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Article: Seasonal and inter-stream variations in the population dynamics, growth and secondary production of an algivorous fish (Pseudogastromyzon myersi: Balitoridae) in monsoonal Hong Kong

TitleSeasonal and inter-stream variations in the population dynamics, growth and secondary production of an algivorous fish (Pseudogastromyzon myersi: Balitoridae) in monsoonal Hong Kong
Authors
KeywordsBenthic Fish
Loach
Population Dynamics
Secondary Production
Tropical Streams
Issue Date2009
PublisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/FWB
Citation
Freshwater Biology, 2009, v. 54 n. 9, p. 1960-1976 How to Cite?
AbstractBalitorid loaches are widespread and highly diverse in Asian streams, yet their life history and ecology have received little attention. We investigated seasonal (wet versus dry season) and spatial variation in populations of algivorous Pseudogastromyzon myersi in Hong Kong, and estimated the magnitude of secondary production by this fish in pools in four streams (two shaded and two unshaded) over a 15-month period. Mean population densities of P. myersi ranged from 6.0 to 23.2 individuals m-2, constituting more than half (and typically >70%) of benthic fishes censused. Abundance was c. 25% greater in the wet season, when recruitment occurred. Significant density differences among streams were not related to shading conditions and were evident despite small-scale variations in P. myersi abundance among pools. Mean biomass varied among streams from 0.85 to 3.87 g ash-free dry weight (AFDW) m-2. Spatial and seasonal patterns in biomass and density were similar, apart from some minor disparities attributable to differences in mean body size among populations. All four P. myersi populations bred once a year in June and July, and life spans varied from 24 to 26 months. Populations consisted of three cohorts immediately after recruitment but, for most of the study period, only two cohorts were evident. Cohort-specific growth rates did not differ significantly among streams but, in all streams, younger cohorts had higher cohort-specific growth rates. Secondary production of P. myersi estimated by the size-frequency (SF) method was 2.7-11.5 g AFDW m-2 year-1 and almost twice that calculated by the increment-summation (IS) method (1.2-6.6 g AFDW m-2 year-1). Annual P/B ratios were 1.17-2.16 year-1 (IS) and 2.73-3.22 year-1 (SF). Highest production was recorded in an unshaded stream and the lowest in a shaded stream, but site rankings by production did not otherwise match shading conditions. Wet-season production was six times greater than dry-season production, and daily production fell to almost zero during January and February. Cool temperatures (<17 °C) may have limited fish activity and influenced detectability during some dry-season censuses. Estimates of abundance and annual production by P. myersi are therefore conservative. Comparisons with the literature indicate that the abundance and production of P. myersi in Hong Kong was high relative to other benthic fishes in tropical Asia, or their temperate counterparts in small streams. Manipulative experiments are needed to determine the influence of P. myersi, and algivorous balitorids in general, on periphyton dynamics and energy flow in Asian streams. © 2009 Blackwell Publishing Ltd.
Persistent Identifierhttp://hdl.handle.net/10722/179151
ISSN
2015 Impact Factor: 2.933
2015 SCImago Journal Rankings: 1.574
References

 

DC FieldValueLanguage
dc.contributor.authorYang, GYen_US
dc.contributor.authorDudgeon, Den_US
dc.date.accessioned2012-12-19T09:52:24Z-
dc.date.available2012-12-19T09:52:24Z-
dc.date.issued2009en_US
dc.identifier.citationFreshwater Biology, 2009, v. 54 n. 9, p. 1960-1976en_US
dc.identifier.issn0046-5070en_US
dc.identifier.urihttp://hdl.handle.net/10722/179151-
dc.description.abstractBalitorid loaches are widespread and highly diverse in Asian streams, yet their life history and ecology have received little attention. We investigated seasonal (wet versus dry season) and spatial variation in populations of algivorous Pseudogastromyzon myersi in Hong Kong, and estimated the magnitude of secondary production by this fish in pools in four streams (two shaded and two unshaded) over a 15-month period. Mean population densities of P. myersi ranged from 6.0 to 23.2 individuals m-2, constituting more than half (and typically >70%) of benthic fishes censused. Abundance was c. 25% greater in the wet season, when recruitment occurred. Significant density differences among streams were not related to shading conditions and were evident despite small-scale variations in P. myersi abundance among pools. Mean biomass varied among streams from 0.85 to 3.87 g ash-free dry weight (AFDW) m-2. Spatial and seasonal patterns in biomass and density were similar, apart from some minor disparities attributable to differences in mean body size among populations. All four P. myersi populations bred once a year in June and July, and life spans varied from 24 to 26 months. Populations consisted of three cohorts immediately after recruitment but, for most of the study period, only two cohorts were evident. Cohort-specific growth rates did not differ significantly among streams but, in all streams, younger cohorts had higher cohort-specific growth rates. Secondary production of P. myersi estimated by the size-frequency (SF) method was 2.7-11.5 g AFDW m-2 year-1 and almost twice that calculated by the increment-summation (IS) method (1.2-6.6 g AFDW m-2 year-1). Annual P/B ratios were 1.17-2.16 year-1 (IS) and 2.73-3.22 year-1 (SF). Highest production was recorded in an unshaded stream and the lowest in a shaded stream, but site rankings by production did not otherwise match shading conditions. Wet-season production was six times greater than dry-season production, and daily production fell to almost zero during January and February. Cool temperatures (<17 °C) may have limited fish activity and influenced detectability during some dry-season censuses. Estimates of abundance and annual production by P. myersi are therefore conservative. Comparisons with the literature indicate that the abundance and production of P. myersi in Hong Kong was high relative to other benthic fishes in tropical Asia, or their temperate counterparts in small streams. Manipulative experiments are needed to determine the influence of P. myersi, and algivorous balitorids in general, on periphyton dynamics and energy flow in Asian streams. © 2009 Blackwell Publishing Ltd.en_US
dc.languageengen_US
dc.publisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/FWBen_US
dc.relation.ispartofFreshwater Biologyen_US
dc.rightsFreshwater Biology. Copyright © Blackwell Publishing Ltd.-
dc.subjectBenthic Fishen_US
dc.subjectLoachen_US
dc.subjectPopulation Dynamicsen_US
dc.subjectSecondary Productionen_US
dc.subjectTropical Streamsen_US
dc.titleSeasonal and inter-stream variations in the population dynamics, growth and secondary production of an algivorous fish (Pseudogastromyzon myersi: Balitoridae) in monsoonal Hong Kongen_US
dc.typeArticleen_US
dc.identifier.emailDudgeon, D: ddudgeon@hku.hken_US
dc.identifier.authorityDudgeon, D=rp00691en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1111/j.1365-2427.2009.02249.xen_US
dc.identifier.scopuseid_2-s2.0-68349128399en_US
dc.identifier.hkuros163363-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-68349128399&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume54en_US
dc.identifier.issue9en_US
dc.identifier.spage1960en_US
dc.identifier.epage1976en_US
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridYang, GY=26645276500en_US
dc.identifier.scopusauthoridDudgeon, D=7006559840en_US
dc.identifier.citeulike5538884-

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