Accurate discrimination of two morphologically similar species of Patella limpets has been facilitated by using qPCR amplification of species-specific mitochondrial genomic regions. Cost-effective and non-destructive sampling is achieved using a mucus swab and simple sample lysis and dilution to create a PCR template. Results show 100% concurrence with dissection and microscopic analysis, and the technique has been employed successfully in field studies. The use of highly sensitive DNA barcoding techniques such as this hold great potential for improving previously challenging field assessments of species abundance.

Realization that hard coastal infrastructures support lower biodiversity than natural habitats has prompted a wealth of research seeking to identify design enhancements offering ecological benefits. Some studies showed that artificial structures could be modified to increase levels of diversity. Most studies, however, only considered the short-term ecological effects of such modifications, even though reliance on results from short-term studies may lead to serious misjudgements in conservation. In this study, a seven-year experiment examined how the addition of small pits to otherwise featureless seawalls may enhance the stocks of a highly-exploited limpet. Modified areas of the seawall supported enhanced stocks of limpets seven years after the addition of pits. Modified areas of the seawall also supported a community that differed in the abundance of littorinids, barnacles and macroalgae compared to the controls. Responses to different treatments (numbers and size of pits) were species-specific and, while some species responded directly to differences among treatments, others might have responded indirectly via changes in the distribution of competing species. This type of habitat enhancement can have positive long-lasting effects on the ecology of urban seascapes. Understanding of species interactions could be used to develop a rule-based approach to enhance biodiversity.

There is clear evidence that marine reserves can be used as effective tools to foster the recovery of disturbed ecosystems. In the Azores, intense exploitation of the patellid limpets Patella candei and P. aspera has led to a rapid decline in their populations and subsequent collapse of the fishery in 1985. In 1993, legislation was passed to protect limpets, including the establishment of limpet protected zones (LPZs) where harvesting was completely prohibited. Outside LPZs, a seasonal fishing closure prohibited the harvesting of limpets from October to May. Here we examine the effect of such measures 16 years after they were put into practice. In each of the 3 years examined, limpet density, biomass and size were generally similar both inside and outside the LPZs. In addition, there were clear signs of exploitation as most individual limpets inside the LPZ were smaller than the legal catch size suggesting that illegal harvesting was taking place. Observations confirmed that illegal harvesting of limpets was common both inside and outside LPZs. Lack of enforcement of regulations is therefore a likely reason for the failure of legislation to protect limpet populations and facilitate stock recovery.

A large (100 km) rocky coast intertidal was sampled several times (from 2004 to 2006) to assess the affection degree of invertebrate assemblages impacted by a continuous oil spill. Twelve locations and two intertidal heights were selected along the coast representing two spatial scales (kilometres and tens of metres). Univariate and multivariate analyses of variance were used to test whether faunal assemblages exposed to different intensities of oil disturbance differ in terms of diversity, total cover, key species cover and trophic guilds. Whereas no significant differences in midshore assemblages were noted, the low intertidal zone exhibited comparatively lower abundance values of the limpet Patella ulyssiponensis at worst affected sites. Besides, a generalized increasing diversity trend was found in the low intertidal from 2004 to 2006. Natural variability of communities is also discussed as the cause of the differences we observed. With respect to spatial and temporal scales of variation, mid- intertidal communities showed a more consistent structure, while lowshore assemblages were markedly heterogeneous in practically all the variables measured.

The aim of this study was to investigate the effect of food deprivation on the cardiac activity of two Mediterranean limpets, the exploiter Patella caerulea and the conserver P. rustica, which have different foraging regimes. Heart rate variations were monitored in the two species according to two experimental protocols: (1) starvation/recovery, during which limpets were starved for up to 15 days and then allowed to feed on boulders covered with microalgae; (2) starvation/forced feeding, during which specimens were starved for 11 days and then fed orally with a test (30 mg/ml glucose) or control solution. Increasing starvation time was associated with a significant decline of heartbeat frequency in both species. The decline was comparable in the two species, but heartbeat frequencies in P. rustica were always significantly lower than in P. caerulea. When the limpets were allowed to feed on natural substrates, a rapid increase in heart rate was observed, with frequencies slightly higher than those measured at the beginning of the experiment. No significant difference in heart rate was observed between the two species. Similarly, both in P. caerulea and P. rustica forced feeding caused a recovery of heart rate to pre-treatment levels. The results are consistent with previous findings on the metabolic consequences of food deprivation in gastropods and demonstrate the ability of both species to depress their heart rate when faced with a food shortage. Moreover, a greater regulative ability was observed in P. rustica than in P. caerulea, confirming their status as conserver and exploiter, respectively.

Traumatic avulsions of ligament or tendon insertions rarely occur at the actual interface with bone, which suggests that this attachment is strong or otherwise protected from injury by the structure of the insertion complex. In this study we describe the terminal extent of quadriceps tendon fibres where they insert into the patellae of adult rabbits, humans, dogs and sheep. Specimens were examined by scanning electron microscopy (SEM) and light microscopy (LM). To facilitate tracing of tendon fibres the specimens were decalcified for SEM, and polarised light microscopy (PLM) was used in the LM segment of the study. By SEM it was possible to identify mature bone by the presence of osteocytes and a lamellar organisation. PLM and SEM showed that, unlike tendon fibres elsewhere, those in the calcified fibrocartilage were not crimped. No specific cement line was identified by SEM. Tendon fibres interdigitated among separate bone lamellar systems, (osteons or marrow spaces), but did not merge with the collagen systems of individual lamellae. The interdigitation was more extensive and the margin between tendon and bone was less distinct in the anterior third of the insertion. The segment of calcified tendon which interdigitated with bone stained less intensely blue and was less cellular than the more proximal calcified fibrocartilage zone adjacent to the tidemark. Lamellar collagen fibres of the bony trabeculae in the anterior patella were unusually parallel and longitudinal in orientation, making distinction of interposed tendon fibres difficult on LM and PLM sections. LM, SEM and transmission electron microscopy of rabbit patellae at birth revealed that anterior quadriceps tendon fibres extended over the patella in a fibrous cellular layer. By 2 wk of age, this layer had acquired chondroid features (i.e. cell lacunae and metachromasia) and contained vessels extending from patellar marrow. At 6 wk of age, part of this fibrocartilaginous layer was replaced by mature bone and osteoid. In the young adult animal, the quadriceps tension interdigitates extensively with the patellar bone. This segment of the insertion is perhaps the remnant of calcified fibrocartilage which has been remodelled by bone formation.