RESEARCH ARTICLE
Felicita Scapini Æ Lorenzo Chelazzi Æ Isabella Colombini
Mario Fallaci Æ Lucia Fanini
Orientation of sandhoppers at different points along a dynamic shoreline
in southern Tuscany
Received: 1 March 2004 / Accepted: 10 February 2005 / Published online: 7 July 2005
Ó Springer-Verlag 2005
Abstract Orientation experiments were carried out on
Talitrus saltator (Crustacea Amphipoda) at four points
along 3 km on a dynamic sandy beach inside the
Maremma Regional Park (Grosseto, Italy) to highlight
behavioural variation related to distance from a river
mouth, to erosion or accretion of shoreline, and to hu-
man trampling on the beach. Tests were performed using
circular transparent Plexiglas arenas, contemporane-
ously at the four points. Replicates were made in 2 dif-
ferent months (September 2002 and May 2003), on 2–3
successive days, in the morning and afternoon. The
distributions of the angles of orientation were compared
for the different points and seasons, and multiple
regression analysis was performed to test the effects of
environmental and intrinsic variables on orientation.
Sandhoppers showed the highest scatter at the eroded
shoreline, intermediate scatter at the accreting beach
most distant from the river mouth, and consistent ori-
entation seaward at the least disturbed point. Orienta-
tion of sandhoppers was significantly affected by season,
global radiation, time of day, distance from the river
mouth, and human trampling. Sex and air humidity
were of minor significance in the multiple regression
model. The results, on the one hand, confirm plasticity
in orientation of sandhoppers living on a dynamic
shoreline, and on the other hand, show that variation in
orientation could potentially be used as a bioindicator of
shoreline changes.
Introduction
This article describes the sun orientation behaviour of
the sandhopper Talitrus saltator (Crustacea: Amphi-
poda), collected at sites with different geophysical
characteristics, on a single beach in Tuscany, Italy, and
considers the potential of such behaviour patterns as
indicators of sand-beach dynamics. This amphipod lives
on sandy beaches above high tide marks, where it is
more concentrated near the water’s edge in summer and
dispersed higher on the beach up the dune in winter
(Fallaci et al. 2003). It performs regular migrations
across the beach at night to feed on detritus and returns
after dawn to the shoreline, where it burrows in the wet
sand (Scapini et al. 1992). When disturbed during the
day, or when the sand dries out, it regains the wet zone
seawards, orientating visually with respect to landscape
at night and to the sun after sunrise (Scapini et al. 1997).
Previous research conducted on different beaches in
Italy, the United Kingdom, and Tunisia had shown that
talitrid populations orient significantly seawards on
stable shorelines and are more scattered on eroded
beaches, and on beaches affected by construction and
human frequentation (Scapini et al. 1995; Borgioli et al.
1999a; ElGtari et al. 2000).
Conventional methods of monitoring change in sand-
beach features, unless carried out continuously, only
show snapshots of such changes. Yet sand-beach ani-
mals have continuous experience of environmental fac-
tors at the site at which they live, and the behavioural
and physiological adaptations of key animal species are
potential bioindicators of changes in shorelines.
Behavioural adaptation in particular could provide a
means of estimating environmental change over a time
scale equal to the life-span of the species, or that of a few
generations, if it is inherited. However, these bio-assays
need to be validated. Changes in animal behaviour un-
der natural conditions may be affected by several fac-
tors, both external and internal (Borgioli et al. 1999a,
1999b). One way to avoid such variation is by the use of
Communicated by R. Cattanevo-Vietti, Genova
F. Scapini (&) Æ I. Colombini Æ L. Fanini
Dipartimento di Biologia Animale e Genetica,
Universita
`
di Firenze, Via Romana 17, 50125 Florence, Italy
E-mail: scapini@dbag.unifi.it
Fax: +39-55-222565
L. Chelazzi Æ M. Fallaci
Istituto per lo Studio degli Ecosistemi, Sezione di Firenze, 50125
Florence, Italy
Marine Biology (2005) 147: 919–926
DOI 10.1007/s00227-005-1617-6