Connectivity among estuarine and coastal fish populations using otolith geochemistry

• Main Author: Tanner, Susanne Eva,1978-
• Publication Date: 2012
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10451/7135
• topic: Geoquímica; Otolitos; Marcadores; Variabilidade; Estrutura populacional

Connectivity is a critical property of marine fish populations as it defines population replenishment, colonization patterns and populations’ resilience to harvesting. Otolith geochemistry is one of the techniques with greatest potential to determine fish movements, especially at early life stages. The accurate use of otolith geochemical signatures as natural tags in connectivity and population structure studies is tied to a thorough assessment of the variability of these markers at different spatio-temporal scales. Additionally, understanding the relationships between otolith geochemical composition and physicochemical properties of ambient water is necessary for tracking fish movement patterns. Several otolith elemental and isotopic ratios were identified as potentially useful proxies for temperature or salinity in estuarine environment which might allow the accurate reconstruction of habitat use of juvenile Solea solea. The significant differences between the geochemical composition of otolith core and edge observed in S. solea and Merluccius merluccius were possibly related to ontogenetic and environmental factors. Otolith geochemical signatures of juvenile S. solea and Solea senegalensis varied significantly between and within years yet without interfering in the spatial discrimination of estuaries. Juvenile soles were accurately assigned to their estuaries of origin and the established geochemical signatures constitute the baseline data for assessments of connectivity between juvenile and adult populations. The estimated relative contributions from estuarine source areas to adult coastal populations allowed the successful identification of the estuarine systems that accounted most for the replenishment of adult stocks of both sole species in two years. The integration of otolith geochemistry and microsatellite DNA markers, applied in a hierarchical manner, enhanced population structure estimates of M. merluccius since the two markers act at different spatio-temporal scales. Overall, the present results should promote the development of effective conservation strategies for ecologically important habitats and integrated fisheries management plans for these commercially important species