Regional oceanographic processes are emerging as strong influences on growth and recruitment of intertidal species, with important consequences for populations. Yet local conditions such as wave exposure are also important. To disentangle these effects for the intertidal barnacle Semibalanus balanoides, we surveyed 259 sites around Scotland in July and August over 6 yr (from 2001 to 2006). Scaled digital photographs at 3 shore levels gave sizes and densities of juvenile and adult barnacles for comparison with wave fetch, remotely sensed chlorophyll a (chl a) concentration and seasonal sea surface temperature (SST). Patterns were also compared with site 'openness': the area of connected open sea < 30 km away. Patterns at the 3 shore levels were similar. Hierarchical partitioning (HP) showed that survey year had the biggest effect and improved the predictive power of other variables: wave fetch for adult and juvenile densities, chl a for juvenile size and openness for adult size. SST had little effect. Regression models selected using information theoretic measures included positive effects of chl a, varying among surveys, on average size of barnacles (R 2 from 0.5 to 0.6), and larger high shore barnacles in greater wave exposure. Population densities of adults and juveniles increased with wave fetch, with chl a only influencing density at high shore levels (R 2 from 0.1 to 0.4). Despite temporal and spatial variation in responses to chl a and wave fetch among surveys, relationships were consistent with growth and size in S. balanoides being limited by food supply, and increased recruitment and adult densities in increased wave exposure. Large-scale ecological patterns in this rocky intertidal species thus result from large-scale oceanographic effects on food concentration with habitat-scale wave-mediated effects on supply of food and larvae. 398: 207-219, 2010 where such features dominate , while local wind-driven flows influence settlement rate (e.g. Hawkins & Hartnoll 1982). Patterns of current flow ultimately result in site-specific transport patterns, as described by dispersal kernels (Aiken et al. 2007), and thus determine population connectivity (Pineda et al. 2007). (2) Oceanographic conditions influence phytoplankton productivity, and this affects feeding success and energy content of dispersing planktotrophic larvae, with continuing effects on postsettlement survival (Emlet & Sadro 2006). In filter feeders such as barnacles, post-settlement growth rates are increased by higher phytoplankton biomass (Menge et al. 1997, Sanford & Menge 2001, while size-specific egg numbers and thus fecundity are also dependent on food supply . (3) At ocean scales, current-driven heat fluxes structure regional climates, with consequent effects (e.g. El Niño) that often trump smaller scale influences of oceanographic conditions on coastal marine systems. KEY WORDS: Phytoplankton · Wave exposure · Growth · Recruitment · Semibalanus balanoides Resale or republication not permitted without written consent of the ...
The distribution, morphology and sensory cell polarity of neuromasts were followed in developing larvae and recently settled juveniles of Dover sole (Solea soled) and plaice (Pleuronectes platessa) using scanning electron microscopy. In plaice the number of neuromasts increased at a similar rate on both sides of the fish throughout development, and most head neuromasts became incorporated into canals. On the trunk presumptive canal neuromasts were outnumbered by accessory superficial neuromasts in early juveniles. In sole the number of neuromasts increased at a similar rate on both sides until the start of metamorphosis. Subsequently a proliferation of superficial neuromasts on the abocular side of the head resulted in 80% of all the neuromasts on this side of the fish being located on the head in early juveniles. Both species had developed asymmetry of the head canals by the early juvenile stage, while canal formation on the trunk commenced later on the abocular side than on the ocular side. Mean numbers of sensory hair cells per neuromast showed little change until metamorphosis in both species, after which there was a two- to three-fold increase in hair cell number. The polarities of the sensory hair cells showed more variability on the head than on the trunk in both species. In general, hair cells were aligned for maximum sensitivity along the axes of the canals which would subsequently enclose them, but in the case of the superficial neuromasts on the abocular side of the head in sole the polarities followed surface features such as the nares, papillae and fin rays.
The distribution of cutaneous taste buds was determined quantitatively in larvae, juveniles and young adults of cod, using scanning electron microscopy. Changes in these distributions associated with development were followed in laboratory reared fish. Taste buds were first seen on the snout and lips of cod at a total length of 8 mm, and on the barbel at a length of 22 mm. The highest taste bud densities were seen at a length of around 90 mm, and subsequently declined on the barbel and pelvic fins with further growth. In these late 0-group fish, mean taste bud densities over much of the head, e.g. throat, dentary and sides of the snout were <100 mm 2 . On the tip of the snout and the lips, mean densities were in the region of 350-400 mm 2 , while on projecting parts of the fish, especially the barbel, anterior naris flap and extremities of the fins, spot densities occasionally exceeded 1000 mm 2 at some sites. Mean taste bud diameter increased rapidly from 2·23 m 0·35 m (..) at a length of 22 mm to 7·19 0·23 m at 90 mm length, with a much slower increase to about 8 m associated with a further doubling in body length. These changes indicate a phase of rapid proliferation and growth in size of cutaneous taste buds in the period preceding the adoption of a benthic habit in their first summer. The presence of high taste bud densities on the barbel and pelvic fins in particular appears to correlate with the known feeding behaviour of cod. 1998 The Fisheries Society of the British Isles
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