Exuvium analysis: A nondestructive method of analyzing copepod growth and development

Twombly, Saran; Burns, Carolyn W.

doi:10.4319/lo.1996.41.6.1324

Cited by 15 publications

(16 citation statements)

References 26 publications

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“…Discussion-Technique evaluation: assessment, prospective refinements and further applications: Unlike previous uses of cast-off moults as a growth marker for small copepods (Twombly and Burns 1996), larger crustaceans like Caridina (Hart 1980), Gammarus (Sutcliffe pers. comm.…”

Section: Methods-underlying Principlesmentioning

confidence: 99%

Rapid estimation of in situ growth rates of Caridina nilotica (Crustacea: Decapoda) inLake Victoria: Description and pilot application of a simple, field‐compatible technique

Hart

2001

Limnology & Oceanography

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A simple rapid approach to estimating in situ growth rates of Caridina nilotica (Roux), a small shrimp that plays a pivotal role in Lake Victoria's food web, is described. The approach, potentially applicable to many arthropods, is based on moulting intervals (MI) and per moult size increments (PMI) determined during brief experimental confinements. Physiological justification of its reliability as a measure of in situ rates is given. Caridina moults at night. Feral animals collected shortly (≤2 h) before dusk were sorted into one of five arbitrary size classes and held around 27°C overnight without food. MI, the inverse proportion of a batch moulting overnight, increased from 2 d in small shrimps (carapace length [CL] ≤1.8 mm) to >9 d in larger animals (CL ≥4.3 mm)‐a value comparable to egg development time (10.3 d) at the corresponding temperature. PMI was measured from differences in CL of postecdysal shrimps (CLi‐1) and corresponding cast exuviae (CLi). In absolute terms, PMI, surprisingly, was constant (0.284 ± 0.027 mm moult−1) over the size range of shrimps tested, although relative growth (PMI as a percentage of CLi) declined with size. Growth trajectories modeled with regressions fitted to the data (MI = 1.573 x CL0.999 and CLi‐1 = 0.284 + 0.977 x CLi) show that C. nilotica grows significantly faster (by at least 20%) in L. Victoria than previously estimated (Ignatow et al.), with corresponding implications to other evaluations of lake productivity. Prospective refinements and future uses for this simple technique are outlined.

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Section: Methods-underlying Principlesmentioning

confidence: 99%

Rapid estimation of in situ growth rates of Caridina nilotica (Crustacea: Decapoda) inLake Victoria: Description and pilot application of a simple, field‐compatible technique

Hart

2001

Limnology & Oceanography

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“…Individuals ingest cyanobacteria like Anabaena flos-aquae, even when these "low-quality" species are offered together with nutritious algae at nonlimiting concentrations (Burns and Xu 1990b, Burns and Hegarty 1994). In this study, we used the exuviae that an individual sheds at each molt (Twombly and Burns 1996) to quantify the effects of diet on growth, development, and individual life history traits in Boeckella triarticulata Thomson. In this study, we used the exuviae that an individual sheds at each molt (Twombly and Burns 1996) to quantify the effects of diet on growth, development, and individual life history traits in Boeckella triarticulata Thomson.…”

Section: Introductionmentioning

confidence: 99%

Life History Consequences of Food Quality in the Freshwater Copepod Boeckella triarticulata

Twombly¹,

Clancy²,

Burns³

1998

Ecology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Food quality often has profound effects on life history traits and individual fitness, altering rates of growth and development, changing the timing of reproduction, and shifting the trade-off between egg size and egg number. Few data are available on the effects of food quality on copepod life history traits. We measured several life history traits on a large number of individuals to document the effects of food quality on individual traits, on life history correlates, and on a composite measure of individual fitness in the freshwater copepod Boeckella triarticulata Thomson. Nauplii were raised individually on two diets: one consisted of the high quality alga Cryptomonas sp. (abbreviated as CR), and the second diet consisted of a combination of Cryptomonas sp. and the low quality cyanobacterium Anabaena flos-aquae (CA). The mixed CA diet slowed growth and development so that individuals raised on this diet were older and smaller at metamorphosis and maturity. Despite these effects, there were no differences between diets in survival to maturity, and male copepods raised on the mixed diet lived significantly longer than females or than either sex raised on Cryptomonas alone. Females raised on the mixed diet produced more and larger clutches than those raised on CR, so that total egg production increased on this diet, although large intradiet variation obscured statistical differences between diets in these parameters. Intradiet variation was due to a large range in the number of clutches produced by individual females: some individuals produced 10-15 clutches, contradicting previous descriptions of this species as semelparous. Although diet affected age at first reproduction, it had no significant effect on individual fitness, estimated as X. Boeckella triarticulata achieved high fitness either by minimizing age at first reproduction (CR diet) or by increasing reproductive output (CA diet). Data collected from cast-off exuviae allow nondestructive measures of individual life history traits along with a composite measure of individual fitness. Combining these two analyses is an important step in unraveling life history correlates and in identifying the selective forces driving life history evolution in these crustaceans.

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“…Development time and growth of Limnoithona tetraspina in the field were determined from molt rate ex-periments (Twombly & Burns 1996, Hirst et al 2005, using copepods that were collected by live surface tows from the sampling stations at a salinity of 2. Copepodites (C2 to C4) were removed from the samples under a dissecting microscope.…”

Section: Methodsmentioning

confidence: 99%

Development, growth, and reproduction of the cyclopoid copepod Limnoithona tetraspina in the upper San Francisco Estuary

Gould

Kimmerer²

2010

Mar. Ecol. Prog. Ser.

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Limnoithona tetraspina is a small cyclopoid copepod that was introduced to the San Francisco Estuary (SFE), USA, in 1993 and became the most abundant copepod species in the lowsalinity zone (LSZ). Two previous studies have shown that it feeds only on motile prey, predominantly ciliates. Little is otherwise known of its biology or its role in the estuarine foodweb. We determined development times, growth rates, and fecundity of L. tetraspina from March to August of 2006 and 2007. The mean growth rate of copepodites in both years was 0.03 d -1 , which is low relative to values reported for related Oithona spp. Development times were longer in the field than in the laboratory at food saturation, indicating food limitation in the SFE. Mean weight-specific fecundity rate in 2007 was 0.10 d -1 , which is twice that of 2006, but within the range of reported values for Oithona spp. Low growth and fecundity rates indicate that the population success of L. tetraspina is due to low mortality. L. tetraspina may avoid certain mortality agents (e.g. visual predation) to which larger copepods are susceptible.KEY WORDS: Egg production · Estuary · Low-Salinity Zone · Bayesian methods · Limnoithona tetraspina Resale or republication not permitted without written consent of the publisher Editorial responsibility: William Peterson,

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Exuvium analysis: A nondestructive method of analyzing copepod growth and development

Cited by 15 publications

References 26 publications

Rapid estimation of in situ growth rates of Caridina nilotica (Crustacea: Decapoda) inLake Victoria: Description and pilot application of a simple, field‐compatible technique

Rapid estimation of in situ growth rates of Caridina nilotica (Crustacea: Decapoda) inLake Victoria: Description and pilot application of a simple, field‐compatible technique

Life History Consequences of Food Quality in the Freshwater Copepod Boeckella triarticulata

Development, growth, and reproduction of the cyclopoid copepod Limnoithona tetraspina in the upper San Francisco Estuary

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