{"id":2119,"date":"2016-06-08T10:47:26","date_gmt":"2016-06-08T10:47:26","guid":{"rendered":"http:\/\/www.vtei.cz\/?p=2119"},"modified":"2024-07-16T11:16:12","modified_gmt":"2024-07-16T10:16:12","slug":"periodic-droughts-in-streams-the-next-negative-factor-influencing-crayfish-populations","status":"publish","type":"post","link":"https:\/\/www.vtei.cz\/en\/2016\/06\/periodic-droughts-in-streams-the-next-negative-factor-influencing-crayfish-populations\/","title":{"rendered":"Periodic droughts in streams: the next negative factor influencing crayfish populations"},"content":{"rendered":"

<\/i> This article is available in Czech only. For translation or more information on this topic, please contact author.<\/h4>\n

Souhrn<\/h2>\n

Periodick\u00e1 sucha v\u00a0mal\u00fdch vodn\u00edch toc\u00edch jsou zp\u016fsobena klimatick\u00fdmi zm\u011bnami, ale i\u00a0nevhodn\u00fdm hospoda\u0159en\u00edm se sr\u00e1\u017ekovou i\u00a0povrchovou vodou. P\u016fsob\u00ed\u00ad\u00ad\u00ad\u2011li tyto faktory najednou, doch\u00e1z\u00ed k\u00a0rychl\u00fdm pokles\u016fm vodn\u00ed hladiny a\u017e \u00fapln\u00e9mu vyschnut\u00ed dlouh\u00fdch \u00fasek\u016f tok\u016f. Takov\u00e9 zm\u011bny jsou pro vodn\u00ed faunu, pota\u017emo zvl\u00e1\u0161t\u011b chr\u00e1n\u011bn\u00e9 druhy rak\u016f, \u010dasto fat\u00e1ln\u00ed.<\/p>\n

Tento p\u0159\u00edsp\u011bvek p\u0159in\u00e1\u0161\u00ed \u0159adu p\u0159\u00edb\u011bh\u016f roku 2015 spojen\u00fdch se suchem, raky a\u00a0jejich z\u00e1chrann\u00fdmi transfery. Tyto z\u00e1chrann\u00e9 transfery byly v\u00a0mnoha p\u0159\u00edpadech provedeny neodborn\u011b, bez pat\u0159i\u010dn\u00fdch povolen\u00ed a\u00a0mohly v\u00edce u\u0161kodit ne\u017e pomoci. Proto se tento p\u0159\u00edsp\u011bvek zab\u00fdv\u00e1 t\u00e9\u017e legislativn\u00edmi a\u00a0odborn\u00fdmi aspekty takov\u00fdchto z\u00e1chrann\u00fdch transfer\u016f a\u00a0navrhuje postupy, jak v\u00a0t\u011bchto p\u0159\u00edpadech spr\u00e1vn\u011b postupovat.<\/p>\n\"Svobodova<\/a>\n

Rak \u0159\u00ed\u010dn\u00ed<\/h6>\n

\u00davod<\/h2>\n

Na p\u0159elomu tis\u00edcilet\u00ed byla na mnoha toc\u00edch opakovan\u011b zaznamen\u00e1na historick\u00e1 minima v\u00a0pr\u016ftoc\u00edch za obdob\u00ed, b\u011bhem nich\u017e jsou toky sledov\u00e1ny [1]. V\u00a0roce 2003 a\u00a02015 hladiny \u0159ek viditeln\u011b poklesly zejm\u00e9na po pr\u016fb\u011bhu extr\u00e9mn\u011b tepl\u00e9ho po\u010das\u00ed. Velmi n\u00edzk\u00e9 pr\u016ftoky a\u017e vyschnut\u00ed toku maj\u00ed z\u00e1va\u017en\u00e9 dopady na p\u0159e\u017e\u00edv\u00e1n\u00ed vodn\u00edch organism\u016f, ale negativn\u011b ovliv\u0148uj\u00ed i\u00a0jakost vody [2]. Krom\u011b ryb ohro\u017euj\u00ed vyschl\u00e9 toky i\u00a0vodn\u00ed makrozoobentos, mezi kter\u00fd pat\u0159\u00ed i\u00a0kriticky ohro\u017een\u00e9 druhy rak\u016f.<\/p>\n

V\u00a0\u010cesk\u00e9 republice se vyskytuje p\u011bt druh\u016f rak\u016f, jen dva jsou zde ale p\u016fvodn\u00ed\u00a0\u2013 rak kamen\u00e1\u010d (Austropotamobius torrentium Schrank, 1803) a\u00a0rak \u0159\u00ed\u010dn\u00ed
\n(Astacus astacus L.). Oba druhy pat\u0159\u00ed mezi zvl\u00e1\u0161t\u011b chr\u00e1n\u011bn\u00e9 druhy v\u00a0kategorii kriticky ohro\u017een\u00fd [3, 4]. Krom\u011b t\u011bchto dvou druh\u016f se\u00a0v\u00a0\u010cR\u00a0vyskytuje rak bahenn\u00ed (Astacus leptodactylus Eschscholtz, 1823), p\u016fvodem z\u00a0v\u00fdchodn\u00ed Evropy. Byl u\u00a0n\u00e1s vysazov\u00e1n na konci 19. stolet\u00ed jako n\u00e1hrada za ra\u010d\u00edm morem zdecimovan\u00e9 populace rak\u016f \u0159\u00ed\u010dn\u00edch. I\u00a0p\u0159esto je chr\u00e1n\u011bn z\u00e1konem, a\u00a0to jako ohro\u017een\u00fd druh [3, 4].<\/p>\n

Dal\u0161\u00ed dva nep\u016fvodn\u00ed druhy, rak pruhovan\u00fd (Orconectes limosus Rafinesque, 1817) a\u00a0rak sign\u00e1ln\u00ed (Pacifastacus leniusculus Dana, 1852) poch\u00e1z\u00ed ze Severn\u00ed Ameriky a\u00a0jsou spojeny s\u00a0ra\u010d\u00edm morem\u00a0\u2013 onemocn\u011bn\u00edm, zp\u016fsoben\u00fdm parazitickou \u0159asovkou (oomycetou) hnile\u010dkem ra\u010d\u00edm (Aphanomyces astaci Schikora, 1906). Americk\u00e9 druhy rak\u016f, samy v\u016f\u010di infekci v\u00fdrazn\u011b odoln\u00e9, jsou p\u0159ena\u0161e\u010di tohoto onemocn\u011bn\u00ed, a\u00a0v\u00a0d\u016fsledku jejich opakovan\u00fdch necht\u011bn\u00fdch (v\u00a0polovin\u011b 19. stolet\u00ed)
\nnebo z\u00e1m\u011brn\u00fdch (v\u00a0druh\u00e9 polovin\u011b 20. stolet\u00ed) introdukc\u00ed do Evropy decimuje tato nemoc populace p\u016fvodn\u00edch rak\u016f ji\u017e po des\u00edtky let.<\/p>\n

Krom\u011b vysych\u00e1n\u00ed tok\u016f existuje v\u00a0sou\u010dasn\u00e9 dob\u011b cel\u00e1 \u0159ada vliv\u016f, kter\u00e9 maj\u00ed negativn\u00ed dopad na populace p\u016fvodn\u00edch rak\u016f. Jedn\u00e1 se p\u0159edev\u0161\u00edm o\u00a0zm\u011bny v\u00a0hydromorfologii tok\u016f [5], predaci [6] nebo lok\u00e1ln\u00ed otravy [7, 8]. Nejv\u00fdrazn\u011bj\u0161\u00ed hrozbou v\u0161ak st\u00e1le z\u016fst\u00e1vaj\u00ed americk\u00e9 druhy rak\u016f a\u00a0jejich\u00a0\u0161\u00ed\u0159en\u00ed; a\u0165 ji\u017e p\u0159irozenou cestou po Labi z\u00a0N\u011bmecka, tak i\u00a0nezodpov\u011bdn\u00fdmi p\u0159enosy rak\u016f na nov\u00e9 lokality, p\u0159edev\u0161\u00edm sportovn\u00edmi i\u00a0profesion\u00e1ln\u00edmi ryb\u00e1\u0159i nebo akvaristy [9].<\/p>\n

Na vysych\u00e1n\u00ed lokalit se pod\u00edl\u00ed \u0159ada faktor\u016f. Prvotn\u00ed v\u00fdznam maj\u00ed postupn\u00e9 zm\u011bny klimatu, doprov\u00e1zen\u00e9 p\u0159edev\u0161\u00edm nerovnom\u011brnou distribuc\u00ed sr\u00e1\u017eek. Dal\u0161\u00edm takov\u00fdm faktorem je hospoda\u0159en\u00ed se sr\u00e1\u017ekovou vodou: \u00fakolem je p\u0159edev\u0161\u00edm zabr\u00e1nit rychl\u00e9mu odtoku sr\u00e1\u017ekov\u00fdch vod, a\u00a0naopak podporovat zadr\u017een\u00ed vody v\u00a0krajin\u011b. Bohu\u017eel v\u00a0\u0159ad\u011b p\u0159\u00edpad\u016f se d\u011bje prav\u00fd opak\u00a0\u2013 cel\u00e9 plochy jsou betonov\u00e1ny nebo asfaltov\u00e1ny, tak\u017ee de\u0161\u0165ov\u00e1 voda rychle odt\u00e9k\u00e1 kanaliza\u010dn\u00edmi svody do vodn\u00edch tok\u016f. Ty byly v\u00a0minulosti v\u00a0r\u00e1mci proti- nebo popovod\u0148ov\u00fdch \u00faprav v\u00a0cel\u00fdch \u00fasec\u00edch nap\u0159\u00edmeny a\u00a0kanalizov\u00e1ny a\u00a0jejich hloubkov\u00e1 diverzita je pak minim\u00e1ln\u00ed. N\u00e1sledn\u00e9 sucho zp\u016fsob\u00ed, \u017ee cel\u00e9 stovky metr\u016f koryt vodn\u00edch tok\u016f jsou zcela bez vody\u00a0\u2013 v\u00a0nap\u0159\u00edmen\u00e9m korytu voda odte\u010de, m\u00edsto aby v\u00a0dob\u011b sucha z\u016fstala v\u00a0hlubok\u00fdch t\u016f\u0148k\u00e1ch, slou\u017e\u00edc\u00edch jako do\u010dasn\u00e9 refugium pro mno\u017estv\u00ed vodn\u00ed fauny. Posledn\u00edm, i\u00a0kdy\u017e nezanedbateln\u00fdm faktorem p\u016fsob\u00edc\u00edm \u010dasto paraleln\u011b s\u00a0ob\u011bma v\u00fd\u0161e uveden\u00fdmi, je je\u0161t\u011b nevhodn\u00e9 hospoda\u0159en\u00ed s\u00a0vodou, kter\u00e1 ve vodn\u00edch toc\u00edch z\u016fst\u00e1v\u00e1. Sem pat\u0159\u00ed p\u0159edev\u0161\u00edm hospoda\u0159en\u00ed na rybn\u00edc\u00edch v\u00a0povod\u00ed\u00a0\u2013 jedn\u00e1 se v\u00a0z\u00e1sad\u011b o\u00a0nedodr\u017eov\u00e1n\u00ed manipula\u010dn\u00edho \u0159\u00e1du; v\u00a0dob\u011b sucha se sna\u017e\u00ed ryb\u00e1\u0159sk\u00fd hospod\u00e1\u0159 zachr\u00e1nit sp\u00ed\u0161e \u201evlastn\u00ed ryby\u201c v\u00a0rybn\u00edce ne\u017e navazuj\u00edc\u00ed vodn\u00ed toky. Nezanedbateln\u00e9 je tak\u00e9 vyu\u017e\u00edv\u00e1n\u00ed vody v\u00a0obydl\u00edch v\u00a0bl\u00edzkosti vodn\u00edch tok\u016f, p\u0159edev\u0161\u00edm na zal\u00e9v\u00e1n\u00ed zahrad, tr\u00e1vn\u00edk\u016f nebo \u010derp\u00e1n\u00ed vody do baz\u00e9n\u016f.<\/p>\n

P\u0159i dlouhotrvaj\u00edc\u00edm suchu hladiny vodn\u00edch tok\u016f st\u00e1le klesaj\u00ed, v\u00a0men\u0161\u00edch toc\u00edch stoup\u00e1 teplota vody a\u00a0jej\u00ed jakost se zhor\u0161uje. Se zvy\u0161uj\u00edc\u00ed se teplotou a\u00a0vy\u0161\u0161\u00edm zne\u010di\u0161t\u011bn\u00edm kles\u00e1 ve vod\u011b obsah kysl\u00edku, tak pot\u0159ebn\u00e9ho pro \u017eivot vodn\u00edch organism\u016f. V\u00a0\u0159ad\u011b p\u0159\u00edpad\u016f jsou jako prvn\u00ed posti\u017eeny ryby, p\u0159edev\u0161\u00edm druhy n\u00e1ro\u010dn\u00e9 na obsah kysl\u00edku, jako jsou ryby lososovit\u00e9, pstruh nebo lipan, d\u00e1le vranka obecn\u00e1 nebo st\u0159evle poto\u010dn\u00ed. P\u0159i sni\u017euj\u00edc\u00ed se hladin\u011b se ryby stahuj\u00ed do t\u016fn\u00ed a\u00a0je jen ot\u00e1zkou, zda dan\u00e1 t\u016f\u0148 p\u0159i pokra\u010duj\u00edc\u00edm vysych\u00e1n\u00ed skute\u010dn\u011b poslou\u017e\u00ed jako dobr\u00e9 refugium. Do t\u016fn\u00ed se stahuj\u00ed i\u00a0raci; ti jsou ov\u0161em oproti ryb\u00e1m ve v\u00fdhod\u011b. Ve vhodn\u00fdch podm\u00ednk\u00e1ch (ve vlhku, nap\u0159.\u00a0pod p\u0159evisl\u00fdmi b\u0159ehy, v\u00a0nor\u00e1ch, pod kameny) dok\u00e1\u017e\u00ed p\u0159e\u017e\u00edt i\u00a0v\u00a0toku, kter\u00fd je zcela bez vody, ostatn\u011b i\u00a0jako dal\u0161\u00ed druhy makrozoobentosu. Je ov\u0161em t\u0159eba zd\u016fraznit, a\u00a0zde se vrac\u00edme k\u00a0t\u00e9matu \u00faprav dna a\u00a0b\u0159eh\u016f vodn\u00edch tok\u016f, \u017ee tok mus\u00ed takov\u00e9 podm\u00ednky poskytovat (zast\u00edn\u011bn\u00e1 m\u00edsta, substr\u00e1t r\u016fzn\u00e9 zrnitosti, \u00fakryty v\u00a0podob\u011b ko\u0159enov\u00e9 vegetace nebo balvan\u016f).<\/p>\n\"Svobodova<\/a>\n

Rak sign\u00e1ln\u00ed<\/h6>\n

P\u0159\u00edb\u011bhy roku 2015<\/h2>\n

Prvn\u00edm zdokumentovan\u00fdm p\u0159\u00edpadem vlivu sucha na raky v\u00a0roce 2015 byla \u201ez\u00e1chrana\u201c rak\u016f na Janovsk\u00e9m potoce. Raci byli na tento potok vysazeni v\u00a0roce 2007, a\u00a0to nejsp\u00ed\u0161 bez d\u016fkladn\u00e9ho pr\u016fzkumu lokality, proto\u017ee zde doch\u00e1z\u00ed k\u00a0vysych\u00e1n\u00ed toku opakovan\u011b. V\u00a0roce 2015 zde v\u0161ak do\u0161lo k\u00a0velmi rychl\u00e9mu \u00fabytku vody.<\/p>\n

N\u00e1sledkem toho se chopila iniciativy m\u00edstn\u00ed skupina ochr\u00e1nc\u016f p\u0159\u00edrody, kte\u0159\u00ed bez p\u0159\u00edslu\u0161n\u00fdch v\u00fdjimek a\u00a0povolen\u00ed provedli transfer do \u0159ady tok\u016f v\u00a0okol\u00ed, p\u0159esto\u017ee jim byl autory tohoto \u010dl\u00e1nku doporu\u010den jin\u00fd postup. V\u00a0d\u016fsledku toho byli vy\u0161et\u0159ov\u00e1ni \u010cI\u017dP\u00a0\u2013 zcela relevantn\u011b, proto\u017ee tento z\u00e1sah mohl nad\u011blat v\u00edce \u0161kody ne\u017e u\u017eitku (viz\u00a0d\u00e1le).<\/p>\n

K\u00a0z\u00e1chrann\u00e9mu transferu se uch\u00fdlili tak\u00e9 na \u0159\u00ed\u010dce Brzina na P\u0159\u00edbramsku. Zde pracovn\u00edci spole\u010dnosti Ochrany fauny \u010cR p\u0159est\u011bhovali p\u0159ibli\u017en\u011b p\u011bt set rak\u016f do n\u00e1honu Kunclova ml\u00fdna, kter\u00fd le\u017e\u00ed v\u00a0\u00fadol\u00ed \u0159eky Brziny. Tak\u00e9 Brzina m\u00e1 probl\u00e9my s\u00a0vodou ka\u017ed\u00fd rok, ale v\u011bt\u0161inou se n\u00edzk\u00e9 pr\u016ftoky objevuj\u00ed a\u017e v\u00a0z\u00e1\u0159\u00ed. Podobn\u00fd transfer zva\u017eovali ochr\u00e1nci p\u0159\u00edrody tak\u00e9 na Jesenicku, kde bylo na potoce Krasovka jednou z\u00a0alternativ z\u00e1chrany rak\u016f z\u00a0vysychaj\u00edc\u00edho toku p\u0159em\u00edstit je do ni\u017e\u0161\u00edch vodnat\u011bj\u0161\u00edch \u010d\u00e1st\u00ed toku. Tato varianta je v\u00a0p\u0159\u00edpad\u011b z\u00e1chrann\u00fdch transfer\u016f z\u00a0d\u016fvodu sucha v\u017edy preferovan\u00fdm \u0159e\u0161en\u00edm \u2013 samoz\u0159ejm\u011b v\u00a0p\u0159\u00edpad\u011b, kdy se podm\u00ednky (rozum\u011bj typ habitatu a\u00a0kvalita vody) p\u0159\u00edli\u0161 neli\u0161\u00ed.<\/p>\n

K\u00a0nejv\u011bt\u0161\u00edmu \u00fahynu do\u0161lo na \u0159ece T\u0159ebovce v\u00a0\u010cesk\u00e9 T\u0159ebov\u00e9. Efekt sucha zde byl umocn\u011bn p\u0159\u00edvalov\u00fdm de\u0161t\u011bm\u00a0\u2013 prudk\u00fd d\u00e9\u0161\u0165 se siln\u011b oh\u0159\u00e1l na rozp\u00e1len\u00e9 asfaltov\u00e9 plo\u0161e p\u0159il\u00e9haj\u00edc\u00ed k\u00a0toku a\u00a0stekl p\u0159\u00edmo do \u0159eky. Ot\u00e1zkou je, zda se do\u00a0oh\u0159\u00e1t\u00e9 vody nevyplavily toxick\u00e9 l\u00e1tky z\u00a0m\u00edstn\u00ed komunikace. V\u00a0\u0159ece uhynulo asi 300\u2008kg rak\u016f a\u00a0ryb.<\/p>\n

V\u00a0\u0159ad\u011b p\u0159\u00edpad\u016f byla mezi suchem a\u00a0\u00fahyny nalezena tak\u00e9 jasn\u00e1 spojitost s\u00a0ji\u017e uveden\u00fdm nevhodn\u00fdm hospoda\u0159en\u00edm na rybn\u00edc\u00edch. Nap\u0159\u00edklad na Svina\u0159sk\u00e9m potoce do\u0161lo v\u00a0srpnu roku 2015 n\u00e1sledkem zav\u0159en\u00ed v\u00fdpusti rybn\u00edka a\u00a0nedodr\u017een\u00ed minim\u00e1ln\u00edho z\u016fstatkov\u00e9ho pr\u016ftoku k\u00a0\u00fahynu ryb i\u00a0rak\u016f. V\u00a0toku se sympatricky vyskytuje rak \u0159\u00ed\u010dn\u00ed a\u00a0rak kamen\u00e1\u010d. P\u0159\u00edpadem se zab\u00fdvala \u010cI\u017dP, ale potok byl ji\u017e tak vyschl\u00fd, \u017ee i\u00a0po z\u00e1sahu \u010cI\u017dP, na jej\u00ed\u017e podn\u011bt byl zv\u00fd\u0161en pr\u016ftok vody v\u00a0potoce pod rybn\u00edkem, nedo\u0161lo ke zv\u00fd\u0161en\u00ed hladiny vody v\u00a0m\u00edstech s\u00a0v\u00fdskytem rak\u016f. A\u010dkoliv Svina\u0159sk\u00fd potok je siln\u011b meliorov\u00e1n, v\u00a0m\u00edstech s\u00a0v\u00fdskytem rak\u016f je lemov\u00e1n sm\u00ed\u0161en\u00fdm lesem, kter\u00fd rak\u016fm poskytuje dostatek \u00fakryt\u016f v\u00a0ko\u0159enech strom\u016f zasahuj\u00edc\u00edch do toku a\u00a0tak\u00e9 st\u00edn, pot\u0159ebn\u00fd k\u00a0p\u0159ekon\u00e1n\u00ed kritick\u00e9ho obdob\u00ed. Oba druhy tak mohly p\u0159e\u010dkat nep\u0159\u00edzniv\u00e9 obdob\u00ed v\u00a0refugi\u00edch; definitivn\u00ed z\u00e1chranu pro oba druhy rak\u016f p\u0159inesla a\u017e zm\u011bna po\u010das\u00ed s\u00a0dlouho o\u010dek\u00e1v\u00e1n\u00fdmi sr\u00e1\u017ekami. Dal\u0161\u00edm m\u00edstem sporu se stala \u0159\u00ed\u010dka Desn\u00e1 u\u00a0Litomy\u0161le, kde podle tvrzen\u00ed ochr\u00e1nc\u016f p\u0159\u00edrody ze z\u00e1chrann\u00e9 stanice m\u011bly m\u00edt rybn\u00edky u\u00a0Budislavi zav\u0159en\u00e9 v\u00fdpust\u011b. P\u0159\u00edpadem se zab\u00fdval odbor \u017eivotn\u00edho prost\u0159ed\u00ed v\u00a0Olomouci, tvrzen\u00ed se ale nepotvrdilo. N\u00e1sledkem sucha na \u0159\u00ed\u010dce uhynulo p\u011bt set rak\u016f, dal\u0161\u00edch asi tis\u00edc rak\u016f se ochr\u00e1nc\u016fm povedlo zachr\u00e1nit. Ve spolupr\u00e1ci s\u00a0hasi\u010di byla zatopena t\u016f\u0148, kam se p\u0159e\u017eiv\u0161\u00ed raci st\u00e1hli a\u00a0ochr\u00e1nci je pot\u00e9 rozvezli do okoln\u00edch lom\u016f, kde by m\u011bli sucho p\u0159e\u017e\u00edt.<\/p>\n

V\u00a0roce 2015 negativn\u011b ovlivnilo zhor\u0161en\u00e9 podm\u00ednky na toc\u00edch i\u00a0\u010derp\u00e1n\u00ed vody z\u00a0tok\u016f. Na Trusovick\u00e9m potoce do\u0161lo k\u00a0t\u00e9m\u011b\u0159 naprost\u00e9mu vyschnut\u00ed toku, nebo\u0165 voda byla od\u010derp\u00e1v\u00e1na na zavla\u017eov\u00e1n\u00ed chata\u0159i, zahr\u00e1dk\u00e1\u0159i a\u00a0provozovateli sportovn\u00edho h\u0159i\u0161t\u011b. K\u00a0velk\u00e9mu odb\u011bru vody doch\u00e1z\u00ed i\u00a0proto, \u017ee obec vyu\u017e\u00edv\u00e1 potok na obm\u011bnu vody v\u00a0m\u00edstn\u00edm koupali\u0161ti. Je zdokumentov\u00e1no, \u017ee tento jev se zde opakuje ka\u017edoro\u010dn\u011b. V\u00a0extr\u00e9mn\u011b tepl\u00fdch letn\u00edch m\u011bs\u00edc\u00edch do\u0161lo v\u00a0letech 2012 a\u00a02015 t\u00e9m\u011b\u0159 k\u00a0vyschnut\u00ed potoka a\u00a0ryby bu\u010f uhynuly, nebo byly p\u0159esunuty do jin\u00fdch \u0159ek. V\u00a0roce 2015 bylo magistr\u00e1tem m\u011bsta Olomouc na popud MO \u010cRS Olomouc zak\u00e1z\u00e1no jak\u00e9koli \u010derp\u00e1n\u00ed vody z\u00a0potoka. A\u00a0podobn\u011b jako v\u00a0p\u0159\u00edpad\u011b Janovsk\u00e9ho potoka, p\u0159esto\u017ee jsou na tomto toku opakovan\u011b probl\u00e9my s\u00a0mno\u017estv\u00edm vody a\u00a0vysych\u00e1n\u00edm, byli zde v\u00a0roce 2007 vysazeni (v\u00a0rozporu s\u00a0legislativou) raci \u0159\u00ed\u010dn\u00ed.<\/p>\n

\"Svobodova<\/a><\/p>\n

Rak bahenn\u00ed<\/h6>\n

Nejz\u00e1va\u017en\u011bj\u0161\u00edm probl\u00e9mem sucha a\u00a0s\u00a0n\u00edm spojen\u00fdmi z\u00e1chrann\u00fdmi transfery je ov\u0161em p\u0159\u00edpadn\u00e1 spojitost s\u00a0ra\u010d\u00edm morem. P\u0159esto\u017ee symptomy prov\u00e1zej\u00edc\u00ed n\u00e1kazu ra\u010d\u00edm morem jsou charakteristick\u00e9 (raci jsou neklidn\u00ed, opou\u0161t\u00ed \u00fakryty, hynou, zat\u00edmco ryby bez probl\u00e9m\u016f p\u0159e\u017e\u00edvaj\u00ed), pro neodborn\u00edky mohou um\u00edraj\u00edc\u00ed raci naka\u017een\u00ed ra\u010d\u00edm morem vypadat velmi podobn\u011b jako raci um\u00edraj\u00edc\u00ed v\u00a0d\u016fsledku n\u00edzk\u00e9 kvality vody nebo \u201esucha\u201c. V\u00a0roce 2015 do\u0161lo k\u00a0\u00fahynu na Kornatick\u00e9m a\u00a0H\u00e1deck\u00e9m potoce na ji\u017en\u00edm Plze\u0148sku. Tento \u00fahyn byl bohu\u017eel zp\u016fsoben ra\u010d\u00edm morem. Byl \u0159e\u0161en na \u00farovni st\u00e1tn\u00ed spr\u00e1vy (M\u017dP, K\u00da Plze\u0148sk\u00e9ho kraje), ryb\u00e1\u0159\u016f (Z\u00daS \u010cRS) a\u00a0tak\u00e9 v\u00a0m\u00e9di\u00edch. V\u00a0n\u00e1sleduj\u00edc\u00edm m\u011bs\u00edci do\u0161lo ke zhor\u0161en\u00ed sucha v\u00a0okoln\u00edch toc\u00edch, na Chocenick\u00e9m potoce a\u00a0na P\u0159e\u0161\u00ednsk\u00e9m potoce. Zde do\u0161lo k\u00a0p\u0159\u00edkladn\u00e9mu \u0159e\u0161en\u00ed\u00a0\u2013 ryb\u00e1\u0159sk\u00fd hospod\u00e1\u0159 ozn\u00e1mil celou situaci jednomu z\u00a0autor\u016f tohoto \u010dl\u00e1nku (P.\u00a0Vlach) a\u00a0n\u00e1sledn\u011b byl proveden odborn\u00fd transfer D. Fischerem. \u00dahyny, ohl\u00e1\u0161en\u00e9 na Chocenick\u00e9m potoce O\u017dP M\u011b\u00da v\u00a0Blovic\u00edch, byly konzultov\u00e1ny s\u00a0P.\u00a0Vlachem; v\u00a0tomto p\u0159\u00edpad\u011b se jednalo v\u011bt\u0161inou o\u00a0svle\u010dky rak\u016f (viz\u00a0d\u00e1le). Pozitivn\u00ed na cel\u00e9 v\u011bci byl fakt, \u017ee ve\u0159ejnost informovan\u00e1 o\u00a0rizic\u00edch ra\u010d\u00edho moru reagovala uv\u00e1\u017een\u011b a\u00a0spr\u00e1vn\u011b.<\/p>\n

V\u00a0roce 2014 byl na \u0159ece Vrchlici u\u00a0Denemarkova ml\u00fdna zaznamen\u00e1n hromadn\u00fd \u00fahyn rak\u016f. Byl vylou\u010den vliv hav\u00e1rie jakosti vody, zato po odborn\u00e9m vy\u0161et\u0159en\u00ed byl potvrzen ra\u010d\u00ed mor. Populace rak\u016f nad p\u0159ehradou u\u00a0Chl\u00edstovic z\u016fstala zachov\u00e1na\u00a0\u2013 p\u0159ehrada p\u016fsobila jako migra\u010dn\u00ed bari\u00e9ra a\u00a0postup onemocn\u011bn\u00ed tokem se zastavil. V\u00a0\u010dervenci roku 2015 v\u0161ak byla Vrchlice nad p\u0159ehradou v\u00a0okol\u00ed obce Chl\u00edstovice t\u00e9m\u011b\u0159 such\u00e1; p\u0159esto\u017ee neuplynul ani rok od n\u00e1kazy ra\u010d\u00edm morem a\u00a0pravd\u011bpodobnost, \u017ee n\u011bkte\u0159\u00ed naka\u017een\u00ed jedinci nebo alespo\u0148 spory je\u0161t\u011b mohly z\u016fstat \u017eiv\u00e9, byla velmi vysok\u00e1, m\u00edstn\u00ed obyvatel\u00e9 p\u0159enesli \u017eiv\u00e9 raky do doln\u00edho toku\u00a0\u2013 na m\u00edsto infekce (\u00fastn\u00ed sd\u011blen\u00ed Ing.\u00a0T. Just).<\/p>\n

Z\u00e1v\u011br aneb co nikdy ned\u011blat, a\u00a0co naopak ud\u011blat<\/h2>\n

Situace roku 2015 se m\u016f\u017ee kdykoliv opakovat. Leto\u0161n\u00ed zima nep\u0159inesla dostatek sn\u011bhov\u00fdch sr\u00e1\u017eek, co\u017e m\u016f\u017ee v\u00e9st k\u00a0poklesu hladiny podzemn\u00edch vod a\u00a0spole\u010dn\u011b s\u00a0nedostatkem sr\u00e1\u017eek v\u00a0letn\u00edm obdob\u00ed budou u\u017eivatel\u00e9 tla\u010deni k\u00a0co nejv\u011bt\u0161\u00edmu zadr\u017eov\u00e1n\u00ed vody v\u00a0n\u00e1dr\u017e\u00edch nebo na jezech.<\/p>\n

Jak se tedy zachovat, pokud nalezneme vysychaj\u00edc\u00ed tok, ve\u00a0kter\u00e9m hynou raci<\/h2>\n

V\u00a0prvn\u00ed \u0159ad\u011b\u00a0\u2013 pro laika je obt\u00ed\u017en\u00e9 odli\u0161it invazn\u00ed severoamerick\u00e9 druhy rak\u016f od druh\u016f p\u016fvodn\u00edch. Jsou \u010dast\u00e9 p\u0159\u00edpady, kdy laick\u00e1 ve\u0159ejnost v\u00a0dobr\u00e9 v\u00ed\u0159e zachra\u0148ovala nep\u016fvodn\u00ed druhy rak\u016f, jako je rak pruhovan\u00fd nebo rak sign\u00e1ln\u00ed. Pokud jsou tito invazn\u00ed raci p\u0159eneseni na lokality s\u00a0v\u00fdskytem raka \u0159\u00ed\u010dn\u00edho nebo raka kamen\u00e1\u010de, hroz\u00ed velk\u00e9 nebezpe\u010d\u00ed, \u017ee cel\u00e1 populace na\u0161ich p\u016fvodn\u00edch rak\u016f vyhyne v\u00a0d\u016fsledku infikace ra\u010d\u00edm morem, kter\u00fdm mohou b\u00fdt p\u0159enesen\u00ed raci s\u00a0vysokou pravd\u011bpodobnost\u00ed naka\u017eeni. Ale ani pokud raci naka\u017eeni ra\u010d\u00edm morem nejsou, nemaj\u00ed na\u0161i raci je\u0161t\u011b vyhr\u00e1no. Invazn\u00ed raci jsou daleko agresivn\u011bj\u0161\u00ed, \u010dast\u011bji a\u00a0d\u0159\u00edve se rozmno\u017euj\u00ed a\u00a0maj\u00ed daleko v\u00edce potomk\u016f [10]. Mnohdy je jen ot\u00e1zka \u010dasu, za jak dlouho p\u016fvodn\u00ed raky, ale i\u00a0dal\u0161\u00ed vodn\u00ed \u017eivo\u010dichy z\u00a0lokality vytla\u010d\u00ed.<\/p>\n

Lep\u0161\u00ed variantou je, pokud ochr\u00e1nci p\u0159\u00edrody zachra\u0148uj\u00ed p\u016fvodn\u00ed raky, ale i\u00a0zde hroz\u00ed mnoho rizik nap\u0159.\u00a0v\u00a0podob\u011b p\u0159enosu r\u016fzn\u00fdch nemoc\u00ed na nov\u00e9 lokality, kter\u00e9 op\u011bt mohou vyhubit p\u016fvodn\u00ed populace raka \u0159\u00ed\u010dn\u00edho nebo kamen\u00e1\u010de v\u00a0jin\u00e9m povod\u00ed. Na ka\u017ed\u00e9 lokalit\u011b je jen omezen\u00fd po\u010det \u00fakryt\u016f a\u00a0pokud jsou raci p\u0159eneseni na jin\u00fd potok nebo rybn\u00edk, dojde ke konkuren\u010dn\u00edmu\u00a0boji o\u00a0vhodn\u00e9 \u00fakryty, o\u00a0potravu\u00a0atd. Slab\u0161\u00ed a\u00a0men\u0161\u00ed raci v\u00a0tomto p\u0159\u00edpad\u011b skon\u010d\u00ed jako potrava pro siln\u011bj\u0161\u00ed jedince. Jedinou \u00fat\u011bchou tak je, \u017ee raci nehynou p\u0159\u00edmo p\u0159ed o\u010dima ve vyschl\u00e9m toku, ale podlehnou a\u017e v\u00a0n\u00e1sledn\u00e9m konkuren\u010dn\u00edm boji ukryti pod hladinou.<\/p>\n

Ale i\u00a0nalezen\u00e9 \u201emrtvolky rak\u016f\u201c mohou b\u00fdt pro laika zav\u00e1d\u011bj\u00edc\u00ed. Rak rychle roste, a\u00a0proto se a\u017e n\u011bkolikr\u00e1t ro\u010dn\u011b svl\u00e9k\u00e1 a\u00a0v\u00a0toku po n\u011bm z\u016fstane tzv.\u00a0svle\u010dka (exuvie), kterou laik rozezn\u00e1 od mrtv\u00e9ho raka jen st\u011b\u017e\u00ed\u00a0\u2013 vod\u00edtkem m\u016f\u017ee b\u00fdt z\u00e1pach, zat\u00edmco svle\u010dka nezap\u00e1ch\u00e1, z\u00e1pach del\u0161\u00ed dobu mrtv\u00e9ho raka p\u0159edstavuje velmi intenzivn\u00ed z\u00e1\u017eitek. Konkr\u00e9tn\u011b druh\u00e1 polovina l\u00e9ta je obdob\u00edm, kdy doch\u00e1z\u00ed ke svl\u00e9k\u00e1n\u00ed rak\u016f, tak\u017ee p\u0159i podrobn\u00e9m pr\u016fzkumu lze snadno zjistit, \u017ee raci se uch\u00fdlili do vlhk\u00fdch \u00fakryt\u016f, a\u00a0ve vysychaj\u00edc\u00edm\u00a0potoce le\u017e\u00ed jen jejich odlo\u017een\u00e9 exuvie.<\/p>\n

Z\u00e1chrann\u00fd transfer rak\u016f nen\u00ed z\u00e1le\u017eitost\u00ed pro laika [11]. Pokud je jasn\u00e9, \u017ee chceme p\u0159em\u00edstit p\u016fvodn\u00ed druhy i\u00a0p\u0159esto, \u017ee v\u00edme, \u017ee populace je zdrav\u00e1, je tu dal\u0161\u00ed probl\u00e9m \u2013 a to naj\u00edt vhodnou lokalitu, na kterou budou raci p\u0159em\u00edst\u011bni. Pokud se poda\u0159\u00ed nal\u00e9zt potok, kde zaru\u010den\u011b (ale to nelze nikdy stoprocentn\u011b zaru\u010dit) nejsou na\u0161i p\u016fvodn\u00ed raci, m\u00e1 to v\u017edy n\u011bjak\u00fd d\u016fvod\u00a0\u2013 jakost vody v\u00a0toku nevyhovuje n\u00e1rok\u016fm raka \u0159\u00ed\u010dn\u00edho nebo kamen\u00e1\u010de, na potoce doch\u00e1z\u00ed k\u00a0hav\u00e1ri\u00edm jakosti vody, v\u00a0potoce je m\u00e1lo \u00fakryt\u016f, nen\u00ed zast\u00edn\u011bn\u00fd nebo se n\u011bkde v\u00a0povod\u00ed nach\u00e1zej\u00ed invazn\u00ed raci.<\/p>\n

V\u0161echny v\u00fd\u0161e vyjmenovan\u00e9 d\u016fvody vedly k\u00a0zaveden\u00ed platn\u00e9 legislativy [3, 4], kter\u00e1 raka \u0159\u00ed\u010dn\u00edho i\u00a0raka kamen\u00e1\u010de \u0159ad\u00ed mezi druhy kriticky ohro\u017een\u00e9. Z\u00a0t\u011bchto d\u016fvod\u016f jsou manipulace s\u00a0jedinci v\u0161ech v\u00fdvojov\u00fdch stadi\u00ed, stejn\u011b jako \u0161kodliv\u00e9 z\u00e1sahy do jejich p\u0159irozen\u00e9ho v\u00fdvoje i\u00a0biotopu, zak\u00e1z\u00e1ny. Je zak\u00e1z\u00e1no raky chytat, ru\u0161it, p\u0159em\u00eds\u0165ovat, dr\u017eet, chovat v\u00a0zajet\u00ed, dopravovat, prod\u00e1vat, vym\u011b\u0148ovat, nab\u00edzet za \u00fa\u010delem prodeje nebo v\u00fdm\u011bny, zra\u0148ovat, ni\u010dit, po\u0161kozovat \u010di usmrcovat, a\u00a0to ve v\u0161ech jejich v\u00fdvojov\u00fdch st\u00e1di\u00edch. Stejn\u011b jako zvl\u00e1\u0161t\u011b chr\u00e1n\u011bn\u00fd \u017eivo\u010dich je chr\u00e1n\u011bn i\u00a0mrtv\u00fd jedinec tohoto druhu, jeho rozpoznateln\u00e1 \u010d\u00e1st nebo v\u00fdrobek z\u00a0n\u011bho. Chr\u00e1n\u011bn\u00e1 jsou rovn\u011b\u017e jimi u\u017e\u00edvan\u00e1 p\u0159irozen\u00e1 i\u00a0um\u011bl\u00e1 s\u00eddla a\u00a0jejich biotop.<\/p>\n

Proto s\u00a0raky ve vysychaj\u00edc\u00edch toc\u00edch pokud mo\u017eno nemanipulujte a\u00a0informujte o\u00a0situaci m\u00edstn\u011b p\u0159\u00edslu\u0161n\u00fd odbor \u017eivotn\u00edho prost\u0159ed\u00ed obce s\u00a0roz\u0161\u00ed\u0159enou p\u016fsobnost\u00ed nebo region\u00e1ln\u00ed pracovi\u0161t\u011b Agentury ochrany p\u0159\u00edrody a\u00a0krajiny \u010cR. Ti zajist\u00ed odborn\u00e9 posouzen\u00ed a identifikaci, o\u00a0jak\u00fd druh rak\u016f se jedn\u00e1, aby nedoch\u00e1zelo k\u00a0neefektivn\u00ed a\u00a0p\u0159edev\u0161\u00edm ne\u017e\u00e1douc\u00ed z\u00e1chran\u011b zavle\u010den\u00fdch druh\u016f a\u00a0p\u0159enosu ra\u010d\u00edho moru, a\u00a0p\u0159\u00edpadn\u011b navrhnou a\u00a0zkoordinuj\u00ed dal\u0161\u00ed opat\u0159en\u00ed.<\/p>\n

Pod\u011bkov\u00e1n\u00ed<\/h3>\n

\u010cl\u00e1nek vznikl s\u00a0podporou grantu EHP z\u00a0Islandu, Lichten\u0161tejnska a\u00a0Norska Monitoring lokalit soustavy Natura 2000 jako n\u00e1stroj pro efektivn\u00ed management a\u00a0ochranu autochtonn\u00edch populac\u00ed rak\u016f.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Periodic droughts in small streams are caused by climate changes but also by the inappropriate management of precipitation and surface water. If these factors act simultaneously, water level rapidly declines even up to the complete drying up of long sections of the stream. <\/p>\n","protected":false},"author":8,"featured_media":2057,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[91],"tags":[468,121,467,466],"coauthors":[403,404,405,406],"class_list":["post-2119","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-applied-ecology","tag-crayfish-plague","tag-drought","tag-invasive-species","tag-negative-factor"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/2119","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/comments?post=2119"}],"version-history":[{"count":2,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/2119\/revisions"}],"predecessor-version":[{"id":30329,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/2119\/revisions\/30329"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media\/2057"}],"wp:attachment":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media?parent=2119"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/categories?post=2119"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/tags?post=2119"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/coauthors?post=2119"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}