Serpulid Worms Research Articles

An assessment of preference for coupon positions by tropical marine fouling organisms

Studies were conducted in Tuticorin harbour, India, to determine the positions of marine fouling organisms on coupons. Censuses were made on coupon subplots of equal areas, which facilitated comparisons of biofouling patterns between coupon centres and coupon edges. Coupon size, substratum and centre‐to‐edge ratio were examined. The nature of the substratum was found not to alter the choice of coupon areas and barnacles and hydroids exhibited a preference for edges. The coefficient of range was least on small coupons and greatest on larger ones. The density of balanids was found to appreciably increase where the centre‐to‐edge ratio was larger. Thus, cylindrical members having “all edges”; were most heavily fouled. Molluscs and sea anemones also preferred to establish along the borders of coupons whereas serpulid worms, a colonial tunicate and encrusting bryozoa were found to show the opposite trend. The ecology of “patch”; fouling is discussed on the basis of this research and existing data. The implicat...

Sandwiched fossils

A little‐known mode of fossil preservation‐bioimmuration‐is responsible for exciting new findings of soft‐bodied organisms. Bioimmuration results from organic overgrowth by animals such as serpulid worms and oysters which form natural moulds of the organisms they have overgrown on their undersurfaces or sandwich overgrown organisms between themselves and their substrate. Overgrowth is a routine occurrence among the many marine organisms lacking mobility, and bioimmured fossils can be extremely common. Discoveries of bioimmured ctenostome bryozoans, hydroids and other soft‐bodied animals that lived attached to hard surfaces are providing important new palaeontological perspectives, especially in the Mesozoic.

Cretaceous Cold-Seep Communities and Methane-Derived Carbonates in the Canadian Arctic

Lower Cretaceous cold-seep fossil assemblages have been found in the Canadian Arctic Archipelago. Serpulid worm tubes and bivalves are most abundant in these communities; in contrast, fossils are scarce in the surrounding strata. The fossils are contained in an isotopically light (delta(13)C = -25 to -50 per mil) carbonate rock groundmass that is interpreted to have formed from bacterial oxidation of methane. The rocks were deposited at intermediate depth (</=400 meters) in a cold marine environment; nearby normal faults may have provided a conduit for seeping methane and hydrogen sulfide needed to fuel chemosynthetic bacteria, and in turn, the higher life forms.

Shoreline Depositional Environments of Glen Rose Formation (Lower Cretaceous) in Type Area, Somervell and Hood Counties, Texas: ABSTRACT

ABSTRACT The Comanchean Series in north-central Texas was deposited along the margin of a shallow sea as it transgressed northwestward across the Central Texas platform during early Cretaceous time. A lithologic and paleontologic study of the Glen Rose Formation (uppermost Trinity Division) in its type area was undertaken to define the shoreline sediments deposited during Aptian-Albian time. The studied interval was subdivided into informal units A, B, and C based on lithology and fossil content. The primary focus was on the lowermost Unit A for purposes of facies analysis. Unit A comprises a clastic-to-carbonate transition deposited in a seaward-fining tidal-flat salt-marsh complex. Eight distinct facies were identified, including the calcareous sandstone, calcareous shale, bivalve shale, oyster shale, transitional terrigenous-carbonate, dolomite, bioclastic packstone-grainstone, and shell fragment wackestone facies. These facies were deposited in sand flats; small fluvial creeks; an ecologically complex, mud-dominated intertidal flat; and an subtidal, nearshore lagoon. Thin bioclastic packstone-grainstones and dolomites of the high energy intertidal and supratidal environments regularly interrupt the terrigenous clastic facies. The microfossils are severely restricted to absent, and the macrofossils are dominated by euryhaline bivalves (including Corbula martinae), gastropods, serpulid worm colonies, and dasychladacean algae. Other abundant nearshore features include salt-tolerant land plants, dinosaur tracks, desiccation cracks, and localized concentrations of gypsum and barite. This tidal flat-salt marsh complex received sediments from both terrestrial and marine sources. A broad intertidal zone of vegetated sand and mud flats was dissected landward by small fluvial creeks and seaward by storm beaches and marine inlets. The fine size of the terrigenous clastics indicates a low energy flat with a very gently seaward-dipping substrate. A warm, semi-arid to arid climate favored the development of salt marshes and the precipitation of evaporites. The faunal restriction also suggests the abnormal salinites of tidal marshes. this sequence is considered ocmparable to the Holocene salt marshes on Sapelo Island, Georgia, based on similar seaward-fining substrates, sedimentary structures, and biological components. Unit B (the Thorp Spring Member) consists of a peloidal, molluscan packstone-wackestone facies. The fossil assemblage (including Orbitolina texana) suggests slightly brackish to near normal marine salinites in a shallow, restricted platform lagoon. Thorough bioturbation indicates deposition in the well aerated subtidal zone. Unit C is characterized by coarsening-upward limestones capped with thin intertidal-supratidal deposits, indicated a transitional nearshor lagoon-tidal flat environment. Repeated inundation with marine waters produced stacked, shallowing-upward sequences. The entire studied interval reflects fluctuating sea levels along a line of section nearly normal to the paleoshoreline, and represents the final waning of Glen Rose seas. End_of_Record - Last_Page 588-------

Late Mississippian bryozoan/microbial build‐ups on a drowned karst terrain: Port au Port Peninsula, western Newfoundland

ABSTRACTBryozoan and microbial carbonate build‐ups occur within the Late Mississippian (mid‐Viséan) Codroy Group on the Port au Port Peninsula, western Newfoundland. Build‐ups formed only adjacent to a rocky, cliffed, shoreline filling narrow submerged palaeovalleys of a well‐developed Late Devonian‐Early Mississippian karst terrain. The nearshore setting was a stressed environment as indicated by (1) the absence of normal marine biota, such as corals, echinoderms, and calcareous algae, (2) high numbers and low species diversity of dominant taxa (bryozoans, brachiopods, and microbial communities), and (3) abundant plant‐bearing siliciclastics deposited by the episodic influx of fresh‐water from adjacent uplands. Build‐up development was terminated by Meramec time, due to falling sea‐level and seaward progradation of terrestrial sediments.Preserved structural and constructional fabrics within the build‐ups include (1) thickets of bryozoans and microbial microthrombolites, structurally enhanced by probable marine Mg‐calcite and aragonite cements, (2) multigeneration internal sediment, and (3) small colonies of serpulid worms and terebratulid brachiopods. Submarine cementation within the build‐ups appears to have been abundant during arrested sedimentation, whereas intermound sediments (carbonates and siliciclastics) were lithified only during burial diagenesis. Shallow‐burial fracturing, stylolitization, sulphide and sulphate mineralization, and precipitation of phreatic, iron‐poor, calcite cement occurred during burial diagenesis.Codroy build‐ups are distinct from the more common Mississippian mud mounds. Their internal characteristics and the geologic setting are more like other Late Palaeozoic and Holocene bryozoan‐rich build‐ups.

Calcium Carbonate Production by Epibionts on Thalassia in Florida Bay

ABSTRACT Annual production of lime mud by two genera of red algae and one genus of serpulid worms was estimated for an area of modern lime mud accumulation in Eastern Florida Bay. The red algae Melobesia membranacea and Fosliella farinosa and the serpulid worm Spirobis sp. live as epibionts on the leaves of Thalassia testudinum, the extensive marine grass. The lime mud produced by the epibionts was estimated by quantifying 1) the life span of Thalassia; 2) the abundance of Thalassia; and 3) the average amount of epibiont calcium carbonate per blade. The estimate also accounts for both aerial variations in standing crop and seasonal variations in growth rate of Thalassia. The estimated annual production of epibiont carbonate is 118 ± 44 g/m2/yr, over six times more than the estimated production by the green alga Penicillus capitatus from the same area (Stockman et at. 1967). This leads to the conclusion that the epibionts on Thalassia produce significant amounts of lime mud in Florida Bay. This result is close to the published estimate for epibiont production in Jamaica of 180 g/m2/yr (Land 1970), but it is significantly less than a published estimate for epibiont production in Barbados (Patriquin 1972). Turtle grass has been around since the late Cretaceous (Eva 1980), and algae most likely has had a longer history. Therefore, epibionts may have been significant contributors since the late Cretaceous.

The Holocene fossil marine macrofauna of the Vestfold Hills, East Antarctica

The Holocene (&lt; 10,000 years old) fossil marine macrofauna (molluscs, polychaetes, mammals and birds) of the Vestfold Hills, Antarctica (68°30'S, 78°00'E) is described. All species are extant, with circumantarctic or wider distributions and wide depth ranges. At Heidemann Bay, Pleistocene‐age (&gt; 30 ky old) shell fragments occur in a Holocene moraine. These are interpreted as being glacially reworked fossil shells. Holocene benthic estuarine and coastal molluses and serpulid worm tubes are abundant on the flanks of terraces above saline and hypersaline lakes. Extensive radiocarbon dating gives a chronology of these deposits which were not synchronous. Mummies of seals and penguins, which are concentrated on the shores of the saline lakes and scattered across the Hills, are of no use in dating geomorphological events. Marine fossils in moraines are difficult to interpret because they can be glacially‐transported live or fossil shells, or deposited after wind transport. The fossil fauna has such a wide ecological range that it indicates only in general terms that for part of the Pleistocene and most of the Holocene, climatic conditions were broadly similar to the present.

Extensive Submarine Lithification in a Cave in the Belize Barrier Reef Platform

ABSTRACT Extensive deposits of submarine cements discovered in a submerged Pleistocene cave in the outer barrier-reef platform off Belize, Central America, occur in an unusual setting--on and within countless calcareous projections formed by serpulid worms on the ceiling of the cave. The cements are predominantly dense submicrocrystalline and microcrystalline to porous chalky or submicrosucrosic magnesium calcite (approximately 15 mole % MgCO3), and they contain minor amounts of acicular aragonite, which generally forms a lining inside the aragonitic serpulid tubes. Radiocarbon dates, three-year artificial substrate experiments, and evidence of the ceiling's original relief indicate a low rate of accumulation for the serpulid-cement projections. The characteristic 20-60 µm peloidal texture associated with magnesium calcite submarine cements is well developed here and there within the projections. These peloids are physiochemical precipitates, having formed during the development of the submarine cement deposits, which accumulated preferentially on substrates that have a slow rate of accumulation and that experience little or no disturbance of their sediment cover. Artificial substrates placed on the ceiling of the cave for three years revealed that the initial stage of precipitation of magnesium calcite from seawater is in the form of a submicrocrystalline magnesium calcite dust.

Macroborings and Epizoans on Late Cretaceous Rudists from West Coast Active-Margin Environments: ABSTRACT

Rudists are a major component of Cretaceous carbonate strata. Studies of rudists from these strata have demonstrated that epizoans are sparse but macroborings are relatively common. Previous studies have not been made of macroborings and epizoans on rudists from nearshore, elastic, active-margin environments. Beds of the Rosario Formation lower sandstone containing the late Campanian rudist Coralliochama orcutti crop out along the northern coast of Punta Banda on the Pacific coast of Baja California, Mexico. Serial sections of rudist skeletons from this area show that borings include Entobia and varying forms of Trypanites, while epizoans include serpulid worms, the bivalve Acila and juvenile Coralliochama. Macroborings occur on 30% of examined specimens, primarily on the upper portion of the attached valve and on the free valve, while epizoans are found on 10% of examined specimens, typically from the middle third to the commissure of the attached valve and on the free valve. Only a small portion of the skeleton may be covered by epizoans, and some boring and encrusting appears to have oc urred during life. Inhibition by rudists of epizonas, a concept proposed by Kauffman and Sohl, probably was not as effective in Coralliochama as in rudists from Antillean reefs. In addition, Coralliochama appears to be more heavily bored than Antillean reef rudists. These results aid in understanding the broad environmental range of Late Cretaceous rudists and the adaptive response to this range. Rudists of clastic environments may have been more susceptible to boring and encrustation than those from reef associations. End_of_Article - Last_Page 452------------

Marginal Marine Evaporites, Lower Cretaceous of Arkansas: ABSTRACT

The mixed evaporite/carbonate/terrigenous clastic sediments of the DeQueen formation, in southwestern Arkansas, were deposited at the End_Page 1467------------------------------ landward margin of a broad shallow lagoon formed behind the Glen Rose reef. About 60% of the sedimentary volume consists of mudstone, silt, and sand, with brackish-water to hypersaline ostracod faunas believed to result from influx of flood waters from the Ouachita highlands a few miles to the north. The lower part of the formation contains discontinuous beds of gypsum, ranging in thickness from a few centimeters to composite beds > 3 m (10 ft), and displaying mosaic structure with vertically oriented, elongate nodules. These beds, which are lenticular, are interpreted to result from subaqueous precipitation of vertical selenite crystals (subsequently recrystallized) in discrete ponds and pools on microtidal-range mud flats. Intrastratal growth of gypsum nodules and displacive hali e occurred at the margins of the pools. The upper part of the formation contains no gypsum beds, but halite pseudomorphs at the base of and within some of the thin limestones suggest the presence of supratidal brine pools. Several minor unconformities exist, of which one has a regional extent and is underlain by red-brown mudstones. Algal-mat lamination, lenticular gypsum pseudomorphs (an intrastratal growth form), and syneresis cracks occur in the limestones, and a supratidal environment is envisaged for a significant proportion of the time of deposition. The limestones generally have a restricted fauna of ostracods, bivalves, cerithid gastropods, serpulid worms, and miliolid Foraminifera, and range in texture from lime mudstones to grainstones. The most abundant grain types are pellets, superficial ooliths, and terrigenous quartz. A paucity of dolomite is a striking feature. Some of the thinner bedded units are rippled, and some ripples were truncated during periods of emergence. The limestones are believed to represent periods of shallow water, slightly hypersaline to slightly hyposaline conditions of variable energy. The regressive trend displayed by these two divisions continued with deposition of the overlying formation. The uppermost 3 m (10 ft) of the DeQueen consists of mudstone with a thin marl at the top. A conformable contac exists with the overlying Antlers formation, which has basal mudstones becoming more silt- and sand-rich upwards and finally giving way to the typical Antlers (Paluxy) sands. End_of_Article - Last_Page 1468------------

Virgin plastic granules on some beaches of Eastern Canada and Bermuda

A survey has been made of the quantities of small virgin plastic pellets and granules present in the litter stranding on shores of eastern Canada and Bermuda. Whilst particularly abundant on beaches of Bermuda, they are most uncommon on those of Nova Scotia and Sable Island—this, it is interpreted, reflects broad oceanic circulation patterns, lengthy residence times and distant sources, for there are no significant local ones. The polyethylene character of the granules was confirmed through burning characteristics and infra-red spectrophotometry. Polystyrene spherules were not identified. These plastic granules are commonly associated with pelagic tar balls and many have a tarry coating. The granules support a restricted, encrusting pseudoplanktonic biota, including serpulid worms and coralline algae, similar to that found on floating Sargassum. It is concluded, however, that their environmental consequence is not great. Although plastic granules progressively disappear through oxidative ageing and other degradational processes, they are an unnecessary contaminant of marine waters and evidence of evergrowing oceanic litter.

Carbonate Stratigraphy of U-Bar Formation (Aptian-Albian) of Southeastern Big Hatchet Mountains, Hidalgo County, New Mexico: ABSTRACT

The U-Bar Formation (Aptian-Albian) consists of five members: they are (in ascending order) brown limestone, oyster limestone, limestone-shale, reef limestone, and suprareef limestone. These members crop out in the area southwest of the Big Hatchet Mountains, Hidalgo County, New Mexico. The U-Bar Formation is overlain by the Mojado Formation (Albian) and underlain by the Hell-to-Finish Formation (pre-Aptian). A composite stratigraphic section (3,115 ft; 950 m) southwest of the Big Hatchet Mountains has been compiled from measured sections at Pierce Tank and Hell-to-Finish Tank. The brown limestone member contains thin-bedded, fine-grained, ledge-forming, silty, gypsiferous, dolomitic to oolitic limestones, arkosic sandstones and siltstones which weather red-brown to dusky red. The sparse fauna contains fragmented diminutive bivalves, Ostrea-type bivalves, and turritelloid-type gastropods. The yellow-gray to red-brown oyster limestone member primarily contains thin-bedded, fine to medium-grained, clastic, silty limestones and covered shale intervals. Massive limestones, thin-bedded arkosic sandstones, and siltstones occur near the base and middle of the member. This richly fossiliferous member contains some limestones consisting almost entirely of small Exogyra and Ostrea-type bivalves. Also common are Pecten, turritelloid-type gastropods, and serpulid worm tubes which commonly encrust Ostrea-type bivalves. The limestone-shale member contains thin to medium-bedded ledge-forming, fine-grained limestone. These pitted blue-gray to medium-gray weathering limestones contain a sparse fauna of turritelloid-type gastropods, small, thin-shelled bivalves, fragmented echinoid spines, and abundant Orbitolina, and large Lunatia-type gastropod steinkerns in the upper part of the member. The reef limestone member is a massive, fine to medium-grained limestone. The light-gray weathering limestone contains fragmented Ostrea-type bivalves, rudists, and abundant orbitolinids at the base. The suprareef limestone member (locally thin) is a medium-grained, clastic limestone, weathering light gray and containing abundant orbitolinids in the base and fragmented Ostrea-type bivalves above. The fossils commonly are iron-stained and weather in relief. End_of_Article - Last_Page 771------------

The Galapagos Rift at 86° W: 4. Structure and morphology of hydrothermal fields and their relationship to the volcanic and tectonic processes of the Rift Valley

The Angus camera system is used to investigate the detailed structure and morphology of the active hydrothermal vent fields of the Galapagos Rift. Precision navigational data are combined with microtopographic information and detailed geological and biological observations obtained from an analysis of the color bottom pictures to create a series of three‐dimensional models for each vent field. The five isolated vents are distributed along the southern boundary of a fissure wedge that cuts along the active axial high. All but one vent occur in pillow terrain. The fifth vent is at the contact between a pillow flow and sheet flow. Vents range in size from 400 m2 to 1600 m2 and are spread out along 2.8 km of a lineated fissure system that trends 095°. They are spaced at intervals ranging from 250 m to 1600 m with an average separation of 700 m. Vents are bound by tectonic features such as fissures or small throw faults. The egress of water is localized in small pockets within the fields. These zones of egress are distinctly unfissured. Instead, the water emanates out of rock to rock brecciated contacts. These thermal pockets range from 15 m to 40 m in diameter and are characterized by large concentrations of benthic fauna. On the basis of animal communities the fields may be divided into two different types, the western and the eastern groups. The two western fields are predominantly populated by clams (Vesicomyidae) and mussels (Mytilidae). The eastern three fields are dominated by tube worms (Vestimentifera), mussels, serpulid worms, and the spherical, colonial animal dandelion. The positioning of the vents on the fissure wedge implies a tectonic propagation and age gradation up and down the rift. At any one time, adjacent segments of the rift valley may be in different stages of a volcanic and tectonic cycle. As cooling of a central magma intrusion occurs, fissures propagate toward the remaining heated core, opening up pathways for the egress of heated bottom water. Cooling continues and the outermost vents die out. Precipitates block passages, capping the terrain. As extension continues, the very oldest sector of the valley will fracture. The incipient stress drop generates the eruption of a new magma center down strike from the former center, thus ensuring a volcanic and tectonic periodicity in space and time up and down the rift valley.

Glacial-Marine Trace- and Body-Fossil Associations, Upper Yakataga Formation (Pliocene-Pleistocene), Gulf of Alaska: ABSTRACT

Glacial-marine deposits of the Yakataga Formation are characterized by six associations of trace and body fossils. These associations can be directly compared to modern associations within the tidewater-fiord and marine-shelf environments in the Gulf of Alaska, and allow definition of specific paleoecologic conditions. Inner-shelf sandstones are extensively bioturbated by a community characterized by the infaunal pelecypods Siliqua and Spisula and the epifaunal gastropod Neptunea. Distinct trace fossils are absent. Open-shelf siltstones are also extensively bioturbated. Epifaunal body fossils of the gastropod Colus and small ophiuroids are abundant. The infaunal pelecypods Mya and Panomya are locally common. Trace fossils include rare small vertical burrows and large pelecypod burrows parallel with and oblique to bedding planes. Major channel systems within the upper Yakataga Formation are interpreted as fiord deposits. The fiord deposits have three rock-fossil associations. Rhythmically bedded siltstones and sandy siltstones have an infaunal community of the pelecypods Acila and Macoma. Distinct trace fossils are absent. Massive siltstones are extensively bioturbated, have locally abundant large burrow networks, and typically have locally abundant body fossils of the epifaunal gastropods Beringius, Colus, and Musashia, as well as small ophiuroids. Within the siltstone sequences of fiord deposits are thin, graded sandstones. These thin sandstones have an associated body-fossil community of shallow-burrowing Nuculana and Clinocardium and trace fossils of small vertical escape burrows, bed-top pelecypod resti g impressions, and pelecypod foot-push trails. A sixth faunal association consists of epifaunal organisms such as serpulid worms and barnacles that are attached to the upper surface of glacially derived dropstones. End_of_Article - Last_Page 411------------

A Lagoonal Crustose Coralline Algal Micro-Ridge: Bahiret El Bibane, Tunisia

ABSTRACT Colonies of Neogoniolithon notarisii (Dufour) Setchell and Mason found within a subtropical, hypersaline lagoon form a wave-resistant ridge 31 km long. The formation of algal ridges in a relatively low wave energy lagoonal setting under hypersaline conditions is highly unusual. Individual heads of mushroom-shaped colonies coalesce to differing degrees, probably in response to local variations in wave energies. Individual heads are circular to oval in plan that average 0.9 m in diameter, but may be as large as 2.0 m in diameter. Three growth modes appear to represent members of a continuum: 1) discontinuous ridges constructed of individual heads that commonly coalesce to form bands of two or three heads; 2) broader ridges of algal heads consisting of 7-10 coalescing heads; and 3 continuous ridges with lobate lagoonward margins. The composite ridge has formed on a wave-cut platform on the lagoonal side of an elongate lithified barrier. Initial growth of small cauliflower-shaped heads is directed upwards. Once the water surface is reached, lateral growth produces overhangs that average 25 cm, but may be as large as 60 cm. Lagoonward-facing rims are best developed, standing 4-8 cm in relief above the center of the colonies. These elevated lips are usually awash, but the remainder of the ridge is exposed only at lowest low water. A consistent overall growth height of 33 cm, measured on the lagoonward-facing rim, probably results from tidal control. Further dependence on wave activity for healthy growth is demonstrated by the disappearance of the ridges in the easte n part of the lagoon as fetch of the dominant summer winds is decreased. The ridge is strikingly sterile, with infrequent associations of Halimeda, serpulid worms, vermetid gastropods and boring clams. The existence of this coralline framework exemplifies a different type of environmental control than algal ridges elsewhere. Salinity and temperature limit potential grazers and other space competitors, so that Neogoniolithon notarisii totally dominates this ecological niche.

Lower miocene polychaetes from the waitakere ranges, North Auckland, New Zealand

Abstract The cast of a sabellid worm and its tube and thirteen species of serpulid worm tube from lower Miocene rocks of the Waitakere Ranges are recorded and described. Their paleoecology is briefly considered. Archesabella n. gen. is proposed for fossil tubes containing the body casts of sabellid-like worms. These worms have the abdomen, collar and tubes of a sabellid and thoracic lateral lobes of a terebellid. A. bartrumi n. sp. is described and figured.

Facultative blood–brain barrier and neuronal adaptation to osmotic stress in a marine osmoconformer

IN most vertebrate and higher invertebrate animals cellular functions are critically dependent on the relative stability of the chemical composition of the body fluids, a requirement epitomised by Claude Bernard's dictum: “la fixite du milieu interieur c'est la condition de la vie libre”1. In higher vertebrates2,3, and in insects4, but not apparently other invertebrates5,6, the ionic homeostasis of the neuronal environment is augmented by extremely effective blood–brain barrier systems. The nerve cells of euryhaline osmoconformers, however, are exposed to considerable fluctuation in the osmotic and ionic concentrations of the body fluids7. As an example we studied the serpulid worm, Mercierella enigmatica (Fauvel), which occurs in waters in which the salinities vary from 1 to 55‰ (refs 8–10) and which can withstand relatively rapid variations in the osmotic concentration of the blood of between 43 and 1,620 mOsm (ref. 11). We report here that in spite of such extreme variations in osmotic and ionic concentration, the axons of Mercierella function using ionic mechanisms which seem essentially similar to those of other marine invertebrates, such as the giant axons of the squid12 or the polychaete, Myxicola infundibulum13. The resting potential approximates to an ideal potassium electrode (with 58.8 mV alteration for decade change in [K+]o), the action potentials are sodium-mediated (exhibiting a 55.8 mV alteration for decade change in [Na+]o) and are blocked by externally applied tetrodotoxin at about 10−7 M.

The cyanophyte Wetheredella in Ordovician reefs and off‐reef sediments

Wetheredella tumulus n.sp. was an important constituent, both binder and frame builder, in reef and off-reef sediments of the Ashgillian Ellis Bay Formation of Anticosti Island in eastern Canada. In individual small, stromatolite-like mounds, it built a skeletal platform for attachment of associated serpulid worm tubes, bryozoans, crinoids and small brachiopods. In larger bioherms, Wetheredella was an encruster, binding waveswept reef tops of halysitid and heliolitid corals. Wetheredella is interpreted as a blue-green alga related to Silurian Rothpletzella from Gotland and the genus Girvanella.

The ecology of sublittoral communities at Abereiddy Quarry, Pembrokeshire

Abereiddy Quarry is shown in Plate I. It lies at 51° 56′N, 5°13′W (Ordnance Survey Reference SM 795315), 6 km northeast of St Davids in Pembrokeshire (Text fig. 1). The quarry, a disused slate working, is surrounded by high cliffs except to the west where there is a channel open to the sea. In 1902–3, operations ceased and the quarry began to fill with fresh water and sea spray. During 1932–3 the west wall was breached to allow access to the sea so that the basin could be used as a harbour. Abereiddy is now a deep, fully saline marine basin which, at low water, is 66 m across from north to south with a surface area of 0.356 ha and a maximum depth of 24 m. In this situation it has been possible to observe sublittoral rocky sea-bed communities in an extremely sheltered area through a summer thermocline and associated oxycline. Abereiddy Quarry has previously been investigated by Bailey, Nelson-Smith &amp; Knight-Jones (1967), who published details of the vertical distribution ofSpirorbisspp. The biology of serpulid worms in Abereiddy Quarry has been the subject of continuing investigations carried out from University College Swansea (E. W. Knight-Jones, personal communication).

Comparative amino acid composition of calcified and non-calcified polychaete worm tubes

1. 1. The proteinaceous cement of non-calcified sabellariid worm tubes consists primarily of glycine and serine. 2. 2. Calcified protein from serpulid worm tubes consists of about 30 per cent acidic amino acids. 3. 3. The protein composition of serpulid tubes is similar to that of some mollusk shells.