Differential transport and preservation of the instars of Limnocythere inopinata (Crustacea, Ostracoda) in three large brackish lakes in northern China

Abstract

Population age structure, preservation, and carapace abundance of the valve remains of Limnocythere inopinata in 88 surface-sediment samples from Lakes Daihai, Dali, and Hulun were examined to better understand taphonomy of limnic ostracods. The spatial changes in population structure of L. inopinata match the within-lake hydraulic gradients, with the older instars preferentially deposited in the littoral zone while the younger instars being more abundant in deeper waters. We propose that molt and mortem remains of ostracods, especially those of the small juveniles, experience downslope transport. The magnitude of transport in a lake is controlled by wind-driven hydrodynamics. There is no chemical dissolution of ostracod valves in these alkaline lakes, and degradation is mainly represented by physical breakage. The preservation of L. inopinata is related to sedimentation rate and hydraulic stability, and the spatial pattern of preservation varies between lakes. Spatial and seasonal changes in sedimentation rate and hydraulic condition, and the ostracod life cycle may have contributed to this complexity. Adult and A-7 carapaces are the most frequent among the instars. We suggest that the preferential preservation of juvenile carapaces is either related to high mortality rate or to the good preservation in deep waters.

Life stages and morphological variations of Limnocythere inopinata (Crustacea, Ostracoda) from Lake Jiang-Co (northern Tibet): a bioculture experiment

“…Slight overlap occurs in other adjacent growth stages. Compared with the data published in Zhai et al (2015) , L. inopinata population living in MP has a less varied growth pattern, including the instars A-5 moulting to A-4. This indicates that there is an intraspecific difference in growth pattern of L. inopinata .…”

“…The K L values of the L. inopinata population in Lake Jiang-Co from the A-8 to the adult was compared with values obtained for a population from Lake Dali ( Zhai et al 2015 ) (Fig. 3 ), a marginal lake, located at the eastern part of MP (43°13'–43°23'N, 116°29'–116°45'E) with a surface area of 192 km 2 ( Zhai et al 2015 ) (Fig. 3A ).…”

“… A Locations of Lake Jiang-Co and Lake Dali B scatter plot with mean value of K L of L. inopinata populations from A-8 stage to adult in Lake Jiang-Co and Lake Dali ( Zhai et al 2015 ). The rounded dot and triangle represent the growth ratio between adjacent instars C comparison between K L of L. inopinata populations from A-8 stage to adult in Lake Jiang-Co and Lake Dali ( Zhai et al 2015 ). The grey dotted lines suggest a growth ratio of 1.26, the value predicted by Brooks’ rule.…”

“…Here we study a biocultured population of L. inopinata collected from Lake Jiang-Co. The aim was to clarify the life stages and morphological variations from A-8 stage to adult, and to compare our data on growth rate (length and height measurements of the shell) with the Brooks’s rule and with the growth rate of the same species from Lake Dali, eastern Mongolian Plateau (MP) ( Zhai et al 2015 ). We also describe shell and soft parts of the Lake Jiang-Co population and compare this with the European population ( Yin et al 1999 ; Meisch 2000 ).…”

Factors controlling the oxygen isotopic composition of lacustrine authigenic carbonates in Western China: implications for paleoclimate reconstructions

“…The wet surface sediment samples were soaked in deionized water for about 2 h and then wet sieved with a 350-mesh (45 μm) sieve. Materials exceeding 45-μm containing detrital mixtures and biogenic carbonates (containing primarily ostracods) were filtered out 37,73 . Only fine sieved fractions smaller than 45 μm were collected, frozen in a refrigerator overnight and then vacuum freeze-dried for 48 h using the Boyikang FD-1A-50 Freeze Dryer at approximately − 50 °C (30 Pa), until the samples were dried.…”