Ecological effects, transport, and fate of mercury: a general review.

Bioavailability, accumulation and effects of heavy metals in sediments with special reference to United Kingdom estuaries: a review

SUMMARY Available literature on the ecological and toxicological aspects of mercury (Hg) in the environment, with special reference to fish and wildlife resources, is reviewed and summarized. Subdivisions include sources, chemical properties, background concentrations, acute and chronic toxicity, sublethal effects, and proposed criteria to protect sensitive resources. Mercury has been used by man for at least 2,300 years, most recently as a fungicide in agriculture, in the manufacture of chlorine and sodium hydroxide, as a slime control agent in the pulp and paper industry, in the production of plastics and electrical apparatus, and in mining and smelting operations. Mercury burdens in some environmental compartments are estimated to have increased up to 5X precultural levels, primarily as a result of man's activities. The construction of artificial reservoirs, for example, which releases Hg from flooded soils, has contributed to the observed elevation of Hg concentrations in fish tissues from these localities. Elevated levels of Hg in living organisms in Hg-contaminated areas may persist for as long as 100 years after the source of pollution has been discontinued. One major consequence of increased mercury use, coupled with careless waste disposal practices, has been a sharp increase in the number of epidemics of fatal mercury poisonings in humans, wildlife, and aquatic organisms. Most authorities agree on six points: (1) mercury and its compounds have no known biological function, and the presence of the metal in the cells of living organisms is undesirable and potentially hazardous; (2) forms of mercury with relatively low toxicity can be transformed into forms of very high toxicity, such as methylmercury, through biological and other processes; (3) mercury can be bioconcentrated in organisms and biomagnified through food chains; (4) mercury is a mutagen, teratogen, and carcinogen, and causes embryocidal, cytochemical, and histopathological effects; (5) some species of fish and wildlife contain high concentrations of Hg that are not attributable to human activities; (6) anthropogenic use of Hg should be curtailed, as the difference between tolerable natural background levels of Hg and harmful effects in the environment is exceptionally small. Concentrations of total Hg lethal to sensitive, representative, nonhuman species range from 0.1 to 2.0 ug/l (ppb) of medium for aquatic organisms; from 2,200 to 31,000 ug/kg body weight (acute oral) and 4,000 to 40,000 ug/kg (dietary) for birds; and from 100 to 500 ug/kg body weight (daily dose) and 1,000 to 5,000 ug/kg diet for mammals. Organomercury compounds, especially methylmercury, …

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Mercury Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review

Several equations have been proposed to describe ontogenetic growth trajectories for organisms justified primarily on the goodness of fit rather than on any biological mechanism. Here, we derive a general quantitative model based on fundamental principles for the allocation of metabolic energy between maintenance of existing tissue and the production of new biomass. We thus predict the parameters governing growth curves from basic cellular properties and derive a single parameterless universal curve that describes the growth of many diverse species. The model provides the basis for deriving allometric relationships for growth rates and the timing of life history events.

A general model for ontogenetic growth

In this review I show that the '3/4-power scaling law' of metabolic rate is not universal, either within or among animal species. Significant variation in the scaling of metabolic rate with body mass is described mainly for animals, but also for unicells and plants. Much of this variation, which can be related to taxonomic, physiological, and/or environmental differences, is not adequately explained by existing theoretical models, which are also reviewed. As a result, synthetic explanatory schemes based on multiple boundary constraints and on the scaling of multiple energy-using processes are advocated. It is also stressed that a complete understanding of metabolic scaling will require the identification of both proximate (functional) and ultimate (evolutionary) causes. Four major types of intraspecific metabolic scaling with body mass are recognized [based on the power function R=aMb, where R is respiration (metabolic) rate, a is a constant, M is body mass, and b is the scaling exponent]: Type I: linear, negatively allometric (b 1) to one or two later phases of negative allometry (b<1). Ontogenetic changes in the metabolic intensity of four component processes (i.e. growth, reproduction, locomotion, and heat production) appear to be important in these different patterns of metabolic scaling. These changes may, in turn, be shaped by age (size)-specific patterns of mortality. In addition, major differences in interspecific metabolic scaling are described, especially with respect to mode of temperature regulation, body-size range, and activity level. A 'metabolic-level boundaries hypothesis' focusing on two major constraints (surface-area limits on resource/waste exchange processes and mass/volume limits on power production) can explain much, but not all of this variation. My analysis indicates that further empirical and theoretical work is needed to understand fully the physiological and ecological bases for the considerable variation in metabolic scaling that is observed both within and among species. Recommended approaches for doing this are discussed. I conclude that the scaling of metabolism is not the simple result of a physical law, but rather appears to be the more complex result of diverse adaptations evolved in the context of both physico-chemical and ecological constraints.

Beyond the '3/4-power law': variation in the intra- and interspecific scaling of metabolic rate in animals.

The retention efficiency of 13 species of suspension feeding bivalves has been determined by analysing the particle size distribution in the inhalant and exhalant water currents using a Coulter electronic particle counter. The bivalves were held in aquaria under conditions very similar to their natural environment. It is shown that 11 species, Cardium echinatum, Cardium edule, Modiolus modiolus, Mytilus edulis, Musculus niger, Cultellus pellucidus, Arctica islandica, Ostera edulis, Hiatella striata, Mya arenaria and Venerupis pullastra, which all possess eu-latero-frontal cirri completely retain particles above 1 μm. Particles down to 1 /Lm were in most cases efficiently retained. The retention efficiency in Pecten opercularis and Pecten septemradiatus both lacking the eu-latero-frontal ciliary tract decreases below 7 μm and reaches only 20 % at 1 μm.

Efficiency of particle retention in 13 species of suspension feeding bivalves

Particle retention efficiency in 6 species of suspension-feeding Northeast American bivalves was determined by simultaneous measurement of clearance of different sized particles. Geukensia dernissa, Spisula solidissirna, Brachidontes exustus, and Mercenaria rnercenana, which all possess large laterofrontal cirri, completely retained particles above 4 pm. Below this the retention efficiency gradually decreased to between 35 and 70 % for 2 kim particles. Crassostrea virginica, which has small laterofrontal cirri, and Argopecten irradians, which has none, entirely retained particles above 5 to 6 pm. Below 5 pm the retention efficiency gradually decreased to 50 '0 for 2 Iim particles in C. virginica while it sharply dropped to 15 % for 2 pm particles in A. irradians. At 27 to 29OC filtration rates (F, I h-') as a function of tissue dry weight ( W , g ) could be described by the allometric equation: F = a ~ " . In C. virginica, G. dernissa and M mercenaria the equations were: 6 . ? 9 ~ O . ' ~ , 6.15 w o H 3 and 1.24 W'.'', respectively. B. exustus and S. sohdissin~a showed intermedial-y filtration rates. In G. demlssa gill area increased with sizc at the same rate as filtration rate.

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Efficiency of particle retention and filtration rate in 6 species of Northeast American bivalves

This review deals with the measurement of filtration rates in suspension feeding bivalves. Currently used methods are described, and some reliable filtration rate data obtained under optimal laboratory conditions are presented. The different methods have often caused troubles, and a number of problems and shortcomings are brought to light. The conflicting data on filtration rates seem partly to be due to the incorrect use of methods, and partly to be caused by differences in experimental conditions.

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On measurement of filtration rates in bivalves — the stony road to reliable data: review and interpretation

Filtration rate capacities in undisturbed freshwater bivalves were determined by means of two different methods (indirect “clearance” and “suction” methods) in Anodonta anatina (L.), Unio tumidus Philipsson, Unio pictorum (L.), Unio crassus Philipsson, Dreissena polymorpha (Pallas) and Sphaerium corneum (L.). In A. anatina, D. polymorpha, and S. corneum the filtration rate (FR, 1 h-1) at 19–20°C as a function of dry tissue weight (DW, g) or ash-free dry weight (AFDW, g) could be expressed by the equations: 1.10 DW0.78, 6.82 DW0.88, and 2.14 AFDW0.92, respectively. In U. tumidus, U. pictorum, and U. crassus filtration rates were comparable with those of A. anatina. In D. polymorpha the b value of the corresponding regression of gill area on dry weight was 0.87. The rates of water transport in freshwater bivalves are 2–8 times lower than in marine bivalves of comparable size. A corresponding difference in the filtration rate per gill area unit is found. The measured filtration rates in undisturbed bivalves are substantially higher (at least 4 times) than previously reported. This indicates that the impact of bivalve water processing on freshwater ecosystems is greater than hitherto suggested.

Filtration rate capacities in 6 species of European freshwater bivalves.

A method for determining filtration rates in undisturbed suspension-feeding bivalves is described. Concentrations of particulate matter in the water collected in the inhalant (Ci) and exhalant (Ce) currents were estimated with an electronic particle counter. The clearance was calculated as \(Y = Fl(1 - \frac{{C_e }}{{C_i }})\), where Fl=flow rate through the tube collecting exhalant water. Only above critical levels of water flow (Fl) were clearances representative of filtration rates. At 10° to 13°C, the filtration rates (F, 1 h-1) within one or two orders of magnitude of dry weight (w, g), in Cardium echinatum L., C. edule L., Mytilus edulis L., Modiolus modiolus (L.) and Arctica islandica (L.) followed the allometric equations: 4.22w0.62, 11.60w0.70, 7.45w0.66, 6.00w0.75 and 5.55w0.62, respectively. Five species of bivalves [Spisula subtruncata (da Costa), Hiatella striata (Fleuriau), Cultellus pellucidus (Pennant), Mya arenaria L. and Venerupis pullastra (Montagu)] filtered with the same rates as individuals of Cardium echinatum and A. islandica of equivalent soft weight. In Pecten furtivus and P. opercularis filtration rates were about twice the rates measured in individuals of Mytilus edulis of comparable body weight. The gill area in M. edulis increases with size at the same rate as the filtration rate.

Hans Ulrik Riisgård

Papers

Efficiency of particle retention in 13 species of suspension feeding bivalves

Efficiency of particle retention and filtration rate in 6 species of Northeast American bivalves

On measurement of filtration rates in bivalves — the stony road to reliable data: review and interpretation

Filtration rate capacities in 6 species of European freshwater bivalves.

Filtration rate, using a new indirect technique, in thirteen species of suspension-feeding bivalves