Fauna des Süßwassers. Parasiten. 99 



Fauna des Süßwassers. 



241) Shelford, Yictor E., Ecological Succession. III. A Reconnais- 

 sance of its Causes in Fonds with Particular Reference to Fish. 

 In: Biol. Bull. XIII, No. 1, December 1911, S. 1—38, 25 tables. 



This paper is a study of the fauna of ponds constituting an ecological age 

 series, the ecological age being determined by study of the auiount of sand bot- 

 tom, humus etc. The physiographic history of the region is in accord with the 

 facts used in deciding age. There are fourteen of these ponds, forming a graded 

 series of ecological age. The study presents (IJ the physical character of the 

 ponds with reference to topography, character of the bottom, and salts and 

 gases in Solution; (2) a study of the biological content of the ponds; and (3) an 

 attempted estimation of the causes of succession of various species of fish in the 

 series of ponds. The general suramary of tentative conclusions follows: 



„1. The quantity of bacteria, plancton, Vegetation and large animals in- 

 creases as a pond grows older. 2. Terrigenous bottom and oxygen content de- 

 crease as a pond grows older. 3. The distribution and succession of fish are not 

 determined by kind of food; kind of food eaten is determined by the availability 

 in localities suitable in other respects. 4. Fish are not necessarily present where 

 food is quantitatively greatest. 5. The food and game fishes here considered 

 are closely associated with their breeding conditions to the neglect of depth of 

 water, food etc. 6. Low oxygen content on breeding grounds is a sufficient 

 cause for their absence from the older ponds. 7. Conditions outside the breeding 

 season are probably of secondary iraportance in the success of fish in a given 

 locality. 8. The food interests and breeding interests of the food and game fish, 

 here considered are decidedly antagonistic. The former continually encroaches 

 upon the latter. 9. Successful fish culture in ponds and small lakes depends 

 upon the maintenance of balance between the breeding and feeding conditions 

 10. Animal succession in ponds is due to an unused increment of excretory and 

 decomposition materials which causes an increase in Vegetation, a decrease in Og, 

 on the bottom and a general change in surrounding conditions, all primarily 

 affecting breeding. 11. Succession of species is the result of stability of the 

 mores of species concerned; when mores are flexible species do not succeed one 

 another but continue with changes in behavior and physiological characters." 



Lillie (Chicago). 

 Hierzu Nr. 253. 



Parasiten. 



/242) Link, E. (Berlin, Tierphysiol. Inst.), Über eine in der Haut von Fischen 

 parasitisch lebende grüne Alge. In: Zool. Anz. 37,23 — 24, S. 506 — 510, 

 3 Fig., 1911. 



Bei der Karpfenbrut einer Lausitzer Teichwirtschaft fand der Verf. in der 

 Haut einzellige, grüne, zu der Familie der Protococcaceen gehörige Algen, die 

 er als Chlor ochytrium piscicolms beschreibt. Im allgemeinen sieht man die Algen 

 ohne jede Störung im Gewebe liegen. Wenn jedoch die Algen am Ende ihrer 

 Wachstumsperiode zur Teilung schreiten, tritt eine starke Trübung des angren- 

 zenden Gewebes infolge entzündlicher Prozesse ein. Dann findet durch massen- 

 hafte Ansammlung von Bindegewebszellen eine Abkapselung des Fremdkörpers 

 statt, indem ihn die Bindegewebszellen ringförmig umschließen und so eine Hülle 



