Effects of sponge and barnacle encrustation on survival of the scallop Chlamys hastata

Abstract

The scallop Chlamys hastata frequently carries epibionts such as sponges and barnacles on its shells. Although the scallop-sponge relationship has been characterized as a mutualism, little is known about the scallop-barnacle relationship. This study investigated the effects of sponge and barnacle encrustation on the ability of C. hastata to avoid predation by the sea star Pycnopodia helianthoides. In feeding trials, P. helianthoides caught and consumed significantly more barnacle-encrusted scallops (7.7 ± 0.8 out of 20 scallops) than scallops encrusted by either of the sponges Myxilla incrustans (4.1 ± 0.9) or Mycale adhaerens (3.0 ± 0.5). Epibiont-free scallops (5.7 ± 0.5) formed an intermediate treatment between barnacle-encrusted and sponge-encrusted scallops. Possible mechanisms by which the sponges protected the scallops were investigated in two ways: two feeding trials were videotaped to allow qualitative analysis of sea star and scallop behavior and sea star feeding responses to scallop and sponge homogenates were determined to investigate if sea stars accept scallops and sponges as prey. Sea stars displayed positive feeding responses to scallop puree 97.5% ± 1.6 of the time while only displaying positive responses to Mycale adhaerens homogenate 4.4% ± 2.0 of the time and to Myxilla incrustans homogenate 4.4% ± 2.9 of the time. The videotaped feeding trials indicated that interference with tube feet adhesion by the sponge deterred predation. Observations of both sea stars that were videotaped showed that neither avoided trying to capture sponge-encrusted scallops, and at no time was a captured scallop willingly released by the sea stars. Thus, it appears that sponges provide tactile-mechanical protection and possibly chemical or tactile camouflage in this predator/prey relationship. Finally, the effects of sponge encrustation on barnacle settlement were determined. Field experiments showed that barnacle larvae settled more frequently on epibiont-free scallops than on those with either of the two sponges, potentially protecting the scallops from an epibiont that increases the scallop's susceptibility to predation.

A Way to Decrease the Negative Impact of Aquaculture on other Marine Inhabitants

“…However, our technology is supported by the fact that the animals and plants within the collector-cages create a multicultural community: mollusks, seaweed, shrimp and sea urchins produce DOM (Dissolved Organic Matter) used as food by bacteria [22] and phytoplankton [23,24], on which bivalves actively feed [25,26]. Cultivated mollusks are often resistant to fouling [27] and use mechanisms to protect themselves against predators [28], with some fouling organisms assisting them in this [29].…”

Sessile biota fouling farmed mussels: diversity, spatio-temporal patterns, and implications for the basibiont

“…The known relationships between bivalves and their epibionts have been considered beneficial for the former since the presence of the latter reduces potential physical stress and promotes escape from predators (Laudien & Wahl, 2004; Cerrano et al , 2006; Farren & Donovan, 2007; but see Buschbaum & Saier, 2001).…”

“…substrate organisms which host the epibionts (Wahl, 1989). Thus, the presence of sponges on farmed bivalves is considered positive, since they protect shellfish from predators and other harmful epibionts by secreting bioactive compounds or camouflaging (Armstrong et al , 1999; Ross et al , 2004; Farren & Donovan, 2007). On the contrary, ascidians are interpreted as typical damaging organisms (Arakawa, 1990; Santacroce et al , 2008); they often aggregate in large numbers and the accumulated biomass highly stresses farmed mussels, even dislodging them from the socks.…”

Treatise Online no. 44: Part N, Revised, Volume 1, Chapter 22: Predation of bivalves

“…These bivalves may promote the growth of camouflaging epibionts by virtue of their spiny ornaments. Several authors suggest that the sponge coatings of certain scallops may also inhibit attack by extra-oral feeding asteroids by interfering with the attachment of their tube feet (blooM, 1975;Marin & lópEz bElluga, 2005;FarrEn & DonoVan, 2007). Epibionts may also provide a chemical defense to their bivalve hosts (lauDiEn & wahl, 2004).…”