Tonsa Nauplii Research Articles

Live Microalgae-Based Diets as Enrichment to Improve the Nutritional Profile of the Calanoid Copepod Acartia tonsa (Dana, 1849) Nauplii

Most emerging species in marine aquaculture and the aquarium industry have a sensitive and small-mouthed larval stage, and their culture is very challenging due to a lack of appropriate early feeding protocols. The use of copepods has been widely recognized as a good alternative to traditional fish live feeds (rotifers and Artemia spp.), especially for new species targeted for the multibillion-dollar marine aquarium trade. However, most copepod culture trials are focused on biomass production, while their nutritional requirements and enrichment protocols remain scarcely known. The main objective of this study was to determine the dietary contribution of three microalgae-based diets, provided as a mono R (Rhodomonas salina) or binary I–R (Isochrysis galbana + R. salina) and T–R (Tetraselmis suecica + R. salina), on the biochemical composition (proximate and fatty acids (FAs)) and survival of the calanoid copepod Acartia tonsa (nauplii) versus the conventional rotifer Brachionus plicatilis throughout 96 hr exposure. Both live preys were characterized by the highest protein and total n-3 long-chain polyunsaturated FAs (LC-PUFAs) content when fed with the binary diet I–R compared to other treatments, although the nutritional value of A. tonsa nauplii was always much higher compared to B. plicatilis. In general, there was a wide difference in proximate and FAs composition between the two preys, denoting A. tonsa as better live feed in terms of capacity to retain n-3 LC-PUFAs, especially eicosapentanoic acid (20 : 5n-3) and docosahexanoic acid (22 : 6n-3). The present study highlights the nutritional profile of enriched A. tonsa nauplii and contributes to the production of high-quality live feeds, which may be able to reach the nutritional needs of new marine fish species during their larval development, as well as contributing to the improvement of A. tonsa culture.

Exploring the potential of providing and feeding pikeperch larvae (Sander lucioperca L.) with euryhaline copepod nauplii: A zoo technical trial

ABSTRACTEgg hatching and nauplii success from three euryhaline calanoid copepod species at low salinities suggest a promising alternative initial live feed for pikeperch (Sander lucioperca L.) to the conventional live feed. Acartia bifilosa and Eurytemora affinis are viable candidates with egg hatching down to zero salinity, and Acartia tonsa nauplii survive up to 2 h at zero salinity after transfer from low-salinity seawater. When offered A. tonsa and Artemia, pikeperch larvae equally consumed both prey types. We suggest that euryhaline copepods can be a supplement to or even a substitute for the normal live feed currently used as larval feed for pikeperch.

Changes in free amino acid content during naupliar development of the Calanoid copepod Acartia tonsa

Changes in free amino acids (FAA) were investigated in the potentially important live feed and neritic copepod species Acartia tonsa during naupliar development. Total content of FAA in A. tonsa nauplii was around 17% of dry weight at first development stage, and declined to 6% for later stages. Relative to body-volume and biomass, the FAA content indicated possible volume-dependent changes. However, changes in FAA with osmolytic activity could not account for this decline in FAA content, but suggests that the decline reflected degradation of residual FAAs from the embryonic stage. Glutamic acid revealed the largest change in relative abundance during naupliar development and declined from 29.0% at first nauplius stage to 7.1% at later stages. The high FAA pool in early naupliar stages may be necessary for naupliar development due to an absence of feeding at first development stages. The high FAA content in early nauplii indicates that A. tonsa is a valuable source for nutritional energy for first-feeding fish larvae and should be further exploited for aquaculture purposes. Enhancements to FAA abundances in nauplii through manipulation of maternal diets could be of future interest, as copepod nauplii can contain a substantial pool of FAAs at first development stage.

First feeding of Eugerres brasilianus (Carapeva) larvae with Acartia tonsa (Copepod) nauplii increases survival and resistance to acute stress

The rotifer Brachionus sp. is commonly used for larval feeding in marine fish hatcheries. The aim of this study was to evaluate whether the inclusion of Acartia tonsa nauplii in the initial diet of carapeva larvae improves their survival, growth and resistance to stress when compared to the regimen containing only rotifers. Adult copepods were collected in the wild and cultured with the microalgae Chaetoceros muelleri , Isochrysis galbana and Nannochloropsis oculata to obtain nauplii. Carapeva larvae were grown for 15 days using four treatments and three replicates: 1) Brachionus plicatilis rotifers (10 to 15/mL); 2) A. tonsa nauplii (0.25 to 0.5/mL); 3) Brachionus plicatilis rotifers (5 to 7.5/mL) + A. tonsa nauplii (0.12 to 0.25/mL), and 4) no supply of live feed. After 15 days, the carapeva larvae were subjected to stress by exposure to air for 10 seconds and then returned to the source tank to evaluate survival after 24 h. Survival and stress resistance were higher in carapeva larvae fed B. plicatilis + A. tonsa nauplii (P<0.05), 20.9 ± 11.2% and 88.9%, respectively. These results confirm the positive effect of the inclusion of copepod nauplii in the diet of fish larvae. However, more research is needed to validate these results.

Seasonal occurrence and hatching success of benthic eggs of calanoid copepods in the Bahía Blanca Estuary, Argentina

The seasonal abundance and hatching success of calanoid benthic eggs were examined during the coexistence of Acartia tonsa and Eurytemora americana in the Bahía Blanca Estuary (BBE). The dormancy behaviour of eggs extracted from surface sediment layers was tested by simulating seasonal conditions during incubation. There was a greater abundance of benthic eggs of E. americana (≤8.68×106 eggs m−2) than of A. tonsa, the latter consistently showing low egg abundance (≤0.8×106 eggs m−2). The emergence of most E. americana nauplii occurred at 17°C after the experimental warming phase (refractory phase of 280 days), confirming the diapause character of these eggs. The emergence of the first A. tonsa nauplii from initial cold season samples occurred at 9–12°C after 60–70 days of incubation. However, a 180-day delay in hatching at temperatures ≥15°C was also observed in A. tonsa eggs from the last sampling days of the cold season, thus suggesting an intermediate behaviour between diapause and quiescence. The benthic egg bank in the inner zone of the BBE provides a temporary reservoir for both key copepods, thus contributing in their survival.

Study of apoptosis induction using fluorescent and higher harmonic generation microscopy techniques in Acartia tonsa nauplii exposed to chronic concentrations of nickel

In this study, we applied different fluorescent techniques to analyse the induction of apoptosis in the copepod Acartia tonsa nauplii exposed to low concentrations of nickel chloride (NiCl2). Newly hatched and later naupliar stages were exposed to increasing concentrations of NiCl2 (0.016, 0.025 and 0.063 mg·L−1) for 7 days and then stained with annexin V–FITC, a vital fluorescent probe commonly used to visualise apoptotic cells in live samples. Nauplii were also stained with TUNEL, a non-vital fluorescent probe used to detect apoptosis in fixed copepods. Moreover, we used for the first time, two-photon fluorescence (2PF) microscopy and higher harmonic generation microscopy (second SHG and third THG harmonic generation) to study apoptosis induction in A. tonsa nauplii without the use of fluorescent probes. 2PF and THG intensity increased in samples exposed to higher Ni concentrations, with respect to the control, whereas SHG signals were similar in all treated samples and visualised muscles. Future perspectives on the use of these new technologies to reveal apoptosis are discussed.

Feeding, bioenergetics and growth in the common jellyfish Aurelia aurita and two hydromedusae, Sarsia tubulosa and Aequorea vitrina

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 346:167-177 (2007) - DOI: https://doi.org/10.3354/meps06959 Feeding, bioenergetics and growth in the common jellyfish Aurelia aurita and two hydromedusae, Sarsia tubulosa and Aequorea vitrina Lene Friis Møller*, Hans Ulrik Riisgård Marine Biological Research Centre, University of Southern Denmark, Hindsholmvej 11, 5300 Kerteminde, Denmark *Email: lene.friismoller@marecol.gu.se ABSTRACT: We assessed feeding and growth of the common jellyfish Aurelia aurita and 2 hydromedusae, Sarsia tubulosa and Aequorea vitrina, by examining the effect of temperature, medusa size, prey concentration and prey species on feeding and growth. In growth experiments with A. aurita ephyrae fed different species and concentrations of prey organisms (Artemia sp., Balanus sp., Brachionus sp., Rathkea octopunctata), the specific growth rate increased with increasing prey concentration, and a maximum specific growth rate of about 0.22 d–1 was obtained. For A. aurita medusae fed Acartia tonsa and Artemia sp., maximum growth was about 0.08 d–1. The minimum prey concentration resulting in maximum growth rate was 80 to 100 µgC l–1 for ephyrae (depending on prey type), and about 100 µgC l–1 for medusae. For S. tubulosa fed different prey concentrations of A. tonsa nauplii, the maximum specific growth rates were 0.32 and 0.1 d–1 for 2 and 4 mm individuals, respectively, achieved at prey concentrations between 15 and 30 µgC l–1. Maximum growth rates decreased with initial size in A. aurita and A. vitrina, to become approximately constant at 0.05 to 0.06 d–1. Clearance rates (F, l d–1) of A. aurita offered different prey types increased as a function of the umbrella diameter (D, mm) squared, expressed as F = aD2, where a-value depends on prey type. Both maximum specific growth rate and clearance rate increased exponentially with temperature between 4 and 19°C for ephyrae, and between 8 and 19°C for medusae, but at higher temperatures both growth and clearance decreased markedly. From experiments with A. aurita (both ephyra and medusae) in which growth, ingestion and respiration were measured simultaneously, carbon budgets were constructed for individuals growing at maximum rates when feeding on different prey types. Assimilation efficiency, net growth efficiency, and minimum concentrations of prey organisms needed for sustaining maximum growth were estimated, allowing evaluation of the degree to which jellyfish realize their growth potential in the field, or whether the jellyfish are controlling the zooplankton. KEY WORDS: Clearance rate · Growth of jellyfish · Effect of temperature · Carbon budget · Bioenergetics · Aurelia aurita · Sarsia tubulosa · Aequorea vitrina Full text in pdf format PreviousNextCite this article as: Friis Møller L, Riisgård HU (2007) Feeding, bioenergetics and growth in the common jellyfish Aurelia aurita and two hydromedusae, Sarsia tubulosa and Aequorea vitrina. Mar Ecol Prog Ser 346:167-177. https://doi.org/10.3354/meps06959 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 346. Online publication date: September 27, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

Feeding efficiency of the larval ctenophore Mnemiopsis leidyi A. Agassiz (Ctenophora, Lobata)

Larval stages of the ctenophore Mnemiopsis leidyi rely on metazoan prey, such as Acartia tonsa nauplii and copepodites, to support high growth rates. However, M. leidyi larvae 2.0 mm, nauplii REs plateaued at a mean of 91.03 ± 1.70%. All larvae 2.5 mm reached a maximum copepodite RE of 63.75 ± 3.01%.

Zooplankton feeding ecology: bacterivory by metazoan microzooplankton

Bacterivory by the rotifer Brachionus plicatilis Müller, nauplii and copepodites of the copepods Centropages Krøyer sp. and Acartia tonsa Dana, and the tintinnid Favella panamensis Kofoid & Campbell was examined using fluorescently labelled bacteria (FLB) and epifluorescence microscopy. FLB were < 1 μm in diameter, and were offered at environmental concentrations (1.47−9.08 × 10 6 cells·ml −1). FLB were visible within rotifers, nauplii, copepodites, and tintinnids, confirming ingestion. Rotifer clearance rates (32–418 μl·animal −1·h −1) exhibited no relation with FLB concentration. In some cases rates of clearance of FLB by rotifers were different with alternative phytoplankton food ( Nanochloris Naumann sp.) than in replicates with FLB alone, whereas in other cases presence of alternative food exhibited no clear effects on rates of ingestion of FLB. Clearance rates for all six naupliar stages of A. tonsa nauplii (0–320 μl·animal −1·h −1) were stage-related, with higher rates by NIII-VI nauplii than NI-II nauplii. Nauplii had higher rates of clearance of FLB in the absence of alternative phytoplankton food ( Isochrysis Parke sp.). Clearance rates of FLB by a single stage of Centropages sp. nauplii, A. tonsa CI copepodites and F. panamensis (each obtained at only a single food concentration of either 1.5 or 5.0 × 10 6 cells·ml −1) were within the range of 85–142 μl·animal −1·h −1. These ranges were similar to those of rotifers and A. tonsa nauplii. This is the first report of FLB ingestion by metazoan marine microzooplankton. Although rotifers and ciliates might be expected to ingest small particles such as FLB using ciliary induced feeding currents, the means by which nauplii and copepodites eat FLB is less clear. We propose that they may “eat” bacteria as they “drink” to osmoregulate.

Chronic tributyltin toxicity experiments with the chesapeake bay copepod,Acartia tonsa

Repeated chronic toxicity experiments were conducted with the Chesapeake Bay zooplankter Acartia tonsa to evaluate its sensitivity to tributyltin (TBT). Experiments were initiated with A. tonsa nauplii <48 h old. All tests were conducted with continuous-flow conditions and measured TBT concentrations. Results from a 9-d range finding experiment and two 6-d chronic experiments are presented. TBT test concentrations were maintained with minimal fluctuations over time and toxicity results were similar in the repeated chronic experiments. The range-finding experiment demonstrated severe reductions in survival of A. tonsa at the lowest measured concentration (0.029 μg TBT/L). In the 6-d experiments, 0.023 and 0.024 μg TBT/L were the lowest measured TBT concentrations to significantly reduce survival relative to the controls (i.e., lowest observed effect concentration [LOEC]). No observed effect concentrations (NOEC) measured at 0.012 and 0.010 μg TBT/L were used to calculate chronic values of 0.016 and 0.017 μg TBT/L for these two experiments. A. tonsa nauplii are very sensitive to TBT relative to other estuarine organisms. These toxicity data are environmentally relevant since TBT concentrations exceeding the chronic value for A. tonsa have been reported from numerous locations in Chesapeake Bay.