Predator-Prey Interactions: an Example of Sander Sander lucioperca and Tyulka Clupeonella cultriventris of the Rybinsk R
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ator-Prey Interactions: an Example of Sander Sander lucioperca and Tyulka Clupeonella cultriventris of the Rybinsk Reservoir in Conditions of Climate Warming M. N. Ivanovaa, A. N. Svirskayaa, *, and M. I. Bazarova aPapanin
Institute for the Biology of Inland Waters, Russian Academy of Sciences—IBIW RAS, Borok, Russia *E-mail: [email protected] Received August 1, 2019; revised November 6, 2019; accepted November 8, 2019
Abstract—The food composition of sander Sander lucioperca in the Rybinsk Reservoir was studied during the period of regional climate warming and along with significant fluctuations in the harvests of the southern invasive fish species, tyulka Clupeonella cultriventris. In the period of the relatively low abundance of tyulka (2007–2014) compared to the year following its mass outbreak (2016), the proportion of this species in zander diet was two-fold less (28.3 versus 60.7% of the number of prey consumed). In 2007−2016 tyulka took the first place in the food of sander: its share in the diet in riverbed and floodplain sections of the reservoir was 39.5 and 33.9%, respectively. In 2010 the period of intensive feeding of sander lasted until December inclusive. Compared to the period of the climatic norm, in the younger age groups of sander (3 + −6 +) the dates and places of feeding have changed: they fed on biotopes of open and protected littoral, feeding on juvenile roach Rutilus rutilus. Tyulka, an inhabitant of riverbed zones, remains the main prey for individuals older than 6+. Keywords: sander Sander lucioperca, tyulka Clupeonella cultriventris, feeding spectrum, size-age composition, climate warming, riverbed and floodplain areas, Rybinsk Reservoir DOI: 10.1134/S0032945220040062
In the XXI century climate warming becomes an important factor affecting the both ecosystem of the Rybinsk Reservoir as a whole and its individual components (Ryby Rybinskogo …, 2015; Lazareva et al., 2018). Over a 30-year period (1976–2005), the average temperature of the surface layer of water in the reservoir increased by 3.1°С, the maximal rate of increase in July was 0.7–1.2°С/10 years (Litvinov and Roshchupko, 2010). In the 2000th the average duration of the growing season increased by 20 days (from 193 to 213) owing to the later onset of ice cover (late November) (Litvinov et al., 2012). All links of the ecological chains of the reservoir and, first of all, the primary one, phytoplankton, reacted to climate change (Devyatkin et al., 2012; Litvinov et al., 2012, 2014; Mineeva et al., 2016; Sakharova and Korneva, 2018). In 2004–2010 in the zooplankton community the number of all copepods and most of the large cladocerans increased by 1.5–3.0 times and a shift in the structure of the community towards an increase in the share of large organisms (Lazareva and Sokolova, 2016) was recorded. Due to warming, the length of the period of mass development of summer zooplankton rose and a powerful peak of its abundance in the second half of summer formed. This served as an important factor for the successful establishing o
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