Effect of growth on reproduction in the freshwater amphipod, Hyalella azteca (Saussure)

Abstract

A gradient in H. azteca growth was created by reducing food ration . .Tests were initiated with neonates (<48 h old) and the effects of an altered food ration on survival and growth were examined after 10 and 49 days . Growth rates decreased significantly with reduced food ration (10 day growth rates ranged from 1 .2 tg d -1 in the highest feeding regime to 0 .5 tg d -1 in lowest feeding regime) . Survival after 10 days was not affected by ration, ranging from 86 to 96% . A growth rate of 1 .2 jig d -1 at day 10 resulted in mean dry weight (1 .0 mg), survival (62%) and reproduction (9 .3 neonates/female) at day 49 similar to reported values for this species . Growth rates <0 .9 Ag d-1 at day 10 corresponded to significantly reduced reproduction at day 49 (i .e ., < 1 neonate per female) . Time to the onset of amplexus increased with decreasing ration suggesting reduced ration may have delayed reproduction .

Use of Sublethal Endpoints in Sediment Toxicity Tests With the Amphipod Hyalella Azteca

“…4). Other investigators have reported a similar degree of variability in reproduction of H. azteca within a narrow range of length or weight, with stronger correlations observed over wider ranges [26,30,48,49]. The degree of correlation between growth and reproduction may also be dependent on the strain of H. azteca evaluated [26,50].…”

DEMONSTRATION OF CULTIVABILITY FOR A LOW IONIC STRENGTH WATERHYALELLA AZTECASTRAIN

“…The gender of the adult H. azteca was not determined prior to distribution and therefore it is possible that some buckets contained only males or only females, which would result in no reproduction. Also, as reported by Moore and Farrar [14], buckets housing a high ratio of males compared with females would produce very few offspring.…”

“…The CCIW strain had, on average, a greater number of adults per breeding bucket which likely increased the chances of successful pairing [14]. In addition, the CCIW H. azteca were cultured in water (SAM-5S) that was optimized for their specific strain by Borgmann [10].…”

Macroinvertebrados bentónicos de dos lagos de alta montaña en el estado de Morelos, México

“…En cuanto a la abundancia de Hyalella azteca, diversos autores han mostrado que tanto el crecimiento como el desarrollo de los anfipodos es afectado por varios factores ambientales, resaltando de manera especial la temperatura (Bovee, 1950;Cooper, 1965;De March, 1977), el fotoperiodo (Pilgrim y Burt, 1993) y la calidad del alimento (Hargrave, 1970;Moore y Farrar, 1996;Wellborn, 1994); ademas estos organismos por su tamaño se encuentran en sitios que ofertan protección contra sus depredadores (peces, aves, insectos acuáticos y anfibios), habitando principalmente entre las macrófitas de la zona litoral, algas bentónicas y el microbentos (Mathias, 1971;Alcocer et al, 2002;Peralta, 2006). Al parecer, las condiciones de los lagos fueron adecuadas, registrando a la especie en los dos periodos de estudio con relativa abundancia en ambos lagos.…”