نتایج جستجو برای: cockle shells
تعداد نتایج: 15024 فیلتر نتایج به سال:
This paper presents an experimental study of imperfection insensitive composite wavy cylindrical shells subject to axial compression. A fabrication technique for making cylindrical shells with intricate shape of cross-sections has been developed. A photogrammetry technique to measure the geometric imperfections has also been developed. The behavior of the wavy shells under axial compression was...
The determination of food web structures using Ecological Network Analysis (ENA) is a helpful tool to get insight into complex ecosystem processes. The intertidal area of the Wadden Sea is structured into diverse habitat types which differ in their ecological functioning. In the present study, six different intertidal habitats (i.e. cockle field, razor clam field, mud flat, mussel bank, sand fl...
Growth is one of the key processes in the dynamic of exploited resources, since it provides part of the information required for structured population models. Growth of mangrove cockle, Anadara tuberculosa was estimated through length-based methods (ELEFAN I y NSLCA) and using diverse shell length intervals (SLI). The variability of L(infinity), k and phi prime (phi') estimates and the effect o...
The New Zealand cockle Austrovenus stutchburyi, whose foot is commonly infected by the digenean trematode Curtuteria australis (Echinostomatidae), is often found heavily infected and unable to burrow on the sediment surface of tidal flats. This has been interpreted as a Curtuteria-manipulation with the purpose of increasing the transmission of the parasite to shorebirds acting as final hosts. U...
In the Lake Tanganyika cichlid Lamprologus callipterus, males were >12 times heavier than females, the most extreme sexual size dimorphism in this direction among animals. L. callipterus males construct nests of empty snail shells in which the females breed. If the ancestors of L. callipterus were small cichlids, both sexes may have used shells for shelter. If the ancestors were larger, snail s...
Bivalve populations are prone to change due sudden or gradual alteration in the natural environment and anthropogenic interference. Fisheries environmental managers therefore interested long-term trends disentangling human influences, assisting them conservation efforts management of bivalve stocks. Here, 64 monitoring reports covering a 50-year period from 1958 2009 cockles Cerastoderma edule ...
The common phenomenon of sublethal predation in soft-bottom bivalves usually involves nipping of siphons. Here we show that foot cropping, hitherto documented only in Donax spp., is widespread in the New Zealand cockle Austrovenus stutchburyi (Veneridae). Depending on the locality, cropping frequency ranged between 14 and 34% of cockles, and the average proportion of the foot area cropped range...
In a ¢eld experiment, the accumulation of trematode (Echinostomatidae) metacercariae by the New Zealand cockle Austrovenus stutchburyi was compared among treatments with di¡erent seabed hydrodynamics and sedimentation rates. There was no signi¢cant di¡erence among the treatments in the rate at which cockles accumulated metacercariae, suggesting that infection rates are not in£uenced by water £o...
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