Short-Term Behavioural Responses of the Great Scallop Pecten maximus Exposed to the Toxic Alga Alexandrium minutum Measured by Accelerometry and Passive Acoustics

Abstract

Harmful algal blooms produced by toxic dinoflagellates have increased worldwide, impacting human health, the environment, and fisheries. Due to their potential sensitivity (e.g., environmental changes), bivalves through their valve movements can be monitored to detect harmful algal blooms. Methods that measure valve activity require bivalve-attached sensors and usually connected cables to data transfers, leading to stress animals and limit the use to sessile species. As a non-intrusive and continuously deployable tool, passive acoustics could be an effective approach to detecting harmful algal blooms in real time based on animal sound production. This study aimed to detect reaction changes in the valve movements of adult Pecten maximus exposed to the toxic dinoflagellate Alexandrium minutum using both accelerometry and passive acoustic methods. Scallops were experimentally exposed to three ecologically relevant concentrations of A. minutum for 2 hours. The number of each type of valve movement and their sound intensity, opening duration, and valve-opening amplitude were measured. Four behaviours were identified: closures, expulsion, displacement, and swimming. The response of P. maximus to A. minutum occurred rapidly at a high concentration. The valve activity of P. maximus was different when exposed to high concentrations (500 000 cells L-1) of A. minutum compared to the non-toxic dinoflagellate Heterocapsa triquetra; the number of valve movements increased, especially closure and expulsion, which were detected acoustically. Thus, this study demonstrates the potential for acoustics and sound production changes in the detection of harmful algal blooms. However, field trials and longer duration experiments are required to provide further evidence for the use of acoustics as a monitoring tool in the natural environment where several factors may interfere with valve behaviours.

PSP-producing dinoflagellate Alexandrium minutum induces valve microclosures in the mussel Mytilus galloprovincialis

“…Similar behavioral responses to toxic microalgae have been reported for the Pacific oyster Crassostrea gigas (Haberkorn et al, 2011;Mat et al, 2016;Tran et al, 2010;Tran et al, 2015), the Akoya pearl oyster Pinctada fucata (Nagai et al, 2006), the Great scallop Pecten maximus (Coquereau et al, 2016), the Northern scallop Argopecten purpuratus (Hégaret et al, 2012), and the Manila clam Ruditapes philippinarum (Basti et al, 2009). As in the case of M.…”

Bioactive extracellular compounds produced by the dinoflagellate Alexandrium minutum are highly detrimental for oysters

“…The increase in frequency of valve micro-closures is probably a protective behavior to increase intervalvar water renewal and minimize contact with BECs, potentially irritant to gill tissues. Increased closures and expulsions observed in Pecten maximus exposed to the PST+BEC strain was also hypothesized to serve as a reaction to expulse A. minutum cells from the mantle cavity (Coquereau et al, 2016). Exposing juvenile Pecten maximus to the BEC strain of A. minutum led to a less effective escape response after a contact with a predator supposedly due to direct tissue damage caused by BECs (Borcier et al, 2017).…”

Mapping the diversity of spectral shapes discriminates between adjacent benthic biophonies

“…This new field of study (referred to as ecoacoustics, Sueur & Farina 2015; or soundscape ecology, Pijanowski et al 2011) mirrors marine fauna by using soundscapes' features to infer information on biodiversity to assess populations (Sueur et al 2008, Zenil et al 2011, Hastings & Širović 2015, ecological process (Hawkins 1986, Crawford et al 1997, Acevedo-Gutiérrez & Stienessen 2004, Amorim 2006, Radford et al 2008, Di Iorio et al 2012, Coquereau et al 2016a, to link soundscape features to oceanographic processes or properties of the habitat or the environment (Mann & Grothues 2009, Ruppé et al 2015 as well as to infer their state of conservation/degradation (Watanabe et al 2002, Coquereau et al 2016c, 2017. To carry out these passive acoustic ecological surveys (PAES) , underwater soundscapes are studied on ecologically relevant time periods and on several sites with contrasting biodiversity, habitats and environmental quality properties.…”