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preprints201805.0388.v1
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Understanding the reproductive patterns and strategies of a species is an important step in establishing the species’ life history. Campostoma oligolepis, the Largescale Stoneroller, is a species that has received little attention in the 90 years since it was first identified, and the work that has been done has been localized in the American Midwest. Collections of C. oligolepis were made monthly from the Flint River in Madison County in northern Alabama, USA, from March, 2014, to September, 2015. A total of 768 fish were collected over the collection period including 492 adults, 268 females and 224 males. We found strong evidence that the peak spawning time for C. oligolepis in the Flint River is March and April. Ovarian maturation, gonadosomatic index for both sexes, and monthly clutch size all support this conclusion. Two unexpected features were found. The first is how few females of mature size were found to carry either oocytes or a clutch except in the peak observed reproductive month of April, 2014. The second unusual feature is the prevalence of asymmetric ovaries, with the left the larger if a difference exists. Campostoma oligolepis may have unusually strong inter-annual responses to abiotic factors such as water temperature and river discharge.
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The Scarlet Shiner (Lythrurus fasciolaris) is a cyprinid species widely distributed in parts of the Ohio, Cumberland and Tennessee river drainages of the United States. The objective of this study was to determine the Scarlet Shiner’s reproductive schedule. Maturation of ovaries and oocytes was determined through the categorization of developmental stages from early maturing to ripe, along with the calculation of monthly gonadosomatic index (GSI) measurements over two reproductive seasons in 2012 and 2015. In both years reproductive competence began in April. Average monthly GSI for females peaked in May, followed by a slow decline through August. Average clutch size was largest both years in April and May, although individual females were found with late developmental stage oocytes as late as August. Compared to other studied sympatric cyprinid species, the Scarlet Shiner was found to be a relatively late spawner with an extended spawning tail well into the summer.
Many river-dwelling species of fish are dependent upon and stimulated by fluctuations in river flow for
successful reproduction. This is especially true of pelagophils, a reproductive guild whose eggs and larvae
require free drifting on river currents for several days. Notropis photogenis (Silver Shiner) is a rheophilic species
with a broad distribution from Ontario to the southeastern United States including northern tributaries to the
Tennessee River in Alabama. Little is known of its reproductive biology. The purpose of this study was to
describe aspects of reproductive biology such as timing and pattern of ovarian development and oocyte
maturation of N. photogenis in the Flint River of Alabama. We investigated whether and how abiotic cues such
as river discharge and temperatures were related to ovulation and spawning. Monthly fish collections were
made from August, 2011, to July, 2013. From these collections monthly gonadosomatic index (GSI) was
evaluated, along with the status of ovarian maturation, oocyte maturation and size, and oocyte counts to
establish fecundity and clutch size. Median monthly river discharges in cubic feet per second for 1999–2015
were obtained from the U.S. Geological Survey database. Observations over two years showed associations
between daily mean discharge and months of peak GSI (February–April). Mean GSI peaked in March of both
2012 and 2013 when median flow was approximately 600 cfs. Large synchronous spawning events appear to
occur during times of steady substantial discharge increases but after peaks of discharge > 3000 cfs.
Important details of the reproductive ecology of many freshwater fishes of the species-rich southeastern
United States are still poorly known. One such species is Erimystax insignis (Blotched Chub), whose range
includes the Tennessee River drainage in northern Alabama, USA. To determine timing and patterns of
reproductive effort, collections were made monthly of as many as 30 individuals from August 2011 through
July 2012 from a 14 km stretch of the Flint River in Madison County, Alabama. Female and male
gonadosomatic index (GSI) and ovarian development data indicate that reproductive activity for the species
peaks from March through May. Ripe and mature oocytes were found in females from March through June
peaking in April but ripe ovaries were found only in March and April. The number of mature and ripe oocytes
was larger than reported for a population in the Little River of Tennessee, and diameter of all stages of
maturing oocytes was smaller than the Little River population.
We conducted a year-long investigation of the effect of watershed urbanization on the life history of Campostoma oligolepis Hubbs and Greene (Largescale Stoneroller). Lifehistory characteristics of separate populations of Largescale Stoneroller were compared by sampling two stream systems differing in urbanization in their upstream catchments. Both streams are located in the Etowah River drainage basin within the Piedmont ecoregion. We determined degree of urbanization by estimating the percent area of impervious catchment surfaces using ArcGIS, and we recorded stream temperatures with continuous-monitor probes. We sampled each stream system once a month during the spawning period and two additional months during the remainder of the year and recorded standard lengths, tuberculation, total weight, and gonadal weight for all retained specimens. Gonadosomatic index (GSI) values showed reproductively active individuals present in January in the urbanized system, one month before we found similar individuals in the non-urbanized system. Comparison of GSI values between systems suggested that reproductive maturity occurs at a larger size for females in the urbanized system. Comparison of standard lengths of reproductively active females indicated that growth rates arc higher in the urban system.
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.
The morphological diversity of the ovaries from a total of 90 species of teleosts in the Mexican fauna was analyzed. Ovaries were classified according to the following characters: their number, symmetry, fusion grade, trajectory, cross section, and topographical location. The fusion of both left and right ovaries was the character showing most diversity, mainly in the Cyprinodontiformes and its tendency to the viviparity. However, the most notably character was the extravisceral development of the ovaries in the Pleuronectiformes, implying the forward orientation of the gonoduct and the forward position of the female genital opening. The urogenital system of a typical perciform, Bairdiella chrysoura is proposed as a morphological pattern of the Teleostei.
Based on an examination of 1,450 stonerollers from throughout the upper Mississippi River valley (embracing the total range of the taxon oligolepis), the specific distinctiveness of Campostoma anomalum and C. oligolepis is confirmed. C. anomalum is generally distributed throughout the entire area from central Wisconsin southward, except for localized areas where suitable habitat is lacking. C. oligolepis has a disjunct range, occurring from northern Wisconsin and adjacent Minnesota and Iowa southward into central Illinois and also in the Ozarks of Missouri and Arkansas. The northern population of oligolepis is rather homogeneous and differs from anomalum more sharply than does the Ozark population, which shows considerable variation from drainage to drainage. In agricultural areas of Illinois and adjacent Wisconsin, Iowa, and Minnesota, C. oligolepis is being supplanted by the ecologically more tolerant C. anomalum.