Browsing by Author "Mendonça, Vanessa"
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- Changing webs—Variation of complex networks over a tidal cycle in an intertidal rocky reefPublication . Vinagre, Catarina; Mendonça, VanessaIncorporating temporal variation in models is one of the most important challenges in food web research. One of the environments where time causes profound changes is the intertidal zone, where the immersion-emersion cycle drastically changes the abiotic and biotic conditions. Intertidal rocky shores have been intensively studied, however the variation in the complex food web network that occurs during a tidal cycle remains undescribed. Highly resolved food web networks were assembled for an intertidal reef depicting the food web during low and high tide, and with and without tide pools. It was concluded that high tide adds new species to the web, but it does not add complexity since network connectance was not changed. This occurs because incoming species are mostly highly generalist fish, which add many new links to the web. Tide pools, however, add not only diversity but also complexity. Webs were dominated by intermediate species, with the proportion of top consumers fluctuating throughout the tidal cycle, being lowest during low tide and highest at high tide, due to the incoming larger vertebrate predators. Consumer taxa outnumbered resource taxa, except at low tide when pools are present. Mean trophic level was lowest at low tide (2.3) and highest at high tide with pools (2.6). Omnivory was high and showed little change. "Chain", the number of links connecting top to basal species, was stable but low. This implies that disturbance can rapidly travel bottom-up or top-down through predator-prey links. The increased connectance given by the addition of tide pools likely increases robustness to disturbances, an important feature in coastal areas so often impacted by human action.
- Environmental factors impacting the abundance and distribution of amphipods in intertidal rock poolsPublication . Carvalho, Jéssica; Mendonça, Vanessa; Vinagre, Catarina; Silva, AnaIntertidal rock pools are considered critical habitats along coastal shores. Amphipods play an important role in intertidal rock pool ecosystems, as food resources for higher trophic levels and sometimes by enriching nutrients through grazing. However, the environmental factors driving their rockpool occupation remain largely unknown. We aimed to examine the importance of the large-scale wave action variation and meso-scale shore variation on the abundance and diversity of rockpool amphipods. A total of 32 intertidal rock pools on four Portuguese shores were studied during the summer spring tide of 2015. We applied multivariate analysis to evaluate the potential impact of wave action (sheltered versus wave exposed shores), physical pool structure (length, width, and depth), and relationships within the pool community on the abundance and diversity of amphipods. Wave exposure significantly influenced amphipod abundance and diversity, and some substrata and biodiversity features of the pool were important in explaining the amphipod abundance. The percentage and composition of coverage and physical features of the rock pools had no significant effect on amphipod abundance and diversity. We showed that the amphipod rockpool community displayed a clear positive response of biodiversity and abundance to the extrinsic factor wave action, and a varied and complex response to within-rockpool biotic variables. In addition, we recorded the presence of the invasive Ampithoe valida for the first time on rocky shores of Portugal. Further investigation into the influence that wave action has on associated pool biota (i.e., dislodgment or deposition of species) could give additional insight into the role of the biotic community in the regulation of amphipod populations within intertidal rock pools
- Warming in shallow waters: Seasonal response of stress biomarkers in a tide pool fishPublication . Vinagre, Catarina; Madeira, Diana; Mendonça, Vanessa; Madeira, Carolina; Diniz, Mário S.Tide pools are rapidly warming environments with low thermal inertia, where organisms are exposed to potentially stressful conditions. This way, tide pools will be among the first and hardest hit environments by climate warming. Studies of thermal stress in situ are rare, but important so that current thermal stress in the wild can be confirmed and serve as reference for the future. This study aims to investigate the seasonal response of stress biomarkers in a common tide pool fish, the blenny Lipophrys trigloides, under natural conditions, in situ. Multiple biomarkers of thermal and oxidative stress were analysed in the tissues of the muscle, visceral mass, gills and brain of L. trigloides, under spring (18.50 +/- 0.71 degrees C) and summer conditions (28.30 +/- 1.30 degrees C), in order to assess tissue-specific seasonal responses to the rapid warming that occurs seasonally in tide pools. It was concluded that L. trigloides seems to be setting in motion relevant thermal stress and antioxidant defences under summer conditions. All tissues analysed were responsive and all biomarkers of thermal and oxidative stress increased in summer conditions, with the exception of SOD, which presented no alterations. The present study offers reference values that will be useful for future comparison during particularly warm summers and in future years as climate warming progresses.