Figure 1
Location map showing the present-day simplified hydrography of the region. White triangles indicate sampling sites from 1c to 6c; yellow star – location of nutrient concentration data; BWS – Black Sea Water; MDW – Mediterranean Deep Water; MS – Marmara Sea; AS – Aegean Sea. The dark grey area represents the surrounding land. The map produced using Ocean Data View (Schlitzer 2018).
Table 1
Average monthly number of vessels transiting the Istanbul and Çanakkale straits between April and July of each year from 2017 to 2020
| Region | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|
| Çanakkale Strait | 3728 | 3751 | 3599 | 3384 |
| Istanbul Strait | 3566 | 3500 | 3363 | 3134 |
Figure 2
Light microscope photo of a specimen showing the total length and operculum width (OW)
Figure 3
Examples of measured specimens with their total length. A) juvenile form; B) mature form and C) adult form
Table 2
Total length and operculum width of 39 individuals
| Sample | Total length (mm) | Operculum width (mm) |
|---|---|---|
| 1 | 7.05 | 0.42 |
| 2 | 7.1 | 0.51 |
| 3 | 7.25 | 0.36 |
| 4 | 7.27 | 0.54 |
| 5 | 7.44 | 0.57 |
| 6 | 7.56 | 0.51 |
| 7 | 7.6 | 0.43 |
| 8 | 7.69 | 0.48 |
| 9 | 7.69 | 0.48 |
| 10 | 7.7 | 0.52 |
| 11 | 7.82 | 0.58 |
| 12 | 7.91 | 0.53 |
| 13 | 8.1 | 0.55 |
| 14 | 8.11 | 0.51 |
| 15 | 8.11 | 0.6 |
| 16 | 8.62 | 0.53 |
| 17 | 8.63 | 0.53 |
| 18 | 8.76 | 0.51 |
| 19 | 8.83 | 0.51 |
| 20 | 8.9 | 0.57 |
| 21 | 8.97 | 0.54 |
| 22 | 9 | 0.54 |
| 23 | 9 | 0.56 |
| 24 | 9.1 | 0.61 |
| 25 | 9.14 | 0.5 |
| 26 | 9.2 | 0.57 |
| 27 | 9.35 | 0.6 |
| 28 | 9.41 | 0.65 |
| 29 | 9.42 | 0.62 |
| 30 | 9.47 | 0.62 |
| 31 | 9.74 | 0.58 |
| 32 | 9.84 | 0.58 |
| 33 | 10.27 | 0.67 |
| 34 | 10.3 | 0.7 |
| 35 | 10.30 | 0.65 |
| 36 | 10.31 | 0.71 |
| 37 | 10.44 | 0.66 |
| 38 | 11.38 | 0.67 |
| 39 | 13.03 | 0.73 |
| Average | 8.87 | 0.56 |
| Min. | 7.05 | 0.36 |
| Max | 13.03 | 0.73 |
| SD | 1.28 | 0.08 |
Figure 4
Operculum width and total length of 39 individuals showing a strong correlation by the quadratic formula at r2 = 0.67.
Figure 5
Plots of the marine environmental parameters measured during the summer seasons (July–August) each year between 2007 and 2020 at six sites (from 1c to 6c) along the Çanakkale Strait. Dashed lines indicate no measurement. Data retrieved from MAREM reports.
Table 3
Physicochemical parameters (temperature, salinity, pH and dissolved oxygen) measured at site 6c in the Çanakkale Strait during summer seasons from 2008 to 2020 (n = 11; significant correlation at p < 0.05 level) showing no significant Pearson correlation.
| Parameter | SST | Sal | pH | DO |
|---|---|---|---|---|
| SST | 1 | |||
| p | - | |||
| Sal | 0.07 | 1 | ||
| p | 0.85 | - | ||
| pH | 0.35 | 0.49 | 1 | |
| p | 0.29 | 0.13 | - | |
| DO | 0.57 | 0.15 | 0.11 | 1 |
| p | 0.07 | 0.65 | 0.75 | - |
Figure 6
Monthly average nitrate concentrations as a nutrient proxy from the Sea of Marmara and the Northern Aegean Sea for the time interval between (a) April 2017 and December 2018; and (b) January 2019 and December 2020. Please note different scales of the two plots. Data retrieved from https://marine.copernicus.eu/
Figure 7
Interpolated Chl-a concentration maps for July in the period between 2017 and 2020 at the vicinity of sampling site 6c in the Çanakkale Strait. The color scale bar applies to all the maps. Data retrieved from https://marine.copernicus.eu/
Figure 8
Map showing Chl-a concentrations observed on the sampling day, 20 July 2020, in the vicinity of sampling site 6c in the Çanakkale Strait and the Sea of Marmara. Data retrieved from https://marine.copernicus.eu/