July 2000 Progress Report on Question AQUA-5

AQUA-5: July 2000 Progress Report

"What are the history, status, and likely future of aquatic habitats and species in the South?"

July 18-19, 2000, Nashville TN

The diversity of aquatic species in the South is unmatched anywhere in the United States and, for some groups of animals, in the world. Aquatic habitats range from ephemeral ponds less than an acre in size to some of the largest rivers in North America. Most of the rare aquatic species are dependent on very specific types of waters that cannot be substituted.

To assess the likely future for these species requires a thorough understanding of the life history needs of the taxonomic group to which they belong, i.e. amphibians. In some cases, individual life history needs have to be assessed. These needs include feeding hierarchies, reproductive strategies, and escape cover.

Which aquatic species to assess, in the 13-state region, is a major consideration. The number of potential species to be investigated could be unmanageable. The appropriate species to study would appear, at first glance, to be the federally listed species; but this list does not reflect well the taxonomic group status. Certain taxonomic groups have received more attention than others have and the listing process may take years. A better list is maintained by The Nature Conservancy and state Heritage Network. This list ranks species based on their global rarity. Each species is given a G-rank from 1 through 5 with other possibilities (i.e. GX = presumed extinct). G1 species are the rarest with 6 or less occurrences while G5 are “demonstrably secure”. See Appendix A for a complete listing of these criteria.

Table 1 shows the G-ranks for all of the aquatic species in the Southern Region. Those species ranked as G4 or G5 will no longer be considered in this evaluation since by definition (TNC Global Rankings) they are demonstrably or apparently secure globally. Also excluded were terrestrial and marine species.

Table 1. Global ranking of species by taxonomic group.

Taxonomic Group	Global Rank		Terrestrial	Marine	Rare Aquatic Species
Taxonomic Group	G1-G5	G4-G5	Terrestrial	Marine	Rare Aquatic Species
Amphibians	218	152	17	0	49
Bivalves	79	1	0	0	78
Crustaceans	332	152	0	0	180
Fish	804	490	0	55	259
Gastropods	303	26	15	2	260
Insects	4334	4141	124	0	69
Reptiles	369	285	43	12	29
Totals	6436	5247	199	69	924

The remaining 924 species will be evaluated, by taxonomical group or individually, for their tolerance to sedimentation, silvicultural chemicals, and temperature changes.

Table 2 displays a breakdown of the taxonomic groups into families, genera and species. Also shown are the number of G1 through G3 species federally listed as Threatened or Endangered and the percentage. Gastropods appear to be fairly secure. In reality, more species and genera of snails have gone extinct than any other taxonomic group.

Table 2. Taxonomic groups by families, genera and species.

Taxonomic Group	Families	Genera	G1-G3 Species	Threatened/ Endangered (percentage)
Amphibians	10	16	49	5 (10%)
Bivalves	3	27	78	73 (94%)
Crustaceans	7	20	180	9 (5%)
Fish	15	57	259	45 (17%)
Gastropods	10	46	260	9 (3%)
Insects	17	30	69	2 (3%)
Reptiles	6	13	29	8 (28%)
Totals	68	209	924	151