The influence of discharge, photoperiod, and temperature on the reproductive ecology of cyprinids in the Paluxy River, Texas

Abstract

The distributions and abundances of cyprinids in North America are declining at an alarming rate with almost half of all known species considered imperiled and in need of conservation. Much of this loss in biodiversity is a result of flow regulation and climate change, especially in streams in the southern Great Plains that are prone to large and rapid fluctuations in discharge. The overall objective of this study was to examine the influence of discharge, photoperiod, and temperature on the reproductive ecology of cyprinids in the Paluxy River, Texas. Our results support previous findings in that photoperiod and water temperature were influential in the initiation and termination of the annual reproductive season. Interannual differences in GSI for Cyprinella venusta and Notropis volucellus indicated that reproductive effort in certain cyprinids was directly linked to discharge. In 2010, mean gonadosomatic index values for C. venusta (9.60 %) and N. volucellus (9.15 %) were at least twice that of 2011 (4.61 and 3.14 %, respectively); discharge during the spawning season of 2010 averaged 1,965 cfs, whereas it averaged only 177 cfs in 2011. Indeed, yearly differences in streamflow (i.e., mean annual discharge) can significantly impact the production of ova in a variety of cyprinids, even those non-broadcast-spawning species such as C. venusta. Consequently, we suggest conservation efforts should focus on maintaining natural flow regimes to combat the overwhelming loss of cyprinid diversity, especially as water extraction and climate change continue to threaten the biodiversity of freshwater fishes.

Effects of sediment burial on grass carp,Ctenopharyngodon idella(Valenciennes, 1844), eggs

“…The possibility of suffocation for semi-buoyant cyprinid eggs in areas lacking flow has been noted for many species (Moore, 1944;Platania and Altenbach, 1998;Munz and Higgins, 2013). Medley and Shirey (2013) suggest that the similar eggs of the Rio Grande silvery minnow (Hybognathus amarus; and potentially other small-bodied cyprinids) are unlikely to be buried by fine sediments due to a density gradient above the riverbed.…”

Plasticity in Reproductive Traits, Condition and Energy Allocation of the Non-Native Pyrenean Gudgeon Gobio lozanoi in a Highly Regulated Mediterranean River Basin

“…Reproductive cycles of freshwater fish depend on a set of environmental factors and rheophilic fish, such as the target species, usually need flow requirements to activate migration processes, gonadal maturation and spawning success [50]. Reproduction is related to stream flow, photoperiod and temperature cues [8,51] and there must be optimal conditions for all these variables to coincide in time for gonadal activation to begin. Similar temporal dynamics of the gonadosomatic index were found in another studied population of G. lozanoi in an upper fluvial sector of the Segura River Basin [37].…”

Implications of climate change for potamodromous fishes

“…The amount of river discharge has previously been shown to be positively associated with migration, reproduction and recruitment of fishes elsewhere (e.g. Reynolds, ; O'Connor et al ., ; Beatty et al ., ; Crook et al ., ; Walsh et al ., ; Munz & Higgins, ). Our findings suggest that potamodromous fishes may be particularly impacted by flow reductions via reduced levels of recruitment and increased resource competition, with potentially serious implications for population dynamics and viabilities (e.g.…”

“…Gorman & Karr, 1978;Allan et al, 1997). Seasonal migrations in potamodromous fishes are critical for completing life cycles; particularly in accessing spawning and nursery habitats and refugia (Reynolds, 1983;O'Connor et al, 2005;Munz & Higgins, 2013). Understanding refuge use and species mobility is important for enhancing conservation efforts; particularly under drought or flow reduction scenarios (Magoulick & Kobza, 2003;Mor an-L opez et al, 2012;Chessman, 2013).…”