Small‐scale variability in growth and condition of dab Limanda limanda (L.) larvae in relation to an Irish Sea tidal‐mixing front off the west coast of the Isle of Man

Abstract

The small-scale variability in condition and growth of dab Limanda limanda larvae was investigated in relation to a tidal-mixing front (Manx West Coast front) off the west coast of the Isle of Man, Irish Sea. RNA:DNA ratios and otolith microincrement analysis were used to estimate nutritional status and recent growth rates of larvae captured on 5 May 1999 in mixed, frontal and stratified waters associated with this front. RNA:DNA ratios were significantly higher at the Manx West Coast front compared to mixed waters, although recent growth rates did not vary significantly with water column stability. More favourable feeding conditions associated with frontal waters from previously reported large-scale investigations in the Irish Sea were reflected on a smaller spatial scale. Although frontal accumulation of dab larvae was not observed in the current study, dab larvae found in the stratified and frontal waters were significantly larger than those captured in the mixed waters. This pattern could suggest an offshore movement of dab larvae into more favourable waters as they develop.

Co-occurrence of European sardine (<i>Sardina pilchardus</i>), anchovy (<i>Engraulis encrasicolus</i>) and sprat (<i>Sprattus sprattus</i>) larvae in southern North Sea habitats: Abundance, distribution and biochemical-based condition

“…The hypothesis that growth of larvae might be promoted in frontal zones (Munk, 1991;Nakata and Zenitani, 1996;Lee et al, 2007) was not unconditionally supported in the present study. Values of RNA:DNA for sprat and sardine were generally high (albeit quite variable) and appeared unrelated to hydrographic conditions in the southern North Sea in June/July 2005.…”

“…The first three categories were based on the stratification variable (f) derived from vertical density profiles r(z) (Simpson et al, 1979). The value of f represents a measure of the amount of energy required to mix the water column and thus increases with increasing water column stratification (mixed waters <10 J m -3 , frontal waters 10-20 J m -3 and stratified waters >20 J m -3 ) (Lee et al, 2007). The Wadden Sea is a flat high-energy system separated from the North Sea by a row of barrier islands and sandbanks.…”

The importance of protozooplankton as prey for copepods in the coastal areas of the central Irish Sea

“…Increasing plankton biomass has been related to the summer water stratification of the Irish Sea (Burkart et al, 1995;Edwards & Burkill, 1995;Gowen et al, 1995Gowen et al, , 1998) that starts in the deeper offshore waters off the west of the Isle of Man and tends to encroach inshore from May onward (Nicholas, 1995;Lee et al, 2007;current study). During the spring and summer, the protozooplankton (15-200 lm) biomass was 1-30 lg C l -1 in the current study, which is similar to that found in the southwestern of the Irish Sea (1-41 lg C l -1 ) where stratification occurs earlier (Edwards & Burkill, 1995).…”

Recruitment of striped bass in Chesapeake Bay: spatial and temporal environmental variability and availability of zooplankton prey

“…There are many examples of such enhancements, e.g. larval cod Gadus morhua (Munk 2007), Japanese sand lance Ammodytes personatus (Nagano et al 2001), dab Limanda limanda (Lee et al 2007), sprat Sprattus sprattus (Munk 1993), and yellowfin tuna Thunnus albacares (Lang et al 1994) in tidal, thermohaline, and river plume fronts.…”