PRESENT STATUS OF DIATOM STUDIES IN THE GULF OF MEXICO 



By Paul S. Conger, Smithsonian Institution 



Very little concerted work has been done on 

 the diatoms of the Gulf of Mexico region to date. 

 Considering its size and diversity of habitat, the 

 Gulf is a virtually untouched area in this regard. 

 The few studies made have been of a somewhat 

 casual, quite limited, and localized nature leaving 

 almost the entire shoreline and open water area 

 of the Gulf completely unexplored. 



Previous records are confined mainly to the 

 southwest corner of the Gulf (Campeche Bay), 

 Mobile Bay on the north, the west coast of Flor- 

 ida (Tampa and Pensacola Bays), the Dry Tor- 

 tugas, and a few in the West Indies, with frag- 

 mentary, unpublished records from a few other 

 places. Few, or almost none of these (see bibli- 

 ography), are well-defined floristic studies. A 

 number of works on diatoms of Honduras and 

 Caribbean waters, not within the Gulf region but 

 closely allied to it in character of flora, add useful 

 supplementary records. 



Most of the previous efl^orts have been con- 

 cerned with mere identification of species with 

 very little data as to precise location, date of 

 occurrence, and habitat. Many of the early 

 listings are included in Schmidt's Atlas der Dia- 

 tomaceenkunde (1876) with references only to 

 the locality but without any further information. 

 Despite the dearth of published records and the 

 very limited territory explored the writer was 

 able to compile from several sources a list (un- 

 published) comprising some 60 genera and about 

 500 species and varieties. The list is incomplete, 

 however, and gives no assurance of what diatoms 

 one may expect to find in the Gulf, because vir- 

 tually no work has been done so far on the pelagic 

 species, their succession and seasonal fluctuations. 

 The diatom flora of many shallow water indenta- 

 tions of the shoreline, of swamps and reefs will 

 also require further studies. 



' Published with the permission of the Secretary of the Smithsonian 

 Institution 



239534 0—54 16 



LITERATURE 



In the appended bibliography are given only 

 those papers which apply specifically to the Gulf 

 or Caribbean waters and such few general works 

 which include the forms found there. For re- 

 liable description of the species concerned it is 

 necessary to consult such useful works as A. 

 Schmidt's Atlas der Diatomaceenkunde (1876), 

 H. Van Heurck's Synopsis des Diatomees de 

 Belgique (1880-85); and H. and M. Peragallo's 

 Diatomees Marines de France (1897-1908). Many 

 of the papers dealing specifically with Gulf dia- 

 toms are merely lists of species or brief unillus- 

 trated accounts which cannot be used for iden- 

 tification. 



The distribution of many diatoms is so wide- 

 spread that it is sometimes necessary, and quite 

 satisfactory, to rely for their identification on 

 literature pertaining to areas entirely remote 

 from the one in question. This is true not only 

 of the free-floating species, but also of many 

 bottom-dwelling and attached forms, such as, for 

 instance, Melosira sulcata and Actinoptychus 

 undulatus, which, despite a sedentary existence, 

 are widely dispersed. 



The standard plankton works of Gran, Nor- 

 disches Plankton (1905), and Marie Lebour's 

 Plankton Diatoms of Northern Seas (1930), will 

 be found applicable to a goodly number of tropical 

 forms, especially the Rhizosolenias and Chaetoceros 

 species, and other typical plankton diatoms 

 although there may be some species in the Gulf 

 waters which will not be found in these publications. 



CAMPECHE BAY 



Mann (1925) called attention to the remarkable 

 correspondence between the diatom flora of the 

 Campeche Bay in the Gulf of Mexico to that of 

 the waters around the Philippine Islands. The 

 list included by him in the introduction to his 

 paper contains 78 forms common to both places 



227 



