Nutrition & growth
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  Food preferences
  The topic of food preferences is considered here, while topics of FEEDING & NUTRITION and SHELL & GROWTH are considered in other sections.
 
photograph of seaweed-rich tidepool on the outer coast of Vanvouver Island, British Columbia

 

 

 

Preferred foods of abalone
include several species of kelps

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Research study 1
 

Laboratory tests of feeding preferences of several abalone species in southern California show that large kelps are favoured.  The giant kelp Macrocystis pyrifera tops the list followed by Egregia laevigata, Laminaria farlowii, and Eisenia arborea Leighton 1966 Pac Sci 20: 104; Drawings courtesy Louis Druehl, SFU modified from Pacific Seaweeds Harbour Publ, BC

NOTE red abalone Haliotis rufescens as adults are known to favour large kelps as food, but researchers at the Hatfield Marine Science Centre, Oregon find not only that the red alga Palmaria mollis ('dulse') is a better food for growth to broodstock size, but is equal to diatoms as a settlement inducer for the larvae. Buchal et al. 1998 Aquaculture 165: 243.

photograph of kelp Macrocystis pyrifera
Macrocystis pyrifera may reach lengths of 50m
photograph of feather-boa kelp Egregia menziezii
Egregia menziezii is the only species in this genus on the west coast
photograph of kelp Laminaria farlowii
Laminaria farlowii reaches 5m in length
photograph of kelp Eisenia arborea
Eisenia arborea grows to 1-2m in height
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Research study 2
 
Along the west coast of British Columbia the northern or pinto abalone Haliotis kamtschatkanaprefers kelps such as Nereocystis luetkeana, Macrocystis integrifolia, and Laminaria spp.  Laboratory observations in Alaska show that the following foods are eaten well by H. kamtschatkana: diatoms Chaetoceros spp. and Navicula spp., green algae Ulva sp. and Enteromorpha sp., and kelps Laminaria groenlandica, L. saccharina, and Alaria marginataPaul et al. 1977 Veliger 19: 303. drawing of kelp Nereocystis luetkeana drawing of kelp Macrocystis integrifolia
 

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Research study 3

 
In the Pacific Grove region of California more than 20 species of algae are eaten by black turban shells Chlorostoma (Tegula) funebralis.  Favoured, however, are large fleshy kelps such as Macrocystis integrifolia and Nereocystis luetkeana that drift into the intertidal region (see illustrations in preceding Research Study, and some red algae including Chondracanthus canaliculatus (photo on far Right). Best 1964 Veliger 6 (Suppl.): 42. photograph of black turban snails Chlorostoma funebralis photograph of red alga Chondracanthus canaliculatus
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Research study 4
 

photograph of trochid snail Calliostoma annulatum courtesy Ron Long, Simon Fraser University, Burnabyphotograph of trochid snail Calliostoma variegatum courtesy Linda Schroeder, Pacific Northwest Shell Club, Seattle, WashingtonTrochid snails belonging to the genus Calliostoma are generally thought to be consumers of kelp or of organisms, such as bryozoans and diatoms, that grow on kelp.  A study at Friday Harbor Laboratories, Washington discloses that at least 2 species, annulatum and variegatum, mainly eat campanularid and sertularid hydroids. 

Of 56 individuals of annulatum collected and dissected, 54 are noted to have guts filled with hydroid fragments, and observation of about 100 individuals in the field shows that nearly all are eating hydroid polyps along with photograph of trochid snail Calliostoma ligatumtheir eggs. When attacking a hydroid polyp, annulatum makes contact with a tentacle, grabs hold of the stem or hydranth with its jaws, and severs it with its radula.  These pieces of stems, in short segments, can be found in the gut.  This species may also attack sea anemones, most notably, brooding anemones Epiactis prolifera.

Of 8 variegatum specimens examined, 7 have guts filled with hydroids. 

In comparison, all intertidal specimens of ligatum have guts filled with detritus, while subtidal representatives of ligatum have guts filled with unidentifiable debris. This species will, however, eat hydroids when kept in the laboratory, but not apparently in the field.  Perron 1975 Veliger 18: 52. Photograph of C. variegatum courtesy Linda Schroeder, Pacific Northwest Shell Club, Seattle, Washington PNWSC. Photos from upper Left, clockwise: C. annulatum, C. variegatum, C. ligatum.

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Research study 5
 

photograph of trochid snail Calliostoma canaliculatum courtesy Linda Schroeder, Pacific Northwest Shell Club, Seattle, WashingtonA study on foods of Calliostoma canaliculatum at Hopkins Marine Station, Pacific Grove, California indicates that not only do they feed by scraping diatoms off the surfaces of kelps, but they are likely scavengers on dead flesh as well.  Keen 1975 Veliger 17: 413. Photograph courtesy Linda Schroeder, Pacific Northwest Shell Club, Seattle, Washington PNWSC.

 

 

 

 

 

 

Calliostoma canaliculatum

 

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Research study 6

 
photograph of trochid snail Promartynia pulligophotograph of trochid snail Chlorostoma brunnea courtesy Gary McDonald, Long Marine Laboratory, Santa Cruz

photograph of trochid snail Chlorostoma montereyi courtesy Gary McDonald, Long Marine Laboratory, Santa CruzThree species of trochid snails live within stands of giant kelp Macrocystis pyrifera that grow in rocky subtidal areas along the central coast of California.  Although the snails may occur on the sea bottom amongst carpeting growth of various red algae, a high proportion live on the kelp itself, especially in areas of the kelp forest where benthic predation is strong.  Tests of feeding preferences of 3 Tegula"”species in Pacific Grove, California show that all prefer kelp Macrocystis over 5 benthic red-algal species, but that best growth and reproductive output over a 6-mo laboratory study is on a mixed-algal diet. There appears to be no significant correlation of feeding preference with caloric content of the algal foods.  Association with Macrocystis therefore provides both a tasty food as well as protection from bottom-dwelling predators but, for best growth and reproduction, the trochids must risk some time feeding on red seaweeds on the sea bottom.  Watanabe 1984 Oecologia 62: 47.

NOTE  3 species formerly in the genus Tegula: Chlorostoma brunnea inhabits depths of 0-6m, Promartynia pulligo, 7-12m, and C. montereyi, 7-12m. Photographs of brunnea and montereyi courtesy Gary McDonald, Long Marine Laboratory, Santa Cruz

NOTE  the author adds a caveat to the results, to the effect that growth is generally poor in the laboratory – about 5-fold less than in the field. However, this should not affect the overall conclusions

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Research study 7
 

photograph of black turban snails Chlorostoma funebralishistogram showing preferences of black turban snails Chlorostoma funebralis for a number of species of brown algaeWhat governs feeding preferences of black turban-snails Chlorostoma funebralis?  A study in Santa Cruz, California that assesses preference of the snails for 13 species of common brown algae in pairwise laboratory feeding tests and in field-array tests shows that content of phenolics is the most important determinant of palatability, while other features such a phagostimulants and nutritional content appear to play lesser roles.  High levels of phenolics in brown algae are a generally effective feeding deterrent against a variety of invertebrate herbivores, including sea urchins, crustaceans, and various gastropods. 

Tests of feeding preferences of C. funebralis show stronger preferences for brown algal-species with low amounts of phenolic compounds than for ones with high levels of phenolics.  Specifically, the 6 most preferred algal species contain an average of 0.8% dry-mass phenolics, while the 7 least preferred species conain an average of 4.5% phenolics. The former are mostly Laminariales, while the latter are mostly Fucales.  Interestingly, with the exception of the feather-boa kelp Egregia menziesii, relatively few of the most preferred species are eaten in the field by C. funebralis. Another possible determinant of feeding preference, namely, nitrogen content, seems not to be important.  Thallus toughness also does not appear to be important in determining overall preferences, but may play a role in determining choices among algae low in phenolics.  The author suggests that evolution of feeding preferences in C. funebralis may owe more to avoidance of algal defenses, with positive aspects of food quality such as nitrogen content probably playing a lesser role.  Steinberg 1985 Ecol Monogr 55: 333; see also Steinberg 1984 Science 223: 405.

NOTE  these polymers of the simple phenolic phloroglucinol (1,3,5-trihydroxybenzene) are common components of brown algae

NOTE nitrogen content of the 13 species averages only 1-3% of dry mass.  It actually correlates positively with feeding preferences of C. funebralis, but the author notes that this may actually owe to an indirect effect of a significant negative correlation between algal nitrogen content and phenolic content

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Research study 8
 

In areas around the Strait of Georgia, British Columbia the snails Pupillaria (Margarites) costalis, Lacuna marmorata (a species actually more closely related to littorines), and other species appear to subsist as adults mainly on diatoms.  At the time of recruitment, however, seaweed detritus is more abundant than diatoms, and there is some thought that the juvenile snails, especially, may utilise this material as a food source.  Such detritus, at its early stages of formation, has C:N ratios of 12:1, which would theoretically provide sufficient nitrogen to promote growth.  Detritus resulting from the degradation of seaweeds may exceed the amount eaten by invertebrate herbivores by several-fold.  The authors acknowledge that they do not actually know the relative importance of either food source to the snails, but argue for greater consideration of the potential role of seaweed detritus as a nutritional source for small gastropods.  Smith et al. 1985 J Exp Mar Biol Ecol 92: 143.

NOTE  defined by the authors as organic particles <2mm in size

NOTE  over time, this detritus may decrease in nitrogen concentration to 17:1, thought by the authors to be the minimum nitrogen content able to sustain such small herbivores


Snail Pupillaria (Margarites) costalis 2.5X Photo courtesy Joel Wooster, Maine
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Research study 9
 

photograph of cluster of Chlorostoma funebralis shellhistogram comparing consumption of agar discs by trochid snails Chlorostoma funebralis and C. brunnea, the discs containing differing amounts of phenolic substancesIn a follow-up article to Research Study 7 above the same author directly tests the deterrent effects of phenolics.  Three invertebrate herbivores, including Chlorostoma funebralis and C. brunnea are presented with agar discs containing different amounts and types of phenolic substances, and the amounts eaten over a 48-h period monitored and compared.  All phenolics deter feeding by Chlorostoma at concentrations of 5mg . mg-1 in the agar discs, but whether the tests are being done at “physiological” levels, in other words, at levels as found naturally in the seaweeds, is not clear (see histogram). Steinberg 1988 J Exp Mar Biol Ecol 120: 221.

NOTE  algal phenolics used include the monomeric phenolic phloroglucinol and other poyphloroglucinols extracted from the brown algae Fucus vesiculosus, Halidrys sp., and Eisenia arborea.  In the data the phenolics are indicated by alga of origin, with 2 extracts from Fucus being used, and also commercial (from terrestrial plants) tannic acid being included.  Fucus vesiculosus inhabits Atlantic shores, but its polyphenolics are thought to be similar to those in west-coast Fucus spp.

NOTE  the third species is the sea urchin Strongylocentrotus purpuratus; only results for C. funebralis are considered here

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