Histologia Informr 2 Unp
Enviado por jreomaro • 27 de Abril de 2012 • 5.838 Palabras (24 Páginas) • 496 Visitas
Burrow morphology, biometry, age and growth of piddocks
(Mollusca: Bivalvia: Pholadidae) on the south coast of England
Received: 11 August 2004 / Accepted: 27 January 2005 / Published online: 11 June 2005
Springer-Verlag 2005
Abstract Biometry and growth of three piddock species
Pholas dactylus, Barnea candida and B. parva, from
chalk and clay substrata were investigated between 1999
and 2000 at five low shore locations along the south
coast of England. Piddock burrow shape was significantly
different (P<0.01) amongst the locations. Burrows
at Lyme Regis showed the largest (height/
maximum diameter) ratio (4.86±2.00) whilst those at
Compton the lowest (3.73±1.62). Using the method of
Bhattacharya, the population structure of P. dactylus,
B. candida and B. parva was separated into eight, three
and five modal size classes, respectively. Age and shell
growth were determined from the number and spacing,
respectively, of annual growth lines present in acetate
peel replicas of shell sections. The von Bertalanffy
growth (VBG) equation fitted the size at age data
obtained for P. dactylus and B. candida (L¥ and K were
79.3±13.8 mm and 0.0011±0.22 and 29.6±1.5 mm
and 1.17±0.47, respectively) whilst the size at age data
for B. parva were linearly related and did not fit the
assumptions of the VBG equation. Male and female
gonads were mature and piddocks competent to spawn
between June and September 1999, with settlement of
juveniles observed between November 1999 and February
2000. A significant relationship between burrow
aperture diameter and age of the occupant piddock was
established for the three species. Burrow morphology
and spatial distribution of burrows were influenced by
substratum hardness and population density. Based on
estimates at Lyme Regis, piddocks are capable of
removing up to 41% of the shore substratum to a depth
of 85 mm over their lifespan (12 years), significantly
compromising the structural stability of the soft rock
shores they inhabit and contributing to bioerosion.
Introduction
Bivalve piddocks are one of the most characteristic
faunal groups inhabiting lower soft rock shores, such as
those comprised of limestone, chalk, sandstone, slate or
stiff clay (Harvey et al. 1980; Trudgill 1983, 1985;
George and Fincham 1989). Despite this, relatively little
is known about their general biology and ecology. Three
species of piddock commonly occur on the English south
coast: the common piddock Pholas dactylus L., the white
piddock Barnea candida (L.) and the little piddock
B. parva (Pennant) (Tittley et al. 1986; Wood and Wood
1986; George and Fincham 1989; Wood 1992). These
bivalves bore into the substratum and, consequently, it
may be this cryptic lifestyle that has resulted in the
general lack of knowledge about these species. This is
despite interest in them from early naturalists fascinated
by their luminescent properties and boring ability. For
example, Pliny the Elder (AD 77) documented the luminscence
of P.dactylus even whilst being eaten. Jefferies
(1865) refers to their use as food and fish bait and
Turner (1954) reported that the Romans ate them.
Pholas dactylus was once prevalent across the entire
Mediterranean and on the Atlantic coast of Europe, but
Communicated by O. Kinne, Oldendorf/Luhe
E. H. Pinn (&) Æ S. J. Hawkins
School of Biological Sciences, University of Southampton,
Southampton, SO16 7PX, UK
E-mail: eunice.pinn@jncc.gov.uk
Tel.: +44-1224-655718
Fax: +44-1224-621488
C. A. Richardson
School of Ocean Sciences, University of Wales Bangor,
Menai Bridge, Anglesey, LL59 5AB, UK
R. C. Thompson
School of Biological Sciences, University of Plymouth,
Drake Circus, Plymouth, PL4 8AA, UK
S. J. Hawkins
The Laboratory, Marine Biological Association, Citadel Hill,
Plymouth, PL1 2PB, UK
Present address: E. H. Pinn
Joint Nature Conservation Committee, Dunnet House,
7 Thistle Place, Aberdeen, AB10 1UZ, UK
Marine Biology (2005) 147: 943–953
DOI 10.1007/s00227-005-1582-0
...