Academic journal article The American Midland Naturalist

Captive Propagation, Reproductive Biology, and Early Life History of the Diamond Darter (Crystallaria Cincotta)

Academic journal article The American Midland Naturalist

Captive Propagation, Reproductive Biology, and Early Life History of the Diamond Darter (Crystallaria Cincotta)

Article excerpt

Introduction

The Diamond Darter, Crystallaria cincotta, is a rare and recently described fish of the Ohio River drainage (Welsh and Wood, 2008). Currently, only a single population is known; it inhabits the lower 37 km of the Elk River (an Ohio River tributary), Kanawha County, West Virginia (Welsh et al., 2013). Based on museum specimens, this species previously occurred over a wider range within the Ohio River drainage, but populations are considered extirpated from Kentucky, Ohio, and Tennessee (Welsh et al., 2009). In Nov. 2009, the Diamond Darter was included as a candidate for listing as endangered or threatened (USFWS, 2009). Recently, USFWS (2013) published a final rule in the Federal Register listing the Diamond Darter as endangered under the U.S. Endangered Species Act.

Data on reproduction and early life history of the Diamond Darter are needed for conservation efforts and can be obtained through studies of captive breeding and rearing (Rakes et al., 1999). The reproduction of darters is partly controlled by the synchronization of temperature and photoperiod (Hubbs, 1985; Bonner et al., 1998), and captive propagation studies allow for an increased understanding of how these variables influence reproduction. In addition to environmental controls on reproduction, data on egg size and development and egg viability and survival are critical to understanding reproductive success. Also, information on the development, growth rate, and survival rate of larvae is needed for documenting the early life history of the Diamond Darter.

Reproductive biology is known, in part, for many darter species (Page, 1983; James and Maughan, 1989; Fisher, 1990; Simon et al., 1992; Brandt et al., 1993; Mattingly et al., 2003; Simon and Wallus, 2006). However, no previous studies have examined the reproductive biology and early life history of the Diamond Darter. Simon and Wallus (2006) reported the Crystal Darter, a close relative of the Diamond Darter, is an egg burier that spawns from Feb. through Apr. They also noted breeding started typically at temperatures of 12-13 C. Given genetic relatedness, life history traits of the Diamond Darter may be similar to those of the Crystal Darter. However, field and laboratory studies are needed to fully understand the reproductive biology of the Diamond Darter.

Through captive propagation, we examined reproduction and early life history of the Diamond Darter. Our objectives were to document important parameters of reproduction and characteristics of early life history including water temperature range during spawning; egg size and development; egg viability; and the development, growth, and survival of larvae. Objectives were also to document specific methods for breeding as well as specific methods for care of eggs and rearing of larval darters.

Methods

A total of 17 Diamond Darters were collected from Elk River during four sampling trips: 12 Aug. 2008 (n = 1, female), 8 Oct. 2008 (n = 2, juveniles), 23 Sep. 2009 (n = 2, female and male), and 13-14 Sep. 2011 (n = 12, 8 females and 4 males). Diamond Darters were successfully transported to Conservation Fisheries, Inc. (CFI), Knoxville, Tennessee and acclimated to aquarium conditions in the laboratory. No disease or excessive stress was noted with the Diamond Darters during this time of transition. During winter months we manipulated water temperature and photoperiod which conditioned Diamond Darters for the upcoming spring spawning period. Photoperiod was controlled with artificial lights (twin 40W natural light fluorescent bulbs) and an astronomic timer (Intermatic Next Generation Year Long Double Circuit Electronic Timer). The astronomic timer mimicked natural lighting conditions by slowly decreasing, then increasing day length on a schedule comparable to ambient seasonal changes. Water temperatures, manipulated by using ventilation of outdoor air, were reduced to a low of 2 C to winter-condition the fish. During summer water temperatures were manipulated with either ambient air circulation or air conditioning and maintained below 25 C using a programmable thermostat. …

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