2008 SOUTHEASTERN NATURALIST 7(3):449–458
Life-history Aspects of Notropis xaenocephalus (Coosa
Shiner) (Actinopterygii: Cyprinidae) in Northern Georgia
Danielle M. Jolly1 and Steven L. Powers1,*
Abstract - The biology of Notropis xaenocephalus (Coosa Shiner) was investigated
using 12 monthly collections from Moore Creek (Etowah River Drainage) in Cherokee
County, GA. Specimens were collected primarily from pools with slow current
and examined to determine age, growth, food habits, and reproductive cycle. The
bulk of the diet consisted of Diptera adults, Chironomidae larvae, Hymenoptera, and
unidentified insect parts. Feeding was greatest in the spring and lowest during winter
months. Spawning occurred in spring to early summer, with 86–540 mature oocytes
ranging from 0.9 to 1.3 mm in diameter present in specimens collected from March to
June. Sexual maturity occurred at 1 year of age. The largest specimen collected was a
female 63.8 mm SL and 4.4 g total weight. Two specimens estimated to be 38 months
of age were the oldest specimens collected. As one of the most abundant minnows in
the upper Alabama River Drainage, these findings provide a greater understanding of
the ecology of this imperiled ecosystem.
Notropis xaenocephalus (Jordan) (Coosa Shiner) was described in 1877
from specimens collected in a tributary to the Etowah River near Rome, GA
(Gilbert 1998). It is a member of the N. texanus Girard (Weed Shiner) species
group and appears to be sister to the widespread N. boops Gilbert (Bigeye
Shiner) (Mayden 1989, Swift 1970). Notropis xaenocephalus is often abundant
in small streams throughout the Coosa and Tallapoosa river drainages
of northwest Georgia and northeast Alabama and is distinguished from other
minnows within its range by its terminal mouth, large eye, and robust body.
Little is known of the biology of N. xaenocephalus other than a spawning
season from April to July as indicated by collections of tuberculate specimens
during these months (Boschung and Mayden 2004). The primary objective
of this study was to document selected aspects of the life history of N. xaenocephalus
and briefl y compare them to those of its sister species N. boops.
Fish were collected from Moore Creek upstream of its confl uence with
Shoal Creek (34.3240°N, 84.5636°W), near Waleska in Cherokee County,
GA (Fig.1). Moore Creek is a typical upland second-order tributary of the
Etowah River between 3.1 and 6.4 m wide and less than 1.0 m deep at
normal fl ows. Substrate is primarily gravel to cobble with sporadic bedrock
in riffl es, gravel to sand in runs, and sand and silt in pools. Notropis
xaenocephalus were collected primarily from pools with slow current.
!Department of Biology, Reinhardt College, Waleska, GA 30183-2981. *Corresponding
author - firstname.lastname@example.org.
450 Southeastern Naturalist Vol.7, No. 3
Upstream of the study area, the Moore Creek watershed is mostly forested
with moderate agricultural use and sparse residential development. Water
temperatures during times of collection ranged from 5 °C in December 2004
and January to 26 °C in July 2005. Species richness of fishes within the
study reach is relatively high, with 30 species collected during this study. A
complete list of species collected from Moore Creek near its confl uence with
Shoal Creek can be found in O’Kelley and Powers (2007).
Notropis xaenocephalus and vouchers of associated species were collected
over a one-year period from August 2004 to July 2005 by monthly
sampling near the end of each month using a 3.3-m x 1.3-m seine and a
Smith-Root model 24 backpack electrofisher. A total of 305 specimens were
collected, preserved in 10% formalin, rinsed with water, and transferred
into 70% EtOH for long-term storage. Specimens were accessioned into
the University of Alabama Ichthyological Collection (UAIC 14729-14740).
Observations of behavior were conducted by snorkeling in multiple 10-minute
intervals on 26 May and 28 June 2005 with qualitative descriptions of
behavior noted immediately following snorkeling.
Standard length (SL) of preserved N. xaenocephalus was measured using
digital calipers and recorded to the nearest 0.01 mm. Sexual size dimorphism
was detected using a two-sample t-test of SL; therefore, all age and growth
analyses were performed separately for sexes. Specimens were blotted dry
and total weight (TW), eviscerated weight (EW), and gonad weight (GW)
were measured using a digital analytical balance and recorded to the nearest
0.001 g. All statistical analyses were executed using Data Desk 6.0 (Data
Description, Inc., Ithaca, NY) at a significance level of alpha equal to 0.05.
In reference to regressions, independent variables are listed first and dependent
variables second unless otherwise noted.
Figure 1. Map of Notropis
xaenocephalus study area in
Moore Creek (34.3240°N,
84.5636°W), near Waleska
in Cherokee County, GA.
2008 D.M. Jolly and S.L. Powers 451
Standard length and EW were plotted against month. Gaps of 3 mm or
more in the SL of specimens from a single month were considered indicative
of different age classes (e.g., for March, all specimens were 29.52–38.06,
47.74–54.71, or 61.34–63.76 mm SL with each cluster lacking gaps approaching
3 mm). If 3 mm gaps in SL did not occur in a particular month, age
classes were delineated by extrapolating lines from gaps in adjacent months.
Gaps indicative of age classes appear in a frequency distribution of selected
months (Fig. 2).
Due to high gonadosomatic index (GSI) values found in specimens
collected in April and May, we assumed spawning occurred in June for
estimating age of individuals. Specimens less than 12 months of age were
counted as age 0+, specimens 12–23 months were counted as age 1+, specimens
24–35 months were counted as age 2+, and specimens greater than
36 months were counted as 3+. Proportion of total specimens collected
represented by each age class was calculated to approximate the age-class
distribution of the population. A chi-square goodness-of-fit test of age in
months was used to test differences in lifespan among sexes. Regressions by
least sum of squares were performed for SL and the natural log of EW.
The anterior third of the gastrointestinal track was opened and its contents
were removed and weighed using a digital analytical balance and recorded
to the nearest 0.001 g. Weight of gut contents for specimens with empty guts
was recorded as “0.” One-way analysis of variance was performed on weight
of gut contents/EW to test differences in feeding among different months.
Variety of gut contents was the total number of different food items in each
specimen. Regressions by least sum of squares were performed for EW and
Figure 2. Frequency distribution of standard length (SL) in categories of 3 mm increments
for Notropis xaenocephalus collected in August and December 2004 and
March 2005 from Moore Creek.
452 Southeastern Naturalist Vol.7, No. 3
weight of gut contents as well as for EW and variety of gut contents to test
infl uence of size on feeding. Food items were counted and identified to the
lowest taxonomic category possible following Thorp and Covich (1991) and
Merritt and Cummins (1996). Due to mastication by pharyngeal teeth, most
food items were not identifiable below the level of family, order, or class.
Gonadosomatic index (GSI) was calculated by dividing GW by EW.
One-way analysis of variance was performed to test mean differences in GSI
among months. In gravid females, greatly enlarged (≈1 mm in diameter),
fully yolked, mature oocytes were counted, and five representative oocytes
were measured to provide an approximation of ova size and number (see
Heins and Baker 1988). Smaller oocytes (<0.5 mm in diameter) were not
counted or measured. Regression of SL as a predictor of number of mature
oocytes was performed to test the infl uence of size on fecundity.
The largest specimen collected was a female 63.8 mm SL and 4.4 g TW
taken in March. The smallest specimen collected was a female 25.1 mm SL
and 0.26 g TW taken in September. The September collection also provided
the earliest capture of young-of-the-year specimens ranging from 25.1–33.5
mm SL (mean = 30.5, SD = 2.98). For all collections, females were outnumbered
by males 0.85:1. Sexual size dimorphism was detected, with
mean SL for females and males 47.7 (SD = 7.18) and 44.4 (SD = 6.55) mm,
respectively (P < 0.001). Due to this sexual size dimorphism, the following
results are presented for females and males, respectively, unless otherwise
noted. Standard length increased with age in months (R2 = 80.6%, P < 0.001;
R2 = 71.8%, P < 0.001). Visual inspection of the data suggested a curvilinear
relationship between SL and EW, so we log transformed EW before regressing
it with SL (R2 = 96.8%, P < 0.001; R2 = 96.1%, P < 0.001). Mean SL and
EW by month are presented for each sex in Figures 3 and 4. Growth rates
appear to increase in spring as indicated by length and weight increases
in specimens approximately 1, 2, and 3 years of age (Figs. 3 and 4). Of the
305 specimens collected, 23.9% were age 0+, 62.6% were age 1+, 12.5%
were age 2+, and 1% were age 3+. Median age in months was different
among sexes (P = 0.001) with the median age for males being 14 months
(SD = 6.03) and for females being 19 months (SD = 7.20). Maximum age of
specimens captured was 38 months and did not differ among sexes.
During snorkeling, Notropis xaenocephalus were observed in pools with
slow current and in the lowermost reaches of runs mostly facing upstream
feeding on benthic and drifting material. They were generally located downstream
of Campostoma oligolepis Hubbs and Greene (Largescale Stoneroller)
and N. chrosomus (Jordan) (Rainbow Shiner), feeding in riffl es and
the uppermost reaches of runs. Unidentified insect parts made up 26.7% of
all food items in N. xaenocephalus examined. Diptera adults, Chironomidae
larvae, and Hymenoptera (Formicidae) made up 26.3%, 19.5%, and 9.2% of
all food items, respectively (Table 1). Of all specimens examined, 59% of
GI tracks were empty. Feeding was not uniform across all months (F = 2.35,
2008 D.M. Jolly and S.L. Powers 453
P = 0.009) and appeared to be greatest in May, with both variety of food
items (n = 7) and weight (0.005 g, SD = 0.006) of gut contents at their peaks
then. Feeding appeared to decrease during July with a low mean weight of
Figure 3. Standard length (SL) in mm ± one standard deviation by age in months for
Notropis xaenocephalus collected from Moore Creek between August 2004 and July
Figure 4. Eviscerated weight (EW) in g ± one standard deviation by age in months
for Notropis xaenocephalus collected from Moore Creek between August 2004 and
454 Southeastern Naturalist Vol.7, No. 3
gut contents (0.001 g, SD = 0.003), low total variety of food items (n = 3),
and 76% of GI tracks empty. Of the specimens collected in December, 84%
had empty guts, with three specimens (12%) containing detritus only, and a
single specimen containing a single nematode and unidentified insect parts.
A low proportion of the variation in the weight of gut contents was explained
by EW (R2 = 9.3% for females and 2.9% for males), but the relationship was
significant (P < 0.001 for females, P = 0.029 for males). Little of the variation
in variety of gut contents was explained by EW as regressions were not
significant (P = 0.196 for females, 0.0515 for males).
No spawning behavior was observed during snorkeling, but mean and
individual GSI peaked in spring with values greater than 0.05 only in specimens
from March to June. Water temperatures during collections for these
months were 11 ºC, 15 ºC, 16 ºC, and 25 ºC, respectively. The highest GSI for
a single individual was 0.39 in a female measuring 51.2 mm SL from April
(Fig. 5). Mean GSI was not uniform among months for females (F = 71.1,
P < 0.001) or males (F = 29.1, P < 0.001) as April had the highest mean
GSI for both sexes, with values of 0.288 (SD = 0.087) for females and 0.025
Table 1. Gut contents of Notropis xaenocephalus from Moore Creek by month. Numbers for
each food item indicates total number of individuals for that item. Detritus and unidentified
insect parts are exceptions due to the difficulty quantifying them. These two items are noted
by occurrence within a single gut (e.g., the occurrence of detritus in two guts from a month is
denoted as “2”). % all = percent of all contents.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total all
# of specimens 26 28 25 25 25 25 25 28 25 25 25 25 307
Detritus 6 1 1 1 3 12 4.6
Nematoda 1 1 0.4
Hydrachnida 1 1 0.4
Diplopoda 1 1 0.4
Unidentified 5 2 2 9 11 16 5 9 10 1 70 26.8
Collembola 1 1 0.4
Odonata 1 1 2 0.8
Ephemeroptera 4 1 1 6 2.3
Plecoptera 1 1 2 0.8
Hemiptera 1 1 2 0.8
Coleoptera 1 1 2 1 5 1.9
Hymenoptera 3 7 8 5 1 24 9.2
Trichoptera 1 2 1 2 6 2.3
Chironomidae 5 3 6 21 3 1 11 1 51 19.5
Simulidae 2 1 1 4 1.5
Tipulidae 1 1 0.4
Pupae 1 1 1 3 1.1
Adults 10 2 3 21 16 9 8 69 26.4
Empty 13 23 21 16 12 8 19 14 13 12 8 21 180
Items/specimen 0.81 0.36 0.24 0.72 2.32 1.68 0.56 0.68 0.48 1.32 0.92 0.20
% empty 50.0 82.1 84.0 64.0 48.0 32.0 76.0 50.0 52.0 48.0 32.0 84.0
2008 D.M. Jolly and S.L. Powers 455
(SD = 0.007) for males (Figs. 5 and 6). The lowest mean GSI values were in
September for females (0.008, SD = 0.004) and November for males (0.005,
SD = 0.002) (Figs. 5 and 6). Gravid females were collected from March to
Figure 5. Gonadosomatic index (GSI) by month of the year (1 = January, 2 = February,
etc.) for Notropis xaenocephalus females collected from Moore Creek between
August 2004 and July 2005.
Figure 6. Gonadosomatic index (GSI) by month of the year (1 = January, 2 = February,
etc.) for Notropis xaenocephalus males collected from Moore Creek between
August 2004 and July 2005.
456 Southeastern Naturalist Vol.7, No. 3
June and contained between 86–540 (mean = 256.7, SD = 108.1) mature
oocytes ranging from 0.9 to 1.3 mm in diameter. Ovaries of gravid females
appeared to contain a single group of mature oocytes. Standard length was
not a significant predictor of number of mature oocytes in gravid females
(R2 = 6.3%, P = 0.06), and the youngest specimens approaching sexual maturity
appeared to be 10 months of age.
Much of the biology of N. xaenocephalus appears similar to that of N.
boops. The above results allow us to conclude that N. xaenocephalus live to
a maximum age of approximately three years, increase feeding and growth
during spring, spawn from May to June, and feed primarily on aquatic and
terrestrial insects. By understanding aspects of the life history of this key component
of the upper Alabama River Drainage, we are better able to understand
the ecology of this imperiled ecosystem allowing for the composition and
implementation of more effective conservation and management strategies.
The increase in size at approximately 1, 2, and 3 years of age (Figs. 3 and 4)
coincides with increases in feeding and indicates increased growth rate in the
spring. The low proportion of age 2+ and 3+ specimens suggests that few individuals
survive to the maximum age as is typical of most species in the N.
texanus group (Boschung and Mayden 2004), and the low number of age 0+
specimens collected is likely due to the ease at which small specimens pass
through the 9.5-mm mesh of the 3.3-m x 1.3-m seine. While maximum age does
not appear to be different among sexes (38 months for both males and females),
median age was greater for females. Only 28% of specimens greater than 24
months in age were males despite the sex ratio for all specimens collected being
0.85:1 in favor of males. This shift in sex ratio by age class is similar to that of
N. rubellus (Agassiz) (Rosyface Shiner) and N. lutipinnis (Jordan and Brayton)
(Yellowfin Shiner), hypothesized to be due to increased behavioral energetic
costs for males increasing post-spawning mortality (Meffe et al. 1988, Reed
1955). This increase in mortality may also explain the shorter median lifespan
for male N. xaenocephalus and scarcity of age 2+ males in our collections. As
age estimates were based on size, an alternate hypothesis is that females grow
faster than males, making them appear to be longer lived when they actually are
not. This possibility is unlikely due to distinct gaps in SL by month throughout
the year (Fig. 2). These gaps would be obscured if females had elevated growth
rates, making it impossible to discern age groups without sex identification.
Increased feeding during the spring appears to coincide with increased
energetic requirements associated with gamete production, spawning, and
increased growth noted earlier. The relatively even occurence of several food
items in N. xaenocephalus suggests that feeding is not particularly selective
(Table 1) and is in stark contrast to that of Hypentelium etowanum Jordan
(Alabama Hog Sucker) within the study area. O’Kelley and Powers (2007)
found that Chironomidae larvae made up 88.8% of gut contents of H. etowanum.
The large proportion of gut contents of N. xaenocephalus as terrestrial
insects and adult Diptera suggests many food items are picked while drifting
2008 D.M. Jolly and S.L. Powers 457
in the current. This hypothesis is also supported by our observation of N.
xaenocephalus feeding on drifting items during snorkeling. The significant
regression between EW and weight of gut contents may suggest that feeding
increases with size. However, low R2 values suggest that any increase
in feeding associated with growth is slight. Eviscerated weight also appears
to be a poor predictor of variety of food items, suggesting that diet does not
become more variable as individuals get larger.
High GSI values in specimens collected from March to June and low values
in specimens from July (Figs. 6 and 7) indicate spawning most likely occurs
from May to June. A single specimen collected in August contained a single
mature oocyte larger than 1 mm in diameter. This specimen only had eight identifiable mature oocytes in the ovaries and had apparently passed peak spawning
condition. All specimens from fall and winter months were latent or maturing
(see Heins and Machado 1993), indicating a single spring-to-early-summer
spawning season. While tubercles did appear to be less conspicuous in specimens
collected during the late fall and winter, tubercles were present on
specimens from throughout the year. Previous reports indicate tubercles present
from April to July (Boschung and Mayden 2004, Etnier and Starnes 1993), but
may not have included examination of specimens from other months. The water
temperatures of the spring collections for this study suggest spawning occurs in
water 16–25 °C. No spawning activity was observed, but most specimens collected
during months when spawning appears to occur were taken in similar
habitat (slow pools) to specimens collected throughout the study. Examinations
of gonads and length-frequency distributions (Fig. 2) indicated that sexual maturity
occurs in the first year of age and first complete spawning season.
The biology of N. xaenocephalus shares many similarities to that of its sister
species N. boops. Both species appear to have similar lifespans and survival
curves, as few maximum age (3+) individuals were encountered in this study
and that of Lehtinen and Echelle (1979). Ova appear similar in size for both species
as Lehtinen and Echelle (1979) report mature oocytes of N. boops ranging
from 0.8–1.2 mm in diameter, while we observed mature oocytes from 0.9–1.3
mm in diameter in this study. Lehtinen and Echelle (1979) suggested that rapid
growth occurred in N. boops from March to June and slowed through the late
summer to very little growth occurring in fall and winter, similar to the pattern
observed in this study. Lehtinen and Echelle (1979) also reported GSI values
for N. boops began increasing in March and peaked in summer during June and
July before falling to minimum levels during September. They suggested that
the cool temperatures during sampling might have caused spawning to continue
anomalously into July. Our data suggest a similar pattern in N. xaenocephalus
as GSI increased in March, peaked in April, and was low by July, suggesting
spawning occurs within a period of several weeks during spring and early summer.
Both species appear to spawn in waters approaching 25 °C. In contrast to
N. boops, which appear to reach sexual maturity approaching two years of age
(Lehtinen and Echelle 1979), N. xaenocephalus appear to reach sexual maturity
as they approach one year of age.
Drifting insects at or near the surface of streams appear to be large components
of the diets of both N. xaenocephalus and N. boops. The prevalance
458 Southeastern Naturalist Vol.7, No. 3
of adult Diptera in the diet may suggest that N. xaenocephalus shares the
behavior of leaping from streams to capture fl ying insects as reported in N.
boops by Trautman (1957). This leaping behavior was not observed during
this study, leaving the possibility that adult Diptera eaten by N. xaenocephalus
were drifting at the surface of the water.
We thank C.T. O’Kelley, C.K. Ray, and J.J. McLaughlin for assistance with field
and lab work. We thank J.M. Scott, B.R. Kuhajda, and M.C. Bennett for suggestions
and assistance regarding analyses and manuscript preparation. Fishes were collected
under Georgia Scientific Collecting Permit number 16494 issued to S.L. Powers. This
study was conducted as an undergraduate independent research project by D.M. Jolly.
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