Allelopathic effect of Prymnesium parvum on a natural plankton community

Abstract

The allelopathic effect of Prymnesium parvum (Prymnesiophyta), which produces toxins with haemolytic, ichthyotoxic and cytotoxic properties, was investigated on a natural plankton community. Under controlled conditions, 3 laboratory bioassays were performed by adding cell-free filtrate from a P. parvum culture into different size fractions (<150, <100 and 20 to 150 µm) of a natural Baltic Sea plankton community. The effect of P. parvum cell-free filtrate was determined by measuring chlorophyll a, cell numbers (phytoplankton, ciliates, bacteria), carbon ( 14 C) uptake by phytoplankton and the incorporation of 3 H-leucine by bacteria. P. parvum cell-free filtrate affected the whole phytoplankton community, resulting in a decrease in both chlorophyll a and carbon uptake. Furthermore, the plankton groups present in the community exhibited different sensitivity to the cellfree filtrate. While growth of cyanobacteria and dinoflagellates was inhibited, that of diatoms and ciliates was not only completely suppressed, but no cells were present at the end of the experiment in the bottles with P. parvum filtrate. In all experiments, therefore, cyanobacteria and dinoflagellates were the most resistant groups, which led to their dominance in the treatments with filtrate compared to controls. Bacterial production was also negatively affected by P. parvum filtrate. The results show that compounds released by P. parvum induce changes in the plankton community structure, killing other members of the marine food-web, especially other phytoplankton (allelopathy), and suggest that secreted compounds of P. parvum are inhibitory to potential grazers (ciliates). It is proposed that allelopathy is an important process in the ecology of P. parvum.KEY WORDS: Prymnesium parvum · Allelopathy · Natural plankton community · Phytoplankton · Ciliates · BacteriaResale or republication not permitted without written consent of the publisher

The effect of costs associated with toxin production in a competitive system

“…In 2008, Chakraborty et al [4] also investigated the effect of nutrient limitation on the toxin production by considering the toxin as a different variable. It is to be noted here that photoxidation can cause rapid degradation of toxic compounds [10,22] and the toxins are quickly inactivated by visible light in the 400-510 mm range and by ultraviolet light in the 225 mm range [7,35].…”

“…Though, some biologists restrict the use of this term to negative effects only [17]. There are several examples of allelopathic interactions among marine algal species both in vitro and in situ [5,10,11,14,23,28,29,33,39,40,42]. A review of different aspects of chemical ecology of microalgae, including allelopathy, can be found in Cembella [3].…”

Effect of different salinities on growth and intra- and extracellular toxicity of four strains of the haptophyte Prymnesium parvum

“…Production of toxins may be the key mechanism by which Prymnesium parvum gains a selective advantage over other phytoplankton (Fistarol et al 2003, Granéli & Johansson 2003, and lower salinity might be a stress factor increasing toxin production in P. parvum (Reigosa et al 1999, Granéli et al 2012). Baker at al.…”

“…As hemolytic assays are often not sensitive enough to determine P. parvum exotoxin production (Uronen et al 2005), bioassays with organisms such as the cryptophyte Rhodomonas salina (Fistarol et al 2003, Tillmann 2003, the brine shrimp Artemia (Meldahl et al 1994) or fish (Reich & Parnas 1962, Schug et al 2010) are used as an alternative. Since intra-and extracellular toxicity are not necessarily linked, both need to be measured to evaluate P. parvum toxicity (Parnas 1963, Manning & La Claire 2010.…”

Coastal biodiversity and bioresources: variation and sustainability

“…Allelopathy as a widespread ecological/ physiological phenomenon is very important to the composition of species, community structure, biomass, and growth dynamics, especially in red-tide blooms (Fistarol et al, 2003(Fistarol et al, , 2004Yamasaki et al, 2009). He et al (2016) studied the allelopathic interaction between microalgae Karenia mikimotoi and Dunaliella salina in laboratory culture, and gave suggestions to reveal the mechanism of the formation and/or maintenance of harmful algae blooms.…”