The species is adapted to cold water and would not survive in rising water temperatures due to climate change
Credit: The University of Jyväskylä/Jouni Taskinen
The glacial relict amphipod Gammaracanthus lacustris only occurs in deep and cold waters. A collaborative study by University of Jyvaskyla and University of Eastern Finland produced new information on the life cycle and ecology of this rare amphipod. G. lacustris is adapted to cold water and would probably not survive in rising water temperatures due to climate change. The study has been published in the journal Freshwater Biology in September 2019.
In Finland, G. lacustris only occurs in about 20 lakes. The researchers of Universities of Jyväskylä and Eastern Finland studied the life cycle and trophic position of this amphipod in a unique study, and found that this large amphipod only inhabits the bottom layers of deep lakes with water temperatures less than 8°C. It was mainly found in depths more than 40 meters.
“G. lacustris is abundant only below 40 meters, where water temperature is permanently less than 8°C. The amphipod does not migrate to surface layers to feed even during the night, in contrast to many other crustaceans”, says postdoctoral researcher Jouni Salonen from the University of Jyväskylä.
During the many years’ of research, samples were also taken during nighttime in Lake Paasivesi, which is a part of the Lake Saimaa complex. The study estimates that there are about 50 million G. lacustris inhabiting the Lake Paasivesi. The species got landlocked in deep, large lakes in southern Finland during the melting process after the latest ice age about 10,000 years ago. Thus, G. lacustris is considered a glacial relict species similar to Saimaa ringed seal, i.e. It adapted to the new lacustrine habitat and diverged from its marine relatives.
Stable isotope analysis proved G. lacustris to be a carnivore
The amphipod is a carnivore that preys on other crustaceans, while itself being the prey for fish that inhabit the bottom layers of lakes. During the study over 600 individual G. lacustris were measured, and the largest ones were over four centimeters long. Based on the length distribution, the largest individuals were four years old.
“The female G. lacustris seem to produce young every year, since all the females longer than 25 mm were gravid, and had an embryo sack. The largest females were carrying over 200 eggs or embryos” tells Jouni Salonen.
The study also included stable isotope and fatty acid analysis of G. lacustris individuals.
“Especially the fatty acid content of gravid females and eggs were high, indicating that G. lacustris invests heavily on producing viable offspring. There also were differences in fatty acid composition between adult amphipods and their eggs. The stable isotope analysis indicated that G. lacustris are carnivores, that feed on zooplankton and other crustaceans”, says postdoctoral researcher Minna Hiltunen from University of Jyväskylä.
The values for nitrogen stable isotopes of G. lacustris were at the same level as studied piscivorous fish, such as perch, pike, and pikeperch, which indicates that the trophic position of the amphipod is rather high.
“Due to the high fatty acid content, G. lacustris likely is a valuable prey for many fish, and also seals have been found to eat these amphipods. We also saw that some G. lacustris individuals attacked other crustaceans in the sample jars – even though they were lifted from depths of 60-65 meters only moments ago”, says Hiltunen.
The study was conducted before the research vessel Muikku was decommissioned
The increase in air and water temperatures due to climate change threatens this cold-adapted glacial relict amphipod.
“G. lacustris as a relict from the ice age is clearly adapted to cold waters. The species is not likely to survive in warmer waters, and previous studies have found that it cannot migrate to new lakes for example via rivers”, say the researchers Jouni Salonen and Minna Hiltunen.
The study was conducted with the unique equipment of research vessel Muikku, which has been decommissioned since then.
“It would not have been possible to do this study and gain this new information on G. lacustris without R/V Muikku. The value of this research on large lakes and their ecosystems will only increase in the future”, says professor Jouni Taskinen from the University of Jyväskylä, who originally started the research while working at the University of Eastern Finland.
The study on the ecology of G. lacustris has been published on the journal Freshwater Biology in September 2019: https:/
Postdoctoral researcher Jouni Salonen, University of Jyväskylä, firstname.lastname@example.org, p. +358 40 750 9537
Postdoctoral researcher Minna Hiltunen, University of Jyvaskyla and University of Eastern Finland, email@example.com p. +358 40 849 0880
Senior Researcher Paula Kankaala, University of Eastern Finland, firstname.lastname@example.org p. +358 50 431 3496
Professor Jouni Taskinen, University of Jyvaskyla, email@example.com p. +358 40 355 8094
Communications officer Tanja Heikkinen, the University of Jyvaskyla, firstname.lastname@example.org, p. +358 50 581 8351
Related Journal Article
Amphipods ya Gammaracanthus, ambayo ni aina ya amphipod, huishi katika maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji ya maji. Uchunguzi uliofanywa na Chuo Kikuu cha Jyväskylä na Chuo Kikuu cha Finland Mashariki ulitoa habari mpya kuhusu mzunguko wa maisha na ikolojia ya amfipodi hii nadra. G. lacustris imejipatanisha na maji baridi na labda haiwezi kuishi katika kuongezeka kwa joto la maji kutokana na mabadiliko ya hali ya hewa. Utafiti huo ulichapishwa katika jarida la Freshwater Biology mnamo Septemba 2019. Katika Finland, G. lacustris hupatikana tu katika maziwa 20 hivi. Watafiti wa Chuo Kikuu cha Jyväskylä na Mashariki mwa Finland walichunguza mzunguko wa maisha na nafasi ya trophic ya amphipod hii katika utafiti wa kipekee, na kugundua kwamba amphipod hii kubwa inakaa tu katika tabaka za chini za maziwa ya kina na joto la maji chini ya 8 ° C. Mimea hiyo ilipatikana katika kina cha zaidi ya mita 40. G. Mto wa Lacustrum ni wa kawaida chini ya mita 40 ambapo joto la maji ni chini ya 8 ° C. Amphipod haihamishi kwenye tabaka za uso ili kula hata wakati wa usiku, kinyume na krustaceans nyingine nyingi, anasema mtafiti wa baada ya udaktari Jouni Salonen kutoka Chuo Kikuu cha Jyväskylä. Wakati wa miaka mingi ya utafiti, sampuli pia zilichukuliwa wakati wa usiku katika Ziwa Paasivesi, ambayo ni sehemu ya Ziwa Saimaa tata. Kwa mujibu wa ripoti hiyo, kuna takriban wanyama milioni 50 wa aina ya G. lacustris katika ziwa la Paasivesi. Mnyama huyo aliishi katika maziwa makubwa ya kusini mwa Finland wakati wa kipindi cha barafu ya miaka 10,000 iliyopita. Hivyo, G. lacustris ni kuchukuliwa glacial relict spishi sawa na Saimaa ringed seal, yaani. Ilijirekebisha kwa mazingira mapya ya ziwa na kutofautiana na jamaa zake wa baharini. Uchunguzi wa isotopu imara ulithibitisha G. lacustris kuwa carnivore. amphipod ni carnivore ambayo hunyanyua crustaceans nyingine, wakati yenyewe kuwa mawindo kwa samaki ambao wanaishi tabaka la chini la maziwa. Katika utafiti huo, watu 600 walipimwa, na wale wakubwa zaidi walikuwa na urefu wa sentimeta 4 au zaidi. Kulingana na ugawaji wa urefu, watu wakubwa zaidi walikuwa na umri wa miaka minne. "Kama ilivyoelezwa hapo juu, ""G. lacustris ya kike inaonekana kuzaa watoto kila mwaka, kwani wanawake wote wa urefu wa zaidi ya 25 mm walikuwa na mimba, na walikuwa na mfuko wa kiinitete.""" "Wanawake wakubwa zaidi walikuwa na mayai zaidi ya 200 au viini-tete,"" anasema Jouni Salonen." Utafiti huo pia ulijumuisha isotopu thabiti na uchambuzi wa asidi ya mafuta ya watu wa G. lacustris. Hasa maudhui ya asidi ya mafuta ya wanawake wajawazito na mayai yalikuwa ya juu, ikionyesha kwamba G. lacustris inawekeza sana katika kuzalisha watoto wenye uwezo wa kuishi. Pia kulikuwa na tofauti katika muundo wa asidi ya mafuta kati ya amfipodi wazima na mayai yao. Uchambuzi wa isotopu thabiti ulionyesha kwamba G. lacustris ni wanyama wanaokula nyama, ambao hula zooplankton na krustaceans nyingine, anasema mtafiti wa baada ya udaktari Minna Hiltunen kutoka Chuo Kikuu cha Jyväskylä. Kiwango cha isotopu za nitrojeni za G. lacustris kilikuwa sawa na kile cha samaki wanaokula samaki kama vile perch, pike, na pikeperch, ambayo inaonyesha kuwa nafasi ya trophic ya amphipod ni ya juu. <unk>Kwa sababu ya kiasi kikubwa cha asidi ya mafuta, G. lacustris yaelekea ni mawindo yenye thamani kwa samaki wengi, na pia selo zimepatikana zikila amfipodi hizi. "Tuliona pia kwamba baadhi ya watu wa G. lacustris walishambulia wanyama wengine wa aina ya crustacean katika chupa za sampuli, ingawa walikuwa wameinuliwa kutoka kina cha mita 60-65 dakika chache tu zilizopita,"" anasema Hiltunen." Utafiti huo ulifanywa kabla ya meli ya utafiti ya Muikkou kuondolewa kazi, na ongezeko la joto la hewa na maji kutokana na mabadiliko ya hali ya hewa linatishia amfipodi hii ya barafu iliyobadilika na baridi. G. Lacustris kama mabaki kutoka enzi ya barafu ni wazi ilichukuliwa kwa maji baridi. "Hii ni kwa sababu ya hali ya hewa ya hewa ya hewa, na kwa sababu ya hali ya hewa ya hewa ya hewa, ""hakuna uwezekano wa kuhamia ziwa mpya, kwa mfano kupitia mito,"" wanasema watafiti Jouni Salonen na Minna Hiltunen." Utafiti huo ulifanywa kwa vifaa vya kipekee vya meli ya utafiti ya Muikku, ambayo imefutwa tangu wakati huo. """Hatungeweza kufanya utafiti huu na kupata habari hii mpya juu ya G. lacustris bila R.V. Muikku." """Tunatarajia kuwa utafiti huu wa maziwa makubwa na mifumo yao ya ikolojia utaongezeka katika siku zijazo,"" anasema profesa Jooni Taskinen kutoka Chuo Kikuu cha Jyväskylä, ambaye awali alianza utafiti huo wakati akifanya kazi katika Chuo Kikuu cha Finland Mashariki." "Kama ilivyoelezwa katika makala ya ""Mwanzoni mwa miaka ya 80"" ya jarida la ""Freshwater Biology"" la Chuo Kikuu cha Jyväskylä, J.S. Salonen, PhD, na ""Mwanzoni mwa miaka ya 90"" ya jarida la ""Jurnal of the University of Jyväskylä"" la J.S. Salonen, PhD, ni ""Mwanzoni mwa miaka ya 90"" ya jarida la ""Jurnal of the University of Jyväskylä"" la J.S. Salonen, PhD, PhD, na J.S.S. Salonen."