Condition factor variations over time and trophic position among four species of Characidae from Amazonian floodplain lakes: effects of an anomalous drought

Abstract

The effects of extreme droughts on freshwater fish remain unknown worldwide. In this paper, we estimated the condition factor, a measure of relative fitness based on the relationship of body weight to length, in four fish species representing two trophic levels (omnivores and piscivores) from Amazonian floodplain lakes for three consecutive years: 2004, 2005 (an anomalous drought year), and 2006. The two omnivores, Colossoma macropomum and Mylossoma duriventre, exhibited trends consistent with their life cycles in 2004 and 2006: high values during the hydrologic seasons of high water, receding water, and low water, with a drop following reproduction following the onset of rising water. However during the drought year of 2005 the condition factor was much lower than normal during receding and low water seasons, probably as a result of an abnormal reduction in resource availability in a reduced habitat. The two piscivorous piranhas, Serrasalmus spilopleura and S. elongatus, maintained relatively stable values of condition factor over the hydrologic cycles of all three years, with no apparent effect of the drought, probably because the reduction in habitat is counterbalanced by the resulting increase in relative prey density. We suggest that if predictions of increasing drought in the Amazon are correct, predatory species may benefit, at least in the short run, while omnivores may be negatively affected. Keywords

Length‐weight relationship of 16 fish species from the Negro River basin (Amazonas state, Brazil)

“…The Amazon Basin is a huge ecosystem composed of many river sub‐basins. Currently, most length‐weight relationships of the fish species studied are based on individuals collected in the Amazon River (Freitas et al., 2017; Oliveira et al., 2020), Solimões River (Dieb‐Magalhães et al., 2015; Matos et al., 2019; Sampaio et al., 2019; Tribuzy‐Neto et al., 2015, 2018; Villacorta‐Correa & Saint‐Paul, 1999), Madeira River (Cella‐Ribeiro et al., 2015) and Xingu River (Giarrizzo et al., 2015). Thus, few studies using this approach analyze species collected in the Negro River basin, which is the second largest sub‐basin of the Amazon basin (Goulding et al., 2003).…”

Efeitos antrópicos e mudanças sazonais podem influenciar a biologia populacional da tilápia-do-nilo (Oreochromis niloticus L.)?

“…Tal análise demonstrou que no período chuvoso os indivíduos apresentaram crescimento isométrico (b = 3,01) e no período seco crescimento alométrico negativo (b = 2,72). O comportamento isométrico no período de cheia do reservatório demonstra que o incremento em peso das tilápias-do-nilo acompanha o aumento em comprimento, resultante de condições mais favoráveis do ambiente [9,13]. Esse é um padrão esperado para uma espécie com comportamento detritívoro/invertívoro, já que a disponibilidade de presas deve aumentar quando ocorrer um revolvimento no substrato no período de chuvas [40].…”

“…Os estudos sobre a relação peso-comprimento e fator de condição das espécies de peixes de água doce têm sido uma das bases para o desenvolvimento de programas de gerenciamento bemsucedido na captura e cultura de peixes em ambientes selvagens e controlados [9,10]. A relação peso-comprimento tem sido empregada para estimar o peso associado ao comprimento do peixe, avaliar taxas de crescimento, estrutura etária e parâmetros da biologia reprodutiva [11,12].…”

Hubungan Panjang Bobot dan Beberapa Aspek Reproduksi Ikan Tongkol Lisong (Auxis rochei Risso, 1810) di Perairan Teluk Bone

“…Faktor-faktor lain yang mungkin berkontribusi terhadap variasi fakto kondisi ikan tongkol di Teluk Bone termasuk musim, ketersediaan pakan, dan parameter kualitas air lainnya. Menurut beberapa peneliti faktor kondisi ikan yang berbeda-beda pada setiap lokasi dapat disebabkan oleh beberapa faktor seperti perbedaan musim (Sarkar et al 2013;Parida et al, 2013), perbedaan lokasi (Blackwell et al, 2000), siklus hidrologi (Tribuzy-Neto et al, 2018) makanan, waktu, ukuran panjang dan bobot tubuh dan parameter kualitas perairan (Fagbuaro et al, 2019).…”