Pelagic larval duration (PLD) can influence evolutionary processes ranging from dispersal to extinction in aquatic organisms. Using estimates of PLD obtained from species of North American darters (Percidae: Etheostomatinae), we demonstrate that this freshwater fish clade exhibits surprising variation in PLD. Comparative analyses provide some evidence that higher stream gradients favour the evolution of shorter PLD. Additionally, similar to patterns in the marine fossil record in which lower PLD is associated with greater extinction probability, we found a reduced PLD in darter lineages was evolutionarily associated with extinction risk. Understanding the causes and consequences of PLD length could lead to better management and conservation of organisms in our increasingly imperiled aquatic environments.

No abstract

No abstract

Captive propagation, reproductive biology, and early life history of Crystallaria cincotta (Diamond Darter), Etheostoma wapiti (Boulder Darter), E. vulneratum (Wounded Darter), and E. maculatum (Spotted Darter) Crystal Ruble Reproductive biology and early life history data are important for understanding the ecology of fishes, and can be used for the management and conservation of rare species. During 2008-2012, a captive propagation study was conducted on Crystallaria cincotta (Diamond Darter), a rare species with a single extant population in the lower Elk River, WV. Also, captive propagation studies were conducting during 2008 on three species of darters of the subgenus Nothonotus: Etheostoma wapiti (Boulder Darter), E. vulneratum (Wounded Darter), and E. maculatum (Spotted Darter). Water temperatures during Diamond Darter spawning ranged from 11.1-23.3°C. Females and males spawned with quick vibrations to bury eggs in fine sand in relatively swift clean depositional areas. Egg size was 1.8-1.9 mm, and embryos developed within 7-11 days. Diamond Darters were 6.7-7.2 mm TL at hatch. Larvae ranged from 9.0-11.0 mm TL following a 5-10 day period of yolk sac absorption. Larvae were provided Artemia nauplii, Ceriodaphnia dubia neonates, Brachionus rotifers, and powdered foods (50-400 microns). Diamond Darter larvae did not feed in captivity, except for cannibalizing other larvae. Larvae survived for a maximum of 11 days. Larvae had relatively large gapes and teeth, suggesting possible larval piscivory and a need for alternative food sources during captive propagation. During the Nothonotus study, the length of spawning period and associated range of water temperatures for the Wounded Darter (89 days, 16.0-24.0°C) exceeded those of the Spotted Darter (46 days, 17.0-22.5°C) and Boulder Darter (48 days, 17.0-22.5°C). Eggs produced per female were least in the Boulder Darter (163), intermediate in the Spotted Darter (191), and highest in the Wounded Darter (345). Diameters of eggs at deposition and prior to hatch were least for Spotted Darter (1.9-2.0 mm, and 1.9-2.1 mm), intermediate for Wounded Darter (2.1-2.2 mm, 2.4-2.5 mm), and largest for Boulder Darter (2.2-2.4 mm, 2.4-2.6 mm).

No abstract