Trace metal-binding proteins in marine molluscs and crustaceans

Some marine invertebrates, such as the American oyster, Crassostrea virginica, the blue crab, callinectes sapidus and the American lobster, Homarusamericanus, concentrate trace metals in their tissues. The occurrence of metallothionein, a low molecular weight, sulfur-containing metal-binding protein, has been correlated with elevated levels of trace metals in these organisms. It is our hypothesis that, whilst metallothioneins are involved in the sequestration of elevated levels of trace metals, they primarily function in regulating normal metal metabolism. In this paper we describe recent field and laboratory experiments designed to examine how oysters, blue crabs and lobsters manage accumulated cadmium, copper and zinc. The possible rôles of metallothionein, as well as the tissue distribution of metals, are emphasized. Metallothioneins were found in all animals we examined; concentrations of metallothioneins and the the amount of bound trace metals are related to time of exposure. We have also demonstrated that the laboratory developed metallothionein models for blue crabs and lobsters may be useful in predicting the partitioning of trace metals in animals living in environments polluted with trace metals.     

Ionic medium effects in sea water — A comparison of acidity constants of carbonic acid and boric acid in sodium chloride and synthetic sea water

It is shown that the values of pK_1C and pK_2C for carbonic acid, pK_B for boric acid and the ionic product of water, pK_w, in sea water may be explained on the basis of their determination in 0.7 M_w sodium chloride and the formation of the following ion-pairs: NaSO₄^?, MgSO₄, CaSO₄, MgCO₃, CaCO₃, MgHCO₃⁺, CaHCO₃⁺, MgOH⁺, HSO₄^?, MgB(OH)₄⁺ and CaB(OH)₄⁺. On the whole the calculated stability constants are lower than those given by Garrels and Thompson (1962).     

An ocean bottom,microprocessor based seismometer

We describe the design and construction of an ocean bottom seismometer configured as a computer, based on an Intersil IM6100 microprocessor plus appropriate peripheral devices. The sensors consist of triaxial 1 Hz seismometers and a hydrophone, each sensor channel being filtered prior to digitizing so that typical noise spectra are whitened. Digital data are recorded serially on magnetic tape. The instrument is placed on the ocean bottom by allowing it to fall freely from just below the surface. An acoustic system allows precise determination of instrument position, acoustic recall, and transmission of operational information to the surface. Release from an expendable anchor is accomplished by redundant pyrotechnic bolts which can be fired by acoustic command or by precision timers.The operational flexibility provided by the micro-computer, which executes the DEC PDP8/E instruction set, enables optimum use of the 6-hr recording capacity (at 128 samples/second/channel) in the context of the particular experiment being performed.

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Multi-AUV Control and Adaptive Sampling in Monterey Bay

Operations with multiple autonomous underwater vehicles (AUVs) have a variety of underwater applications. For example, a coordinated group of vehicles with environmental sensors can perform adaptive ocean sampling at the appropriate spatial and temporal scales. We describe a methodology for cooperative control of multiple vehicles based on virtual bodies and artificial potentials (VBAP). This methodology allows for adaptable formation control and can be used for missions such as gradient climbing and feature tracking in an uncertain environment. We discuss our implementation on a fleet of autonomous underwater gliders and present results from sea trials in Monterey Bay in August, 2003. These at-sea demonstrations were performed as part of the Autonomous Ocean Sampling Network (AOSN) II project