The Next Bifax Trip Will Go Back To Tallapoosa County

First of all, let me congratulate myself, this is my 200th post on this blog over about 2 years. It just keeps chugging along...

I've sat down and drawn up a list of the dates and sites we've gone down to the Tallapoosa River area looking for stippled studfish. We've visited the sites of 30 of 48 collections in our records, which is at 13 individual sites. This includes almost all of the non-river sites so the project is going well. There remain two sites in Tallapoosa County we haven't visited yet, Sweetwater Creek and a branch of Elkahatchee Creek. There's also Emuckfaw Creek where we found no stippleds in February. I looked up the records today and there have been 7 collections made there over the years, although the largest was of five fish. So I'd like to revisit the place in warm weather when we won't have to worry about stepping into some of the deeper holes in the creek. Tentatively this trip will be on Friday, June 20.

I have an electronic version of Rachel's thesis from last year on black darter reproduction at two sites. I spent an hour this afternoon boiling down some of her introduction for the introduction of a journal article. Here's what I came up with:

The reproductive schedule and effort of a species is a crucial feature of its life history, and is often poorly known in relatively common species. The purpose of this investigation was to compare reproductive traits between two populations of a percid fish, Etheostoma duryi (Henshell), the Blacksided Snubnose Darter, in north Alabama and to closely-related members of the subfamily Etheostomatinae, where such information is available.

E. duryi belongs to the subgenus Nanostoma (Page 1983), which was sometimes previously referred to as Ulocentra. This species is a common inhabitant of runs and pools in streams having a moderate current and a limestone rock substrate throughout the central Tennessee River system in Georgia, Alabama, Tennessee and, probably, Mississippi (Etnier and Starnes 1993).

Page (1983) suggests that spring is the season during which most darters spawn, with southern latitudes typically spawning from February until late April. However, since bodies of water in states having more southern latitudes often have less seasonal variation in water temperature, the darters living there may exhibit a somewhat different spawning pattern. Hubbs (1961a) notes that species spawning earlier in the season were more cold-temperature tolerant than were species spawning later. There is noted latitudinal, geographical, (Hubbs 1958; Hubbs 1961b; Marsh 1984; Parrish et al., 1991), and temporal (Joachim et al., 2003; Heins and Machado 1993) variation in reproductive development within some darter species. As the spawning season approaches, female darters produce increasingly higher percentages of mature ova (often indicated by an increase in size and transparency) (Page and Mayden 1981). The testes of the males become larger and white in color with a spongy texture. There is typically no migration to the spawning grounds because they usually spawn in a certain area within their microhabitat. Nanostoma species are known to attach their eggs to some substrate and subsequently abandon the eggs. Since Nanostoma darters are egg-attachers that abandon their eggs following attachment, one can predict that the females will produce a large number of small eggs.

This study contributes to the natural history of darters. The choice of sites for the study, in that one was in a rural area and one was in an urban area, allows for comparison of environmental impact on darter reproduction. Reproductive traits examined in this study include ovarian and testicular development, the maturation of ova and spermatocytes as the breeding season progresses, and the size and number of ripening ova.This study is unique for two reasons. First, the methodology utilized was new. The study uses a histological approach, which has not been used in darter population studies. Because of the small body size (♂: 32.33-52.95 mm, 0.5-2.6 g; ♀: 28.15-50.06 mm, 0.3-2.2 g) some of the usual methods for measurement could not be employed. Second, most previous studies typically used just one stream for measurement, while data were collected from two streams for this study. One additional aspect of this study that has not been examined much in darters, and has never been studied in E. duryi is the determination of what, if any, effects the presence of the apicomplexan parasite Sarcocystis encapsulated in the tissues of the gastrointestinal region has on their reproduction.

(The above is copyrighted material, 2008, Rachel Bedingfield and Bruce Stallsmith.)