Sandbar Breaches Control of the Biogeochemistry of a Micro-Estuary

Micro-estuaries in semi-arid areas, despite their small size (shallow depth of a few meters, length of a few kilometers, and a surface area of less than 1 km2) are important providers of ecosystem services. 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 detailed monthly 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 micro-estuary 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 stormwater runoff events (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

The ecological risk dynamics of pharmaceuticals in micro-estuary environments

Micro-estuarine ecosystems have a surface area < 1 km2 and are abundant in Mediterranean regions. As a result of their small size, these systems are particularly vulnerable to effects of chemical pollution. Due to fluctuating flow conditions of base-flow dominated by treated wastewater effluents and flood events transporting rural and urban non-point-source pollution, micro-estuaries are under a dynamic risk regime, consequently, struggling to provide ecological services. This two-year study explored the occurrence and risks of pharmaceutical contamination in the Alexander micro-estuary in Israel. Pharmaceuticals were detected in all samples (n=280) at as high as 18 µg L-1 in flood events and 14 µg L-1 in base-flow. Pharmaceutical mixtures composition was affected by flow conditions with carbamazepine dominating base-flow and caffeine dominating flood events. Median annual risk quotients for fish, crustaceans and algae were 19.6, 5.2, and 4.5, indicating that pharmaceuticals pose high risk to the ecosystem. Ibuprofen, carbamazepine and caffeine were contribute most to the risk quotients. The current work highlights that micro-estuary ecosystems, like the Alexander estuary, are continuously exposed to pharmaceuticals and most likely to other pollutants, placing these ecologically important systems under an elevated risk, in comparison to the more frequently studied large estuarine systems.  

Single beam bathymetry processed data (Humminbird Helix 10 echosounder entire dataset), Israeli coastal estuaries Lachish, Sorek, Yarkon, Alexander, Taninim and Kishon

We present the data from a bathymetric mapping project in the Israeli coastal estuaries (Lachish, Sorek, Yarkon, Alexander, Taninim and Kishon). The data was collected using a combination of fish finder and GPS operated on a Kayak. The data preperation consisted of: a) manual removal of outliers which were mostly caused by instrument echo in water depths below the instrument 0.5 minimum. b) correction of the mesured water level to the sea level. c) interpolated into regular grid using a terrain following interpolation algorithm. For each of the streams we present the raw measurements, and the interpolated data both as text (csv) file and as GeoTiff file

Monthly surveys of water properties along the Alexander micro-estuary

Monthly surveys of water properties along the estuary. These surveys include water column CTD profiles of temperature, salinity, dissolved oxygen, chlorophyll fluorescence, and turbidity (OBS). Profile data are accompanied by Secchi depth measurements and discrete water samples collected by a horizontal Niskin bottle near the surface and near the bottom. Water samples are analyzed for the concentrations of Phosphate, Nitrate, Nitrite, Ammonium, Total and particulate nitrogen and phosphorus, total suspended solids, particulate organic matter, biological oxygen demand, chlorophyll-a, cell counts of nano and pico planktonic algae and non-photosynthetic bacteria

Bi-weekly surveys of water properties at two marine stations at Alexander micro-estuary

Bi-weekly surveys of water properties at two marine stations ~1 and 6.6 Km from the estuary mouth at bottom depths of 8 and 48 meters. These surveys include water column CTD profiles of temperature, salinity, dissolved oxygen, chlorophyll fluorescence, and Turbidity (OBS). Profile data are accompanied by discrete water samples collected by a Niskin bottle at 10 m depth, these samples are analyzed for the concentrations of chlorophyll-a and pico and nano planktonic algae and non-photosynthetic bacteria

A long term physical and biogeochemical database of a hyper- eutrophicated Mediterranean micro-estuary

Long-term, multi-parameter monitoring database that covers physical, chemical, and biological water properties at several stations along a Levantine micro-estuary and its neighboring coastal sea. The data are divided into two separate databases: Monthly surveys of water properties along the estuary and Bi-weekly surveys of water properties at two marine stations

Pesticides and pharmaceuticals data collected during two consecutive years in a Mediterranean micro-estuary

The Alexander micro-estuary, located at the eastern edge of the Mediterranean Sea, is a typical example of small water bodies that suffer from a combination of urban and agricultural pollution, and overuse of its natural water sources. It is∼6.5 km long, with maximum depth of 3 m and maximum width of 45 m. To evaluate the anthropogenic stress on the system and its ability to mitigate pollution, water samples were collected within the framework of Ruppin's Estuarine and Coastal Observatory (RECO, see Suari, Y. et al. 2019). Water samples were collected from the estuary head, which drains about 510 km2, and at a point 300 m upstream from the estuary mouth before water flows into the Mediterranean Sea. A total of 236 stormwater and 44 base-flow water samples between December 2016 and December 2018. Stormwater samples were collected every 0.25 – 4 h along the entire course of the flow events using an automated samplers (Sigma 900, Hach Company, Loveland CO, USA; and ISCO 3700 Full-Size Portable Sampler, Teledyne, Lincoln, NE, USA). Base-flow samples were taken once a month using a horizontal grab sampler (5 L, model 110B, OceanTest Equipment, Fort Lauderdale, FL, USA). All samples were filtered using 90mmGF/F filters (nominal pore size of 0.7 μm, MGF, Sartorius, Göttingen, Germany) and immediately frozen (−20 °C) before chemical analysis. Chemical analysis was performed using liquid chromatography with high-resolution mass spectrometry (LC–HRMS) analysis using a QExactive Plus hybrid FT mass spectrometer coupled with a Dionex Ultimate 3000 RS UPLC (Thermo Fisher Scientific, Waltham, MA, USA). The targeted analysis, which included 15 fungicides, 25 herbicides, 18 Insecticides, and 19 pharmaceuticals, concluded with a total of 21,142 entries. The dataset contains the sampling locations, sampling dates, flood section duration, discharge rate, and the total water volume discharged during the relevant period. The provided data offers an opportunity to explore the sources, transport, and impact of a large mixture of organic pollutants in a confined aquatic system located in an urbanized coastal environment

Exploring Per- and Polyfluoroalkyl Substances (PFAS) in Microestuaries: Occurrence, Distribution, and Risks

Microestuaries have a crucial role in supporting biodiversity and human life quality in heavily populated areas. They are also the last barrier controlling fluxes of pollutants from the land to sea. Here, we report the occurrence and distribution of per- and polyfluoroalkyl substances (PFAS) during the dry season in three microestuaries. The total PFAS concentration (n = 12) at the studied estuaries was very high from a global perspective with maximum and median concentrations of 17.4 and 3.4 μg L–1, respectively. These concentrations significantly exceed the recommended benchmarks for recreational activity. Our analysis reveals that a major fraction of PFAS originated from wastewater effluents, whereas point source pollution dominated when the estuary met an industrial zone containing refinery facilities. In the case of limited dilution by natural riverine water, we suggest using carbamazepine as a steady indicator for the identification of PFAS originating from wastewater. Although the three studied microestuaries exhibit similar characteristics (morphology, precipitation, watershed size, water volume, etc.), changes in water input and connectivity to the sea, along with local anthropogenic activity, dramatically alter the occurrence, concentrations, and distribution of PFAS. This study suggests that microestuaries are subjected to high ecological risk from PFAS pollution due to intensive anthropogenic activity

Ribosomal Antibiotics: Contemporary Challenges

Most ribosomal antibiotics obstruct distinct ribosomal functions. In selected cases, in addition to paralyzing vital ribosomal tasks, some ribosomal antibiotics are involved in cellular regulation. Owing to the global rapid increase in the appearance of multi-drug resistance in pathogenic bacterial strains, and to the extremely slow progress in developing new antibiotics worldwide, it seems that, in addition to the traditional attempts at improving current antibiotics and the intensive screening for additional natural compounds, this field should undergo substantial conceptual revision. Here, we highlight several contemporary issues, including challenging the common preference of broad-range antibiotics; the marginal attention to alterations in the microbiome population resulting from antibiotics usage, and the insufficient awareness of ecological and environmental aspects of antibiotics usage. We also highlight recent advances in the identification of species-specific structural motifs that may be exploited for the design and the creation of novel, environmental friendly, degradable, antibiotic types, with a better distinction between pathogens and useful bacterial species in the microbiome. Thus, these studies are leading towards the design of “pathogen-specific antibiotics,” in contrast to the current preference of broad range antibiotics, partially because it requires significant efforts in speeding up the discovery of the unique species motifs as well as the clinical pathogen identification