Rock-pools as nurseries for co-existing limpets: dynamics of limpet nursery grounds in SW Portugal
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1
University of Evora, MARE- Marine and Environmental Sciences Centre, Laboratório de Ciências do Mar, Universidade de Évora, Apartado 190, 7521-903 Sines, Portugal
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2
Escola de Ciência e Tecnologia, Universidade de Évora, Departamento de Biologia, Portugal
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3
Marine Biological Association of the United Kingdom, United Kingdom
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4
School of Ocean and Earth Science, University of Southampton, United Kingdom
Limpets are key-organisms structuring rocky intertidal assemblages. Here we studied recruitment patterns of the patellids Patella depressa and Patella ulyssiponensis, and of the pulmonate striped-limpet Siphonaria pectinata, which are common inhabitants on Iberian rocky shores.
Rock-pools are presumably important nursery grounds for limpets, due to high sensitivity of their early-benthic life-stages to environmental variation present in open-rock habitats at emersed conditions. However, the relative importance of rock-pools as nurseries relatively to other habitats (namely other wet and patchy microhabitats) has been rarely assessed.
In Sines region (SW coast of Portugal), the shoreline has experienced major anthropogenic changes since the ‘70s due to the setting of the Port of Sines, a deep oceanic port with worldwide maritime importance. Inside the limits of the Port, man-made breakwaters mainly compose the rocky-intertidal environment, where rock-pools are mostly absent. A lower density of limpets inside this Port, compared with outside adjacent areas, was previously reported.
In this study, the following questions are addressed, separately for each of the three species: i) what is the relative importance of rock-pools as habitats for juvenile limpets comparatively to other intertidal habitats?; ii) what is the temporal (seasonal and inter-annual) variation of limpet recruitment?; iii) how does limpet recruitment vary spatially among one shore located within an oceanic port and two nearby shores located at increasing distances relatively to the port? Moreover, inter-specific correlative hypotheses on the patterns of limpet recruitment into rock-pools were tested, namely if recruitment of co-existing limpet species is correlated in time and in space.
Two field-surveys (August / Early September 2007 and February 2009) focused on the search for limpet juveniles (maximum shell length – MSL – of less than 10 mm for Patella spp. and less than 5 mm for S. pectinata) were carried out at three natural shores in the region of Sines, covering a wide range of intertidal habitats (rock-pools, open-rock and crevices at different tidal levels; North and South-oriented vertical walls; patches of mussels, Lichina pygmaea and Fucus).
Temporal variation in recruitment was examined in a series of mid-shore rock-pools present in the same three shores, which were limpet-cleared at three-monthly intervals from May 2005 to July 2008. Recruitment to three months was defined as the density of individuals measuring less than 5 mm in MSL (recruits) recorded at each sampling time in each limpet-cleared rock-pool. This size limit (MSL < 5mm) was established in common for all the three species, based on a preliminary analysis of size-frequency distribution of each species densities during the total period of study. Among-shore variation of recruitment to three-months into rock-pools was also assessed for each species (one natural shore located inside the Port, and the other two shores were outside the Port, 4 and 9 km away).
In general, juvenile densities of all species were significantly highest in rock-pool habitats, although the spatial pattern of distribution and abundance of juveniles across intertidal habitats was unique for each species.
Recruitment to three months of Patella depressa and Patella ulyssiponensis into rock-pools was consistently low during all summer periods of the whole study period. The density of recruits of these species was higher during other seasonal periods but there was inter-annual variability of the highest recruit density peaks. The maximum density of Siphonaria pectinata recruits (average of 102 individuals in 15 x15 cm2) was recorded for the summer of 2005. During the following years recruitment of S. pectinata was comparatively low, but consistently higher during summer or autumn comparatively with the other seasons.
Recruitment of Patella depressa varied significantly among all the three shores, being lowest in the shore inside the Port and highest in the farthest shore from the Port. Recruitment of Patella ulyssiponensis and Siphonaria pectinata was significantly higher in the farthest shore from the Port than in the other two shores.
Overall, Pearson correlation analyses showed a significant positive relationship between recruitment of Patella depressa and Patella ulyssiponensis along space and time, and that recruitment of Siphonaria pectinata was not correlated with any of the other two species.
Keywords:
Rocky-shore ecology,
recruitment,
Patella,
Siphonaria,
Sympatry,
Intertidal habitats
Conference:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019.
Presentation Type:
Oral Presentation
Topic:
Ecology, Biodiversity and Vulnerable Ecosystems
Citation:
Seabra
M,
Cruz
T,
Espírito Santo
CI,
Castro
JJ and
Hawkins
SJ
(2019). Rock-pools as nurseries for co-existing limpets: dynamics of limpet nursery grounds in SW Portugal.
Front. Mar. Sci.
Conference Abstract:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) .
doi: 10.3389/conf.fmars.2019.08.00019
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Received:
22 Aug 2019;
Published Online:
27 Sep 2019.
*
Correspondence:
Miss. Maria Inês Seabra, University of Evora, MARE- Marine and Environmental Sciences Centre, Laboratório de Ciências do Mar, Universidade de Évora, Apartado 190, 7521-903 Sines, Évora, 7004-516, Portugal, iseabra@uevora.pt