Variability in transport of fish eggs and larvae. III. Effects of hydrodynamics and larval behaviour on recruitment in plaice

Abstract

Transport of plaice eggs and larvae in the southern North Sea was modelled using a finite-volume advection-dispersion model with high spatial and temporal resolution. Hydrodynamic forcing was based on actual river discharge and meteorological data for a 7 mo period in the winter and spring of 1989 and 1996 to 2003. Egg and larval development was linked to temperature and each developmental stage had its own physical and behavioural properties. Two hypotheses on transport mechanisms in the late larval stages were compared: passive drift versus selective tidal stream transport (triggered by environmental cues). Modelled larval stage durations closely corresponded to empirical estimates based on otolith daily ring counts. Close correspondence was also observed between model results and survey data on settlement in the western Wadden Sea, especially for the abundance of the strong 1996 year-class and the early settlement of the 2002 year-class. Transport patterns and the proportion of larvae reaching inshore nurseries varied substantially between years. Recruitment was negatively correlated with the distance over which eggs and larvae were transported, probably because of a breakdown in connectivity between spawning and nursery areas with increased transport rates. In conclusion, meteorologically driven variability in the hydrodynamics of the southern North Sea greatly affects the transport patterns of plaice eggs and larvae and may play an important role in determining recruitment variability and spatial connectivity. KEY WORDS: Biophysical model · Hydrodynamic transport · Larval behaviour · Interannual variability · Connectivity · Recruitment · Pleuronectes platessa · North SeaResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 390: 195-211, 2009 important nursery area for North Sea plaice (Zijlstra 1972), density-dependent mortality only fine-tunes recruitment variability, and the main factors driving variations in recruitment occur prior to the juvenile life-phase (van der Veer 1986, van der Veer et al. 2000.Several hypotheses have been postulated on the factors causing recruitment variability during the egg and larval stages. Cold winters often produce strong yearclasses (van der Veer & Witte 1999, Fox et al. 2000, and low egg mortality is associated with low seawater temperatures (Harding et al. 1978, Dickey-Collas et al. 2003. These low temperatures may also reduce larval mortality due to lower predator activity or to an improved match between the production cycles of larvae and their food (Cushing 1972, Leggett & Deblois 1994; however, this may be offset by slower development of the larvae (Pepin 1991). Finally, variations in transport of larvae to coastal nursery grounds may contribute to variations in recruitment success (Nielsen et al. 1998, van der Veer et al. 1998.In the present study we examined interannual variability in plaice egg and larval transport in the southern North Sea. We focused on the role of transport in determining recruitment var...

Variability in transport of fish eggs and larvae. IV. Interannual variability in larval stage duration of immigrating plaice in the Dutch Wadden Sea

“…The relationship between larval development time and temperature was calculated from published values (see Bolle et al 2009). The relationship takes the form of ln(D) = 5.0 -0.15T, where D is larval stage duration in days and T is temperature in °C.…”

“…van der Veer & Witte 1999). Next, the observed relationship between larval development times and prevailing water temperatures was compared to experimental (Talbot 1977) and other growth data (compiled in Bolle et al 2009) and deviations were considered to indicate the occurrence of poor growth or starvation conditions. Finally, the relationship between abundance of immigrating larvae and temperature during the pelagic period (c.f.…”

Connectivity as a Management Tool for Coastal Ecosystems in Changing Oceans

“…Indeed, several recent genetic studies have shown substantial spatial heterogeneity between life stages and temporal variability in genetic structure with metapopulations (Hogan et al, 2010;Selkoe et al, 2010). Likewise, several studies have explored hypotheses of oceanographic variability to explain fine-scale genetic patchiness (Banks et al, 2007) or chaotic genetic patchiness (Hogan et al, 2010), and certain larval transport models suggest that large variations in PLD and recruitment patterns could even be linked to hydrodynamic variability (Bolle et al, 2009;Connolly & Baird, 2010). Indeed, even knowledge of the PLD is not sufficient to predict scales of dispersal and gene flow among populations (Mitarai et al, 2009;Weersing & Toonen, 2009).…”

Modelling survival and connectivity of <i>Mnemiopsis leidyi</i> in the south-western North Sea and Scheldt estuaries

“…Under stratified conditions, a subsurface jet induced by density differences transports water around the north, east, and south-east slopes of the Dogger Bank into the Oyster Grounds (Brown et al, 1999;Hill et al, 2008). The thermal stratification breaks down in the autumn, and is absent throughout the winter.…”