Marine fish assemblage typologies for the portuguese coast in the context of the European Marine Strategy Directives

• Author(s): Pais, Miguel Pessanha Freitas Branco
• Date: 2007
• Persistent ID: http://hdl.handle.net/10451/1396
• Origin: Repositório da Universidade de Lisboa
• Subject(s): Pesca; Teses de mestrado
• Document Type: Master thesis
• Language: English
• Advisor(s): Cabral, Henrique N.; Costa, Maria José Rosado
• Contributor(s): Repositório da Universidade de Lisboa

Description

Tese de mestrado em Ecologia e Gestão Ambiental, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2007

The proposed European Marine Strategy Directive (MSD) enforces the need for protection and conservation of the marine environment, having as the main objective the achievement of good environmental status' of the marine waters under jurisdiction of the Member States by 2021. In the MSD, fish are included as a biological element, thus constituting a new requirement for the assessment of marine waters that needs to be evaluated on the initial assessment to be presented by the fourth year after entry into force. These requirements urge the definition of marine fish assemblage typologies in order to permit the establishment of type-specific reference values that characterise a good' marine fish assemblage. With the aim of establishing and characterising marine fish assemblages for the Portuguese continental shelf, from intertidal areas down to the 200 m isobath, a large variety of available data from studies conducted in Portuguese waters was collected and species were assigned into ecological guilds of several categories. Using guild and species data independently, a detrended correspondence analysis identified depth and bottom type as the factors underlying the main distribution gradient and led to the establishment of six assemblage typologies. A non-metric analysis of similarities (ANOSIM) tested the consistency of the defined typologies and a similarity percentage analysis (SIMPER) routine identified the species and guilds that characterise each typology. Furthermore, the effects of latitude and seasonality were tested using ANOSIM and SIMPER within each typology, revealing that the first mainly affects soft substrate assemblages 20 to 100 m deep and the latter is noticed only deeper assemblages, within the same substrate. The established typologies revealed distinct structural and functional characteristics, thus requiring the establishment of different reference values for quality assessment

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