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 [1]. 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. All entries are organized in a worksheet, along with location, date, 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.

Invading bivalves replaced native Mediterranean bivalves, with little effect on the local benthic community.

The construction of the Suez Canal connected the Red Sea and the Mediterranean Sea, which allowed rapid marine bio-invasion. Over the last century, several bivalve species have invaded the Levantine basin, yet their distribution and impact on the benthic community have not been thoroughly studied. Large-scale benthic surveys along the rocky substrate of the Israeli Mediterranean coastline indicate that invading bivalves, such as Spondylus spinosus, Brachidontes pharaonis, and Pinctada radiata, now dominate the rocky environment, with densities of tens to hundreds of individuals per m2. No native bivalve specimens were found in any of the transects surveyed. The small-scale ecological effects of the established invading populations on the benthic community were examined over a year using an in-situ exclusion experiment where all invading bivalves were either physically removed or poisoned and kept in place to maintain the physical effect of the shells. Surprisingly, the experimental exclusion showed a little measurable effect of bivalve presence on the invertebrate community in close vicinity (~ 1 m). Bivalve presence had a small, but statistically significant, effect only on the community composition of macroalgae, increasing the abundance of some filamentous macroalgae and reducing the cover of turf. The generally low impact of bivalves removal could be due to (1) wave activity and local currents dispersing the bivalve excreta, (2) high grazing pressure, possibly by invading herbivorous fish, reducing the bottom-up effect of increased nutrient input by the bivalves, or (3) the natural complexity of the rocky habitat masking the contribution of the increased complexity associated with the bivalve's shell. We found that established invading bivalves have replaced native bivalve species, yet their exclusion has a negligible small-scale effect on the local benthic community. Supplementary Information: The online version contains supplementary material available at 10.1007/s10530-022-02986-1.

Hydrodynamics of sponge pumps and evolution of the sponge body plan.

Sponges are suspension feeders that filter vast amounts of water. Pumping is carried out by flagellated chambers that are connected to an inhalant and exhalant canal system. In 'leucon' sponges with relatively high-pressure resistance due to a complex and narrow canal system, pumping and filtering are only possible owing to the presence of a gasket-like structure (forming a canopy above the collar filters). Here, we combine numerical and experimental work and demonstrate how sponges that lack such sealing elements are able to efficiently pump and force the flagella-driven flow through their collar filter, thanks to the formation of a 'hydrodynamic gasket' above the collar. Our findings link the architecture of flagellated chambers to that of the canal system, and lend support to the current view that the sponge aquiferous system evolved from an open-type filtration system, and that the first metazoans were filter feeders.

Environmental risk dynamics of pesticides toxicity in a Mediterranean micro-estuary.

Pesticides are potentially toxic to aquatic systems, even at low concentration, depending on their individual ecotoxicological properties and their mixture composition. Thus, to evaluate possible ecological stress due to pesticide load, a thorough assessment of the potential toxicity of pesticide mixtures is required. Here we report water discharge and quality data of an eastern Mediterranean micro-estuary (Alexander stream), targeting the temporal distribution of a pesticide mixture. Over 150 water samples were collected during 2 hydrological years representing base-flow and flood conditions. On average, each water sample contained 34 and 45 different pesticides with peak concentrations of 1.4 µg L-1 of Imidacloprid and 55 µg L-1 of Diuron during base-flow and flood events, respectively. Pesticide mixtures were potentially toxic to benthic invertebrates and algae during flood events, surpassing the toxicity benchmark with medians of 110% and 155%, respectively. The herbicide Diuron and the insecticide Imidacloprid were the main pesticides responsible for the high potential toxicity during flood events. The falling limb of the flood hydrographs was found to inflict the highest stress on the estuarine environment due to elevated toxicity combined with prolonged residence time of the water. Examination of the potential chronic toxicity of single compounds showed continuous stress for plants, algae, amphibians, crustaceans, insects and fish from nine pesticides. Our data show that the ecosystem of the Alexander micro-estuary is under a continuous chronic stress with acute peaks in potential toxicity during flood events and the period that follows them. We propose that analyzing a small set of flood-tail samples is needed for the evaluation of small estuarine ecosystems risk during the rainy season. From a management perspective, we suggest better control of application practices for Diuron in the watershed to minimize the stress to the estuarine ecosystem.

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

Ruppin's Estuarine and Coastal Observatory (RECO) is a Long-Term Ecological Research station positioned on the East Mediterranean shoreline between Tel-Aviv and Haifa, Israel. We present a comprehensive online database and an accompanying website that provides direct access to the physical, chemical, and biological characteristics of the local coastal marine ecosystem and the Alexander micro estuary. It includes three databases that are updated continuously since 2014: a) In situ stationary sensors data (10 min intervals) of surface and bottom temperature, salinity, oxygen and water level measured at three stations along the estuary. b) Monthly profiles and discrete biogeochemical samples (surface and bottom water) of multiple parameters at four stations located at the inland part of the estuary. Measured parameters include concentrations of chlorophyll-a, microalgae and bacteria (counted with a flow cytometer), Nitrate, Nitrite, Ammonium, Phosphate, total N, total P, particulate organic matter (POM), total suspended solids (TSS), biochemical oxygen demand (BOD), as well as Secchi depth in each station c) Bi-weekly profiles, chlorophyll-a concentrations and cell counts at two marine stations adjacent to the estuary, (1, and 7 Km from the estuary mouth, at bottom depths of 8 and 48 m). The database also includes historical data for the Taninim micro-estuary (2014-2016). The RECO observatory provides a unique data set documenting the interaction of highly eutrophicated estuarine water with the ultra-oligotrophic seawater of the Eastern Mediterranean. This combination results in sharp gradients of salinity, temperature, dissolved oxygen, and nutrients over very small scales (centimeters to meters) and therefore offers an important data set for the coastal shelf research community. The data set also provide a long-term baseline of the estuary hydrography and geochemistry with the hope to foster effective science-based management and environmental planning of this and similar systems.

Size Is the Major Determinant of Pumping Rates in Marine Sponges.

Sponges play an important ecological function in many benthic habitats. They filter large volumes of water, retain suspended particles with high efficiency, and process dissolved compounds. Nevertheless, the factors that regulate sponge pumping rate and its relation to environmental factors have been rarely studied. We examined, in situ, the variation of pumping rates for five Mediterranean sponge species and its relationship to temperature, particulate food abundance and sponge size over two annual cycles. Surprisingly, temperature and food concentration had only a small effect on pumping rates, and the seasonal variation of pumping rates was small (1.9-2.5 folds). Sponge size was the main determinant of the specific pumping rate (pumping normalized to sponge volume or mass). Within the natural size distribution of each species, the volume-specific pumping rate [PR V , ml min-1 (cm sponge)-3] decreased (up to 33 folds) with the increase in sponge volume (V, cm3), conforming to an allometric power function (PR V = aVb ) with negative exponents. The strong dependence of the size-specific pumping rate on the sponge size suggests that the simplistic use of this value to categorize sponge species and predict their activity may be misleading. For example, for small specimens, size-specific pumping rates of the two low-microbial-abundance (LMA) species (allometric exponent b of -0.2 and -0.3) were similar to those of two of the high-microbial-abundance (HMA) species (b of -0.5 and -0.7). However, for larger specimens, size-specific pumping rates were markedly different. Our results suggest that the pumping rate of the sponges we studied can be approximated using the measured allometric constants alone in conjunction with surveys of sponge abundance and size distribution. This information is essential for the quantification of in situ feeding and respiration rates and for estimates of the magnitude of sponge-mediated energy and nutrient fluxes at the community level. Further work is required to establish if and to what extent the low seasonal effect and the strong size dependency of pumping rate can be generalized to other sponges and habitats.

Author Correction: Surface properties of SAR11 bacteria facilitate grazing avoidance.

In the version of this Letter originally published, the authors incorrectly stated that primers 28F-519R were reported in ref. 54 to underestimate the abundance of SAR11 in the ocean. This statement has now been amended in all versions of the Letter.

Surface properties of SAR11 bacteria facilitate grazing avoidance.

Oceanic ecosystems are dominated by minute microorganisms that play a major role in food webs and biogeochemical cycles 1 . Many microorganisms thrive in the dilute environment due to their capacity to locate, attach to, and use patches of nutrients and organic matter 2,3 . We propose that some free-living planktonic bacteria have traded their ability to stick to nutrient-rich organic particles for a non-stick cell surface that helps them evade predation by mucous filter feeders. We used a combination of in situ sampling techniques and next-generation sequencing to study the biological filtration of microorganisms at the phylotype level. Our data indicate that some marine bacteria, most notably the highly abundant Pelagibacter ubique and most other members of the SAR 11 clade of the Alphaproteobacteria, can evade filtration by slipping through the mucous nets of both pelagic and benthic tunicates. While 0.3 µm polystyrene beads and other similarly-sized bacteria were efficiently filtered, SAR11 members were not captured. Reversed-phase chromatography revealed that most SAR11 bacteria have a much less hydrophobic cell surface than that of other planktonic bacteria. Our data call for a reconsideration of the role of surface properties in biological filtration and predator-prey interactions in aquatic systems.

VacuSIP, an Improved InEx Method for In Situ Measurement of Particulate and Dissolved Compounds Processed by Active Suspension Feeders.

Benthic suspension feeders play essential roles in the functioning of marine ecosystems. By filtering large volumes of water, removing plankton and detritus, and excreting particulate and dissolved compounds, they serve as important agents for benthic-pelagic coupling. Accurately measuring the compounds removed and excreted by suspension feeders (such as sponges, ascidians, polychaetes, bivalves) is crucial for the study of their physiology, metabolism, and feeding ecology, and is fundamental to determine the ecological relevance of the nutrient fluxes mediated by these organisms. However, the assessment of the rate by which suspension feeders process particulate and dissolved compounds in nature is restricted by the limitations of the currently available methodologies. Our goal was to develop a simple, reliable, and non-intrusive method that would allow clean and controlled water sampling from a specific point, such as the excurrent aperture of benthic suspension feeders, in situ. Our method allows simultaneous sampling of inhaled and exhaled water of the studied organism by using minute tubes installed on a custom-built manipulator device and carefully positioned inside the exhalant orifice of the sampled organism. Piercing a septum on the collecting vessel with a syringe needle attached to the distal end of each tube allows the external pressure to slowly force the sampled water into the vessel through the sampling tube. The slow and controlled sampling rate allows integrating the inherent patchiness in the water while ensuring contamination free sampling. We provide recommendations for the most suitable filtering devices, collection vessel, and storing procedures for the analyses of different particulate and dissolved compounds. The VacuSIP system offers a reliable method for the quantification of undisturbed suspension feeder metabolism in natural conditions that is cheap and easy to learn and apply to assess the physiology and functional role of filter feeders in different ecosystems.

The sponge pump: the role of current induced flow in the design of the sponge body plan.

Sponges are suspension feeders that use flagellated collar-cells (choanocytes) to actively filter a volume of water equivalent to many times their body volume each hour. Flow through sponges is thought to be enhanced by ambient current, which induces a pressure gradient across the sponge wall, but the underlying mechanism is still unknown. Studies of sponge filtration have estimated the energetic cost of pumping to be <1% of its total metabolism implying there is little adaptive value to reducing the cost of pumping by using "passive" flow induced by the ambient current. We quantified the pumping activity and respiration of the glass sponge Aphrocallistes vastus at a 150 m deep reef in situ and in a flow flume; we also modeled the glass sponge filtration system from measurements of the aquiferous system. Excurrent flow from the sponge osculum measured in situ and in the flume were positively correlated (r>0.75) with the ambient current velocity. During short bursts of high ambient current the sponges filtered two-thirds of the total volume of water they processed daily. Our model indicates that the head loss across the sponge collar filter is 10 times higher than previously estimated. The difference is due to the resistance created by a fine protein mesh that lines the collar, which demosponges also have, but was so far overlooked. Applying our model to the in situ measurements indicates that even modest pumping rates require an energetic expenditure of at least 28% of the total in situ respiration. We suggest that due to the high cost of pumping, current-induced flow is highly beneficial but may occur only in thin walled sponges living in high flow environments. Our results call for a new look at the mechanisms underlying current-induced flow and for reevaluation of the cost of biological pumping and its evolutionary role, especially in sponges.