Beyond the Ridge: Currents in the Carmel bypass and Achziv Canyon and their role in sediment and pollution transport and zooplankton community structure
Leading researcher: Dr. Revital Bookman
Together with the research team:
In collaboration with the institutions: Universty of Haifa, Geological Survey of Israel, Israel Oceanographic and Limnological Research (IOLR)
In the early morning at mid-August we sailed for a cruise off shore the Haifa Bay. On board the scientific crow consisted of three groups leaded by Revital Bookman that included Nadya Teutch a geochemist from the Geological Survey, Keren Weiss, a Phd student, Mingjian Wang, a master student. This group was responsible for box core sampling. The second group included Tamr Guy-Haim, a biologist from IOLR. The third group was leaded by Roee Diamant, who supervised the marine technological staff that included Ben Hertzog, Ilan Shachar, Hadar Shalev, Guy Guvnitski a master student, and Shmuel Salomon. We also invited Prof Amir Boag from the university of Tel Aviv.
The cruise started with the deployment of autonomous drifters and an AUV, with the objective to estimate the water current. Unfortunately, the AUV failed during the experiment and two of the beacons we deployed to localize the drifters were malfunctioned. As a result, the main task could not be done. We did however managed to record the self-noise of the AUV for a project focused on noise cancellation of self-noise for long range underwater acoustic communication to AUVs. By comparing the log of the AUV to the recordings made, we identified six main categories of noise. This categorization is currently being analyzed to develop an interference rejection algorithm. For prelimnary results https://www.dropbox.com/s/zpx8z28q5c90vp9/AUVnoise%20Analysis%2020200616.pdf?dl=0
During and after the finalization of the AUV recording, we deployed a box corer and a multi-net at sites along the path of the drifters and AUV. The main objective is to describe the transport of sediments and plankton with the currents flowing across the Carmel Bypass.
From each site, (table 1) two short cores were collected. The cores were visually described, and measured. One core was sub-sampled at 1 cm resolution, the second was archived. The sediments from the cores are being currently analyzed in the Environmental Sedimentology for grain size distribution and Inorganic and Organic Carbon. The isotopic Pb signature of total and leached samples will be used to determine dominant anthropogenic sources to the sediments. Elemental and isotopic composition heavy metals will be measured by MC-ICP-MS in the Geological Survey of Israel by our PhD and MSc students.
Table 1 – core locations
|Station||Collection hour||Location||Water Depth (m)||number of cores collected||Core length (cm)||Remarks|
|2||10:40||32.910855/34.919785||59.2||2||23 + 17|
|6||12:50||32.511057/34.526814||63.4||The sea bottom was rocky (“kurkar”). Only a surface sample was collected in a cup|
|1||13:55||32.838637/34.877427||69.5||2||21 + 17|
|3||16:00||32.56.25/34.55.40||62.5||2||15 + 15|
|4||18:30||32.58.51/34.56.24||64.8||2||23.4 + 23|
|5||19:30||33.00.52/34.57.28||63.4||2||33 + 35|
|6||20:30||33.02.2/34.59.13||61.3||2||~20 + 17.5|
Zooplankton was sampled in the box-corer sites using vertical hauls of an automated multiple plankton sample (150-µm mesh-size, MultiNet Midi, Hydro-Bios, Germany) hoisted at 0.5 m/s, in five discrete layers of 10-20 m from 5 m above the seafloor to the surface. Filtered volume per each of the nets was obtained using electronic flow meters integrated into the MultiNet. The samples were sieved using a 100-µm mesh sieve, and preserved in -20 °C for further analyses. In lab, the thawed samples were scanned using an integrated system for acquisition and classification of digital zooplankton images will be applied to detect, enumerate, measure, and classify the digitized objects. The system includes scanning of preserved samples, segmentation, measurements, and a web-based application for annotation and classification (Eco-Taxa) using artificial intelligence (AI). Following scanning, each sample was split using a Motoda splitter. Half of the sample was preserved in 4% buffered formaldehyde, and the other half was used for biomass determination by filtering on pre-weighed and pre-combusted GF/F 47mm filters. Filters were placed on Aluminum tins and dried at 60 °C for 24 h before weighing to obtain biomass data (mg dry weight m-2). Further analysis will be done with a student we will recruit.