Egg trait variation in anchoveta Engraulis ringens: a maternal response to changing environmental conditions in contrasting spawning habitats

Abstract

The Engraulis ringens distribution (4 to 42°S) covers a wide variety of environmental conditions. We assessed the coping mechanisms used by this anchoveta in different spawning habitats, reporting differences in egg traits between populations off northern (Iquique, 20°S) and southern Chile (Talcahuano, 36°S) and throughout the spawning season. Eggs were smaller off Iquique, declined in size during the reproductive season (both populations), and inter-population differences persisted throughout the spawning season. Batch fecundity (eggs per batch per female) and relative fecundity (eggs per female weight) were lower off Talcahuano during the peak spawning months. Thus, larger eggs spawned in the southern population seem to be produced at the cost of a reduction in fecundity. The eggs also differed biochemically between the 2 populations; total lipids and triacylglycerides were much higher off Talcahuano. The biochemical composition (both populations) also changed throughout the spawning season, with higher lipids early in the spawning season (July to August) off Talcahuano. Hatching success decreased during the spawning season, and correlated positively with egg size and lipid contents. Environmental conditions differed markedly between spawning areas and from mid-winter to late spring. Off Talcahuano, the temperature and winter-time water column productivity are lower and turbulence is higher, while eggs are larger, lipid contents higher, and batch fecundity lower. This mechanism seems to facilitate survival of young offspring in the more adverse winter conditions off Talcahuano. These egg characteristics are determined by the adult female reproductive system, representing a maternal influence on the early life-history traits of anchoveta that might enable rapid changes in population densities in some years of improved habitat conditions. KEY WORDS: Anchoveta · Engraulis ringens · Upwelling · Reproductive strategy · Egg quality · Lipids · Humboldt Current · Small pelagic fishes Resale or republication not permitted without written consent of the publisher

Fatty acids in eggs of anchoveta Engraulis ringens during two contrasting winter spawning seasons

“…Our data on surface temperature at the coastal oceanographic stations as well as over the entire region confirm the difference in the thermal regime between these years for the anchoveta spawning zone. The hydrographic information for 2007 and wind data analyses carried out during the same months indicated that south winds occurred inducing upwelling at the coast in winter (Castro et al 2008), although downwelling usually occurs in the coastal zone during this season (Castro et al 2000). The different oceanographic conditions found in the 2 studied years also extended to the microand mesozooplankton composition.…”

“…In mid-winter 2005, mostly omnivorous and carnivorous small-sized copepods (Oncaeidae and Oithonidae) predominated, unlike winter 2007, when larger herbivorous-omnivorous calanoid copepods (mostly copepodites and adult Calanidae), typical of upwelling conditions, were predominant. In terms of zooplankton biomass, winter 2007 revealed the highest biomass values during the 7 yr time-series (Castro et al 2008).…”

“…The overall biological environmental conditions (larger copepods, highest zooplankton biomass in many years), reproductive characteristics (larger gonads, increased batch and relative fecundity), egg size (larger egg volumes, which have been reported to correlate with total lipids and increased hatch success), and biochemical indicators of egg quality (higher PUFA) suggest that the fate of the spawn in 2007 should have been good. However, this particular set of characteristics cannot arise in this environment and population without the presence of unusual upwellingfavorable winds in the area for several weeks in winter (Castro et al 2008). Interestingly, the occurrence of this process may also have involved major trade-offs for small pelagic fish populations because these winds induce the transport of eggs and larvae away from the coastal environment, which has rich, favorable conditions for larval development.…”

Potential zooplankton preys (Copepoda and Appendicularia) for <i>Engraulis anchoita</i> in relation to early larval and spawning distributions in the Patagonian frontal system (SW Atlantic Ocean)

“…Furthermore, the higher biomass (mainly calanoids) in these stratified waters would contribute to the carbon transfer to the upper trophic levels and anchovy adults would be benefited. During winter, Castro et al (2009Castro et al ( , 2010 reported that variations in the biochemical composition of Engraulis ringens eggs in the upwelling system off the Chile coast were beneficial for young larvae. These authors found a negative relationship between egg size and food availability for larvae: smaller-sized copepods (presumably more prone to being captured by the youngest larvae) were most abundant when eggs were smaller because larvae would not need much lipid reserves to survive due to the abundance of small food sources in the sea.…”

Using oocyte essential fatty acid composition to assess spawner reproductive potential under hypersaline conditions

“…Our findings illustrate a trade-off mechanism between ovary weight (number of produced oocytes) and maternal 18:1 (n-9) supply to individual oocytes. Accordingly, Peruvian anchoveta Engraulis ringens (Jenyns, 1842) produced smaller amounts of eggs, albeit of larger sizes and lipid contents, to enhance egg and larvae survival under conditions with low water temperatures and low prey abundances (Castro et al 2009). EFA ratios remain more or less constant across the first 3 trophic levels of the food chain (St. John & Lund 1996).…”