Figure 1
Locations of the sampling sites. GIS layers used for drawing the map were obtained from the GIS Centre of the University of Gdańsk.
Table 1
Abundance of Sinelobus vanhaareni, information on the main associated taxa and key environmental parameters at the study sites in Polish coastal waters. Numbers in brackets before sites’ names in the first column refer to those given in Fig. 1 (T – temperature, S – salinity).
| Site | Sampling date | Abundance (max) | T (°C) | S (PSU) | Depth (m) | Substrate/sampling method | Main associated taxa |
|---|---|---|---|---|---|---|---|
| (1) Port of Gdynia | July 2014 (first record) | 3530 ind. m−2 | 22.0 | 6.9 | 1–3 | Horizontal artificial hard bottom (settlement plates) | Amphibalanus improvisus Gonothyraea loveni Cordylophora caspia |
| Sept. 2014 | 47 400 ind. m−2 | 19.0 | 7.0 | 1–7 | Horizontal artificial hard bottom (settlement plates) | Amphibalanus improvisus Gonothyraea loveni Einhornia crustulenta | |
| Oct. 2014 | 37 000 ind. m−2 | 16.3 | 7.1 | 1–7 | Horizontal artificial hard bottom (settlement plates) | Amphibalanus improvisus Gonothyraea loveni Einhornia crustulenta | |
| Oct. 2014 | 100 per trap | 16.1 | 7.1 | 9 | Artificial habitat collector | Leptocheirus pilosus Melita nitida Apocorophium lacustre | |
| July 2015 | 500 per trap | No data | 6.9 | 9 | Artificial habitat collector | Mytilus trossulus Leptocheirus pilosus Melita nitida | |
| Jan. 2016 | 100 ind. m−2 | 1.7 | 7.3 | 14 | (Soft sediment Van Veen grab) | Oligochaeta Polychaeta Limecola balthica Cerastoderma glaucum | |
| June 2016 | 1 per trap | 19.2 | 6.9 | 9 | Artificial habitat collector | Oligochaeta Polychaeta Amphipoda Jaera spp. | |
| Aug. 2016 | 10 ind. m−2 | 21.1 | 7.1 | 14 | Soft sediment (Van Veen grab) | Oligochaeta Polychaeta Amphibalanus improvisus Limecola balthica Mytilus trossulus | |
| (2) Gdynia Babie Doły | July 2015 | 3825 ind. m−2 | 18.6 | 6.4 | 2–8 | Vertical concrete walls of a man-made offshore structure (Kautsky sampler) | Mytilus trossulus Amphibalanus improvisus Amphipoda |
| July 2015 | 358 ind. m−2 | 18.6 | 6.4 | 8 | Natural boulders up to 1 m diameter (Kautsky sampler) | Mytilus trossulus Amphibalanus improvisus Leptocheirus pilosus | |
| (3) Jastarnia | March 2016 | 1133 ind. m−2 | 4.0 | 6.7 | 2–4 | Vertical concrete walls of a man-made offshore structure (Kautsky sampler) | Mytilus trossulus Amphibalanus improvisus Amphipoda |
| (4) Naval Base in Hel | April 2016 | No data | 4.2 | 6.5 | 2–5 | Vertical concrete walls of a breakwater (Kautsky sampler) | Mytilus trossulus Amphibalanus improvisus Gammarus spp. |
| (5) Gdańsk National Sailing Centre | May 2016 | No data | 19 | 4.9 | 2–4 | Verfical man-made concrete piles(Kautsky sampler) | Mytilus trossulus Amphibalanus improvisus |
| (6) Gdynia Orłowo | June 2016 | 1791 ind. m−2 | 6.1 | 6.5 | 5 | Natural boulders up to 1 m diameter (Kautsky sampler) | Mytitrossulus Amphibalanus improvisus Heterotanais oerstedii |
| (7) Port of Hel | Sept. 2017 | 60 per trap | 18.1 | 7.2 | 2 | Artificial habitat collectors | Hydrobiidae Jaera spp. Mytilus trossulus Heterotanais oerstedii |
| (8) ORP “Bryza” Shipwreck | Jan. 2016 | Not present | 4.0 | 7.2 | 12 | Steel plating of a shipwreck (Kautsky sampler) | Mytilus trossulus Amphibalanus improvisus Amphipoda Jaera spp. |
| April 2018 | Not present | 3.9 | 7.2 | 12–16 | Steel plating of a shipwreck (Kautsky sampler) | Mytilus trossulus Amphibalanus improvisus Amphipoda Jaera spp. | |
| (9) Słupsk Bank | Jan. 2018 | Not present | 3.6 | 7.3 | 14 | Natural boulders up to 2 m diameter (Kautsky sampler) | Mytilus trossulus Amphibalanus improvisus Amphipoda Jaera spp. |
| March 2018 | Not present | 4.0 | 7.3 | 14 | Natural boulders up to 2 m diameter (Kautsky sampler) | Mytilus trossulus Amphibalanus improvisus Amphipoda |
Table 2
Comparison of the main taxonomic features used to distinguish S. vanhaareni from H. oerstedii (Haaren & Soors 2009; Bamber 2014; personal observations)
| Feature | Sinelobus vanhaareni Bamber, 2014 | Heterotanais oerstedii (Krøyer, 1842) |
|---|---|---|
| Max body length | 3.0 mm | 2.0 mm |
| External pigmentati on | Dark mottling on dorsal surface of the entire body | Creamy white body with no mottling |
| Thorax | Pereonites rounded or trapezoidal in shape, which creates notched lateral edges of the animal | Pereonites more rectangular in shape, which makes the notching less visible |
| Pleon | 4 pleonites and pleotelson | 5 pleonites and pleotelson |
| Each of pleonites 1–3 twice as long as pleonite 4 | Pleonites 1–5 subequal in length | |
| Pleonite 1 narrowed anteriorly, which makes the entire pleon well pronounced | Pleonite 1 rectangular in shape, which makes the entire pleon less distinct | |
| 3 pairs of ventral pleopods on pleonites 1–3 | 5 pairs of ventral pleopods on pleonites 1–5 | |
| Two rows of plumose setae on dorsal side of pleonites 1–3 | No plumose setae on dorsal side of pleon |
Figure 2
Non-native and native representatives of Tanaidacea collected in the Gulf of Gdansk, S. vanhaareni: A – female, B – male, C – pleon and H. oerstedii: D – female, E – male, F – pleon (P – pleonite; PT – pleotelson). The scale bar on photograph A applies to photographs B, D and E as well.