Hypoxia Tolerance in Twelve Species of East African Cichlids: Potential for Low Oxygen Refugia in Lake Victoria

Chapman, Lauren J.; Kaufman, Leslie S.; Chapman, Colin A.; McKenzie, F. Ellis

doi:10.1046/j.1523-1739.1995.9051274.x

Cited by 50 publications

(63 citation statements)

References 38 publications

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“…Oxygen levels were dropped progressively until the fish spent 90% of the observation time performing ASR or until the fish lay on the bottom of the aquarium. Using a digital video recorder (TroubleShooter TM High-Speed Camera, Fastec Imaging, San Diego, CA, USA), gill ventilation rates, measured as the number of ventilations per 10s, were determined at the beginning and at the very end of the trial (Chapman et al, 1995). Carbon rod electrodes (38.1cm length) mounted opposite each other diagonally at either end of the fish chamber were used to record EOD (frequency and amplitude) simultaneously with P O2 and water temperature using custom-written routines in MATLAB R2007b.…”

Section: Critical Oxygen Tension and Metabolic Ratementioning

confidence: 99%

Energetic constraints on electric signalling in wave-type weakly electric fishes

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Parisi

Krahe

et al. 2011

Journal of Experimental Biology

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SUMMARY Gymnotiform weakly electric fishes generate electric organ discharges (EODs) and sense perturbations of the resulting electric field for purposes of orientation, prey detection and communication. Some species produce oscillatory (‘wave-type’) EODs at very high frequencies (up to 2 kHz) that have been proposed to be energetically expensive. If high-frequency EODs are expensive, then fish may modulate their EOD frequency and/or amplitude in response to low-oxygen (hypoxic) stress and/or compensate for costs of signalling through other adaptations that maximize oxygen uptake efficiency. To test for evidence of an energetic cost of signalling, we recorded EOD in conjunction with metabolic rates, critical oxygen tension and aquatic surface respiration (ASR90) thresholds in Apteronotus leptorhynchus, a species found in high-oxygen habitats, and Eigenmannia virescens, a species more typically found in low-oxygen waters. Eigenmannia virescens had a lower mean ASR90 threshold and critical oxygen tension compared with A. leptorhynchus, consistent with field distributions. Within each species, there was no evidence for a relationship between metabolic rate and either EOD frequency or amplitude under normoxia, suggesting that there is no significant direct metabolic cost associated with producing a higher frequency EOD. However, when exposed to progressive hypoxia, fish generally responded by reducing EOD amplitude, which may reduce energetic costs. The threshold at which fish reduced EOD amplitude tended to be lower in E. virescens, a pattern consistent with higher tolerance to hypoxic stress. The results of this study suggest that wave-type fish reduce their EOD amplitude to reduce direct energetic costs without reducing metabolic rate under hypoxia.

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Section: Critical Oxygen Tension and Metabolic Ratementioning

confidence: 99%

Energetic constraints on electric signalling in wave-type weakly electric fishes

Reardon

Parisi

Krahe

et al. 2011

Journal of Experimental Biology

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“…Dissolved oxygen concentrations In general, Lake Victoria haplochromines, including those of the shallow sandy and rocky habitats, are tolerant to low DO regimes (Chapman et al 1995). Verheyen et al (1986) measured relatively high haemoglobin-oxygen affinities (P 50 = 1.7-2.3 mmHg) in three typically sand dwelling haplochromine species from Lake Victoria.…”

Section: Discussionmentioning

confidence: 99%

Cichlid species diversity in naturally and anthropogenically turbid habitats of Lake Victoria, East Africa

et al. 2012

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During the past decades, major anthropogenic environmental changes occurred in Lake Victoria, including increased predation pressure due to Nile perch introduction, and decreases in water transparency and dissolved oxygen concentrations due to eutrophication. This resulted in a collapse of the haplochromine cichlids in the sub-littoral waters of the Mwanza Gulf in 1986-1990, followed by a recovery of some species in the 1990s and 2000s, when Nile perch densities declined. We studied two data sets: (1) haplochromines from sand and mud bottoms in the pre-collapse period; (2) haplochromines from sub-littoral areas during the precollapse, collapse and recovery periods. Water over mud is murkier and poorer in oxygen than water over sand, and differences in haplochromine communities in these natural habitats during the pre-collapse period may predict the effects of anthropogenic eutrophication during the collapse and recovery periods. In the pre-collapse period, haplochromine densities over sand and mud did not differ, but species richness over sand was 1.6 times higher than over mud bottoms. Orange-and white-blotched colour morphs were most common at the shallowest sand station. More specifically, insectivores and mollusc-shellers had higher numbers of species over sand than over mud, whereas for mollusc-crushers no difference was found. Laboratory experiments revealed that mollusc shelling was more affected by decreased light intensities than mollusc crushing. During the pre-collapse period, spawning occurred year-round in shallow areas with hard substrates and relatively clear water. In deeper areas with mud bottoms, spawning mainly occurred during months in which water clarity was high. No effects of hypoxia on spawning periods were found. It follows that clearer water seems to support differentiation in feeding techniques as well as year-round spawning, and both may facilitate species coexistence. Water clarity is also known to be important for mate choice. These observations may explain why, since the decline of Nile perch, haplochromine densities have recovered, the numbers of hybrids increased and species diversity in the current eutrophic sub-littoral waters has remained 70 % lower than before the environmental changes.

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“…The respiratory frequency (RF) was determined from the direct observation of opercular movements (Saint-Paul & Bernardinho, 1988;Chapman et al, 1995). To measure the locomotory activity of the animal, we measured vertical (VM) and horizontal movements (HM), using a 5 x 5 cm grid, drawn in the aquarium wall and counted the number of horizontal and vertical lines crossed by the medial line of fish eye during a 2 min period (Weber & Kramer, 1983).…”

Section: Methodsmentioning

confidence: 99%

Phenotypic plasticity associated to environmental hypoxia in the neotropical serrasalmid Piaractus mesopotamicus (Holmberg, 1887) (Characiformes: Serrasalmidae)

Fernández-Osuna

Scarabotti

2016

Neotrop. ichthyol.

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Many South American characid fishes develop reversible dermal protuberances in the jaws to optimize aquatic surface respiration (ASR) during hypoxia. To date, basic aspects of this adaptation remain unknown, mainly due to the scarcity of experimental studies. In laboratory experiments, we determined time necessary for the complete formation and reversion of these structures in Piaractus mesopotamicus, and studied comparatively behavioral, morphological, and respiratory responses along gradients of dissolved oxygen (DO) concentration. Morphological changes during hypoxia consisted in dermal protuberances of lower lip, anterior border of maxillary and distal border of opercular valve, increasing the known number of structures modified. These structures developed completely in less than 6 hours and reversed in less than 3 hours. Most of observed traits showed a logistic response curve with threshold DO values between 0.90 and 2.70 mgL -1 . Respiratory frequency and opercular valve development showed similar threshold values above the level of tolerance of DO, whereas ASR and dermal protuberances of the jaws showed threshold values below this level. This observation supports the functional link between these groups of behavioral and morphological traits. This study demonstrates that this species is able to modify reversibly portions of the respiratory system to optimize responses to hypoxia.Muchos peces carácidos sudamericanos desarrollan protuberancias dérmicas reversibles en las mandíbulas para optimizar la respiración acuática superficial (RAS) durante la hipoxia. Actualmente, aspectos básicos de esta adaptación permanecen desconocidos, principalmente debido a la escasez de estudios experimentales. En experiencias de laboratorio, determinamos el tiempo necesario para el desarrollo y la reversión completos de estas estructuras en Piaractus mesopotamicus, y estudiamos comparativamente respuestas conductuales, morfológicas, y respiratorias en un gradiente de concentración de oxígeno disuelto (OD). Los cambios morfológicos durante la hipoxia consistieron en protuberancias dérmicas del labio inferior, el borde anterior del maxilar, y el borde distal de la válvula opercular, incrementando el número conocido de estructuras modificadas. Éstas se desarrollaron completamente en menos de 6 horas y se revirtieron en menos de 3 horas. La mayoría de los rasgos observados siguieron una curva de respuesta logística, con valores críticos entre 0,90 y 2,70 mgL -1 de OD. La frecuencia respiratoria y el desarrollo de la válvula opercular presentaron valores críticos similares ubicados por encima del nivel de tolerancia al OD, mientras que la RAS y las protuberancias dérmicas mandibulares presentaron críticos por debajo de dicho nivel. Estas observaciones apoyan la relación funcional existente entre estos grupos de rasgos conductuales y morfológicos. Este estudio demuestra que esta especie puede modificar reversiblemente porciones del sistema respiratorio para optimizar las respuestas a la hipoxia.

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Hypoxia Tolerance in Twelve Species of East African Cichlids: Potential for Low Oxygen Refugia in Lake Victoria

Cited by 50 publications

References 38 publications

Energetic constraints on electric signalling in wave-type weakly electric fishes

Energetic constraints on electric signalling in wave-type weakly electric fishes

Cichlid species diversity in naturally and anthropogenically turbid habitats of Lake Victoria, East Africa

Phenotypic plasticity associated to environmental hypoxia in the neotropical serrasalmid Piaractus mesopotamicus (Holmberg, 1887) (Characiformes: Serrasalmidae)

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