Marked seasonality and high spatial variation in estuarine ciliates are driven by exchanges between the ‘abundant’ and ‘intermediate’ biospheres

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Parental contributions and growth rate in an atlantic x mediterranean cross of the clam ruditapes decussatus

Trabajo presentado en la International Conference & Exposition Aquaculture Europe, celebrada en Funchal, Maderia (Portugal) del 04 al 07 de octubre de 2021.The interest of the native European clam Ruditapes decussatus for aquaculture is increasing (da Costa et al., 2020). Spat of this species is usually utilized to restocking harvested natural populations (Borrell et al., 2014). A detailed knowledge of the performance in hatcheries and an adequate management of the species¿ genetic diversity are essential to develop a science-based management of clam fisheries and aquaculture. Adequate levels of genetic diversity in the hatchery stock depends on the contribution of a large number of parents, but this often is not the case in bivalves (Borrell et al., 2014). Moreover, R. decussatus is characterized by the existence of three races, which could be maintained by endogenous barriers to gene flow (Cordero et al, 2014; Arias-Pérez et al., 2016). Applying microsatellites as genetic markers to the progeny of a cross between clams of Atlantic and West Mediterranean races, we have studied three topics which are important for clam production and conservation of genetic resources: 1) male and female contributions to offspring after conditioning and spawning induction in the hatchery; 2) testing for genetic barriers between the two races; and 3) growth rate differences among families and populations.Financed through grants AGL2017-87745-C2-1-R and AGL2017-87745-C2-2-R. from (MINECO/AEI/FEDER, UE

Diatom ecological preferences in a shallow temperate estuary (Ria de Aveiro, Western Portugal)

The study of the diatom ecological preferences was conducted from January 2002 to June 2003 in Canal de Mira, Ria de Aveiro, Western Portugal. Three sampling stations along a salinity gradient were sampled monthly, in new moon, at high and low tide. Salinity, temperature, pH, dissolved oxygen and nutrient contents were measured for each sampling station; chlorophyll a and diatom diversity and abundance were also evaluated. Canonical correspondence analysis was used to identify the environmental variables governing the composition and structure of diatom assemblage. The variation in the species data among the different reaches was strongly determined by the salinity spatial gradient and by the temperature temporal gradient. The lower reaches were dominated by marine species (e.g. Auliscus sculptus, Chaetoceros densus, Fallacia forcipata,Licmophora flabellata, L. grandis, Surirella comis), while in the most upstream station typical freshwater species dominated (e.g. Caloneis permagna, Cymatopleura solea, Cymbella tumida, Gomphonema longiceps, Pinnularia stommatophora, Stauroneis smithii). Weighted averaging was used to estimate optima and tolerances of some diatom taxa for the most influential variables. It was possible to establish groups oftaxa with defined and distinctive salinity and temperature preferences