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Seston quality controls zebra mussel (Dreissena polymorpha ) energetics in turbid rivers (1998)

Schneider, Daniel W. ; Madon, Sharook P. ; Stoeckel, James A. ; [et al.]

Springer

Oecologia 117 (1998), S. 331-341

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ISSN: 1432-1939

Keywords: Key words Food quality ; Seston ; Suspended sediment ; Pseudofeces ; Particle selection

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Feeding processes and energetic balance of zebra mussels were both related to the quantity and quality of natural seston. Filtration rate and pseudofeces production increased while clearance rate remained constant with increasing seston concentration. Ingestion rate, assimilation efficiency, and assimilation rate all increased with increasing food quality, measured as the ratio of organic to inorganic material in the seston. Respiration rate did not change with either food quantity or quality. As a result, scope for growth declined with decreasing food quality, and fell below 0 cal mg−1 h−1 at an organic:inorganic ratio of 0.5. The association between feeding processes and food quality appears related to a breakdown in the ability of zebra mussels to selectively ingest high-quality organic particles when the organic content of the seston is low. Ingestion, assimilation efficiency, assimilation rate and scope for growth were all higher when seston was amended with an addition of a natural assemblage of algae. Food quality may be a better indicator of environmental conditions suitable for growth than food quantity. These results suggest that the conditions of high suspended inorganic sediment concentrations in large turbid rivers represent a difficult growth environment for the zebra mussel.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420050666

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Development of the intrarenal vascular system of the puppy kidney (1979)

Evan, Andrew P. ; Stoeckel, James A. ; Loemker, Vickie ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

The @Anatomical Record 194 (1979), S. 187-199

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ISSN: 0003-276X

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Medicine

Notes: This study investigates the development of the vascular system of the puppy kidney (1-21 days after birth) after preparing casts of the renal vessels. At two days, the intrarenal vascular system distal to the afferent arteriole is strikingly different than that of the adult. The glomeruli of the outer cortex consist of a single dilated vessel while those of the mid and inner cortex possess an increasingly larger number of capillary loops. The efferent arterioles vary greatly in appearance from outer to inner cortex. Those in the nephrogenic zone are characteristically short and narrow and join a larger venous vessel termined a sinusoidal capillary. An efferent system somewhat similar to that of the adult is seen in the mid and inner cortex. One of the most obvious differences noted between the puppy and adult kidney is the relative lack of peritubular capillary networks throughout the cortex of the puppy kidney. The puppy possesses large, irregular vessels termed sinusoidal capillaries. The most rudimentary sinusoids are found in the outer cortex with more mature vessels in the inner cortex. The vascular arrangement of the efferent arteriole and sinusoidal capillary appears as a post-glomerular shunt. Functionally, the shunt would direct blood flow away from the proximal tubule and thus could result in a low extraction ratio and Tm for secreted solutes.

Additional Material: 23 Ill.