Tidal, diel and longer term changes in the distribution of fishes on a Scottish sandy beach

Abstract

ABSTRACT. Fishes were sampled by seine and beam trawl over tidal and diel cycles on a sandy beach on the west coast of Scotland in J u n e and August Species composition of the catches of the 2 gear types differed. There was a signif~cant pos~tive relationsh~p between depth (0 to 5 m ) and species richness but a few specles were restricted to depths of < S m Although s~gnif~cantly more species and individuals were caught at night and at low tide there was no evidence for the existence of d~stinct 'day' and 'night' communities. D~fferences between catches at hlgh and low water were caused by the movement of a few species into the ~ntertidal zone on the rising tide. Diel differences In abundance were pnnc~pally d u e to an inshore migration of several species of gadoids at dusk and movement offshore at dawn. Longer term changes in abundance and distr~bution were attributed to predation and movement ~n t o deeper water

Movements of Marine Fish and Decapod Crustaceans: Process, Theory and Application

“…Not all animals move inshore with a rising tide (Gibson et al, 1996) and an inshore assemblage may be composed of animals with varying dependencies on periodically available intertidal resources. Janssen and Kuipers (1980) sampled common shrimp (Crangon crangon) in the Wadden Sea, Netherlands, at a range of water depths and found that only 5% of the population made extensive tidal excursions.…”

“…The most commonly reported ontogenetic changes in movement patterns are associated with refuge function, predation pressure, physiological requirements and diet, all of which are usually associated with increasing body size (Werner and Gilliam, 1984;Dahlgren and Eggleston, 2000). For many species, significant shifts in space-use patterns are reported to occur within the first few weeks and months after settlement, when movement patterns are often represented by a strong sizedepth relationship (Ruiz et al, 1993;Gibson et al, 1996Gibson et al, , 2002. For example, after settlement, plaice (Pleuronecles platessa) in the North Sea concentrate in shallow waters (< 1 m deep) and show a positive relationship between body length and water depth (Gibson et al, 2002).…”

“…For instance, when sampling fish undergoing tidal excursions, sampling should be spatially distributed over a range of depths, taking into account the changing phase of the tide (Gibson et al, 1996;Rozas and Minello, 1997). Combinations of techniques may be necessary to achieve this and care must be taken with regard to their suitability for comparative purposes.…”

Annual and Monthly Variation in Species Composition and Catches of Fishes from the Tabusintac River Estuary in the Southern Gulf of St. Lawrence

“…Temporal variation is assumed to be concentrated at periodic scales, e.g. tidal, diel, lunar, seasonal and annual (Laevastu and Hayes 1981), with numerous studies reporting high contrasts in catches and species richness of estuarine and coastal marine fishes at these Annual and Monthly Variation in Species Composition and Catches of Fishes from the Tabusintac River Estuary in the Southern Gulf of St. Lawrence scales (Dahlberg and Odum 1970;Gibson et al 1996;Lazzari et al 1999;Methven et al 2001;deBruyn and Meeuwig 2001).…”

Diel Variations and Ecological Aspects in Fish Assemblages of a Sandy Beach in the Semi-Arid Region of Northeast Brazil.

“…There are many reasons for juvenile and small-sized fishes to approach shallow and coastal areas. One of these reasons is the search for shelter and refuge from predators in subtidal zones (Wright, 1989;Gibson et al 1996;Pesanha et al 2003b;Dulcic et al 2004). Also, it is believed that the lack of larger fish at night is related to the low depth of the beach, which is naturally shallow.…”