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You can expect that someone drinking from a water source regularly will develop immunity to the pathogens in that water source by being repeatedly exposed to them. However, it's not quite right to say that poor quality drinking water impacts mostly tourists. It mostly impacts the people drinking that water, especially children. Immunity comes at a cost. Some ...


18

Humans and all other animals actually are net producers of water ("metabolic water") by oxidizing sources of energy including fats, proteins, and carbohydrates - effectively the opposite of the chemical reactions that photosynthetic plants use to turn water and atmospheric CO$_2$ into biological materials and oxygen gas. There are also many metabolic ...


9

Hard to tell because of the poor picture/video quality, but almost immediately the body shape, distinct "face", size and behavior made me think of a small invertebrate animal called a rotifer (Phylum Rotifera). Rotifer eating protists. Photo Credit: Jacqueline Ronson, 2016 There are about 2000 species occurring worldwide within this primarily ...


6

You are right - the 800 Watts are not constantly produced: There are three types of electrical discharge: (i) low voltage (ii) high voltage doublets or triplets and (iii) high voltage high frequency. (i) low voltage allows the animal to orient itself in its environment [b]. (ii) high voltage doublets or triplets are used for hunting: By discharging a high ...


6

If you keep reading the next sentence it makes clear what is meant (emphasis mine): Crocodiles (subfamily Crocodylinae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. Crocodylinae, all of whose members are considered true crocodiles, is classified as a biological subfamily. A ...


6

The traditional explanation for this is that nitrogen compounds are more mobile than phosphorus compounds. As a result, nitrogen is more likely to flow through terrestrial ecosystems and accumulate in freshwater ecosystems, making P relatively more limiting than N in freshwater. Phosphorus compounds (e.g., phosphate) are more "sticky" and tend to ...


5

That is a hydra. They are a kind of jellyfish, and as such they do technically have stinging tentacles. However, they're also very small, so they're not a danger to most fish or shrimp. If you're planning on breeding your fish they will eat fish fry if they get a chance. On the other hand some fish species will eat them, so it's a bit of a wash. Generally ...


4

Short answer Plants with storage compartments can grow for extended periods on water alone. Background It indeed seems the question is indeed different from the suspected dupe after all. According to Turesson (2014) Seeds, tubers and roots are the most common sites for [...] energy storage and the forms in which energy is stored are predominantly oil, ...


4

This looks like a spotted bass (Micropterus punctulatus). Here's an image showing some quick differences between some common bass species: Using the above photo and this source to guide our judgment we can see your specimen appears to: Have a jaw that does not go posterior to the eye (as it otherwise would in a largemouth). Have rows of pigment towards ...


4

A crustacean (land crayfish). There are a lot to choose from. http://web.nchu.edu.tw/~htshih/crab_fw/fw-crabe.htm


3

Yes there are many aquatic plant species which do not stand up in water. You need to look at the lifeform of the plants, such as introduced by Raunkiaer ( https://en.wikipedia.org/wiki/Raunki%C3%A6r_plant_life-form ) and later work by Ellenberg & Mueller-Dombois (1967). In fact, you're mixing up two different lifeforms : true aquatic plants are unable ...


3

This research states that an eel whose size is 90 cm can provide 6.05 mW, which is 145 mWh every day. They say you'd need 165 eels to be able to read for 24 hours using a 1W lightbulb like the one on a phone. An electric eel should be able to flash a 0.6W L.E.D. light for 10 milliseconds at full power every second, which would be very visible in daylight, ...


3

After a quick glance at the book "Light and Photosynthesis in Aquatic Ecosystems" by Kirk (2010), I think that the cause for the productivity dip towards the surface partially lies in photoinhibition, due to high light intensities at the surface. Here are a couple of relevant quotes from the book (Google books: p. 371): In this light saturated state, the ...


2

From Wikipedia: Eutrophication arises from the oversupply of nutrients, which leads to over growth of plants and algae. After such organisms die, the bacterial degradation of their biomass consumes the oxygen in the water, thereby creating the state of hypoxia.


2

As stated in Plant Signal Behav. 2010 Dec; 5(12): 1568–1570: Phytopathogenic bacteria do not enter plant host cells, but proliferate in the intracellular space. But as they can reach the apoplast, pathogenic bacteria can take advantage of environmental humidity levels and manipulate water content inside plant leaves to reproduce and spread infection as ...


2

This is a Burrowing Mayfly nymph (order Ephemeroptera), more than likely of the family Ephemeridae. The Bugguide site has very few photos of nymphs, but you'll find a near miss here (the species shown is not Californian, but the related Ephemera simulans Walker, 1853 is; see here for other possibilities [you'll want to look for nymph photos of the species ...


2

Many can breath air directly ; examples - bettas, gouramis, paradise , some catfish . No doubt others that do not come to mind .


2

Fish that live in cold water for most of the year actually have particularly strong hypoxia-tolerance adaptations, i.e. from summer heatwaves and algal blooms, compared to fish that are better oxygenated by waves and flowing rivers. Goldfish and other fish are able to rapidly change the surface area of their gills in less than a day. Carp, killifish, ...


1

Color is a characteristic of visible electromagnetic spectrum, see the graph here. Electromagnetic means here that it has the same nature as radio-waves, X-rays, and gamma radiation, whereas visible refers to the region of spectrum - waves of frequencies ranging from TeraHertz to PetaHerz (i.e., from $10^{12}$ Hz to $10^{15}$ Hz). Specific colors essentially ...


1

I found some information on how much energy an electric eel can theoretically produce for an hour, but not per day. Thanks to this excellent answer from dtrades and my own research. Apparently, electric eels can produce up to 860 watts, at up to 1 amp, with 1ms pulses and up to 500hz, with older/longer eels being able to produce a more stable output. That ...


1

The Jane Goodall website says: "You’ll rarely see a chimp paddling about in the water as they don’t like to swim. Their low body fat ratio causes them to sink and their top heavy body composition makes it difficult for them to keep their heads above water. However, some chimpanzees do enjoy a good splash around in shallow water." Some monkeys have ...


1

That looks very much like a duckweed. The multiple roots rule out most genera within this group and so this is probably a Spirodela. The apparently relatively large size and red undersides are consistent with this being Spirodela polyrhiza. Picture by Christian Fischer available under Creative Commons Attribution-Share Alike 3.0 Unported.


1

This is a water-primrose Ludwigia, probably Ludwigia peploides but I am not sure about the species (also because you didn't provide a location). Luwigia peploides and L. grandiflora are native to South america. However, in the rest of the world they are considered invasive weeds. In the European union L. peploides and L. grandiflora are considered "Invasive ...


1

Judging from the curved caudal (tail) fin, which is more square in brown trout, this appears to be a chinook salmon. The mouth also appears to be black whereas in brown trout the mouth is white. Sources: Michigan Department of Natural Resources


1

The oxygen is used up by bacterial decay of the plants and algae that overgrow when there is too much phosphorus or nitrogen available; the plants grow so quickly that they compete with each other for sunlight. Any basic source on eutrophication, even Wikipedia, will talk about this extensively.


1

I think it has to do with what wavelength of light is absorbed by photosynthetic organisms at what depth. Ultraviolet light with short wavelength is absorbed closest to the surface. Red light (which is responsible for photosynthesis) is absorbed at a deeper point in aquatic systems by the primary producers like phytoplankton and metaphyta which increase the ...


1

Take a look at Paragraph 2. I'll outline it in more or less plain english (I hope). for 37 lakes they used this method: 1) they took a sample of water from 0.1 to 0.25 m below the surface. Using a thermos bottle. This would minimize change of the gas composition of the water with a change of temperature. The bottle was not sealed, but left out for a ...


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