Secondary production of Chaoborus ceratopogones (Diptera: Chaoboridae) in Lake Bosumtwi, Ghana

Abstract

Preliminary surveys of the zooplankton of Lake Bosumtwi revealed copious amounts of larval stages of Chaoborus ceratopogones in the water column. Secondary production was subsequently determined to assess its role in the zooplankton community. Head capsule length distinguished consecutive larval instars without overlaps. Growth rates were low in instar I and pupae. Instars II and III were the focal points of population growth. Growth equations were used to compute stage-specific biomass and production. Mean larval density was 16,053+15,865 organisms per m 3 . Daily standing stock varied from 80 to 4180 mg dw m 73 and an annual average production of 920 mg dw m 73 yr 71 . Prey biomass was weakly correlated with Chaoborus biomass so most of the variance in Chaoborus production was controlled by mechanisms external to food abundance. Transfer efficiency of Chaoborus production to planktivorous fish may be low because of intense fishing pressure on the lake.

Occurrence and seasonal dynamics of metalimnetic Deep Chlorophyll Maximum (DCM) in a stratified meromictic tropical lake and its implications for zooplankton community distribution

“…The zooplankton community in Lake Bosumtwi is species‐poor (Sanful, Aikins, Frempong, et al, ). The highly simplified zooplankton community contain nine different taxa with an endemic copepod Mesocyclops bosumtwii (Mirabdulayev, Sanful, & Frempong, ), a dense Chaoborus ceratopogones larval assemblage, several rotifer species and a small‐sized cladoceran Moina micrura (Sanful, Frempong, Aikins, Hall, & Hecky, ). The two major rotifer species are Brachionus calyciflorus and Hexarthra intermedia .…”

“…The zooplankton community in Lake Bosumtwi is species-poor (Sanful, Aikins, Frempong, et al, 2017). The highly simplified zooplankton community contain nine different taxa with an endemic copepod Mesocyclops bosumtwii (Mirabdulayev, Sanful, & Frempong, 2007), a dense Chaoborus ceratopogones larval assemblage, several rotifer species and a small-sized cladoceran Moina micrura (Sanful, Frempong, Aikins, Hall, & Hecky, 2012 Members of the genus Daphnia are absent from the lake and in most tropical systems (Lehman, 1988). Chaoborus reside in deep, anoxic water during the day and move upwards into surface waters at night (Sanful, Aikins, & Hecky, 2017…”

Depth distribution of zooplankton in relation to limnological gradients under different stratification and interannual regimes in a deep, tropical crater lake

“…The phytoplankton community is dominated by Cyanobacteria (Poste et al, 2008;Awortwi, 2009). Previous studies characterized the zooplankton community as consisting of only nine taxa namely an endemic copepod Mesocyclops bosumtwii (Mirabdulayev et al, 2007), a dense Chaoborus larval assemblage, several rotifer species and a small-sized cladoceran Moina micrura (Kurz) (Sanful et al, 2012). The major rotifer species are Brachionus calyciflorus (Pallas) and Hexarthra intermedia (Wiszniewski).…”

“…The major rotifer species are Brachionus calyciflorus (Pallas) and Hexarthra intermedia (Wiszniewski). Species that are uncommon in the water column include Brachionus dimidiatus (Bryce), Keratella cochclearis (Gosse), Filinia pejleri (Hutchinson) and Filinia camascela (Myers) (Sanful et al, 2012). A seasonal band of green and purple sulphur bacteria peaks in metalimnetic layers (12.5-15 m) at the hypoxic-anoxic interface between March and July.…”

The influence of horizontal and vertical biodiversity on the effects of stressors on aquatic ecosystems

“…We then estimated their biovolume (mm 3 ) as 0.074 × 2.92 (Horn 1991), and its fresh body weight by multiplying the biovolume with a conversion factor of 1 (mg mm -3 ) (Havens 1995) and (Hwang & Heath 1999). To estimate fresh body weight of the predator, the dry biomass (mg) of one Chaoborus individual was taken as 0.05 × 3.66 (L is length in mm) as done in (Sanful et al 2012), and then transformed to fresh body weight by multiplying with a dry-wet weight conversion efficiency 10 (Havens 1995;Hwang & Heath 1999).…”