If someone called you scum, you'd probably be offended, but scientifically, they might not be far off. Have you ever thought about where your food comes from? You might say it comes from plants, animals, or even fungi, but you'd probably rather not think about the rotting organisms and poop that feed those plants, animals, and fungi. So really, you and most of the matter in your body are just two or three degrees of separation from things like pond scum. All species in an ecosystem, from the creatures in a coral reef to the fish in a lake to the lions on the savannah, are directly or indirectly nourished by dead stuff. Most of the organic matter in our bodies, if we trace it back far enough, comes from CO2 and water through photosynthesis. Plants use the energy from sunlight to transform carbon dioxide and water from the environment into glucose and oxygen. That glucose is then transformed into more complex organic molecules to form leaves, stems, roots, fruit, and so on. The energy stored in these organic molecules supports the food chains with which we're familiar. You've probably seen illustrations like this or this. These green food chains start with living plants at their base. But in real-life terrestrial ecosystems, less than 10% of plant matter is eaten while it's still alive. What about the other 90? Well, just look at the ground on an autumn day. Living plants shed dead body parts: fallen leaves, broken branches, and even underground roots. Many plants are lucky enough to go their whole lives without being eaten, eventually dying and leaving remains. All of these uneaten, undigested, and dead plant parts, that 90% of terrestrial plant matter? That becomes detritus, the base of what we call the brown food chain, which looks more like this. What happens to plants also happens to all other organisms up the food chain: some are eaten alive, but most are eaten only when they're dead and rotting. And all along this food chain, living things shed organic matter and expel digestive waste before dying and leaving their remains to decay. All that death sounds grim, right? But it's not. All detritus is ultimately consumed by microbes and other scavengers, so it actually forms the base of the brown food chain that supports many other organisms, including us. Scientists are learning that this detritus is an unexpectedly huge energy source, fueling most natural ecosystems. But the interactions within an ecosystem are even more complex than that. What a food chain really represents is a single pathway of energy flow. And within any ecosystem, many of these flows are linked together to form a rich network of interactions, or food web, with dead matter supporting that network at every step. The resulting food web is so connected that almost every species is no more than two degrees from detritus, even us humans. You probably don't eat rotting things, poop, or pond scum directly, but your food sources probably do. Many animals we eat either feed directly on detritus themselves, like pork, poultry, mushrooms, shellfish, or catfish and other bottom feeders, or they are fed animal by-products. So, if you're thinking nature is full of waste, you're right. But one organism's garbage is another's gold, and all that rotting dead stuff ultimately provides the energy that nourishes us and most of life on Earth, as it passes through the food web. Now that's some food for thought.
Nese dikush do t'ju therriste, "felliqesire", me shume gjasa do te ofendoheshit, por shkencerisht, edhe ato mund te mos jene shume larg te njejtes gje. A keni menduar ndonjehere se prej nga vjen ushqimi qe konsumoni? Mund te thoni se ai vjen nga bimet, kafshet ose edhe kerpurdhat, por perpiqeni te mos mendoni se jane organizmat e dekompozuar dhe jashteqitja ato qe ushqejne keto bime, kafshe dhe kepurdha. Pra, ne te vertete, ju dhe pjesa me e madhe e mases ne trupin tuaj jane vetem dy ose tre perqind larg te qenurit llum pellgu. Te gjitha speciet ne nje ekosistem, duke filluar me krijesat e gunave koralore tek peshqit ne liqen luaneve ne savane, jane te ushqyer, ne menyre te drejtperdrejte ose jo te drejtperdrejte, nga gjera te vdekura. Pjesa me e madhe e perberesve organike ne trupat tone, nese e ndjekim aq larg sa duhet, vjen si rezultat i CO2 (dioksid karboni) dhe ujit nepermjet fotosintezes. Bimet e perdorin energjine nga drita e diellit per te transfromuar dioksidin e karbonit dhe ujin nga ambjenti ne glukoze dhe oksigjen Kjo glukoze, me pas transformohet ne molekula organike me komplekse per te krijuar gjethe, dege, rrenje, fruta e keshtu me rradhe. Energjia e ruajtur ne keto molekula organike mbeshtet zinxhiret ushqimor te cilet te gjithe i njohim. Ndofta keni pare ilustrime si ketu ose ketu. Keto zinxhire te gjelbert ushqimore fillojne me bimet e gjalla ne bazamentin e tyre. Por, ne jeten e vertete te ekosistemeve ne toke, me pak se 10% e bimesise konsumohet sa eshte ende e gjalle. Po me 90% tjeter cfare ndodh? Mjafton te shihni token ne nje dite te zakonshme vjeshte. Pemet e gjalla, lene tu bien pjeset e vdekura: gjethe te rena, dege te thyera, madje dhe rrenje nentokesore. Shume bime jane me fat sepse jetojne pa u ngrene, dhe shuhen natyrisht duke lene pas mbetje. Te gjitha keto pjese te pa ngrena, te patretura dhe te vdekura pjese bimesh, ai 90% i bimeve ne toke? Ajo behet detrit, ajo qe ne e quajme zinxhiri i kafenjte i ushqimit, qe ngjason me teper me kete. Cfare u ndodh bimeve i ndodh te gjithe organizmave ne zinxhirin ushqimor: disa i hane te gjalle, por pjesa me e madhe hahet pasi ato kane vdekur dhe dekompozohen. Dhe pergjate gjithe ketij zinxhiri ushqimor, gjallesat leshojne mase organike dhe nxjerrin jashte mbetje te tretshme para se te vdesin dhe te kalben. Gjithe kjo e folur per vdekje ngjason e zymte apo jo? Po ja qe nuk eshte keshtu. Te gjitha mbetjet ne fund konsumohen nga mikrobe dhe kafshe qe ushqehen me kerma, duke krijuar keshtu bazen e zinxirit te kafenjte ushqimor qe mbeshtet shume organizma te tjere, perfshire dhe ne. Shkencetaret po mesojne qe keto mbetje jane nje burim papritshmerisht i madh energjie, duke ushqyer keshtu pjesen me te madhe te ekosistemit natyror. Por nderveprimet ne nje ekosistem jane edhe me komplekse se kaq. Ajo qe nje zinxhir ushqimor perfaqeson eshte nje rruge e shtruar ku buron energji. Dhe brenda cdo ekosistemi, shume prej ketyre burimeve jane te nderlidhur dhe krijojne nje rrjet te pasur nderveprimesh, ose me mire thene nje rrjet ushqimor, ku masa e vdekur e mbeshtet ate rrjet ne cdo hap. Rrjeti ushqimor qe del nga kjo eshte kaq i lidhur sa pothuajse cdo specie nuk eshte vec disa hapa distance nga mbetjet, madje edhe ne humanet. Ju ndoshta nuk ushqeheni me gjera te kalbura, jashteqitje, llum ujrash ne menyre te drejteperdrejte, por burimet e juaja te te ushqyerit ndoshta e bejne kete. Shume kafshe qe ne hame ose ushqehen drejtperdrejte me mbetje, si derri, pula, kerpurdha, butaket, mustaket ose ushqyes te tjere fundesh, ose te ushqyer me nenprodhime kafshesh. Pra, nese mendoni se natyra eshte e mbushur me mbetje, keni te drejte. Por plehrat e nje organzmi, jane floriri i nje tjetri, dhe i gjithe ai material i kalbur sherben si burim energjie qe na ushqen ne dhe pjesen me te madhe te jetes ne toke, teksa kalon permes rrjetes se ushqyerit. Kjo po qe ishte ushqim per te menduarin.