Insufficient evidence for BMAA transfer in the pelagic and benthic food webs in the Baltic Sea

Abstract

The evidence regarding BMAA occurrence in the Baltic Sea is contradictory, with benthic sources appearing to be more important than pelagic ones. The latter is counterintuitive considering that the identified sources of this compound in the food webs are pelagic primary producers, such as diatoms, dinoflagellates, and cyanobacteria. To elucidate BMAA distribution, we analyzed BMAA in the pelagic and benthic food webs in the Northern Baltic Proper. As potential sources, phytoplankton communities were used. Pelagic food chain was represented by zooplankton, mysids and zooplanktivorous fish, whereas benthic invertebrates and benthivorous fish comprised the benthic chain. The trophic structure of the system was confirmed by stable isotope analysis. Contrary to the reported ubiquitous occurrence of BMAA in the Baltic food webs, only phytoplankton, zooplankton and mysids tested positive, whereas no measurable levels of this compound occurred in the benthic invertebrates and any of the tested fish species. These findings do not support the widely assumed occurrence and transfer of BMAA to the top consumers in the Baltic food webs. More controlled experiments and field observations are needed to understand the transfer and possible transformation of BMAA in the food web under various environmental settings.

No β-N-Methylamino-L-alanine (BMAA) Was Detected in Stranded Cetaceans from Galicia (North-West Spain)

“…In other studies of fish collected in the Baltic Sea, the Eastern North Atlantic, and the Mediterranean Sea, no BMAA was detected in the fish muscle [16,26,28,61].…”

“…BMAA contents in organisms may vary, depending on the methodological differences between studies, inter-specific variations in their trophic status, geographical and seasonal parameters, and ecological responses of its producers [37]. Thus, as previously documented for fish [16,25,26,28,32,60,61], dolphins of certain geographical areas might also contain higher concentrations of BMAA than others. Accordingly, Davis et al (2019) reported three-fold higher concentrations of total BMAA in dolphins stranded in Florida than in dolphins from Massachusetts [45].…”

“…Moreover, the predominant wind and oceanographic conditions of NW Spain enhance phytoplankton production, and diatoms and dinoflagellates blooms are recurrently reported [20]. The presence of BMAA has been described in several organisms along the aquatic and terrestrial food chains, including zooplankton [24][25][26], crustaceans [27,28], bivalves [25,[29][30][31], fish [25,32], and terrestrial plants and animals [33][34][35][36]. However, a review by Lance et al (2018) [37] observed no clear indication of the BMAA trophic transfer.…”

Stable isotope analysis in food web research: Systematic review and a vision for the future for the Baltic Sea macro-region

“…In particular, BSIA helped to elucidate the role of microbial food webs and zooplankton grazing strategies (e.g., Rolff 2000 ; Eglite et al 2018 ; Motwani et al 2018 ) as well as benthic feeders (e.g., Limén and Ólafsson 2002 ; Karlson et al 2014 ) in the transfer of diazotrophic nitrogen, whereas CSIA was used to elucidate the role of complex biochemical processes and cyanobacterial supply of de novo synthesized amino acids for planktonic food webs (e.g., Loick-Wilde et al 2012 , 2018b ; Eglite et al 2019 ). Moreover, SIA studies addressed cyanobacterial toxins in fish (e.g., Lesutienė et al 2018 ) and neurotoxins in coupled pelagic–benthic food webs (Zguna et al 2019 ).…”

Is Exposure to BMAA a Risk Factor for Neurodegenerative Diseases? A Response to a Critical Review of the BMAA Hypothesis

“…Even the intestinal flora of humans has been hypothesized to be a potential source of BMAA (Nunes-Costa et al 2020) and related hypotheses have emerged which implicate the human microbiota in neurodegenerative disease (Obrenovich et al 2020). In recent studies, BMAA has been detected within several of these organisms including microbial biofilms, marine and freshwater diatoms, dinoflagellates, and zooplankton (Réveillon et al 2016;Chatziefthimiou et al 2018;Jungblut et al 2018;Violi et al 2019;Zguna et al 2019;Metcalf et al 2020;. This expanding field of research will provide interesting data to help us understand the complex interactions of non-protein amino acids in a variety of organisms and ecosystems.…”