The role of upwelling in determining the composition, species distribution and genetic structure of intertidal communities in a time of climate change

Lourenço, Carla Sofia Emídio Rodrigues

Title: The role of upwelling in determining the composition, species distribution and genetic structure of intertidal communities in a time of climate change
Creator: Lourenço, Carla Sofia Emídio Rodrigues
Subject: Upwelling (Oceanography)
Subject: Intertidal organisms -- Morocco -- Atlantic Coast
Subject: Intertidal organisms -- Canary Current -- Effect of water currents on
Subject: Intertidal animals -- Canary Current -- Effect of water currents on
Subject: Intertidal animals -- Morocco -- Atlantic Coas
Subject: Mytilus galloprovincialis -- Morocco -- Atlantic Coast
Subject: Mytilus galloprovincialis -- Canary Current -- Effect of water currents on
Subject: Intertidal ecology -- Canary Current
Subject: Sea surface microlayer -- Morocco -- Atlantic Coast
Date Issued: 2018
Date: 2018
Type: text
Type: Thesis
Type: Doctoral
Type: PhD
Identifier: http://hdl.handle.net/10962/61614
Identifier: vital:28042
Description: Upwelling is an oceanographic process that strongly influences coastal species and the communities they belong to. In upwelling areas, colder, denser, nutrient-rich subsurface waters are transported to the nearshore surface, replacing warmer superficial waters that are advected offshore. Such effects influence the composition and dynamics of coastal communities, for example by affecting species abundance, recruitment, dispersal and distribution. Upwelling areas are key model regions to study the responses of coastal species to climate change because they are characterized by cooler conditions and experience lower warming rates than adjacent regions. In particular, intertidal rocky shore species are ideal coastal sentinel organisms to study distributional changes driven by climate warming because they inhabit the interface between marine and terrestrial habitats and are exposed to extremely severe environmental conditions. In fact, sharp distributional shifts have been reported for multiple intertidal species as a response to ocean warming. Although some studies have investigated the role of upwelling in influencing abundance and distribution of intertidal species, little is known about its potential as refugia against climate warming and the degree to which upwelling shapes species genetic structure is yet not fully understood. The aim of this thesis is to understand the influence of the Canary Current upwelling system on intertidal community composition, including species distribution and the genetic structure of intertidal species under current climate change. To do this, I investigated community structure of intertidal assemblages along the Atlantic shores of Morocco and Western Sahara, performed large scale surveys on species distribution, evaluated species abundance and frequency of parasitism and examined species genetic patterns. I further coupled biological data with upwelling indices, sea surface temperatures (SST) and the rate of SST warming. I demonstrate that strong upwelling influences abundance and distribution of intertidal rocky shore species and that upwelling cells can act as refugia from climate change by ameliorating thermal conditions. Upwelling cells also conserve the genetic diversity of the marine macroalga Fucus guiryi, promoting intraspecific genetic diversity by preserving unique genetic lineages. However, no evidence was found that upwelling affects the genetic structure for either F. guiryi or the brown mussel Perna perna. Instead, the genetic patterns presented in this thesis seem to result from a combination of species’ life history traits, population size and habitat suitability. My results also suggest that upwelling intensity affects the frequency of endolithic parasitism on the Mediterranean mussel Mytilus galloprovincialis. In times of climate change, upwelling events provide suitable environmental conditions for species to counter act climatic change. As upwelling is project to intensify in the future, its influence on benthic intertidal species might be greater than previously anticipated.
Format: 204 pages
Format: pdf
Publisher: Rhodes University
Publisher: Faculty of Science, Zoology and Entomology
Language: English
Rights: Lourenço, Carla Sofia Emídio Rodrigues

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