1,721,046 research outputs found
Intertrochanteric Varus Osteotomy for the treatment of the canine hip joint incongruence
No full textThe Role of the seagrass Posidonia oceanica on the sea urchin Paracentrotus lividus
Full text linkIn this research several aspects of the interaction between the seagrass Posidonia oceanica and
the sea urchin Paracentrotus lividus were investigated. The 1st experiment was a descriptive study
that had the aim to investigate whether protection has the same effect on the population structure of
P. lividus occurring on rocky reef habitat and in P. oceanica. The 2nd is also a descriptive study that
had the aim to estimate herbivory pressure of P. lividus on P. oceanica through indirect measures.
Specifically, it was asked what portion of the seagrass leaf is attacked by the sea urchins, whether
the abundance of grazing marks depend on the number of sea urchins and whether herbivory of P.
lividus depends on shoot density of the seagrass. The 3rd experiment was done to estimate the daily
migrations of P. lividus from a rocky habitat to P. oceanica patches and particularly if they depend
on the size of sea urchins and the distance from the patch edge. It was postulated that P. lividus
moves randomly to the seagrass patch and that the probability of reaching it could decrease with the
distance. The 4th experiment had the purpose to investigate the role of P. oceanica structure on P.
lividus distribution manipulating the seagrass structure and modifying the shoot density and leaf
high. Also, in this experiment artificial (plastic) seagrass units mimicking natural seagrass have
been used so that different combinations of shelter and food were provided
Evaluating the effects of protection on Paracentrotus lividus distribution in two contrasting habitats
No full textThe sea urchin Paracentrotus lividus is common in the Mediterranean in shallow subtidal rocky habitats and in Posidonia oceanica beds. The aim of this study is to investigate whether protection has the same effect on the population structure of P. lividus occurring in rocky reef habitats and in P. oceanica beds. These results are important to generate hypotheses about the influence of human harvesting, predatory pressure and migration processes on P. lividus in the two habitats.
Paracentrotus lividus was sampled at seven locations within the Gulf of Alghero (North West Sardinia) where the Capo Caccia–Isola Piana MPA (Marine Protected Area) is sited: 1 location was sited in Zone A, where no harvesting of P. lividus is allowed (NH), 3 locations were sited in Zone B, where harvesting is restricted (RH), and the other 3 were located outside the MPA where no restrictions apply to sea urchin harvesting (UH). For each combination of habitat × location, P. lividus density was assessed in 10 replicates using quadrats of 1 × 1 m and the size of 20 individuals (test diameter without spines) was measured. Finally, the specimens were grouped into size-classes to examine frequency distributions at each location. Sampling was performed at the end of the sea urchin harvesting period (April–May 2006).
Analyses of data have highlighted significant variability among locations for both response variables. In both habitats, no differences were found in Paracentrotus lividus abundance among levels of protection (NH vs. RH vs. UH), while a significantly higher size was found in NH rather than in RH and UH locations. Differential direct and indirect effects of protection on P. lividus size is discussed. Also, P. lividus size seemed dependent on the habitat being quite larger in Posidonia oceanica than in the rocky reefs. This finding suggests that settlement and recruitment could be more highly successful events in rocky habitats, and that in P. oceanica meadows large-sized immigrants coming from the rocky habitat contribute to the population structure. The need to define the role of the P. oceanica habitat is also discussed
Investigating on the occurrence of Paracentrotus lividus in rocky and Posidonia oceanica habitat
No full textDoes accessibility of locations interact with protection effect on shallow rocky habitats?
No full textCanopy structure at the edge of seagrass affects sea urchin distribution
No full textThe purpose of this study was to add insights to the understanding of seagrass
Posi-
donia oceanica
–sea urchin
Paracentrotus lividus
interactions, evaluating whether the canopy
structure at the edge of meadows next to rocks affects the distribution of
P. lividus
. The experi-
ment consisted of the manipulation of seagrass structure by modifying the shoot density (20, 50,
and 100%) and leaf length (natural and reduced). Plastic seagrass was used to test for the mecha-
nism of attraction to the seagrass edge. Thus, for each treatment combination (shoot density ×
canopy height), 3 types of
Posidonia
were considered: natural seagrass, artificial seagrass, and
natural seagrass + frame as a procedural control. The results highlighted that
P. oceanica
canopy
structure influences the distribution of
P. lividus
, as the mean abundance of the sea urchin was
directly proportional to the shoot density at both canopy heights. Since the type of
Posidonia
did
not influence seagrass density, grazing is not the mechanism of attraction of the sea urchins
towards the seagrass edge — a more plausible reason, thus, is the search for shelter. Although
these findings add to the understanding of
P. oceanica–P. lividus
interactions at the edge of the
seagrass, space use patterns in sea urchins and the structure of the seascape over which they tra-
verse must be quantified so that a more complete understanding of species–habitat relationships
and seascape connectivity can be developed
Radiographic measurement of the quadriceps angle in dogs.
Full text linkThe direction of the force of the quadriceps muscle group is expressed by the value of the quadriceps angle, between the long axis of the muscle rectus femoris and the patellar ligament. This value is often modified in dogs with patellar luxation, a common orthopaedic disease of the stifle joint in both small and large dogs. The aims of the present study were to give a reference value for the quadriceps angle in healthy small and medium-large breed dogs. The medical records of healthy dogs and their pelvic limb radiographs (2014-2016) were reviewed. The radiographs were then divided into two groups: Group A (small dogs 15 kg). The quadriceps angle of each pelvic limb was assessed using a digital software program in order to compare values between the two groups. The radiographs of 160 dogs, 80 per group were studied along with the assessment of the 320 pelvic limbs. The median quadriceps angle values obtained were in contrast with the literature: in Group A, it was 18.3° and, in Group B, it was 8.7°; moreover, the quadriceps angle value for Group A was statistically higher than for Group B (p<0.0001). No significant difference was present between males and females, or between right and left hindlimbs. In Group B, the Labrador Retriever breed influenced the quadriceps angle (p = 0.0005). The outcome of this survey provides an objective parameter, or additional information, to explain the different quadriceps mechanisms of small and medium-large dogs. In future studies the QA range values assessed in the two size groups may be useful in defining the magnitude of the malalignment of the extensor mechanism in both healthy dogs and ones with patellar luxation
Evidence-Based Veterinary Medicine: a tool for evaluating the healing process after surgical treatment for cranial cruciate ligament rupture in dogs
Full text linkThis study aims to validate a tool, the Bologna healing stifle injury index (BHSII), for the evaluation of the clinical picture and the healing after surgical treatment for cranial cruciate ligament (CCL) rupture. The study included 158 client-owned dogs with CCL rupture and 20 healthy dogs. The BHSII is a questionnaire made up of 34 multiple-choice questions, divided into a part directed to the clinician and a part for the dog's owners. It was applied twice in the healthy dogs in order to test and retest the device. It was evaluated for reliability, validity, and responsiveness to clinical changes involving the dogs treated at the time of surgery, and 1, 3, and 6 months postoperatively. Statistical analyses were performed and the intraclass correlation coefficient test was ≥0.9 and the Cronbach-α was 0.84 suggesting good stability and good internal consistency of the tool. The area under the curve of the receiver operating characteristic curve was >0.9, indicative of the high accuracy of this tool. The clinician survey correlated with the owner questionnaire. In dogs with CCL rupture, the scores of the BHSII increased significantly postoperatively as compared with baseline. In conclusion, this clinical study proved the reliability, validity, and responsiveness of the BHSII. The results achieved from the BHSII provided an instantaneous, collective complete vision of the healing process of the stifle joints treated. It can be considered a valid tool for collecting data and for assessing successful surgical treatment in clinical practice
Habitat preferences of the sea urchin Paracentrotus lividus
No full textPopulation structure of the sea urchin Paracentrotus lividus seems to vary depending on the habitat, as, on average, urchin density is higher on rocks, and size is larger in Posidonia oceanica seagrass. Here, we tested the hypothesis that P. lividus would choose P. oceanica rather than rocky habitat due to the greater availability of shelter and food in the seagrass. We conducted 2 experiments by using aquaria divided into 2 equal sections, each containing an array of 2 habitats: natural P. oceanica (P) and rocks (R) in the first experiment and natural (NP) and artificial (AP) P. oceanica in the second (to highlight the reason for preference). Each experiment included 2 experimental stages of no-choice (Stage 1) and choice (Stage 2): in the 2 no-choice treatments, sections were filled with the same habitat, and in the 2 choice treatments, sections were filled with P and R in Expt 1 and NP and AP in Expt 2. Under the null hypothesis that preference of habitat is random, the expected numbers of sea urchins that were distributed in the 2 sections of the habitat after 24 h were estimated by using formulae derived from maximal likelihood estimates. The results evidenced a preference by P. lividus for P. oceanica habitat rather than rocky habitat in the first experiment and for natural P. oceanica rather than artificial seagrass in the second experiment, thus suggesting that P. lividus individuals searched for a well-structured habitat where they could find both shelter and food
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