title used in learnabout sections of A SNAIL'S ODYSSEY
  Habitats & ecology
   
 

Only a few studies have been done on ecology of tubeworms and these mainly involve interspecific competition.

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Research study 1
 

sketch of a tubeworm assemblage in the sediments at Mission Bay, CaliforniaAn example of interference competition among tubeworms is described in laboratory studies done on sediment cores taken from a mudflat in Mission Bay, California.  The infaunal assemblage on the mudflat is dense, with over 100,000 individuals . m-2 in some areas.  Of the several taxa present, 3 species of tube-dwelling polychaetes predominate, Pseudopolydora paucibranchiata (spionid, up to 20mm body length: mainly low intertidal area), Streblospio benedicti (spionid, 10mm, mainly mid-intertidal level), and Faricia limnicola (sabellid, 6mm with a 2mm-diameter crown of tentacles). Intraspecific spacing of Pseudopolydora is more even than expected from randomness, while spacing of Streblospio is more random.  Spacing in Pseudopolydora begins at larval settlement, with the adults directly interfering with settlement and/or eating the settling larvae.  As adults, Pseudopolydora defends territories of a size necessary for movement of its palps and acquisition of food. The 2 species P. paucibranchiata and S. benedicti are both suspension/deposit-feeders, with the last being exhibited more in conditions of low current flow.  During deposit-feeding the ciliated palps of Pseudopolydora wander over the substratum picking up detrital particles, and food fights between neighbouring individuals are common.  These involve palp-fighting, palp-pulling, and biting at encroaching palps.  The palps of one individual overlap those of several others, and each palp can carry on separate struggles simultaneously.  In simulated laboratory tests, it is not uncommon for 3-5 individuals to fight over the same food particle (dried bits of the green alga Enteromorpha).  The author notes that this is the first report of territoriality in a non-nereid polychaete.  Levin 1981 J Mar Res 39: 99.

NOTE  the drawing provided by the author (see above) doesn't help much in the species' identifications. Presumably the larger worms are Pseudopolydora, but what the little ones are is anyone's guess. Pseudopolydora paucibranchiata is an introduced species from Japan, while S. benedicti has been introduced from the Atlantic

NOTE  reproduction can occur all year long, but is mainly Feb-May in P. paucibranchiata.  The 3-setiger larvae spend only 7-10d in the plankton before settling

 
Research study 2
 

photograph of a spionid tubeworm Pseudopolydora paucibranchiata with feeding tentacles extended courtesy Jeff Shimeta, RMIT University, Melbournephotographs of spionid tubeworm Streblospio benedicti courtesy David Samuel Johnson and Smithsonian Marine Station at Fort Pierce, FloridaThe 3 species inhabiting the mudflats of Mission Bay, California construct tubes of cemented sediments and withdraw into them when disturbed. Withdrawal affects feeding time. The 2 spionids are facultative surface deposit-feeders in slow current and suspension-feeders in stronger currents. They eat organic aggregates of detritus and phytoplankton. The sabellid Fabricia suspension-feeds with its tentacular crown, but also has 2 palps for deposit feeding.  Intraspecific contact between Pseudopolydora leads to palp-fights (see Research Study 1 above), but essentially no withdrawal. Interspecific contact between the larger worm Pseudopolydora and the other species does not seem to affect Pseudopolydora. However, such contact leads to Streblospio withdrawing 32% of the time and Fabricia withdrawing 12% of the time.  Contact between the 2 smaller species leads to essentially no withdrawal and no loss of feeding time.  Overall, the author calculates that contact between Pseudopolydora and the other polychaetes results in 4-7% loss of feeding time for the smaller species.  The author notes that up to this time there has been little quantification of interference competition in infaunal assemblages.  Levin 1982 J Exp Mar Biol Ecol 65: 107. Photograph of Pseudopolydora paucibranchiata courtesy Jeff Shimeta, RMIT University, Melbourne. Photographs of Streblospio bendicti courtesy David Samuel Johnson and Smithsonian Marine Station at Fort Pierce, Florida.

 
Research study 3
 

histograms showing recruitment of predatory nereids to sediments uncontaminated (control) and contaminated with brominated aromatic compounds originating from the terebellid tubeworm Thelepus crispusphotograph of a terebellid tubeworm Thelepus crispusThe terebellid polychaete Thelepus crispus releases relatively large amounts of brominated aromatic metabolites into the sediments surrounding its tube.  These metabolites impart a strong odour to the living worm and to the sediments. The authors note that this family of compounds has low solubility in seawater and thus potentially long residence time in the sediment.  Laboratory tests at Friday Harbor Laboratories, Washington on the possible function of the chemicals reveal that 6-setiger-stage demersal juveniles of a sympatric free-living polychaete Nereis vexillosa, actively reject such sediments as they crawl about investigating for a suitable spot to burrow.  Thus, more juvenile Nereis  burrow into control sediments than into contaminated sediments (see Left part of histogram).

Results of field tests in San Juan Island, Washington involving cores excavated in sediment and filled with either contaminated sediment from nearby Thelepus beds or uncontaminated sediment from outside of the beds, show similarly that more Nereis juveniles avoid the contaminated sediments (see Right part of histogram). The authors remark that theirs is the first evidence that biogenic cues can be negative and cause rejection of sites by settling individuals. They summarise that the contamination of sediments by release of chemicals represents a novel and perhaps important mechanism governing interactions among sediment-dwelling organisms.  Woodin et al. 1993 J Chem Ecol 19: 517.

NOTE  analyses for amounts of the metabolite (3,5-dibromo-4-hydroxy benzyl alcohol) show that contaminated sediments contain a minimum of 2 orders of magnitude more metabolite than uncontaminated sediments

NOTE  substances with negative effects as shown here are known as allelochemicals

 
Research study 4
 

photograph of aggregations of tubeworms Pragmatopoma californica on a boulder on a California Beach, courtesy Simmons et al. 2005 J Mar Res 63: 623Phragmatopoma californica is a suspension-feeding tubeworm that grows in sometimes large aggregations on boulders in the intertidal zone along the California coast.  An interesting publication by researchers at the University of California, Los Angeles centres around causes of local distributions of the worms, focusing on 5 boulder fields at sites encompassing much of the species range.  The major finding is that the aggregations are larger on the back or shoreward faces of boulders (in some cases numbering up to 10,000 tubes) diagrams showing tube orientations of Phragmatopoma californica on boulders on Coleman Beach, California in 2003than on the front or seaward faces.  Orientation of the worm-tubes differs significantly between front and back boulder faces, with growth being in the direction of predominant water flow around the boulder.  Thus, tube orientation on the front faces is angled to the right or left, while on the back faces tube orientation is more perpendicular to the boulder surface (see diagrams). The authors hypothesise that Phragmatopoma larvae are carried in water flows around a boulder and then entrained in the eddies at the back-side where they settle and metamorphose.  As the back-sides of boulders are in the lee of wave impact the resulting calm-water eddies would possibly favour fertilisation, as well.  Simmons et al. 2005 J Mar Res 63: 623. Photograph courtesy the authors.

NOTE  the authors title their article “life in the lee” and write of the “hostile rocky intertidal”, but they are surely aware that there is nothing “hostile” about such an area for organisms like P. californica and thousands of other species that have evolved adaptations for living under such conditions. For them, the place is just fine

 
Research study 5
 

In Elkhorn Slough, California large areas of the sea bottom are inhabited by the non-native reef-building tubeworm  Ficopomatus enigmaticus.  Its presence prompts questions as to its  effects on other benthic community members – does it exclude other native and non-native species, or perhaps facilitate the presence of one or the other of these?  Researchers at Hopkins Marine Station, Pacific Grove find, in fact, that the tubeworm reefs host significantly greater abundances of non-native polychaetes and amphipods as compared with nearby mudflats.  Removal of the reefs is no solution, photograph of tubeworms Ficopomatus enigmaticus courtesy Kimberley Heiman, Muhlenberg College, Allentown, PAbecause the newly exposed mudflat, rather than providing space for recolonisation by native infaunal species, is more likely to allow  various opportunistic non-native amphipods and polychaetes (such as Streblospio benedicti) to move in.  The authors conclude that removal of the tubeworms, a type of invader termed  “ecosystem engineers” by these and other researchers, is a questionable strategy for control.  In that the presence of Ficopomatus and other types of non-native ecosystem engineers such as mussels, oysters, and marsh plants provide space for other non-native species and irreversibly alter native habitats, they may have disproportionate and serious impacts on community composition of a region.  Heiman & Micheli 2011 Integr Comp Biol 50: 226; see also Heiman et al. 2008 Aquatic Biol 2: 47. Photograph courtesy Kimberley Heiman, Muhlenberg College, Allentown, PA.

NOTE  the species originates from Australia and has spread to many locations around the world, including North and South America, Europe, Japan, and elsewhere.  Its introduction may be from fouling growths on boats


Clusters of tubeworms Ficopomatus enigmaticus on
and around pilings in Elkhorn Slough, California

 
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