Phenotypic variability in byssus thread production of intertidal mussels induced by predators with different feeding strategies

Abstract

Predator-induced defenses have a significant influence on the expression of morphological and behavioral traits of marine species. In mussels, common responses to predators include thickening of the shell, enlargement of the adductor muscle and increases in byssus production. We hypothesize that predators with different feeding strategies have different effects on byssus production of the common intertidal mussels Perumytilus purpuratus and Semimytilus algosus in central Chile. Predators that dislodge prey mussels before killing them, such as crabs and seastars, should elicit increased byssus production in their prey compared to other predators such as whelks, which use different feeding mechanisms. Laboratory experiments with the seastar Heliaster helianthus, the crab Acanthocylus gayi, and the muricid gastropods Concholepas concholepas and Acanthina monodon showed that only A. gayi induced significant increases in byssus production, causing remarkably similar responses in both mussel species. Further experiments in which individual mussels with different attachment strengths were offered to A. gayi showed that the crabs first tried different mussels and then selected those with the weakest attachment, leading to consumption rates of weakly attached mussels that were 5 to 6 times higher than those of mussels with strong attachment to the substratum. Measurements of mussel attachment strengths in the field showed that, where A. gayi is abundant, both mussel species are more strongly attached than in habitats where this predator is scarce. While responses of mussels to crabs seem to be adaptive, the lack of a response to H. helianthus is intriguing, because it is one of the most important mussel predators in the system which can dislodge entire clumps of mussels at a time. It is possible that increased byssus production is ineffective in reducing predation by this large predator; however, this adaptive explanation requires further studies. These results highlight the predator-specific nature of many prey phenotypic responses and the importance of considering the multiplicity of predators typically present in most habitats.KEY WORDS: Byssal thread production · Tenacity · Dislodgement · Predator-prey interaction · Predator-induced defenses · Mussels · Sub-lethal effectsResale or republication not permitted without written consent of the publisher

Risk recognition and variability in escape responses among intertidal molluskan grazers to the sun star Heliaster helianthus

“…Predators not only have direct effects on prey populations and their communities by causing mortality of prey individuals, but they can also induce non-consumptive effects in the form of reversible or non-reversible phenotypical changes in prey traits, such as morphology (e.g. Lively 1986, Appleton & Palmer 1988, Caro & Castilla 2004, Caro et al 2008, growth (Peckarsky et al 1993, Yamada et al 1998, and behavior (Harrold 1982, Côté & Jelnikar 1999, Espoz & Castilla 2000, Trussell et al 2006, and see Havel 1987, Stearns 1989, Harvell 1990, Lima 1998and Miner et al 2005 for reviews). Indeed, several authors have argued that non-consumptive effects of predation might be equally or even more important than consumptive effects on prey distribution, prey growth rates and even on population abundance and community dynamics (Werner et al ABSTRACT: Escape responses are a common form of inducible defense in the presence of a predator, which can be species-specific and adaptive.…”

Selective byssus attachment behavior of mytilid mussels from hard- and soft-bottom coastal systems

“…Pansch et al, 2009), predators (e.g. Côte, 1995Reimer and Tedengren, 1997;Kobak et al, 2010), or injured conspecifics, which is a strategy to reduce mortality risk (e.g., Caro et al, 2008;Cheung et al, 2009;Garner and Litvaitis, 2013). Thus, it is possible that mussels avoided dead shells in our experiments because of chemical cues that remained within the empty shells after removing the flesh just before starting the experiments.…”

Morphological diversity of microstructures occurring in selected recent bivalve shells and their ecological implications

“…For this reason, it belongs to byssally attached bivalve ecological category (Harper and Skelton 1993). Byssal thread production is also considered as anti-predator adaptations (Cheung et al 2006;Caro et al 2008;López et al 2010), bivalves like Asian green mussel (Perna viridis, Mytilinae) and Brachidontes variabilis (also Mytilinae) increased byssal thread production, as well as the thicker and longer byssal threads when they were exposed to shell-crushing crabs. By increasing the strength of byssal attachment as a defensive trait, the chance of being dislodged and consumed by crabs is reduced (Cheung et al 2006).…”