Influence of invader ctenophores on bioluminescence variability off the coast of Western Crimea

Abstract

In the second half of the XX century, Black Sea ecosystem has undergone significant changes: a number of storm winds and upwellings decreased, precipitation abundance increased, coastal waters salinity decreased, temperature increased; moreover, ctenophores invaded. As a result, in the late 1980s, Black Sea pelagic ecosystem abruptly got restructured. This research is based on the studies performed in 1965–1966 and 2007–2012 near Sevastopol (Western Crimea) using the remote sensing data. Analysis of satellite data over the past 20 years showed the presence of positive dynamics in surface water temperature in Sevastopol water area. In the mid-1960s, the annual bioluminescence was characterized by seasonal peaks of dinophytes luminescence. In recent years, this rhythm has changed due to ctenophores invasion. The increase in Mnemiopsis leidyi abundance leads to a decrease in bioluminescence of luminous microalgae being consumed by these ctenophores. Due to Beroe ovata invasion and reproduction, M. leidyi biomass decreased; as a result, bioluminescence increased.

A review of mechanically stimulated bioluminescence of marine plankton and its applications

“…This species is a threat to local fisheries as it decimates zooplankton and ichthyoplankton populations. Melnik et al (2020) noted that an increase in M. leidyi biomass resulted in a decrease of dinoflagellate bioluminescence in the Black Sea. Since emissions of these two groups are distinct (Table 3), the relative contribution of both to water column bioluminescence may be a good indicator of the ecosystem's state, and could be measured remotely without intensive field deployments (Widder, 2010b).…”

Bioluminescence of ctenophores near the boundary of oxygen‐depleted waters at the redoxcline of the Black Sea

“…For the measurement of integral bioluminescence, the Salpa-M biophysical system [28] was used. This system allows the simultaneous measurement of bioluminescence, temperature, hydrostatic pressure, turbidity, and photosynthetically active radiation.…”

“…Discreteness of the device measurements during the 'down' operation at a speed of 1.2 mÁs −1 was about 0.25 m. To plot graphs of vertical profiles, data were integrated every 1 m. The method of collecting and processing information using the Salpa-M system has been previously described in detail. [28]…”