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Research Project
Integrative Approach to develop bioindicators of overfishing symptoms in fully-exploited species in areas with differente protection and management regimes
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Publications
Major ocean currents may shape the microbiome of the topshell Phorcus sauciatus in the NE Atlantic Ocean
Publication . Sousa, Ricardo; Vasconcelos, Joana; Vera-Escalona, Iván; Delgado, João; Freitas, Mafalda; González, José A.; Riera, Rodrigo
Studies on microbial communities are pivotal to understand the role and the evolutionary paths of the
host and their associated microorganisms in the ecosystems. Meta-genomics techniques have proven
to be one of the most efective tools in the identifcation of endosymbiotic communities of host
species. The microbiome of the highly exploited topshell Phorcus sauciatus was characterized in the
Northeastern Atlantic (Portugal, Madeira, Selvagens, Canaries and Azores). Alpha diversity analysis
based on observed OTUs showed signifcant diferences among regions. The Principal Coordinates
Analysis of beta-diversity based on presence/absence showed three well diferentiated groups, one
from Azores, a second from Madeira and the third one for mainland Portugal, Selvagens and the
Canaries. The microbiome results may be mainly explained by large-scale oceanographic processes
of the study region, i.e., the North Atlantic Subtropical Gyre, and specifcally by the Canary Current.
Our results suggest the feasibility of microbiome as a model study to unravel biogeographic and
evolutionary processes in marine species with high dispersive potential.
The protection effects of marine protected areas on exploited molluscs from an oceanic archipelago
Publication . Sousa, Ricardo; Henriques, Paulo; Vasconcelos, Joana; Pinto, Ana Rita; Delgado, João; Riera, Rodrigo
1. Limpets are one of the most successful intertidal algal grazers in the north-eastern
Atlantic. They provide valuable ecosystem services, playing a pivotal role in
maintaining rocky shore ecological balance and have an important economic
value, being subject to high levels of exploitation in several oceanic archipelagos.
Limpets represent one of the most profitable economic activities of small-scale
fisheries in the Madeira archipelago. However, limpets are extremely vulnerable
to anthropogenic impacts, such as overharvesting, habitat fragmentation, and
pollution.
2. The protection effects and the effectiveness of marine protected areas (MPAs) on
the population dynamics of two historically highly exploited limpet species, Patella
aspera and Patella candei, were analysed through a comparative study of size,
reproduction, and biomass in the Madeira archipelago.
3. The effects of protection from MPAs on limpet populations resulted in a
differential increase on size at first maturity, shell size, and capture per unit effort
according to the degree of protection.
4. Old and enforced MPAs showed the best-preserved limpet populations in the
study area, and both variables (age and enforcement) best explained the observed
variability among the MPAs studied.
5. A thorough and multidisciplinary study is necessary to obtain a reliable picture of
commercial stocks of the two targeted species (P. aspera and P. candei). Genetic
analysis and studies on the food source of limpets may shed light to develop
integrative conservation strategies.
Pleistocene expansion, anthropogenic pressure and ocean currents: Disentangling the past and ongoing evolutionary history of Patella aspera Röding, 1798 in the archipelago of Madeira
Publication . Sousa, Ricardo; Vasconcelos, Joana; Vera-Escalona, Iván; Pinto, Ana Rita; Hawkins, S. J.; Freitas, Mafalda; Delgado, João; González, José A.; Riera, Rodrigo
Aims: Rising sea-level following the Last Glacial Maximum lead to fragmentation of coastal limpet populations
between islands of the Archipelago of Madeira. This fragmentation is reinforced by recent heavy exploitation
reducing effective population size on Madeira Island. We use the limpet P. aspera to understand how the role of
processes at different time scales (i.e. changes in the sea level and overexploitation) can influence the genetic
composition of an extant species, relating these processes to reproductive phenology and seasonal shifts in ocean
currents.
Location: Madeira Island, Porto Santo and Desertas (Archipelago of Madeira, NE Atlantic Ocean).
Taxon: The limpet Patella aspera.
Methods: Twelve microsatellite genetic markers were used. A power analysis was used to evaluate the power of
the microsatellite markers to detect a signal of population differentiation. Long-term past migrations were
assessed using a Bayesian Markov Montecarlo approach in the software MIGRATE-n to estimate mutation-scaled
migration rates (M = m/μ; m, probability of a lineage immigrating per generation; μ, mutation rate). Two sce narios were evaluated using an Approximate Bayesian Computation (ABC) in the software DIYABC 2.1 (i) Sce nario 1: considered a population scenario from a reduced Ne at time t3 to a higher Ne at time t2; and (ii) Scenario
2 considering a reduction of Ne from a time t3 to a time t2.
Results: Colonization of the archipelago by Portuguese settlers six centuries ago probably led to an important
decrease in the genetic diversity of the species (Ne). Contemporary gene flow strongly support a pattern of high
asymmetric connectivity explained by the reproductive phenology of the species and spatio-temporal seasonal
changes in the ocean currents. Spatio-temporal reconstructions using Bayesian methods, including coalescent
and Approximate Bayesian Computation (ABC) approaches, suggest changes in the migration patterns from
highly symmetric to highly asymmetric connectivity with subtle population differentiation as consequence of
post-glacial maximum sea level rise during the Holocene.
The shell phenotypic variability of the keyhole limpet Fissurella latimarginata: insights from an experimental approach using a water flow flume
Publication . Vasconcelos, Joana; Caamaño, Diego; Tuset, Víctor M.; Sousa, Ricardo; Riera, Rodrigo
Hydrodynamics are a major environmental factor on intertidal rocky shores. Morphological responses to
this factor are expected to strongly influence spatial distribution of species across environmental gradients.
We here analysed the shell phenotypic variability of the limpet Fissurella latimarginata using geometric mor phometric analysis. The limpets were obtained from a sheltered intertidal coastal area and a wave-exposed
environment. To determine whether the shell shape variation of the intertidal molluscs is linked to their
resistance to differential intertidal wave exposure, mesocosm studies were developed in a hydraulic flume
to explore the effects of hydrodynamic forces on this limpet species. A unidirectional current was used to
test the impacts of step-by-step increased current flow velocities for each limpet. The phenotypic variability
observed in the populations of F. latimarginata was associated with habitats characterized by contrasting wave
exposure. Limpets from exposed environments showed a flattened, round to laterally wider and posteriorly
narrower shell shape, larger foot and higher full limpet height, and were dislodged at higher velocities. A
more laterally compressed and peaked shape was found in limpets from sheltered areas and these showed a
lower resistance to wave action by dislodging at lower velocities.
Unravelling the effects of exploitation on the size–structure of the intertidal topshell Phorcus sauciatus in harvested and non-harvested Atlantic regions
Publication . Sousa, Ricardo; Vasconcelos, Joana; Riera, Rodrigo
Intertidal molluscs are keystone species often used as biological indicators of human-driven pertur bations. The increasing levels of harvesting pressure on these intertidal grazers, due to the expansion
of human population on coastal areas, is known to affect negatively the exploited populations by
altering population size–structure and decreasing abundances. A comparative study on the effect
of harvest on the size–structure of Phorcus sauciatus populations was conducted according to the
exploitation level, harvested and non-harvested, throughout the intertidal zone of mainland Portugal,
Azores, Madeira, and the Canaries. The comparative analysis of the size–structure of 10,480 individuals
of P. sauciatus showed that the largest individuals were recorded in the Azores and the smallest in
Madeira. In harvested populations, P. sauciatus showed to be under greater harvesting pressure in the
archipelago of Madeira, where the lowest mean size was observed. In the Canaries the harvesting is
regulated whilst in the mainland Portugal the regulation is scarce. The Azores showed no harvesting
pressure. Marine Protected Areas showed individuals with the highest mean sizes supporting their
effectiveness in preserving the size–structure of this species, regardless the ecoregion and thus,
the harvesting pressure. The present results highlight the importance of harvesting regulation of P.
sauciatus in Madeira, as well as the implementation of management measures aiming at the sustainable
exploitation and conservation of this species.
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Funders
Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
Funding Award Number
SFRH/BSAB/143056/2018