Facultative amphidromy involving estuaries in an annual amphidromous fish from a subtropical marginal range

Abstract

Variation in the life cycle of diadromous fishes can be explained by differential food availability between marine and freshwater habitats, since migration is often interpreted as a mechanism for exploiting food resources. Theoretically, a migration pattern of mainly remaining in freshwater occurs in tropical and subtropical habitats where fluvial productivity possibly exceeds marine productivity. However, in Yakugachi River, Amami-Oshima Island, southern Japan, low nutrient concentrations in the river suggest that food availability is limited for the subtropical Ryukyu-ayu Plecoglossus altivelis ryukyuensis. Since Ryukyu-ayu is an amphidromous fish that mainly grows in rivers after spending 2 months in the sea, limited food availability in rivers would force this species to migrate to other habitats with better food availability. Otolith increment and Sr:Ca analyses of 48 adult Ryukyu-ayu collected from the Yakugachi River revealed that all individuals visited estuaries more than three times after moving upstream. Although the specific growth rates of this species in the river had no correlation with the salinity profile in the fluvial period, this movement may be an adaptive choice because the salinity profile significantly affected the body size at maturity. Our results highlighted individual-based variations in amphidromous migration for utilizing estuaries, which could be explained by relatively higher productivity in estuarine than in freshwater and marine habitats. K E Y W O R D S estuary, individual-based migration pattern, otolith Sr:Ca, subtropical amphidromous fish

Morphology and growth pattern of Nike fish (amphidromous goby larvae) in Gorontalo Waters, Indonesia

“…In other words, salinity, as well as life phases, simultaneously determine and support the existence of goby larvae in nature. Murase and Iguchi (2019) reported that variations in the diadromous fish life cycle could be explained by differences in food availability between marine and freshwater habitats because migration is often interpreted as a mechanism for exploiting food resources. A life-history stage of organisms that can disperse through seawater requires a physiologically challenging migration across a salinity boundary (Kaemingk et al, 2019).…”

Application of the analysis of trace elements composition for calcified structures of fish to solve fundamental and applied scientific tasks: a review

“…Динамика соотношения Sr : Ca на протяжении трансекты от ядра к периферии отолита айю Plecoglossus altivelis ryukyuensis -амфидромной рыбы, ранний нагул которой проходит в море, после чего происходит миграция в реки южной Японии, где рыба заканчивает свой жизненный цикл. Стрелками обозначены средние значения отношения Sr : Ca, равные 6,0 (черный цвет) и 4,0 (белый цвет), принятые авторами в качестве граничных пределов между морской (> 6,0), солоноватой (6,0-4,0) и пресноводной средой обитания (< 4,0) [Murase, Iguchi, 2019] Fig. 2.…”

“…Sr : Ca ratio along the transect from center to periphery of otolith from amphidromous Plecoglossus altivelis ryukyuensis after its migration from the sea to the rivers of southern Japan where the fish ends its life cycle. Arrows indicate the Sr : Ca ratio values equal to 6.0 (black) and 4.0 (white) accepted as the boundaries between marine (> 6), brackish (6-4) and freshwater (< 4) environments [Murase, Iguchi, 2019] Расстояние от примордиума, мкм Расстояние от ядра отолита, мкм В большинстве опубликованных работ верхняя пороговая величина пропорции Sr : Ca для пресноводной среды обитания варьирует в пределах (0,2-2,5) . 10 -3 , что было выявлено для многих видов рыб: сельдей Alosa pseudoharengus и A. aestivalis рек Лонг Айленда, Коннектикут, США [Gahagan et al, 2012]; налима Lota lota и гольяна Phoxinus phoxinus Балтийского моря [Rohtla et al, 2014;Svirgsden et al, 2018]; леща Abramis brama и судака Sander lucioperca канала Киел, Германия [Kafemann et al, 2000]; камбалы Paralichthys lethostigma северной части Мексиканского залива [Lowe et al, 2011]; мраморного угря Anguilla marmorata Юго-Восточной Азии [Arai, Chino, 2018].…”

“…10 -3 [Hata et al, 2016] и 4,0 . 10 -3 [Murase, Iguchi, 2019], что может определяться различиями в гидрохимии водоемов [Tian et al, 2019]. Также сравнительно высокая величина 4,0 .…”

Temporal variation in abundance of bully sleepers (Pisces: Eleotridae) larvae and juveniles in Cisolok Estuary, Palabuhanratu Bay, Indonesia

“…Without exception, the people of Cisolok have utilized bully sleepers either as consumption fish or for sale to traditional markets. Estuary ecosystems play a crucial role for many kinds of fishes, particularly for small-sized fishes, as nursery habitat, a refuge from predators, and a migration path for freshwater amphidromous 1033 (2022) 012003 IOP Publishing doi:10.1088/1755-1315/1033/1/012003 2 fishes [2,3,4]. Freshwater amphidromous fish need more than one habitat to undertake ontogenetic processes [5].…”