Eiropas plekstes (Platichthys flesus) un Baltijas plekstes (Platichthys solemdali) sugu diferencēšana
Date
2022
Authors
Tetere, Rebeka
Journal Title
Journal ISSN
Volume Title
Publisher
Latvijas Universitāte
Abstract
Jau gandrīz gadsimtu plekstei ir zināmas vairošanās stratēģijas atšķirības Baltijas jūra. Jaunākie pētījumi apliecinājuši, ka tie nav ekotipi, bet ir atšķirīgas sugas. Iepriekš zināma bija tikai Eiropas plekste (Platichthys flesus), kas nārsto dziļūdens nogāzēs ar pelaģiskeim ikriem. Jaunatklātā suga Baltijas plekste (Platichtys solemdali) vairojas piekrastē ar bentiskiem ikriem un tā ir vienīgā endēmā zivs suga Baltijas jūrā. Līdz šim sugas atšķirt var tikai ar ikru morfoloģiju un ģenētiskajām analīzem. Baltijas jūras ūdens sāļumam samazinoties un anoksiskajām zonām palielinoties, Eiropas plekstes populācijas var tikt apdraudētas. Nepieciešams noteikt viegli pielietojamas metodes sugu diferencēšanai, lai saglabātu tā jau nelielo bioloģisko daudzveidību Baltijas jūrā. Pētījums veikts Latvijas piekrastes atklātās jūras daļā, kur novērojama lielākā abu sugu pārklāšanās. Ievāktajām plekstēm ģenētiski noteica sugu un analizēja morfoloģiskos un augšanas parametrus. Pētījuma rezultāti liecina, ka par spīti iepriekš konstatētajām spuru staru skaita atšķirībām sugu starpā, tas lielākai paraugkopai neuzrādās, kā būtisks sugas diferencējošs parametrs. Šajā darbā noskaidrots, ka galvas garuma attiecība pret ķermeņa garumu Baltijas plekstei ir lielāka. Tā kā šī sugas noteikšanas metode būtu vienkārša un lēta, nepieciešams veikt tālākus pētījumus, lai novērtētu iespējas tās praktiskai pielietošanai.
Differences in Baltic Sea flounder breeding staregy have already been known for about a century. A recent study shows that they are not ecotypes, but different species. Previously, the only species known was European flounder (Platichthys flesus) which spawn in deep water slopes with pelagic eggs. The newly discovered species Baltic flounder (Platichthys solemdali) reproduces on the coast with demersal eggs. It is the only endemic fish species in the Baltic Sea. Until now, the species can only be distinguished by egg morhology and genetic analyses. As salinity of the Baltic Sea decreases and anoxic zones increase, populations of Eauropean flounder may be threatened. So it is necessary to determine easy-to-apply methods of species differentiation in order to preserve the already small biodiversity of the Baltic Sea. This study was conducted in the open sea part of the Latvian coast, where the greatest overlap of both species can be observed. Species were genetically assigned to flounder samples and morphological and growth parameters were analyzed. Results of this study show that, despite the previously noted differences in the number of fin rays between species, it does not appear to be a significant differentiating parameter for a larger sample size. It was found that the ration of head length to body length is greater in the Baltic flounder. Since this species determination method could be simple and inexpensive, it is necessary to carry out further research to evaluate the possibilities for its practical application.
Differences in Baltic Sea flounder breeding staregy have already been known for about a century. A recent study shows that they are not ecotypes, but different species. Previously, the only species known was European flounder (Platichthys flesus) which spawn in deep water slopes with pelagic eggs. The newly discovered species Baltic flounder (Platichthys solemdali) reproduces on the coast with demersal eggs. It is the only endemic fish species in the Baltic Sea. Until now, the species can only be distinguished by egg morhology and genetic analyses. As salinity of the Baltic Sea decreases and anoxic zones increase, populations of Eauropean flounder may be threatened. So it is necessary to determine easy-to-apply methods of species differentiation in order to preserve the already small biodiversity of the Baltic Sea. This study was conducted in the open sea part of the Latvian coast, where the greatest overlap of both species can be observed. Species were genetically assigned to flounder samples and morphological and growth parameters were analyzed. Results of this study show that, despite the previously noted differences in the number of fin rays between species, it does not appear to be a significant differentiating parameter for a larger sample size. It was found that the ration of head length to body length is greater in the Baltic flounder. Since this species determination method could be simple and inexpensive, it is necessary to carry out further research to evaluate the possibilities for its practical application.
Description
Keywords
Bioloģija , plekste , endēma suga , Baltijas jūra , diferencēšana , morfoloģija