Event Abstract

Back to Event

Growth of the sword razor (Ensis magnus) early stages: modelling juvenile seasonal growth

Alba Hernández Otero1*, Aldo Barreiro2, Gonzalo Macho1, 3 and Elsa Vazquez1
  • 1 Universidade de Vigo, Dpto. Ecoloxía e Bioloxía Animal and Estación de Ciencias Mariñas de Toralla, Spain
  • 2 Interdisciplinary Center of Marine and Environmental Research (CIIMAR), Portugal
  • 3 University of South Carolina, Department of Biological Sciences, United States

The sword razor Ensis magnus Schumacher, 1817 [syn. E. arcuatus (Jeffreys, 1865)] is a Northeast Atlantic temperate species that lives buried in low intertidal and subtidal sandy-muddy bottoms from Norway to Spain and along the Faroe and British Islands. It is the most important commercial species of razor clams in both Europe and Spain and one of the most important shellfisheries in Galicia (NW Spain) (459 t sold in 2015, ~4 million €), being the Ría de Vigo the second most productive area (113 t in 2015) (www.pescadegalicia.com). Despite its economic importance, information about some biological aspects as growth is scarce. Modelling growth is required in many ecological studies and stock assessment applications, but most studies on shellfish growth focus only on the adult phase, without considering the early developmental stages. Most marine bivalves exhibit different growth patterns depending on their life history stage (Urban, 2002) and consequently different mathematical models must be used. However, most bivalve growth studies used the von Bertalanffy growth model (VBGM) as default without testing their fitness, which has long been criticized (e.g. Cailliet et al., 2006; Katsanevakis, 2007). Additionally, the classical models do not reflect the seasonal growth pattern, widely described in bivalve species of temperate regions. To our knowledge, larval and postlarval growth was never modelled for any razor clam whereas adult growth was always modelled assuming annual growth rings (Robinson and Richardson, 1998; Hernández-Otero et al., 2014). In the present study we describe with accuracy the early stages of E. magnus growth cultured on its optimal habitat and evaluate the influence of environmental variables on growth. Larval and postlarval culture was conducted at the Estación de Ciencias Mariñas de Toralla (ECIMAT, Universidade de Vigo) following da Costa et al. (2008) while juvenile growth assays were carried out in buried cages in a subtidal bed of E. magnus in the Ría de Vigo. Environmental parameters (temperature, salinity and concentration of chlorophyll a) were provided by the INTECMAR (Instituto Tecnolóxico para o Control do Medio Mariño de Galicia, Xunta de Galicia) whereas daily upwelling indices were calculated from surface wind data recorded by the Seawatch buoy of Puertos del Estado. Larval and postlarval growth was modelled with linear and sigmoidal (Logistic, Gompertz and Richards) functions. To model juvenile growth and incorporate the seasonal oscillation we used temperature-dependent growth models previously described on literature (Kielbassa et al. 2010; Otterlei et al. 1999) and develop two upwelling-dependent growth models. The model with the smallest AIC (Akaike, 1974) was selected as the “best” among all tested models. Analyses were conducted with R vs 3.0.2. E. magnus larval and postlarval growth results agreed with those reported by da Costa et al. (2008, 2011). Thus, larvae grew linearly reaching 250 µm 20 days after fertilisation, when settlement started (Figure 1, Supplementary Material), while postlarvae grew slowly during the first 10 days after settlement, fast during the next month and finally declined in the last month of culture, reaching 750 µm after one month of fertilisation, 10.5 mm at two months old and 25 mm at three months old (Figure 2, Supplementary Material). Larval growth followed a linear function while postlarval growth was sigmoidal and thereby adequately represented by the Richards model. By contrast, E. magnus juveniles seeded on subtidal bed of the Ría de Vigo showed a higher growth rate than other razor clam culture experiences which used intertidal or suspended culture methods (da Costa and Martínez-Patiño, 2009; da Costa et al., 2011, 2013). Thus, E. magnus was 50 mm at six months old, 67 mm at 1 year old and 82 mm when the experiment finished, 1.5 years after fertilisation (Figure 3, Supplementary Material). During winter, a growth cessation period was observed. Juvenile growth was better described when using growth models that incorporate environmental variables in their functions, especially the VBGM that included temperature, as the estimated curves reflected better the growth cessation period observed during winter, caused by a combination of downwelling conditions and low seawater temperature values, and the posterior growth recovery period, observed during upwelling conditions and increasing seawater temperatures (Figures 3, Supplementary Material). The temperature-dependent VBGM used in the present study predicted that the optimum temperature for the sword razor growth ranged between 14.5 and 15ºC. Under these values the growth will be slower but the asymptotic length attained would be higher. These results provide important information for aquaculture techniques and confirm that each growth ring is laid down annually, which is crucial to apply indirect ageing methods such as the ones used in the adult growth studies (Robinson and Richardson, 1998; Hernández-Otero et al., 2014). Figure 1. Growth in length of Ensis magnus larvae (0-20 days post-fertilisation): (A) observed values of length (µm) at age (post-fertilisation days), (B) observed values of box-cox transformed length (circles) and predicted values (red line) estimated by linear regression. Figure 2. Growth in length of Ensis magnus postlarvae (21-102 days post-fertilisation or 0-81 post-settlement days). Observed values (circles) and predicted values estimated by the different growth models employed (lines). p-set days = post-settlement days; p-fert days = post-fertilisation days. Figure 3. Growth in length of Ensis magnus juveniles (124-529 days post-fertilisation or 27-432 post-seeding days). Observed values (circles) and predicted values estimated by the different growth models (lines). VB: Von Bertalanffy growth model, VBTI: Temperature dependent VB with Φ independent on temperature, VBTD: Temperature dependent VB with Φ dependent on temperature, VBQ: Upwelling dependent VB, G: Gompertz model, GT: Temperature dependent Gompertz model, GQ: Upwelling dependent Gompertz model.

Figure 1
Image
Figure 2
Image
Figure 3
Image

Acknowledgements

The authors thank Damián Costas, Roberto Gómez and Enrique Poza (ECIMAT, Universidade de Vigo) for providing culture and sampling assistance. We acknowledge the INTECMAR and Puertos del Estado for supplying data on environmental variables. This study was financially supported by the Xunta de Galicia through the Consellería de Innovación e Industria (10MMA312025PR) and the Consellería de Educación-FEDER.

References

Akaike, H. (1974). A new look at the statistical model identification. IEEE Transactions on Automatic Control 19, 716-723.
Cailliet, G.M., Smith, W.D., Mollet, H.F. and Goldman, K.J. (2006). Age and growth studies of chondrichthyan fishes: the need for consistency in terminology, verification, validation, and growth function fitting. Environmental Biology of Fishes 77 (3-4), 211-228.
da Costa, F., Darriba, S. and Martinez-Patiño, D. (2008). Embryonic and larval development of Ensis arcuatus (Jeffreys, 1865) (Bivalvia: Pharidae). Journal of Molluscan Studies 74, 103-109.
da Costa, F., Darriba, S., Martinez-Patiño, D. and Guerra, A. (2011). Culture possibilities of the razor clam Ensis arcuatus (Pharidae: Bivalvia). Aquaculture Research 42, 1549-1557.
da Costa, F. and Martínez-Patiño, D. (2009). Culture potential of the razor clam Solen marginatus (Pennánt, 1777). Aquaculture 288, 57-64.
da Costa, F., Novoa, S., Ojea, J. and Martinez-Patiño, D. (2013). Biochemical and fatty acid dynamics during larval development in the razor clam Ensis arcuatus (Bivalvia: Pharidae). Aquaculture Research, 44, 1926-1939.
Hernández-Otero, A., Gaspar, M.B., Macho, G. and Vázquez, E. (2014). Age and growth of the sword razor clam Ensis arcuatus in the Ría de Pontevedra (NW Spain): influence of environmental parameters. Journal of Sea Research 85, 59-72.
Katsanevakis, S. (2007). Growth and mortality rates of the fan mussel Pinna nobilis in Lake Vouliagmeni (Korinthiakos Gulf, Greece): a generalized additive modelling approach. Marine Biology 152, 1319-1331.
Kielbassa, J., Delignette-Muller, M.L., Pont, D. and Charles, S. (2010). Application of a temperature-dependent von Bertalanffy growth model to bullhead (Cottus gobio). Ecological Modelling 221(20), 2475-2481.
Otterlei, E., Nyhammer, G., Folkvord, A. and Stefansson, S.O. (1999). Temperature and size-dependent growth of larval and early juvenile Atlantic cod (Gadus morhua): a comparative study of Norwegian coastal cod and northeast Arctic cod. Canadian Journal of Fisheries and Aquatic Sciences 56, 2099-2111.
R Development Core Team, 2013. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria.
Robinson, R.F. and Richardson, C.A. (1998). The direct and indirect effects of suction dredging on a razor clam (Ensis arcuatus) population. ICES Journal of Marine Science 55, 970–977.
Urban, H.J. (2002). Modeling growth of different developmental stages in bivalves. Marine Ecology-Progress Series 238, 109-114.

Keywords: Bivalve, Ensis magnus, culture, growth model, Model selection, seasonal growth., razor clam

Conference: XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016.

Presentation Type: Oral Presentation

Topic: 4. FISHERIES, AQUACULTURE AND BIOTECHNOLOGY

Citation: Hernández Otero A, Barreiro A, Macho G and Vazquez E (2016). Growth of the sword razor (Ensis magnus) early stages: modelling juvenile seasonal growth. Front. Mar. Sci. Conference Abstract: XIX Iberian Symposium on Marine Biology Studies. doi: 10.3389/conf.FMARS.2016.05.00077

Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.

The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.

Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.

For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.

Received: 30 Apr 2016; Published Online: 02 Sep 2016.

* Correspondence: PhD. Alba Hernández Otero, Universidade de Vigo, Dpto. Ecoloxía e Bioloxía Animal and Estación de Ciencias Mariñas de Toralla, Vigo, 36200, Spain, alba.hernandez@uvigo.es