# Zooplankton Community Responses to Oxygen Stress
## 2 Study Area and Methods  
The study was conducted in 41 lakes in north-eastern Poland (Figure 1) with different morphometric parameters, trophic status, and oxygen conditions (Table 1). The area under investigation represents a typical landscape formed during the last Vistulian glacial period [35] and includes the Masurian Lakeland and Suwalki Lakeland. The maximum depth of the lakes ranged from 3 to 73 m, and the surface area ranged from 0.96 ha to 2118.3 ha. Lake Wigry was the largest and deepest, and it is distinguished by very diversified morphometry and a highly developed shoreline [16]. The smallest lakes were mid-forest dystrophic lakes (Table 1), which are usually oval, without any inflows and outflows [36]. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Lakes**} & **Surface** & **Max** & **Avg.** & **Meta** & **SDV** & **Max ch \(a\) & **TSI** & **HDI** & **Trophic** & **Oxygen** \\  & & **(ha)** & **Depth** & **Depth** & **(m)** & **(m)** & **(m)** & **(ug L\({}^{-1}\))** & **TSI** & **HDI** & **Status** & **Group** \\ \hline
1 & Biale Filipowskie & 132.4 & 52 & 17.1 & 7–10 & 7.5 & 2.6 & 29.6 & 35.1 & oligo & G1 \\
2 & Galadus & 728.6 & 54.8 & 12.7 & 7–10 & 5.7 & 1.6 & 33.8 & 35.3 & oligo & G1 \\
3 & Serwy & 460.3 & 41.5 & 14.6 & 6–10 & 3.8 & 5.6 & 38.5 & 35 & oligo & G1 \\
4 & Leleskie & 423.5 & 49.5 & 12.2 & 7–10 & 5.5 & 3.5 & 39.7 & 37.3 & oligo & G1 \\
5 & Jegocin & 127.4 & 36.1 & 9 & 6.5–9 & 7 & 32.7 & 39.7 & 37.7 & oligo & G2 \\
6 & Buwelno & 360.3 & 49.1 & 12.4 & 7.5–10 & 2.4 & 7.3 & 42.4 & 30.7 & meso & G1 \\
7 & Majcz Wielki & 163.5 & 16.4 & 6 & 6–9 & 2.7 & 4.1 & 42.8 & 34.1 & meso & G2 \\
8 & Kuc & 98.8 & 28 & 8 & 6–9.5 & 4 & 8.8 & 43.5 & 34.7 & meso & G1 \\
9 & Biale Wigierskie & 100.2 & 34 & 13.2 & 6.5–11 & 5.7 & 2.3 & 44.3 & 33.3 & meso & G1 \\
10 & Busznica & 49.4 & 48 & 6.8 & 4–10 & 6.6 & 4.8 & 44.3 & 34.8 & meso & G1 \\
11 & Wigry & 2118.3 & 73 & 15.8 & 7.5–10 & 5.2 & 3.8 & 45.4 & 30.9 & meso & G1 \\
12 & Probarskie & 201.4 & 31 & 9.2 & 6.5–9.5 & 3.8 & 7.6 & 46.3 & 33.6 & meso & G1 \\
13 & Okragle & 13.7 & 13 & 5.6 & 3.5–8. & 3.1 & 6.8 & 49.7 & 31.4 & meso & G3 \\
14 & Brzozolasek & 155.9 & 17.2 & 5.1 & 6–9 & 1.2 & 6.4 & 49.4 & 36 & meso & G3 \\
15 & Mikolajskie & 497.9 & 25.9 & 11.2 & 7–10 & 2 & 10.8 & 50 & 34.8 & eu & G2 \\
16 & Kalwa & 562.2 & 31.7 & 7 & 5–8 & 2 & 26 & 50 & 34.8 & eu & G3 \\
17 & Jagodne & 942.7 & 37.4 & 8.7 & 6.5–9 & 2.2 & 11.9 & 50.3 & 29.6 & eu & G2 \\
18 & Boczne & 183.3 & 17 & 8.7 & 7–9.5 & 1.4 & 11.4 & 51.1 & 32.2 & eu & G2 \\
19 & Wirartel & 178.6 & 29 & 4.5 & 7–10 & 1.6 & 15.6 & 51.7 & 37.7 & eu & G3 \\
20 & Pyrskie & 670.8 & 50.8 & 10 & 6–9 & 1 & 9 & 52.5 & 34.3 & eu & G3 \\
21 & Kierzlärskie & 92.8 & 44.5 & 11.7 & 6–9 & 1.5 & 23.5 & 53.1 & 32.7 & eu & G2 \\
22 & Dhugie & 80 & 14.8 & 6.4 & 4–8 & 1.65 & 26.8 & 53.5 & 30.3 & eu & G3 \\
23 & Leszczewek & 21 & 6.5 & 3.6 & \(>\)3 & 2.3 & 97.8 & 54.4 & 32.1 & eu & G4 \\
24 & Nidzkie & 1818 & 23.7 & 6.2 & 6–9 & 0.9 & 34.4 & 55.4 & 35.4 & eu & G4 \\
25 & Garbas & 152.5 & 48 & 20.9 & 4–9 & 2 & 34.5 & 58 & 30.1 & eu & G1 \\
26 & Milkowskiie & 23.7 & 15 & 4.2 & 5–7 & 0.5 & 73.9 & 59.4 & 32.3 & eu & G4 \\
27 & Juno & 380.7 & 33 & 11.9 & 6–9 & 0.7 & 33.7 & 62.9 & 32.7 & eu & G4 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Morphometric and trophic characteristics of the lakes. SDV—Secchi disc visibility; meta depth—depth range of the metalimion; TSI—Carlson trophic state index; HDI—hydrochemical dystrophy index; oligo—oligotrophic; meso—mesotrophic; eu—eutrophic; dy—dystrrophic; nd.—no data. The number of lakes corresponds to the map in Figure 1. For the oxygen group characteristics, see the Method section and Figure 2.  
Figure 1: Localization of the studied lakes in NE Poland.