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Journal of Experimental Marine Biology and Ecology 243 2000 81–94
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Estimation of the life history parameters of Mytilus galloprovincialis Lamarck larvae in a coastal lagoon
Ria Formosa — south Portugal
´ ´
Luıs M.Z. Chıcharo , M. Alexandra Chicharo
ˆ ´
Unidade de Ciencias e Tecnologias dos Recursos Aquaticos — CCMAR , Universidade do Algarve,
Campus de Gambelas , 8000 Faro, Portugal
Received 5 February 1999; received in revised form 22 July 1999; accepted 23 July 1999
Abstract
The life history parameters of early stages of marine invertebrates, particularly field estimations, have received relatively little attention. The aim of this research was to estimate in situ abundance
and growth of Mytilus galloprovincialis planktonic larvae. Plankton samples were filtered through gauze of 63 mm mesh and identified, counted and measured using an inverted microscope.
Short-term fluctuations in Mytilus galloprovincialis larvae abundance and environmental parame- ters water temperature, salinity, wind velocity direction, tidal amplitude and chlorophyll a were
monitored two to three times a week. Larval cohorts were identified using size–frequency distributions and age estimates compared with larval shell growth lines. Data were fitted to the
linear, exponential, von Bertalanffy and Laird–Gompertz growth models. Larval growth adjusted
21 2
better to the Laird–Gompertz model 0.52560.073 mm d ; r 5 0.768; P , 0.05. Reduction of
shell growth after 1 to 1.5 months in the plankton suggests the occurrence, in this period, of a ‘delay of metamorphosis’ phase. The results of our study indicate that advection and availability of
settlement substratum may be the key factors for the life history parameters of this species in a coastal system such as the Ria Formosa.
2000 Elsevier Science B.V. All rights reserved.
Keywords : Bivalve larvae; Growth; Mussel; Mytilus galloprovincialis
1. Introduction
The high productivity of shallow coastal lagoons, such as the Ria Formosa, is the result of contact of the water column and the sediment with good light conditions
Corresponding author. Tel.: 1351-89-800-900; fax: 1351-89-818-353. ´
E-mail address : lchicharualg.pt L.M.Z. Chıcharo
0022-0981 00 – see front matter
2000 Elsevier Science B.V. All rights reserved. P I I : S 0 0 2 2 - 0 9 8 1 9 9 0 0 1 1 2 - 4
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L .M.Z. Chıcharo, M.A. Chicharo J. Exp. Mar. Biol. Ecol. 243 2000 81 –94
Sprung, 1994. The Ria Formosa is a highly dynamic system and is characterised by ´
high larval abundance, especially of Mytilus galloprovincialis Chıcharo, 1996. The Ria Formosa has a long tradition of bivalve culture, especially Ruditapes decussatus,
contributing 90 of Portuguese production. However, the importance of diversification of cultured species is recognised. The high availability of mussel larvae in the plankton
offers an important alternative for bivalve production, if adequate research on the subject is implemented.
In situ Mytilus galloprovincialis larval growth and mortality have not received much attention, despite their ecological importance. This is probably because their life history
variables are difficult to assess due to methodological problems. The most accurate estimations of field growth and mortality result from continuously sampling the larvae in
the plankton from the same water column and detecting their variation in length and in number. However, identifying and following larval cohorts in the plankton is very
difficult Morgan, 1994, 1995. Due mainly to this limitation, estimates of mortality and growth of bivalve larvae based on larval cohorts in the plankton have only been made by
Korringa 1941, Quayle 1964, Jørgensen 1981 and You and Ryu 1985. A comparatively larger number of studies have analysed laboratory reared bivalve larvae
growth and mortality e.g., Bayne, 1965; Walne, 1966; Pechenik et al., 1990; Rumrill, 1991; Beiras et al., 1994.
Several environmental factors, such as temperature and salinity Calabrese, 1969; Kingston, 1974; Hrs-Brenko, 1978, food concentration Sprung, 1984; Pechenik et al.,
1990, physical mechanisms Morgan, 1994; Belgrano et al., 1995; Richards et al., 1995, or predation Young and Chia, 1987 may affect bivalve larval growth and
mortality rates. Whereas in laboratory experiments some of these factors can be controlled, their influence in natural habitats is impossible to ascertain.
The dynamics of larvae from planktonic populations have important implications for the life histories of marine benthic invertebrates Vance, 1973a,b; Strathmann, 1985;
Hines, 1986. Thorson 1950, 1966 highlighted the impact of larval mortality in the recruitment of benthic populations. In fact, rates of growth and natural mortality can
vary among populations of larvae, and the availability of settling larvae may influence patterns of recruitment.
Specific objectives of the present study were the estimation of abundance and growth during the planktonic life of Mytilus galloprovincialis in a coastal lagoon, Ria Formosa.
The abundance results were compared with tidal amplitude, water temperature, salinity, wind velocity and direction and a food availability indicator chlorophyll a.
2. Methods
