نتایج جستجو برای: bivalves
تعداد نتایج: 2200 فیلتر نتایج به سال:
Ongoing controversies surrounding the end-Triassic extinction highlight the need for identifying a causal mechanism leading to extinction. Bivalve data from Lombardia (Italy), Northern Calcareous Alps (Austria and Germany), and northwest Europe (England and Wales) provide the biologic signal of selective extinction to compare two competing extinction hypotheses: (1) sea-level change and associa...
One of the biggest obstacles to studying recruitment variation in marine bivalves is the need to collect and process large numbers of plankton samples. Larval bivalves are notoriously difficult, if not impossible, to identify to species using morphological criteria alone. Remote time-series collections could satisfy the sampling challenge, but efficient identification techniques must be develop...
Bivalves and gastropods are the two largest classes of extant molluscs. Despite sharing a huge number of features, they do not share a key ecological one: gastropods are essentially epibenthic, while most bivalves are infaunal. However, this is not the ancestral bivalve condition; Cambrian forms were surface crawlers and only during the Ordovician a fundamental infaunalization process took plac...
1. Spent shells of bivalves can provide habitat for other organisms, as well as playing important roles in biogeochemical cycles. The amount of spent shell material that will accumulate at a site depends on rates of both shell production and decay, although the latter is rarely considered. 2. We measured the instantaneous decay rates of four species of freshwater bivalves across a range of site...
Community composition of the infaunal bivalve fauna of the St. Lucie Estuary and southern Indian River Lagoon, eastern Florida was sampled quarterly for 10 years as part of a long-term benthic monitoring program. A total of 38,514 bivalves of 137 taxa were collected and identified. We utilized this data, along with sediment samples and environmental measurements gathered concurrently, to assess...
Many exogenous factors (temperature, salinity, pH, light, oxygen tension, turbidity etc.) affect the rate of oxygen consumption in bivalve molluscs (Bayne, 1976; Samant and Agrawal, 1978). Most of the vital activities in bivalves are regulated by neuroendocrine centers. The respiratory rate data of the animals reflect their general metabolic rate. The existence of neuroendocrine modulations of ...
Diseases are a critical bottleneck for the culture of bivalves causing important yield losses. The study of bivalve diseases has relied on histological techniques and has focused on pathogen morphology, the effect of external factors on the pathogens and infectivity, and on the development of immune and molecular diagnostic techniques. Recently, significant advances in the study of bivalve path...
The bioaccumulation and retention capacities of some key local contaminants of the New Caledonia lagoon (Ag, As, Cd, Co, Cr, Cu, Mn, Ni and Zn) have been determined in the oyster Isognomon isognomon and the edible clam Gafrarium tumidum during transplantation experiments. In a first set of experiments, oysters and clams from a clean site were transplanted into contaminated sites. Uptake kinetic...
As in other cold seeps, the dominant bivalves in mud volcanoes (MV) from the Gulf of Cadiz are macrofauna belonging to the families Solemyidae (Acharax sp., Petrasma sp.), Lucinidae (Lucinoma sp.), Thyasiridae (Thyasira vulcolutre) and Mytilidae (Bathymodiolus mauritanicus). The delta(13)C values measured in solemyid, lucinid and thyasirid specimens support the hypothesis of thiotrophic nutriti...
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