b PLANTS IlSr PONDFISH CULTURE. 



IMPORTANCE OF ALGAL MATS AS FORAGE. 



The larva of the chironomid, Orthoclad'ms nivoriundus, forms an 

 important item in j:he dietary of the hirgemouth bhick bass. In 

 turn the alga Mougeotia and other filamentous types supply forage 

 for the chironomids. Thus these common pond plants contribute 

 in a material way to the support of the bass. 



Xearly all of the aforementioned algce are commonly distributed 

 in ponds. Where they do not occur and the region is within 

 their i-ange, they can easily be introduced into the ponds by trans- 

 ferring a roll or wad of the alga befoiXi it dries out. If the alga is 

 to be transferred by mail it should be rolled in a wet cloth, wrapped 

 in thick paper, and dispatched at once. 



Unfortunately the notion exists that algal mats serv^e no useful 

 2)urpose, and wasteful practices prevail in the seining operations. 

 "Without discrimination they are raked out, thrown upon the bank, 

 and left to decompose, regardless of kind or function in the economy 

 of the pond. The author's obserA^ations thus far on the value of 

 algal mats, which may be called locally " moss," " moss blanket," or 

 " water moss," lead to the conclusion that discrimination must be 

 exercised if the ponds are to be properly stocked with useful forage 

 ])lants. For help in such discrimination the species which com- 

 monly produce the algal mats, or " moss," floating on the surface of 

 ])onds, are given as follows: Oladophora crispataj Ilydrodictyon 

 Tcticulatu^n^ Plthophora (xdogonia var. vaiocherioides, Q^dogonmm 

 7)iartenicense^ RMzodonhim hieroglyphicum^ and Spirogyra species. 

 Generally not one form alone produces the mat or blanket but a com- 

 bination, as Cladophora and Pithophora; Hydrodictyon, ODdogo- 

 nium, and Cladophora, etc. 



Blankets in which Cladophora, Pithophora, and Rhizoclonium 

 are the prominent forms appear to be least desirable, though the 

 subject warrants further investigation. This blanket complex re- 

 produces and forms a coarse, thick mat which readily covei-s a pond 

 and shuts out the light. Under control, however, this mat may be 

 regarded as useful. It should be conserved near the edges only. 



FIELD CHARACTERS OF VARIOUS ALGAL MATS. 



The following field characters will assist in discriminating the 

 different kinds of algal mats or blankets: 



Mmifjeotm genu^exa when abundant forms a loose, filmy, floating 

 aggregation of delicate, light-gi'een, gossamerlike threads lightly 

 suspended near the surface of the water and easily wafted about 

 by the wind. It is as difficult to scoop up in the hand as a floating 

 spider web would be. This alga does not accumulate in sufficient 

 quantity to become detrimental, since its filaments are so delicate and 

 form so loose a mesh that light is not appreciably shut out by it. 



MougeoticL sphccrocarpa is also a delicate alga, though a little less 

 so than M. genu^exa.^ and its growth habit is different. It has a 

 light yellow-green frothy look and floats on the surface of the water 

 as a thin film. It is found in the sheltered places usually, though 

 it may spread over a small pond as a surface fihn when undisturbed 

 by the wind. The frothy appearance is due to the very active photo- 

 synthetic capacity of tlie alga, the oxygen bubbles being confined, 



