Details

Autor(en) / Beteiligte

• Fahnenstiel, Gary L.
• Carrick, Hunter J.
• Iturriaga, Rodolfo

Titel

Physiological Characteristics and Food-Web Dynamics of Synechococcus in Lakes Huron and Michigan

Ist Teil von

• Limnology and oceanography, 1991-03, Vol.36 (2), p.219-234

Ort / Verlag

Waco, TX: American Society of Limnology and Oceanography

Erscheinungsjahr

1991

Link zum Volltext

Quelle

EZB*

Beschreibungen/Notizen

• Single Synechococcus cells accounted for an average of 10% (range 1-26%) of surface mixed-layer primary production in Lakes Huron and Michigan in 1986-1988. Maximal photosynthetic rates $(P_max)$ were relatively low $(range = 1.9-6.0 fg C cell^-1 h^-1)$ and no significant photoinhibition was found at irradiances as high as 3.0 Einst $m^-2 h^-1$. Synechococcus growth rates estimated by four techniques (ampicillin, $^14C$ uptake, dilution, and small inocula) ranged from 0.1 to $0.9 d^-1$ with a mean of 0.37. Although substantial variability was noted among techniques on any one date, on average all estimates were in reasonable agreement with the exception of the dilution estimates which were significantly lower (P<0.01). Three techniques for estimating grazing loss rates (ampicillin, dilution, and $^14C-labeling$ of Synechococcus) provided similar estimates ranging from 0.1 to 0.7 $d^-1$. On specific dats, grazing loss rates were 33-120% of growth rates, suggesting that grazing was the major loss for Synechococcus populations in these lakes. Most of the grazing loss (68%) was attributable to small $(4-10 !mum)$, heterotrophic flagellates and ciliates. Crustaceans and rotifers accounted for only a small percentage of total grazing loss (5-21%) even when Daphina accounted for 40% of crustacean biomass.