Abstract
Micro-estuaries in semi-arid areas, despite their small size (shallow depth of few meters, length of few kilometers and a surface area of less than one square kilometer) are important ecosystem services providers. Despite their high abundance, tendency to suffer from eutrophication and vulnerability to other anthropogenic impacts, such systems are among the least studied water bodies in the world. In low tidal amplitude regions, micro-estuaries often have limited rate of sea-river water exchange, somewhat similar to fjord circulation, caused by a shallow sandbar forming at the coastline. The long-term study we report here was inspired by the idea that, due to their small size and low discharges regime, relatively small interventions can have large effects on micro-estuaries. We used a stationary array of sensors and monthly detailed water sampling to characterize the Alexander estuary, a typical micro-estuary in the S.E. Mediterranean, and to identify the main stress factors in this aquatic ecosystem. The Alexander stream is stratified throughout the year with median bottom salinity of 18 PSU. Prolonged periods of hypoxia were identified as the main stress factor. Those were alleviated by breaching of the sandbar at the estuary mouth by sea-waves or floods (mostly during winter) that flush the anoxic bottom water. Analysis of naturally occurring sandbar breaches, and an artificial breach experiment indicate that the current oxygen consumption rate of the Alexander micro-estuary is too high to consider sandbar breaches as a remedy for the anoxia. Nevertheless, it demonstrates and provides the tools to assess the feasibility of small-scale interventions to control micro-estuaries hydrology and biogeochemistry.
Highlights
Estuaries, the enclosed water bodies where fresh water is mixed with sea water (Elliott and McLusky, 2002; Tagliapietra et al, 2009; Day et al, 2013), are aquatic ecosystems which are among the most dynamic, diverse, and productive in the world, and as such they are highly sensitive to environmental disturbances (Barrett, 2002; Ducrotoy and Elliott, 2006)
Its structure can be dynamic as dictated by sea and fresh water currents and waves (Lichter et al, 2010)
The goal of the present study was to characterize the coastal section of the Alexander stream as an example of a typical partially connected eastern Mediterranean micro-estuary
Summary
The enclosed water bodies where fresh water is mixed with sea water (Elliott and McLusky, 2002; Tagliapietra et al, 2009; Day et al, 2013), are aquatic ecosystems which are among the most dynamic, diverse, and productive in the world, and as such they are highly sensitive to environmental disturbances (Barrett, 2002; Ducrotoy and Elliott, 2006). The sheltered waters of Sandbars and Micro-Estuary Biogeochemistry healthy estuaries are home to rich and diverse communities where marine, aquatic, and terrestrial flora and fauna mix and interact. This diversity of ecological niches exists partly because of the high salinity and nutrient gradients created from the mixing of fresh stream water with seawater (Bárcena et al, 2012). Occasional breach of the sandbar can cause an increased river-marine water exchange that is commonly followed by rapid change of water quality (Barton and Sherwood, 2004; Gale et al, 2006; Schallenberg et al, 2010) and ecological assemblages (Hastie and Smith, 2006; Avnaim-Katav et al, 2016)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
