Marta M. Rufino

Male and female carapace shape differences in Liocarcinus depurator (Decapoda, Brachyura): An application of geometric morphometric analysis to crustaceans

Abstract Liocarcinus depurator is the most abundant brachyuran by—catch from commercial trawl fisheries along the Spanish Mediterranean coast. Individuals of this species were collected from bottom trawl surveys covering the entire Iberian Mediterranean coast (from Gibraltar to Cape Creus), throughout the species’ depth distribution. Geometric morphometric techniques were used to determine any differences in shape between male and female crabs. Differences in shape not observed with traditional morphometric techniques were detected. Females were found to have a larger base of the abdomen which is discussed in the context of reproductive success.

The influence of coastal processes on inner shelf sediment distribution: The Eastern Algarve Shelf (Southern Portugal)

This study examines sediment distribution patterns in the Southeastern Algarve inner shelf (southern Portugal), an area characterized by marked variations in its coastal environment and low continental supply of sediments. The specific goals of this study were to identify the principal sediment sources and the factors influencing sediment transport paths and deposition. A total of 199 samples, collected along the shelf from the Guadiana River mouth to Olhos de Agua, were analyzed. Grain-size distribution and parameters were measured for all the samples. Terrigenous and biogenic components of sand were identified in 38 samples, and results analyzed using multivariate non-linear multidimension scaling (MDS) and cluster analysis. Patterns of sediment distribution in this area of the inner shelf vary according to water depth and exhibit significant longshore variation, related mainly to coastal processes (littoral drift and storm currents) and to a lower degree to sediment sources. Sand is dominant at all depths, reflecting the influence of littoral drift in the supply and redistribution of shelf sediments. Fine and gravelsized deposits are significant in specific areas and are usually associated with changes in sediment composition. Five sectors have been identified according to sedimentary dynamics. The results, based on geostatistical and multivariate analysis, have allowed detailed sediment distribution maps to be generated, which represent an update of the existing cartography and serve as a tool for the management of coastal and marine resources. They have been furthermore compared with inner shelf sediment dynamics in other regions worldwide, to distinguish between specific regional responses to forcing mechanisms and processes that are more generalized within this type of shelf environments. In this context, the results obtained results in the Algarve study area are of great interest for the understanding of sediment dynamics of sand dominated inner shelves with reduced continental supply.

Spatial and environmental factors affecting the distribution of the main decapod crustacean prey species in the NW Mediterranean

The decapod crustaceans Alpheus glaber, Calocaris macandreae, Processa canaliculata and Solenocera membranacea are some of the most common prey items for both fish and other decapod crustaceans in the muddy bottom communities of the lower continental shelf and upper slope in the western Mediterranean Sea. Despite their high densities and key ecological role, these species are often neglected in scientific studies due to their relatively small size and the associated difficulties in adequately sampling them, so little information is available on their biological and ecological characteristics. We studied the spatial distribution of these four main crustacean prey species in an area off the Ebro Delta (W Mediterranean), using non-linear geostatistics. We performed log-normal kriging, considering depth as a covariate in the spatial model (universal kriging with external trend). All semivariograms were fitted to a spherical model, but with different relationships to depth. All species were more abundant in a sub-area characterised by a gentler slope and the presence of submarine canyons. The spatial correlation between densities of all species and sediment variables were analysed. All species except Solenocera membranacea were negatively correlated with sorting coefficient (IGSD), showing a preference for well sorted, homogeneous sediments corresponding to low energy areas. Further, Calocaris macandreae higher densities were associated with areas of coarser grain size (Φ) and Processa canaliculata density was negatively correlated with carbonate content of the sediment (CO3).

Morphology of the larval and first juvenile stages of the spider crab Lissa chiragra (Brachyura: Majidae: Pisinae)

The two zoeae, megalopa and first crab stage of the majid crab Lissa chiragra are described and illustrated from laboratory-hatched and reared material obtained from an ovigerous female collected on the western Mediterranean continental shelf. The morphology of the larval stages and first crab is compared with the corresponding stages of other known species of the subfamily Pisinae. The larval development and the first crab stages of L. chiragra are morphologically very similar to other larval descriptions of species of the genus Pisa.

First record of Albunea carabus (Decapoda, Anomura, Hippidea) from the Algarve coast, South Portugal

Abstract During an annual bivalve dredge survey undertaken in April 2005 along the Portuguese coast, one specimen of the sand crab Albunea carabus was collected. This is the first record of this species on the Portuguese continental shelf. The individual found was a male with 11.31 mm carapace length and was collected off Faro at 3 m depth in a sandy area considerably hydrodynamic during winter. This occurrence is one of the few records outside the Mediterranean Sea. A short review of previous findings on this species is presented.

Diversity of planktonic foraminifer fauna found in 18 deep-sea cores from the North Atlantic

Greenland stadial/interstadial cycles are known to affect the North Atlantics hydrography and overturning circulation and to cause ecological changes on land (e.g., vegetation). Hardly any information, directly expressed as diversity indices, however, exists on the impacts of these millennial-scale variations on the marine flora and fauna. We calculated three diversity indices (species richness, Shannon diversity index, Hurlberts probability of interspecific encounter) for the planktonic foraminifer fauna found in 18 deep-sea cores covering a time span back to 60 ka. Clear differences in diversity response to the abrupt climate change can be observed and some records can be grouped accordingly. Core SO82-05 from the southern section of the subpolar gyre, the cores along the British margin and core MD04-2845 in the Bay of Biscay show two modes of diversity distribution, with reduced diversity (uneven fauna) during cold phases and the reverse (even fauna) during warm phases. Along the Iberian margin high species diversity prevailed throughout most of the glacial period. The exceptions were the Heinrich stadials when the fauna abruptly shifted from an even to an uneven or less even fauna. Diversity changes were often abrupt, but revealed a high resilience of the planktonic foraminifer faunas. The subtropical gyre waters seem to buffer the climatic effects of the Heinrich events and Greenland Stadials allowing for a quick recovery of the fauna after such an event. The current work clearly shows that planktonic foraminifer faunas quickly adapt to climate change, albeit with a reduced diversity.