Pedal mucus and its influence on the microbial food supply of two intertidal gastropods, Patella vulgata L. and Littorina littorea (L.)

The phenomenon of shell wiping in Calliostoma zizyphinum (L.) was investigated with regard to its potential function as a feeding adaptation. It was determined that C. zizyphinum will, on average, wipe the surface of its shell with its foot twice every 24 h, in the process consuming any matter that has adhered to the pedal mucus present on the surface of its shell. Examination of the importance of shell wiping to C. zizyphinum, both as a mechanism to reduce shell fouling and as a source of nutrition, revealed that the prevention of shell wiping resulted in a reduction in shell growth by a factor of 0.67 and an increase in shell fouling by a factor of 9. Measurement of the metabolic rate of C. zizyphinum ascertained that an average sized adult had a metabolic requirement of ~117 J 24 h -1 . Examination of the ability of the pedal mucus produced by C. zizyphinum to act as a provendering agent showed that the pedal mucus produced by C. zizyphinum could increase the entrapment of particulate matter by a factor of 8, and increase the chlorophyll a content of a substratum by a factor of 3. Calculation of the potential contribution of the matter trapped by pedal mucus, which is ingested through shell wiping, to the daily energetic requirements of C. zizyphinum revealed that shell wiping can contribute to approximately one-fifth of the daily energetic requirement of C. zizyphinum. Shell wiping therefore has an important role for both feeding and antifouling in C. zizyphinum.

Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Shell wiping in Calliostoma zizyphinum: the use of pedal mucus as a provendering agent and its contribution to daily energetic requirements

Holmes¹,

Sturgess²,

Cherrill³

et al. 2001

“…The explanations above for grazing history boosting biofilm biomass may equally apply to areas exposed to grazing. Intertidal snails can additionally fertilise micro-algae by excretion of limiting nutrients (Plagányi & Branch 2000) and mucus deposition can stimulate micro-algal attachment and growth (Davies et al 1992). Williams et al (2000), however, found a negligible effect of snail mucus deposition in comparison to the increase in biomass that resulted from snail exclusion.…”

Section: Discussionmentioning

confidence: 99%

Past and present grazing boosts the photo-autotrophic biomass of biofilms

Skov¹,

Volkelt-Igoe²,

Hawkins³

et al. 2010

Little is known about the long-term consequences of grazing effects on microphytes. This study tested density-dependent responses to grazer removal on the biomass (chlorophyll a, chl a) and composition of natural high rocky-shore biofilms over a 7 mo period. Gastropod snails Melarhaphe neritoides graze entirely within circular halos generated in biofilms surrounding their refuges. The experiment crossed 3 levels of original snail density per halo with 3 levels of grazing intensity (generated by 100, 50 and 0% snail removal). Areas inside halos from which all snails had been removed sustained significantly higher chl a than never-grazed control areas outside the halos. This effect of grazing history was still present after 7 mo, suggesting that past grazing had an enduring positive influence on biofilm biomass. Against expectation, chl a-biomass was not increased by removing snails, regardless of original grazer density. Half-and fully-grazed halos peaked to a higher chl a than ungrazed halos in spring. Grazing did not affect the presence of major biofilm taxonomic groups, although it did alter their relative contributions. Never-grazed areas were covered by a thick biofilm-detritus complex and had proportionally more filamentous cyanobacteria than grazed areas, which sustained abundant clusters of coccoid cyanobacteria and lichen within micro-pits inaccessible to snail radulae. The present study shows that effects of grazing history are not exclusive to macrophytic systems. Grazers boosted the concentration of micro-autotrophs relative to non-chl a biofilm constituents, probably by removing an unproductive biofilm canopy and facilitating light and nutrient penetration for new growth.

“…Due to its high energy content and the ability to trap microalgae and enhance microbial growth (e.g. Connor & Quinn 1984, Connor 1986, Davies et al 1992b, Davies & Williams 1995, mucus reingestion may constitute an extra value, not considered in our model, in revisiting a prior location. Interestingly, trapping of microalgal particles is usually maximal after a short time (a few hours: Davies et al 1992b, Santelices & Bobadilla 1996 and this could represent a further stimulus to return to recently visited patches.…”

Section: Discussionmentioning

confidence: 99%

Bioeconomics of foraging route selection by limpets

Santini¹,

Burrows²,

Chelazzi³

2004

Homing limpets are central place foragers whose activity is constrained to restricted diel and tidal phases. The limpets' slow motion and high energy requirements render the problem of early choice of suitable foraging sites a critical issue. Mucous trails could be used, however, to relocate previously visited foraging areas. In this paper we describe a simulation model comparing 3 possible patch-choice tactics. These are random choice (RC) and 2 strategies (MVK and MVU) based on a marginal-value rule. The MVK strategy assumes that the forager is able to perceive and keep track of changes in energy return from successive visits to the same patch, while the MVU does not. The average long-term energy gain provided by the 3 strategies was calculated under a set of external factors: variability in the distance of patches from the central place, average value and variability in standing crop and predictability of rewards from the same foraging site when visited over successive times (autocorrelation). In the absence of variability in food sources, the different tactics yielded comparable energy returns, irrespective of average standing crop level, distance from home and autocorrelation in rewards. As variability in food sources increased, the final energy gain provided by MVK and MVU strategies changed according to the degree of autocorrelation. The MVK strategy performed increasingly better than RC for increasing autocorrelation values. The MVU strategy performed better than RC when energy returns from successive visits were positively correlated. On the contrary, in the case of a negative correlation the RC strategy was better than the MVU one. KEY WORDS: Intertidal molluscs · Limpets · Optimal foraging · Central placeResale or republication not permitted without written consent of the publisher