Egg viability in the copepod Temora stylifera

Several experiments were performed to determine the effects of cell toxin concentration, composition and toxicity of Alexandrium minutum on ingestion rate, egg production, hatching success and naupliar fitness of the copepod Acartia clausi. A combination of A. minutum and nontoxic algae (Prorocentrum micans, Tetraselmis suecica and Isochrysis galbana) was used as food. Copepods ingested a higher amount of A. minutum cells as the concentration of these toxic dinoflagellates increased, and also in response to decreasing total food concentration available for the copepods. A positive relationship was obtained between A. minutum cells ingested by copepods and total toxin concentration per copepod. Hatching success and naupliar production were lower when copepods ingested a higher amount of toxic dinoflagellates. This negative effect could has been due to the accumulated toxins in the egg and copepod tissues, and was higher when A. minutum had a higher cell concentration of GTX1. Finally, the results obtained from nauplii incubated with T. suecica and I. galbana showed that nauplii hatched from females fed non-toxic food (T. suecica and I. galbana) reached copepodite stage earlier than those nauplii hatched from females fed with a combined of toxic (A. minutum) and non-toxic (T. suecica and I. galbana) food. KEY WORDS: Dinoflagellate · Copepod · Toxins · PSP · ReproductionResale or republication not permitted without written consent of the publisher

Section: Discussionmentioning

confidence: 99%

Short-term and long-term effects of the toxic dinoflagellate Alexandrium minutum on the copepod Acartia clausi

Frangópulos¹,

Guisande²,

Maneiro³

et al. 2000

“…Toxic Nodularia spumigena is low-quality food for copepods (Sellner et al 1996, Schmidt & Jónasdóttir 1997, Koski et al 1999a, which is in accordance with our findings on low pellet production rates on this species. In contrast, Ianora & Poulet (1993) suggested that pellet production increases on low-quality diet because bad food can neither be properly assimilated nor transferred into production. Some studies have also suggested that low-quality food may be fed at a high rate to attain enough essential elements and energy for maintenance and growth, i.e.…”

Section: Pellet Productionmentioning

confidence: 99%

Fate of cyanobacterial toxins in the pelagic food web: transfer to copepods or to faecal pellets?

Lehtiniemi¹,

Engström‐Öst²,

Karjalainen³

et al. 2002

Toxic cyanobacterial blooms are a common phenomenon in the Baltic Sea. The fate of the toxin in the food web is largely unknown. We studied the effect of algal diets on production of pellets and toxin content of the calanoid copepod Eurytemora affinis in the northern Baltic Sea. Fieldcollected copepods were fed with (1) cultured toxic cyanobacteria Nodularia spumigena; (2) cultured non-toxic flagellates Brachiomonas submarina; and (3) a natural phytoplankton assemblage. Natural phytoplankton was dominated by non-toxic cyanobacteria Aphanizomenon flos-aquae, but also remnants of toxic N. spumigena were found. Pellet production was highest on cultured B. submarina, second highest on N. spumigena and lowest on natural phytoplankton. Because pellets were produced on cultured N. spumigena, this shows that toxic cyanobacteria are consumed if no other food is available. The toxin content of E. affinis was highest in copepods fed with cultured N. spumigena, but toxin was also found in lower concentrations in animals fed with natural phytoplankton. Results indicate that an accumulation of toxins mainly occurs during a growing phase of cyanobacterial blooms. The toxin concentration in the pellets was approximately 6 to 12 times lower than in the copepods. We suggest that a large part of the ingested toxin accumulates in copepod tissues, although some is egested with pellets. This may lead to transport and, possibly, accumulation of cyanobacterial toxin in higher pelagic trophic levels in the Baltic Sea. KEY WORDS: Cyanobacterial toxin · Nodularia spumigena · Toxin transfer · Copepods · Faecal pelletsResale or republication not permitted without written consent of the publisher

“…Mar Ecol Prog Ser 216: [151][152][153][154][155][156][157][158][159][160][161][162][163][164][165] 2001 Some studies have found consumption of diatoms by females to result in low hatching success (Ianora & Poulet 1993, Poulet et al 1994, Chaudron et al 1996, Ban et al 1997), but this is still open to discussion (Jónasdóttir & Kiørboe 1996, Jónas-dóttir et al 1998, Irigoien et al 2000b.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Influence of algal diet on growth and ingestion of Calanus helgolandicus nauplii

Rey¹,

Harris²,

Irigoien³

et al. 2001

Nauplii of Calanus helgolandicus were raised from eggs, laid within a 12 h period, to Copepodite Stage I (CI) on 5 different species of algae at high concentrations at 15°C. The diets used were Isochrysis galbana (5 µm spherical diameter), Rhodomonas baltica (7 µm), the coccolithophorid Pleurochrysis carterae (12 µm), the diatom Thalassiosira weissflogii (14 µm) and the dinoflagellate Prorocentrum micans (30 µm). Each day a sample was taken and preserved for later cohort analysis. Growth was estimated from CHN samples collected almost daily, from which naupliar stages were also distinguished. Ingestion was measured for each naupliar feeding stage. The fastest development was obtained with I. galbana and P. micans. We found the highest value of carbon and nitrogen content of Naupliar Stages NV to CI for individuals reared on the smallest algae, I. galbana and R. baltica. However, ingestion rate in terms of carbon or nitrogen was lowest with these same (smallest) algae. Therefore, the gross growth efficiency was highest for the smallest algae. These results suggest the following: Firstly, that factors influencing development time and weight in stage are different; weight in stage is negatively related to algal size, whereas development time is independent of it. The quality of the algal biochemical components could be the factor influencing development. Secondly, that small algae are fully assimilated in the gut whereas larger cells, i.e. those with indigestible components around the cell (theca, frustule, calcium layer) are only partly assimilated.KEY WORDS: Calanus helgolandicus · Nauplii · Growth · Development · Ingestion · Efficiency · Food quality Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 216: [151][152][153][154][155][156][157][158][159][160][161][162][163][164][165] 2001 Some studies have found consumption of diatoms by females to result in low hatching success (Ianora & Poulet 1993, Poulet et al. 1994, Chaudron et al. 1996, Ban et al. 1997), but this is still open to discussion (Jónasdóttir & Kiørboe 1996, Jónas-dóttir et al. 1998, Irigoien et al. 2000b.Development, body size and weight of nauplii and copepodites have been negatively related to temperature (Thompson 1982, Peterson 1986, Hopcroft & Roff 1998. Ontogenetic differences in the physiological response to temperature in copepods have also been noted (Pedersen & Tande 1992). The effect of food quantity on growth processes has often been unclear (Hart 1990, Hopcroft & Roff 1998, but some studies have clearly established an effect of food limitation on wild nauplii (Lopez 1991, Melle 1998, and this has been further substantiated by laboratory studies (Green et al. 1991, Lopez 1996.Food quality is another factor which has to be considered when examining variability in naupliar growth (Mullin & Brooks 1970, Paffenhöfer 1971, 1976, Fernández 1979a,b, Diel & Klein Breteler 1986, Verity & Smayda 1989. The major algal characteristics of importance are biochemical content, morphology, and di...