A massive summer-kill of the dog-whelk, Nucella lapillus, on the north Cornwall coast in 1995: freak or forerunner?

1999 ◽  
Vol 79 (1) ◽  
pp. 103-109 ◽  
Author(s):  
P.E. Gibbs ◽  
J.C. Green ◽  
P.L. Pascoe
Keyword(s):  
High Mortality ◽  
Laboratory Experiments ◽  
Algal Bloom ◽  
Extended Period ◽  
Littorina Littorea ◽  
Nucella Lapillus ◽  
Sewage Outfall ◽  
The North ◽  
Algal Toxicity ◽  
Calm Weather

In the summer of 1995 a massive kill of the dog-whelk, Nucella lapillus, occurred in Bude Bay on the north Cornish coast. High mortality was detectable along 12 km of shoreline. The only other intertidal species affected appeared to be another neogastropod, Ocenebra erinacea. The cause of the kill is unknown but the evidence suggests that it occurred in early July following an extended period of warm, calm weather in June. Possible causes of this event are discussed: algal toxicity may have been responsible since an algal bloom was detected offshore in July in the area. Laboratory experiments exposing gastropods to different species and concentrations of microalgae, designed to test whether N. lapillus is more sensitive than Monodonta lineata and Littorina littorea, gave inconclusive results. No comparable kill has occurred in the Bude area for at least 20 y, but it is suggested that nutrients from a newly-constructed, offshore sewage outfall may now stimulate local algal bloom development during calm weather periods.

The use of byssus threads by Mytilus edulis as an active defence against Nucella lapillus

2007 ◽  
Vol 87 (2) ◽  
pp. 559-564 ◽  
Author(s):  
Edward D. Farrell ◽  
Tasman P. Crowe
Keyword(s):  
Mytilus Edulis ◽  
Laboratory Experiments ◽  
Littorina Littorea ◽  
Nucella Lapillus ◽  
Field Exposure ◽  
Active Defence

To assess whether Mytilus edulis is selective in its secretion of byssus threads and entrapment of gastropods, experiments were conducted in laboratory aquaria and in the field. Exposure to dogwhelks (Nucella lapillus) or their effluent induced mussels to produce twice as many byssus threads as mussels exposed only to winkles (Littorina littorea) or those exposed only to seawater. There were no significant differences among treatments in the area over which byssus threads were secreted. Significantly more byssus threads were attached to the shells of dogwhelks than to winkles. Laboratory experiments produced broadly similar results to those in the field, but the level of response in the laboratory was greater. It is concluded that byssus threads were attached selectively to dogwhelks and that they may serve as a defence against predation.

scholarly journals Declines over the last two decades of five intertidal invertebrate species in the western North Atlantic

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Peter S. Petraitis ◽  
S. R. Dudgeon
Keyword(s):  
North Atlantic ◽  
Littorina Littorea ◽  
Rocky Shores ◽  
Nucella Lapillus ◽  
Important Food ◽  
Semibalanus Balanoides ◽  
Saturation State ◽  
Invertebrate Species ◽  
The North ◽  
The Common

Abstract Climate change has already altered the environmental conditions of the world’s oceans. Here we report declines in gastropod abundances and recruitment of mussels (Mytilus edulis) and barnacles (Semibalanus balanoides) over the last two decades that are correlated with changes in temperature and ocean conditions. Mussel recruitment is declining by 15.7% per year, barnacle recruitment by 5.0% per year, and abundances of three common gastropods are declining by an average of 3.1% per year (Testudinalia testudinalis, Littorina littorea, and Nucella lapillus). The declines in mussels and the common periwinkle (L. littorea) are correlated with warming sea temperatures and the declines in T. testudinalis and N. lapillus are correlated with aragonite saturation state, which affects rates of shell calcification. These species are common on shores throughout the North Atlantic and their loss is likely to lead to simplification of an important food web on rocky shores.

Modeling Transit Flow Through Port Gates and Connecting Channel in Baltic Sea—Liepaja Port—Liepaja Lake System

2021 ◽  
Vol 8 ◽  
Author(s):  
Vilnis Frishfelds ◽  
Juris Sennikovs ◽  
Uldis Bethers ◽  
Jens Murawski ◽  
Andrejs Timuhins
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
Sea Water ◽  
Lake System ◽  
The North ◽  
Transit Flow ◽  
Trade Channel ◽  
Calm Weather ◽  
Set Up ◽  
The Baltic

This study investigates a water transport features by extending Copernicus Marine Environment Service (CMEMS) to the Liepaja coast-port-channel-lake system with a two-way nested model. The Liepaja lake and Liepaja port are connected by Trade channel. The Liepaja port has three gates—the openings in wave breakers connecting the port aquatory with the Baltic sea. Each of gates has a corresponding dredged channel for securing the navigation. A hydrodynamic model is set up to study the flow and water level in this system. The area of the port gates, port and Trade channel are resolved by 33 m grid. The model results are verified against currents and sea level observations inside/outside port, Trade channel and Liepaja lake. Results and observations show that strong currents occur in the Trade channel in case of rapid sea level change in Baltic sea despite the Trade channel is rather shallow at the connection with Liepaja lake. The northern part of the Liepaja lake gets filled with brackish water during storm surge events. The channel has notable alternating current also during a relatively calm weather due to the port seiches. Long and narrow shape of the channel implies the Helmholtz type oscillations between the lake and the port with a period in approximately semidiurnal range. Hydrodynamic simulations describe well these oscillations but the phase of hourly scale oscillations in the port may differ in case of weak external forcing. Water exchange is significantly increased by the transit (gate to gate) sea currents. This transit flow usually occurs between South or Central gate and the North gate carrying sea water into the port. Northward flow of the surface layer is more characteristic in the port aquatory due the prevailing south-western winds. There are intense morphological processes at the coastline and underwater slope near the Liepaja port due to a sandy western coastline of Latvia, long fetch of the waves and strong currents at the port gates. Liepaja port is one of the Latvian ports in HywasPort operational service of hydrodynamics, waves and siltation.

An exposure scale for marine shores in western Norway

1978 ◽  
Vol 58 (4) ◽  
pp. 975-996 ◽  
Author(s):  
D. H. Dalby ◽  
E. B. Cowell ◽  
W. J. Syratt ◽  
J. H. Crothers
Keyword(s):  
Species Abundance ◽  
Shell Shape ◽  
Rocky Shores ◽  
Shape Variation ◽  
Nucella Lapillus ◽  
Extended Form ◽  
Independent Evidence ◽  
The North ◽  
Western Norway ◽  
The North Sea

A rocky shore exposure scale, intended primarily for use in the Fensfjord area, Western Norway, has been prepared. This scale is developed from an earlier scale devised by Ballantine for Milford Haven, Wales, making use of species abundance curves along the wave exposure gradient. Independent evidence for the validity of the scale is provided by shell shape variation in Nucella lapillus and by the height of the black lichen zone in the supralittoral fringe. The successive steps in the preparation of the scale are outlined, definitions of the exposure grades are given in tabular form for the restricted set of species analysed numerically and descriptions are provided in an extended form to provide a fuller picture for users of the scale. It is believed that the scale will prove applicable to other rocky shores around the North Sea.

scholarly journals High mortality of Pacific oysters in a cold winter in the North-Frisian Wadden Sea

2011 ◽  
Vol 65 (4) ◽  
pp. 525-532 ◽  
Author(s):  
Heike Büttger ◽  
Georg Nehls ◽  
Sophia Witte
Keyword(s):  
High Mortality ◽  
Wadden Sea ◽  
Cold Winter ◽  
The North ◽  
Pacific Oysters ◽  
North Frisian

Methodologies for Evaluating and Qualifying External Pipeline Coatings for Northern Pipelines

2006 ◽  
Author(s):  
S. Papavinasam ◽  
A. Doiron ◽  
T. Panneerselvam ◽  
Y. Lafrenie`re ◽  
M. Attard ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Low Temperatures ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Climatic Conditions ◽  
Limited Data ◽  
The North

The design of coatings must be adequate to protect pipelines under long-term, severe environmental conditions, including the extreme climatic conditions that will apply in the North before the pipe is installed and operation begins. Practices and standardised methodologies for evaluating and qualifying pipeline coatings for application in northern pipelines are discussed. Results from laboratory and field experiments, carried out under the conditions to which coatings will be exposed during construction, are presented. Based on 1-year laboratory experiments in which samples were exposed to temperatures as low as −45°C and limited data from the field experiments, it is concluded that Canadian Standards Association (CSA) standards CSA Z662, CSA Z245.20 and CSA Z245.21 adequately cover evaluation of coatings for northern pipelines. However, in order to evaluate the effects of low-temperatures, the specimens should be exposed for at least 4 months. Coatings qualified by CSA Z245.21 (System B1 and B2) are less affected from exposure to low-temperatures than those qualified by CSA Z245.21 (System A1) and CSA Z245.20.

Determining the operational limits of the biosand filter

2013 ◽  
Vol 13 (1) ◽  
pp. 56-65 ◽  
Author(s):  
Timothy J. Kennedy ◽  
Todd A. Anderson ◽  
E. Annette Hernandez ◽  
Audra N. Morse
Keyword(s):  
Laboratory Experiments ◽  
Extended Period ◽  
Fecal Coliforms ◽  
Log Reduction ◽  
Biosand Filter ◽  
Slow Sand Filter ◽  
Improve Water Quality ◽  
Recovery Performance ◽  
Clean Drinking Water ◽  
Startup Period

Worldwide, access to clean drinking water is not available for more than 800 million people. The biosand filter (BSF), an intermittently operated slow sand filter, was developed to address this problem. The BSF is used in homes to improve water quality. Three main objectives were examined in this research: (1) investigate initial startup and recovery performance after cleaning BSF, (2) examine the number of people the BSF may effectively serve, and (3) determine effects of an extended pause period on BSF performance. Laboratory experiments examined the BSF's ability to reduce fecal coliforms (FC) and turbidity for the various objectives. Results indicate that during the startup period, 27 days were needed to achieve 1 log reduction, while only 17 days were needed after cleaning the BSF to achieve 1 log reduction. A maximum of six people can be effectively served by a single BSF based upon the results of the experiment. A 7-day extended pause period determined that the bacterial layer will begin to go dormant or die off when the filter is not used for an extended period.

The distribution of metacercariae of Maritrema arenaria (Digenea: Microphallidae) in the barnacle Balanus balanoides at three sites on the east coast of Northern Ireland

1980 ◽  
Vol 60 (4) ◽  
pp. 959-962 ◽  
Author(s):  
S. W. B. Irwin ◽  
B. C. Irwin
Keyword(s):  
Northern Ireland ◽  
East Coast ◽  
Littorina Littorea ◽  
British Isles ◽  
Littorina Saxatilis ◽  
Nucella Lapillus ◽  
Detailed Survey ◽  
Marked Preference ◽  
Balanus Balanoides

Overall incidence of metacercariae of Maritrema arenaria differed substantially at each of the three sites investigated. In each case, however, numbers were higher than those previously observed in the British Isles. Results indicate that gulls rather than waders are the more important final hosts of this parasite in the areas investigated. At one site where a more detailed survey was carried out metacercariae were more abundant on the upper half of the shore and they displayed a marked preference for barnacles on living Littorina littorea shells as compared to barnacles on rocks. Evidence would suggest that the two most likely molluscan hosts of this trematode are Littorina saxatilis and Nucella lapillus.

Physical properties of the Great Barrier reef Lagoon waters near Townsville. II. Seasonal variations

1981 ◽  
Vol 32 (3) ◽  
pp. 321 ◽  
Author(s):  
E Wolanski ◽  
M Jones ◽  
WT Williams
Keyword(s):  
Physical Properties ◽  
Great Barrier Reef ◽  
Seasonal Variations ◽  
High Salinity ◽  
Dry Season ◽  
Barrier Reef ◽  
Reef Lagoon ◽  
The North ◽  
Strong Winds ◽  
Calm Weather

The distribution of salinity, temperature, suspended particles, light transmissivity, chlorophyll a and phaeopigments across the Great Barrier Reef lagoon offshore Townsville, was measured from 9 January 1979 to 23 January 1980 at approximately weekly intervals. Previous observations at Low Isles. 400 km to the north, on seasonal variations of temperature and salinity were generally applicable here. A shallow summer thermocline was frequently observed in offshore waters, in the dry season and in calm weather. As a result of evaporation from the lagoon and adjoining mangrove swamps during the dry season, an inverse estuarine circulation can exist when high salinity, sediment-rich, nearshore waters sink below the less saline offshore waters. Only nearshore were bottom sediments strongly entrained in the water column during strong winds, principally in winter.

Nerik and its “Weather-God”

1980 ◽  
Vol 30 ◽  
pp. 179-187 ◽  
Author(s):  
J. G. Macqueen
Keyword(s):  
Extended Period ◽  
Small Contribution ◽  
Long Period ◽  
The North ◽  
The Town

Hittite geography and Hittite religion have for many years been among Oliver Gurney's principal interests. It therefore gives me the greatest pleasure that this small contribution in his honour deals with both these subjects, especially since the text with which it is mainly concerned is one which I first studied many years ago under his supervision. Like so many others, I owe him a debt of gratitude which can never be adequately repaid.For many years now it has been clear that in any attempt to locate the site of Nerik the most important fact to be kept in mind is that the town was for a long period in the hands of the Gasga-peoples. Their capture of it was allegedly in the reign of Hantilis, and it was calculated that five hundred years passed before it was recovered by Hattusilis III. More probably however it fell into enemy hands in the reign of Arnuwandas I and his queen Asmunikkal, shortly after 1450 B.C. But whatever the exact details may be, it has to be accepted that any town subjected to an extended period of Gasgan occupation must have been situated to the north of Hattusas, in the direction of the area known in Classical times as Pontus. More recently there has been further evidence pointing to a similar conclusion.

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