Diel vertical migration of Cladocera in a compartment of a tropical reservoir

Abstract

Aim This study seeks to analyze the vertical migration pattern of Cladocera species as related with the physical and chemical parameters of the water. Methods Samplings were carried out at 3-h intervals for 24 h in January 15 on the Sapucaí River compartment of Furnas reservoir, Minas Gerais State, Brazil. These samples were taken at five depths, from the surface to the near-bottom layer (0, 2, 4, 6, 8, and 9 m) totalizing 54 samplings for each limnological variable (temperature, pH, dissolved oxygen, electrical conductivity, chlorophyll-a content, Index of Trophic State, water transparency and Cladocera populations abundance). The samplings were performed at the limnetic region at a point with total depth of 9 meters. Results Water column thermal and chemical stratifications and thermocline occurrences were registered in the middle of the day. Among the 14 Cladocera species, only Ceriodaphnia cornuta and C. silvestrii displayed a significant migration pattern, which was mainly related to chlorophyll-a and dissolved oxygen concentrations. Diaphanosoma birgei and D. spinulosum are found at high densities near the surface and low ones in depth. The migration of Diaphanosoma was directly related to the concentration of chlorophyll a and pH, thus acting as a limiting factor. Feeding at high temperatures in the surface layer and assimilating at lower ones in depth, usually confer metabolic advantages to the vertically migratory species. Conclusions In this study, a well-defined pattern of vertical migration was found for two Cladocera species and its possible causes were hypothesized. To the species with less locomotory capacity, thermal and chemical stratifications can act as barriers to migration and distribution through the water column. This pattern may probably be found for zooplankton species in other compartments of Furnas reservoir, with similar physical and chemical properties.

Behavioral Avoidance Response of Daphnia to Fungal Infection Caused by Metschnikowia Species in a Temperate Reservoir

“…In this study, D. pulicaria was more abundant in the bottom than in the surface layers to avoid predators. However, for the bottom layer of a lake or reservoir to become a refuge for cladocerans, light must be introduced and DO levels should be low [ 72 , 73 ]. Fish distribution might be limited when DO is less than 20% in the bottom layer [ 74 ].…”

Variação espaço-temporal e nictemeral dos parâmetros limnológicos no Delta do Jacuí, Lago Guaíba, RS, Brasil

“…Martins et al (2019) destacam que o acompanhamento e análise nictemeral são relevantes para a compreensão da situação comportamental das variáveis abióticas, visto que em seus estudos observaram variações limnológicas ao longo da coluna d'água em um ciclo de 24 horas, em uma área no Delta do Jacuí. Essa compreensão é importante, uma vez que as propriedades físicas e químicas da água influenciam os organismos aquáticos, podendo afetar sua distribuição vertical e nictemeral (RANGEL et al, 2009), tais como fitoplâncton (BECKER e HUSZAR, 2009;BARBOSA et al, 2011;PINTO e BECKER, 2014) e zooplâncton (SILVA et al, 2018).…”