Dog Whelk Research Articles

Nucella lapillus as a paratenic host for Maritrema arenaria

Metacercariae of the microphallid trematode Maritrema arenaria are found in the shore barnacle Semibalanoides balanoides which is heavily predated by the dog whelk, Nucella lapillus. This study demonstrated that, under experimental and natural conditions, M. arenaria metacercarial cysts were ingested by N. lapillus and the metacercariae retained their viability while passing through the molluscs' digestive systems. Dog whelks are a known food source for numerous bird species, leading to the conclusion that they may act as paratenic hosts of M. arenaria. The strategic importance of the adoption by M. arenaria of N. lapillus as a paratenic host is discussed.

Postembryonic stages of Nucellicola holmanae Lamb et al., 1996 (copepoda, poecilostomatoida), an endoparasite of the dog whelk Nucella lapillus (gastropoda)

The external morphology of the first three larval stages of Nucellicola holmanae is described. These stages were cultured from eggs found with the adults in the viscera of dog whelks collected from Robin Hood's Bay, North Yorkshire. The nauplius develops within the whelk. It moults to a metanauplius which is released as a free-swimming stage. The metanauplius moults to a free copepodid stage which exhibits a combination of characters typical of the first, second and third copepodid stages of other poecilostomatoid copepods. The infective copepodid stage which locates and penetrates the host is visible through the integument of this free-swimming copepodid.

Tributyltin and Policies for Antifouling

The paper describes development of policies for TBT in relation to antifouling history, scientific assessment of environmental impact and future developments. Major break throughs in development of policies for TBT were triggered by scientific evidence of a specific and very sensitive effect, Vs imposex. Consequently policies were developed in a step-wise process. Restrictions for small vessels followed alarm about coastal dog whelks, while policy initiatives for offshore shipping only started after findings of imposex in relation to shipping in the North Sea. Global policies were further inspired by a consequent inventory in tropical offshore waters. At present global policies, with the framework of IMO, move towards a total ban of TBT within the next decade together with a strong stimulation of development and application of environmentally safe alternatives.

Subcellular Cd accumulation and Cd-binding proteins in the netted dog whelk, Nassarius reticulatus L.

The subcellular accumulation of Cd in different tissues of the marine gastropod Nassarius reticulatus was determined following exposure to 0.1, 0.3 and 0.9 mg Cd/litre seawater (nominal concentrations) and the importance of cytosolic Cd-binding components for the sequestration and immobilisation of the metal evaluated. Different tissues from exposed whelks were removed, pooled, homogenised, the homogenates subjected to subcellular fractionation and fractions measured for Cu, Zn and Cd by atomic absorption spectrophotometry. Cytosols were further separated and heat-stable Cd-binding capacity determined. All subcellular fractions in different tissues accumulated Cd at all exposures. The total cytosolic protein concentration in some tissues was strongly affected, but there was no concentration-dependent increase in Cd-binding capacity of the heat-stable protein pool. The major cytosolic Cu- and Cd-binding components in all four tissues were low molecular weight ( M r 5–10 kDa), whereas most cytosolic Zn coeluted with components of very low molecular weight.

Three years after Chernobyl: Some γ-radioactivity values from barra, Outer Hebrides, UK

Plants and animals were investigated to ascertain theirγ- radioactivity values on both dune sites (machair) and inter-tidal sites on the western coast of Barra, Outer Hebrides, UK. Material in both habitats was clearly contaminated. The accumulation ofγ-radioactivity through food webs to organisms such asNucella lapillus (dog whelk) in the inter-tidal sites and in sheep and cattle in terrestrial sites is described.

Occurrence of tri-n-butyltin-caused imposex in the North Pacific marine snail Nucella lima in Auke Bay, Alaska

Like female dog whelks (Nucella lapillus) in the Atlantic Ocean, females of the Pacific gastropod N. lima respond to low concentrations of tri-n-butyltin (TBT) by growing a penis and vas deferens. This condition, termed imposex, was found to occur in N. lima collected from August 1987 to May 1988 along a TBT pollution gradient associated with a marina in Auke Bay, Alaska. The suite of symptoms characteristic of imposex in N. lima was slightly different than in N. lapillus. Imposex, as measured by relative penis size (RPS) of females to males, increased from 0.0 to 34.27 along this gradient and as measured by vas deferens sequenceindex (VDS) increased similarly from 0.0 to 4.29. Concentrations of TBT in N. lima increased from below detection limits (about 0.010 μg Sn g-1 dry tissue wt) to 0.065 μg Sn g-1 dry tissue wt along the gradient. The gradient was determined by measuring TBT in whole-body tissues of bay mussels (Mytilus edulis). Concentrations of TBT in mussels increased from below detection limits to 0.833 μg Sn g-1 dry tissue wt in mussels from within the marina that was the major local source of TBT. Imposex, tissue TBT burden, and position along a TBT pollution gradient are significantly correlated (P<0.01) in N. lima. TBT was tested as a causative agent for imposex by exposing snails at a distant control site to TBT paint. After 1 mo exposure, 33% of the females grew a penis ranging in size from 0.2 to 0.8 mm. Our results generally corroborate those found for N. lapillus and indicate that imposex in N. lima is caused by environmental TBT exposure. We suggest that the RPS in the genus Nucella may be useful in monitoring TBT in coastal waters worldwide.

Cadmium content, accumulation and toxicity in dog whelks collected around the Welsh coastline

The concentration of cadmium in sexually mature Nucella lapillus was investigated around the coast of Wales. Higher concentrations of cadmium were found in whelks located in the Bristol Channel compared with Cardigan Bay Nucella. Accumulation and toxicity of cadmium were investigated at 50–600 μg Cd l −1 over a period of 21 days. At the lower concentrations of 50–100 μg Cd l −1 all Nucella survived the 21 days of experimentation. The rate of cadmium uptake after exposure to cadmium was inconsistent and not related to the degree of site contamination. At all sites the concentration of cadmium in Nucella, after treatment with 50–600 μg Cd l −1 for 21 days, was significantly different from controls, but after 7 days it varied with the site and cadmium concentration. Only samples collected at Fishguard, Dale, and Swansea survived 21 days at 600 μg Cd l −1. Tissue cadmium concentrations did not significantly effect the whole body concentration of zinc.

THE USE OF MUCOUS TRAILS BY INTERTIDAL LIMPETS TO ENHANCE FOOD RESOURCES.

The mucous trails secreted by certain species of intertidal limpets serve as adhesive traps for the microalgae that are their primary food resources. The mucous trails of two solitary homing limpets, Lottia gigantea and Collisella scabra, also stimulate the growth of microalgae. In contrast, the mucous trails of an aggregating limpet, Collisella digitalis, and the carnivorous dog whelk, Nucella emarginata, do not stimulate microalgal growth. These results may be explained by differences in the behavior of these gastropod species. Homing species can capitalize on the production of a food enhancing mucus because they have restricted home ranges and retrace their own mucous trails. The persistence time of mucus in the field varied with gastropod species, mucus type (i.e., mucus produced by moving or stationary limpets), and tidal height. Field studies suggest mucous trails can, but may not always, persist long enough to allow algal enhancement. Biochemical analyses suggest that the ability of mucous trails to trap microalgae adhesively is correlated with carbohydrate content. The ability of mucous trails to stimulate microalgal growth is correlated with higher total organic content of mucous secretions and an ability to stimulate bacterial growth. A bacterial film may be important in the stimulation effect.

Seasonal studies on cadmium concentration and toxicity, oxygen consumption, digestive gland glycogen, and lipid in dog whelks collected at Aberystwyth, Wales

The concentration of cadmium in Nucella was investigated at different times of the year at one site. There was no significant difference in tissue cadmium at the times of the year investigated but tissue zinc was more variable. Accumulation and toxicity of cadmium were studied using 50–600 μg Cd l −1 for 21 days. There was no significant seasonal difference in the rate of cadmium uptake but mortality appeared to vary with the season. Nucella did not survive 21 days at 600 μg Cd l −1, but at lower concentrations 50–100 μg Cd l −1 all survived. Although there was significant drop in oxygen consumption between 7 and 14 days it did not appear to be related to the cadmium exposure. Glycogen levels on the other hand showed a decrease after cadmium treatment, while lipid values remained unchanged. Results are discussed in relation to energy source, season, and adaptation to the environment.

Phenotypic evolution in a poorly dispersing snail after arrival of a predator

The phenotypic stability of many species in the face of changing conditions suggests that adaptive evolution can occur only under limited circumstances. One of the necessary conditions may be the lack of genetic mixing between dispersed populations inhabiting different environments. Intertidal molluscs on the east coast of North America between Cape Cod and Nova Scotia were exposed to an increase in the abundance of shell breaking predators when the green crab Carcinus maenas spread gradually northward from Cape Cod in the first half of the twentieth century1. The periwinkle Littorina littorea, which produces larvae that become widely dispersed, did not show an increase in shell thickness as an adaptation to shell-breaking predation1. However, I show here that the dog whelk Nucella lapillus, which is poorly dispersed in the bottom-dwelling juvenile phase, did adapt phenotypically after establishment of the green crab. This suggests that phenotypic stasis and gradual change are alternative responses depending on the degree of genetic mixing between populations.

Behavioral response of the New England dog whelk, Nassarius trivittatus, to a temperature gradient

Thirty New England dog whelks (Mollusca: Gastropoda: Nassariidae), Nassarius trivittatus, were tested as a group for 3 days in a long linear gradient trough encompassing a thermal gradient ranging from 5°C to 45°C. The modal thermal preferendum of the snails lay between 30°C and 35°C. The lowest temperature interval voluntarily occupied by the snails was 15–20°C, the highest 35–40°C. W e believe this to be the first published study of temperature preference and avoidance behavior of gastropod molluscs.

Absorption of Cadmium, Copper and Zinc by Dog Whelks in the Bristol Channel

SEVERAL independent studies have established that unusually high concentrations of certain heavy metals, most notably cadmium, are found in littoral flora and fauna of the Bristol Channel1–4. An experiment by Peden et al.5 established that the concentrations of cadmium and zinc in dog whelks (Nucella lapillus) did not markedly decrease after transferring specimens to clean water for seven weeks. Bristol Channel dog whelks have shells with an elongated shape, clearly distinguishable from the usual shell shape. This feature, together with the fact that dog whelks move very little (J. H. Crothers, personal communication), makes the species ideal for studying the absorption of metals.

ON THE MAINTENANCE OF A SHELL PATTERN AND BEHAVIOR POLYMORPHISM IN ACMAEA DIGITALIS, A LIMPET.

Crypsis is a common phenomenon in many animal groups and, with its attendant selective pressures, has been the subject of considerable discussion. It has been studied intensively in the snails Cepaea nemoralis and C. hortensis (Lamotte, 1959; Carter, 1967; Clarke, 1962; Cain and Sheppard, 1950, 1952, 1961; Owen, 1965; Sheppard, 1951). Briefly, Cepaea exhibit several colors and patterns which often match the habitat of the animal. Sheppard (1951) found that the thrush, Turdus ericetorum, selectively preys on color morphs of the snail, and Owen (1965) and Clarke (1962) report that the selection is frequency dependent or apostatic. This type of selection allows a highly diverse polymorphism to be maintained. Moths such as Biston betularia are also selectively preyed on by birds (Kettlewell, 1955) and the moths appear to actively select a matching background, enhancing their effective crypsis (Kettlewell, 1955; Sargeant, 1966). Colton (1916) described a polymorphism in Thais lapillus, the dog whelk, correlated it subjectively with background, and invoked weak natural selection as being responsible for reducing natural variety to a complex of inconspicuous forms. Moore (1936) found that the color of these whelks is a function of pigment quality of their food. In the limpet, Acmaea digitalis, two form complexes exist. The one, subjectively, is characteristic of beds of the gooseneck barnacle, Pollicipes polymerus

Recent Acquisitions at the British Museum (Natural History)

THE Rev. A. H. Cooke has given the whole of his collection of shells of land-snails of the genus Clausilia and of the dog whelk (Thais lapillus); the former is very rich in series from central Europe and the Balkans, and the latter includes specimens from practically the whole distributional area, and illustrates very completely the remarkable variation of this species. Recent accessions to the Department of Entomology include the final instalment, consisting of several hundred Hymenoptera, of the very large amount of material collected by the Percy Sladen Trust Expedition to the Seychelles and other islands of the western Indian Ocean. This expedition, which was led by Prof, (then Mr.) Stanley Gardiner, in 1905 and 1908–9, resulted in the gift of many thousands of specimens to the Museum. The final instalment consists almost entirely of small or minute wasps, many of them obviously new, which it has so far proved impossible to work out owing to the lack of specialists in these groups. The Department has also received a set of the Hymenoptera collected on the island of Rodriguez by the late H. J. Snell and by Mr. H. P. Thomasset. From Mount Kina Balu in North Borneo a series of a new species of Blepharocera has been sent by Mr. H. M. Pendlebury. Flies of this genus have hitherto been found only in the north temperate regions, and their discovery in Borneo is therefore both surprising and of importance in zoogeography. The larvse of these insects live only in waterfalls and rapids, attaching themselves to rocks and stones by means of ventral suckers; and it has been considered therefore that they would be able to spread only along land routes. The four, widely separated, compound eyes in this species give the head a most remarkable appearance. The American Museum of Natural History has presented to the Department of Geology a model of an extinct straight-tusked elephant.

Variation in the Dog Whelk, Thais (Purpura Auct.) Lapillus

EcologyVolume 3, Issue 2 p. 146-157 Article Variation in the Dog Whelk, Thais (Purpura Auct.) Lapillus Harold Sellers Colton, Harold Sellers ColtonSearch for more papers by this author Harold Sellers Colton, Harold Sellers ColtonSearch for more papers by this author First published: 01 April 1922 https://doi.org/10.2307/1929149Citations: 21AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume3, Issue2April 1922Pages 146-157 RelatedInformation