The Protective Role of Dietary Calcium Against Cadmium Uptake and Toxicity in Freshwater Fish: an Important Role for the Stomach

2006 ◽  
Vol 3 (6) ◽  
pp. 389 ◽  
Author(s):  
Chris M. Wood ◽  
Natasha M. Franklin ◽  
Som Niyogi
Keyword(s):  
Freshwater Fish ◽  
Calcium Uptake ◽  
Dietary Calcium ◽  
Freshwater Ecosystems ◽  
Cadmium Uptake ◽  
Diet Switching ◽  
Uptake Pathway ◽  
Waterborne Exposure ◽  
In The Wild ◽  
Waterborne Cadmium

Environmental Context. Contamination of freshwater ecosystems by cadmium is of increasing concern with accumulation and toxicity in aquatic animals occurring through both waterborne and dietary routes. Increases in water calcium (‘hardness’) levels protect against waterborne uptake. Physiological research on freshwater fish has demonstrated that this occurs because cadmium moves through the calcium uptake pathway at the gills. Surprisingly, elevated dietary calcium also protects against waterborne exposure by down-regulating the calcium uptake pathway at the gills, and against dietary exposure by reducing cadmium uptake through the gastrointestinal tract. In both cases, the stomach is the critical site of action. Abstract. Waterborne cadmium causes toxicity in freshwater fish by inducing hypocalcaemia. Research on the rainbow trout (Oncorhynchus mykiss), a sensitive model species, has demonstrated that this occurs because Cd2+ ions compete with waterborne Ca2+ ions for the active branchial uptake pathway which normally ensures internal homeostasis of calcium levels. Therefore, increases in waterborne calcium concentrations (‘hardness’) protect against waterborne cadmium uptake and toxicity in both acute and chronic exposures. Increases in dietary calcium concentration also protect against waterborne exposure, because elevated gastrointestinal calcium uptake down-regulates the Ca2+ uptake pathway at the gills, thereby simultaneously reducing Cd2+ entry. Furthermore, dietary calcium also protects against dietborne cadmium exposure, although the physiological mechanisms appear to differ from those at the gills. Surprisingly, the principal site of this inhibitory action of dietary calcium on gastrointestinal cadmium uptake appears to be the stomach, which is also the major site of gastrointestinal calcium uptake, rather than the intestine as in mammals. These results underline the importance of considering not only water chemistry but also dietary chemistry in the environmental regulation of cadmium, and suggest that fish in the wild under chronic cadmium stress would benefit by switching to a more calcium-rich diet. While diet switching has been seen in the wild in fish under metal stress, its etiology remains unknown; to date, laboratory experiments have not been able to show that voluntary diet-switching of an adaptive nature actually occurs.

A protective effect of dietary calcium against acute waterborne cadmium uptake in rainbow trout

2004 ◽  
Vol 67 (1) ◽  
pp. 57-73 ◽  
Author(s):  
B. Baldisserotto ◽  
C. Kamunde ◽  
A. Matsuo ◽  
C.M. Wood
Keyword(s):  
Rainbow Trout ◽  
Protective Effect ◽  
Dietary Calcium ◽  
Cadmium Uptake ◽  
Waterborne Cadmium

Regulation of calcium balance in the sturgeon Acipenser naccarii: a role for PTHrP

2007 ◽  
Vol 293 (2) ◽  
pp. R884-R893 ◽  
Author(s):  
Juan Fuentes ◽  
Christophe Haond ◽  
Pedro M. Guerreiro ◽  
Nádia Silva ◽  
Deborah M. Power ◽  
...  
Keyword(s):  
Calcium Transport ◽  
Calcium Uptake ◽  
Dietary Calcium ◽  
Calcium Deficiency ◽  
Cell Number ◽  
The Body ◽  
Whole Body ◽  
Calcium Balance ◽  
Parathyroid Hormone Related Protein ◽  
Juvenile Sturgeon

Calcium regulation in sturgeon is of special interest because they are a representative of the ancient fishes possessing mainly cartilaginous skeletons and a supposedly low calcium demand. The present study aimed to characterize the effect of a chronic absence of dietary calcium and the effect of parathyroid hormone-related protein (PTHrPA) (1-34) ( 7 ) on calcium balance in juvenile sturgeon ( Acipenser naccarii). At rest, sturgeon juveniles are in net positive calcium balance, since whole body calcium uptake is significantly higher than efflux and calcium accumulates in the body. To study the importance of dietary calcium, the sturgeon were kept on a calcium-free diet for 8 wk. This manipulation impaired growth as measured by failure to gain weight or increase in length and indicates that dietary calcium is important for growth in sturgeon. An increased whole body calcium uptake partially compensated dietary calcium deficiency and was associated with increased gill chloride cell number in lamellae and filaments in parallel with increased gill Na+K+-ATPase activity. In addition, a single injection of piscine PTHrP(1-34) significantly increased whole body calcium uptake and decreased whole body calcium efflux. Administration of PTHrP significantly increased circulating plasma calcium 4–24 h postinjection. The increase in net calcium transport and increased plasma levels of calcium is consistent with the actions of a hypercalcemic factor. It would appear that the sturgeon rely on calcium for growth and tightly regulate calcium transport. The action in calcium balance is consistent with PTHrP acting as a hypercalcemic factor in sturgeon.

scholarly journals Assessing the Species in the CARES Preservation Program and the Role of Aquarium Hobbyists in Freshwater Fish Conservation

Fishes ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 49
Author(s):  
Jose W. Valdez ◽  
Kapil Mandrekar
Keyword(s):  
Freshwater Fish ◽  
Wild Species ◽  
Information Exchange ◽  
Iucn Red List ◽  
Vital Role ◽  
Red List ◽  
Priority List ◽  
In The Wild ◽  
Conservation Organizations

Freshwater fish represent half of all fish species and are the most threatened vertebrate group. Given their considerable passion and knowledge, aquarium hobbyists can play a vital role in their conservation. CARES is made up of many organizations, whose purpose is to encourage aquarium hobbyists to devote tank space to the most endangered and overlooked freshwater fish to ensure their survival. We found the CARES priority list contains nearly six hundred species from twenty families and two dozen extinct-in-the-wild species. The major families were typically those with the largest hobbyist affiliations such as killifish, livebearers, and cichlids, the latter containing half of CARES species. CARES included every IUCN threatened species of Pseudomugilidae and Valenciidae, but only one percent of threatened Characidae, Cobitidae, and Gobiidae species. No Loricariidae in CARES were in the IUCN red list as they have not been scientifically described. Tanzania and Mexico contained the largest amount of species, with the latter containing the most endemics. Many species were classified differently than the IUCN, including a third of extinct-in-the-wild species classified as least concern by the IUCN. This vast disconnect exemplifies the importance of future collaboration and information exchange required between hobbyists, the scientific community, and conservation organizations.

The «Empty Forest Syndrome» and the Herpetofaunal Communities in Laos (South-Eastern Asia)

2021 ◽  
Vol 28 (6) ◽  
pp. 333-347
Author(s):  
Tomas Zuklin ◽  
Nathanael Maury ◽  
Saly Sitthivong ◽  
Thong Van Pham ◽  
Olivier Le Duc ◽  
...  
Keyword(s):  
Conservation Status ◽  
Habitat Type ◽  
Great Majority ◽  
Terrestrial Ecosystems ◽  
Freshwater Ecosystems ◽  
Amphibian Species ◽  
Turtle Species ◽  
Main River ◽  
In The Wild ◽  
Study Sites

Nowadays, Laos remains one of the scientifically least known countries of Asia in terms of herpetological knowledge. Here, we evaluate composition of species in freshwater ecosystems (main river courses) and terrestrial ecosystems (forests) in two distinct regions using Visual Encounter Surveys along designed transects, examination of fishers’ catches and standardized interviews. In Northern Laos, we recorded only 18 reptile individuals (2 turtle and 1 snake species). Interview surveys demonstrated that in Nam Xam River, fishers are more likely to hunt turtles and we identified one potential site where the world’s rarest turtle, Rafetus swinhoei, could be still present in the wild. In Nam Et Phou Louey National Park, we found 19 reptile species (8 lizard, 10 snake, 1 turtle species) in the different study sites, demonstrating a low species density in all different surveyed habitats. In Central/Southern Laos, we observed 30 species of reptiles (14 snake, 16 lizard, 35 amphibian species). Our study offers preliminary insights into the composition of amphibians and reptiles in Laos. The great majority of the species were non-threatened or not evaluated, and a few were threatened, suggesting that more research is needed to proper understand the conservation status of Laos’ herpetofauna. We highlighted, indirectly by interviews with local fishers, the possible presence of the turtle Rafetus swinhoei, thus providing a new hope for avoiding the extinction of this species. Finally, we observed a relatively low number of species in each habitat type, which is remarkably lower than in tropical forests of other continents or of nearby south-east Asian countries, indicating that the herpetofauna communities in Laos are depleted, reflecting an ‘empty forest syndrome’.

scholarly journals Freshwater Reservoir Effect in 14C Dates of Food Residue on Pottery

Radiocarbon ◽  
2003 ◽  
Vol 45 (3) ◽  
pp. 449-466 ◽  
Author(s):  
Anders Fischer ◽  
Jan Heinemeier
Keyword(s):  
Freshwater Fish ◽  
Freshwater Ecosystems ◽  
Stone Age ◽  
Radiocarbon Dates ◽  
Reservoir Effect ◽  
Food Residue ◽  
Northern European ◽  
Food Residues ◽  
Freshwater Reservoir

Radiocarbon dates of food residue on pottery from northern European inland areas seem to be influenced significantly by the freshwater reservoir effect (“hardwater” effect) stemming from fish and mollusks cooked in the pots. Bones of freshwater fish from Stone Age åmose, Denmark, are demonstrated to be 100 to 500 14C yr older than their archaeological context. Likewise, food residues on cooking pots, seemingly used for the preparation of freshwater fish, are shown to have 14C age excesses of up to 300 yr. It is probable that age excesses of similar or even larger magnitude are involved in food residue dates from other periods and regions. Since this effect cannot, so far, be quantified and corrected for, 14C dating of food residue, which may potentially include material from freshwater ecosystems, should be treated with reserve.

scholarly journals Scientific Methods to Understand Fish Population Dynamics and Support Sustainable Fisheries Management

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 574
Author(s):  
Shewit Gebremedhin ◽  
Stijn Bruneel ◽  
Abebe Getahun ◽  
Wassie Anteneh ◽  
Peter Goethals
Keyword(s):  
Developing Countries ◽  
Population Dynamics ◽  
Life History ◽  
Freshwater Fish ◽  
Life History Traits ◽  
Stock Assessment ◽  
Freshwater Ecosystems ◽  
Sustainable Fisheries ◽  
Fish Stocks ◽  
The World

Fisheries play a significant role in the livelihoods of the world population, while the dependence on fisheries is acute in developing countries. Fisheries are consequently a critical element for meeting the sustainable development (SDG) and FAO goals to reduce poverty, hunger and improve health and well-being. However, 90% of global marine fish stocks are fully or over-exploited. The amount of biologically unsustainable stocks increased from 10% in 1975 to 33% in 2015. Freshwater ecosystems are the most endangered ecosystems and freshwater fish stocks are worldwide in a state of crisis. The continuous fish stock decline indicates that the world is still far from achieving SDG 14 (Life Below Water), FAO’s Blue Growth Initiative goal and SDG 15 (Life on Land, including freshwater systems). Failure to effectively manage world fish stocks can have disastrous effects on biodiversity and the livelihoods and socio-economic conditions of millions of people. Therefore, management strategies that successfully conserve the stocks and provide optimal sustainable yields are urgently needed. However, successful management is only possible when the necessary data are obtained and decision-makers are well informed. The main problem for the management of fisheries, particularly in developing countries, is the lack of information on the past and current status of the fish stocks. Sound data collection and validation methods are, therefore, important. Stock assessment models, which support sustainable fisheries, require life history traits as input parameters. In order to provide accurate estimates of these life history traits, standardized methods for otolith preparation and validation of the rate of growth zone deposition are essential. This review aims to assist researchers and fisheries managers, working on marine and freshwater fish species, in understanding concepts and processes related to stock assessment and population dynamics. Although most examples and case studies originate from developing countries in the African continent, the review remains of great value to many other countries.

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