Diversity and Physiological Tolerance of Native and Invasive Jellyfish/Ctenophores along the Extreme Salinity Gradient of the Baltic Sea

Abstract

Global change has led to manifold changes of marine ecosystems and biodiversity world-wide. While it has been shown that certain jellyfish and comb jelly species have increased regionally, it remains to be investigated if this is a general trend or localized phenomenon. Especially for the economically important Baltic Sea, which is characterized by an extreme physical environmental gradient, this question has not been addressed to date. Here we present a detailed account of the gelatinous macro-zooplankton community including their physiological tolerance towards abiotic conditions and resulting distribution ranges in the Baltic. We show that the arrival and establishment of non-indigenous species has led to a rising importance of jellyfish and comb jellies in the Baltic. This accounts for the comb jelly Mnemiopsis leidyi, which was first observed in Northern Europe in 2005, as well as for the hydromedusae Blackfordia virginica, first sighted in 2014. Both species have been shown to attain high population densities with pronounced grazing impact in other invasive regions. Given the current and anticipated changes of the physical environment of the Baltic Sea, especially ongoing warming, amplification of their impact can be expected.

Towards an integrated view on microbial CH4, N2O and N2 cycles in brackish coastal marsh soils: A comparative analysis of two sites

“…1 B) were selected as study sites. All studied sites were similarly affected by the brackish water, with water salinity around 7–8 ‰ ( Yang et al, 2020 ; Jaspers et al, 2021 ). The Estonian and Chinese sites have an average annual temperature of 6.8 °C and 15.9 °C and an annual precipitation of 761 and 1150 mm, respectively.…”

“…Coastal habitats face local and global risks from both direct (e.g., temperature, rainfall, water quality disturbances) and indirect (e.g., sea-level rise, coastal erosion) factors linked to environmental and climate changes ( Burden et al, 2020 ; Zhu et al, 2020 ; Liu et al, 2021 ), and rapid urbanisation have amplified these impacts ( Craig-Smith et al, 2006 ). Human coastal habitats often lie within river deltas (e.g., Shanghai) or have limited oceanic connections despite receiving substantial riverine inputs (e.g., Baltic Sea), resulting in lower water salinity and slower pollutants dispersion compared to the open oceans, making it important to study those urbanised coasts with brackish water (mixed saline and freshwater) greatly impacted by pollution ( Yang et al, 2020 ; Jaspers et al, 2021 ). Excessive nutrient pollution from agricultural, industrial, and domestic sources is a major concern for coastal ecosystems, impacting their ecological integrity and biodiversity globally ( Deegan et al, 2012 ; Newton et al, 2020 ).…”

Amazing Graze: Shifts in Jellyfish and Clam Distributions During Dry Years in the San Francisco Estuary

“…For example, increases in abundance of jellyfish worldwide have caused collapses in fish stocks as a result of competition and predation (Richardson et al 2009), most notably in the Black Sea where the invasive ctenophore Mnemiopsis leidyi caused a crash in planktivorous fish abundance and diversity (Shiganova 1998). Similarly, in the Baltic Sea, invasive cnidaria and ctenophores have been linked to decreased populations of zooplankton and increased chlorophyll concentrations (Schneider and Behrends 1998;Jaspers et al 2021;Stoltenberg et al 2021). Jellyfish may form "blooms" that cause far-reaching, short-term effects on estuaries (Lars Johan et al 2005;Manzari et al 2015;Amorim et al 2018;Gueroun et al 2020), and the collapse of these blooms can negatively affect water quality (Baliarsingh et al 2020;Guy-Haim et al 2020).…”

A trait‐based approach to assess niche overlap and functional distinctiveness between non‐indigenous and native species

“…pollution or warming) make the Baltic Sea highly susceptible to the arrival and establishment of NIS from both marine and limnetic origin (Paavola et al, 2005;Reusch et al, 2018). Although numerous studies have been conducted on NIS in the region (Jaspers et al, 2021;Ojaveer et al, 2010Ojaveer et al, , 2021Paavola et al, 2005), little is known about the underlying processes determining their establishment or the degree of niche overlap with native species across spatial scales.…”