemical precipitation (coagulation and flocculation). The study confirmed the pollution of the river by suspended solids (TSS > 1100 mg/L) and heavy metals such as iron, zinc, aluminium, and arsenic. For the restoration methods, it was illustrated through description of their mode of operation and through some case studies presented, that all the four methods have proven their effectiveness in treating rivers but have differences in their costs, their sustainability (detrimental to living organisms or causing a second pollution) and social acceptance. They also have weaknesses and issues that must be addressed to ensure success of rehabilitation. For the case of the Faleme river, after analysis, floating treatment wetlands are highly recommended for their low cost, good removal efficiency if the vulnerability of the raft and buoyancy to strong waves and flow is under control.

THREE BAYS ESTUARY(BARNSTABLE,CAPE COD)WATERSHED RESTORATION PL AN:A GREEN INFRASTRUCTURE APPROACH

This paper presents an approach described as“non-traditional”for restoring water quality and ecosystem services that have been degraded as a result of excess nitrogen.It focuses on emerging technologies often referred to as green infrastructure.These technologies may provide cost effective alternatives to traditional,gray infrastructure such as sewering and is likely to provide significant co-benefits including the creation of local jobs,the preservation of real estate values,and habitat enhancement.The paper focuses on the Three Bays estuary on Cape Cod to illustrate the benefits and potential of green infrastructure technologies.The Three Bays estuary is presented as a case study and as a representative example of implementation of the broader Cape Cod Water Quality Management Plan Update(208 Plan Update)-a nationally-recognized watershed planning project designed to provide a pathway for the fifteen towns of Cape Cod to achieve compliance with Section 208 of the Clean Water Act.The Three Bays estuary and embayment system is a scenic Cape Cod bay that hosts sailing,kayaking,swimming and shellfishing and is located in the Town of Barnstable.It is comprised of three primary segments that include West Bay,North Bay and Cotuit Bay.Sub-systems include Prince Cove that flows into North Bay,the Narrows that flows between North Bay and Cotuit Bay and Eel Pond that flows into East Bay(see Figure 1).The Massachusetts Estuaries Project(MEP)is a state-sanctioned watershedmodeling project that assesses the conditions of the state’s estuaries and required restoration goals.Its technical report(2006)indicates that the water quality of the Three Bays system has resulted in seriously degraded to moderately degraded habitat.The system is listed as an impaired water body on the US Environmental Protection Agency(EPA)303d list of impaired waters.An approved Total Maximum Daily Load(TMDL)for nitrogen has been established for the embayment.This assessment is supported by more recent empirical water quality data collected within the embayment.The more current data documents a continuing decline in water quality with more common algae blooms(see Figure 2).