Recruitment of the limpet Patella ulyssiponensis and its relationship with crustose coralline algae: patterns of juvenile distribution and larval settlement

Recruitment of the limpet Patella ulyssiponensis was investigated in relation to the presence of living crustose coralline algae (CCA) in rocky-shore habitats. Juvenile limpets (≤10 mm maximum shell length) were counted in CCA-present and CCA-absent habitats, on three shores in SW Portugal during summer 2007 and winter 2009. Furthermore, the settling response of laboratory-reared larvae of P. ulyssiponensis to CCA-covered substratum, and bare-rock, was examined. Across the intertidal zone, we found a clear association between the distribution and abundance of juveniles and the presence of CCA. Although the presence of CCA was not an absolute requisite for juvenile occurrence, null juvenile densities were mostly recorded in CCA-absent areas. The highest juvenile densities (maximum of 64 individuals in 15 × 15 cm) were consistently found in CCA-dominated habitats, namely steep wave-exposed areas at low-shore and rock-pools. The hypothesis of CCA-enhanced settlement was not supported, as settlement intensities of laboratory-reared larvae were similar between chips of rock encrusted by CCA and chips of bare-rock. From the overall number of settlers onto CCA-encrusted rock chips, 51% were found in tiny pits lacking CCA. This was the first study of the settlement patterns of larvae of the genus Patella using naturally occurring rocky substrata. These results are preliminary and should be confirmed with choice-experiments and improved monitoring of the position of settlers. We suggest that CCA plays a role in the recruitment of P. ulyssiponensis, potentially promoting survivorship of early benthic stages, but possibly not enhancing settlement.

Megalochelys: gigantic tortoise from the Neogene of Myanmar

Background. The genus Megalochelys is the largest known testudinid (family Testudnidae) found from the upper Miocene to lower Pleistocene of India to Indonesian Islands. The maximum length of the shell in this genus has been estimated as up to about 2 m long based on a specimen from the lower Pleistocene of Java Island, Indonesia. Recently, joint paleontological expeditions of Japan and Myanmar led by M. Takai have unearthed abundant fossils of this genus from the Neogene since 2003. These materials shed new light on this unique gigantic tortoise. Methods. All materials of Megalochelys were found from the Lower Irrawaddy Beds in poor preservation except for one nearly complete shell. The shell lengths from the fragmentary materials were estimated by using those of medium to large–sized testudinids. Results. Postcranial materials, including twenty-five epiplastra, one cervical vertebra, appendicular skeletons, and one nearly complete shell (about 180 cm long) have been discovered from the Lower Irrawaddy Beds in narrow area near Pauk Township. They are associated with terrestrial mammals such as Stegodon, suggesting that the age of the fossil bearing beds are attributed to the late Miocene to the early Pliocene. Of these, the epiplastra in two morphological states appear to be derived from sexual dimorphism of this genus as seen in several testudinids and noted previously by second author on the relevant materials. A huge distal portion of the humerus (ca. 31 cm long) suggests that its original length was about 75 cm. Discussion. A nearly complete shell is about 180 cm long, although this seems a rather young male individual of Megalochelys based on its rather slender epiplastral morphology, which is nearly as large as given estimation of the maximum shell length from Java material. On the other hand, the largest humerus, estimated as 75 cm in original length, suggests its shell was about 270 cm long. This estimation seems to be supported by other isolated materials such as the nuchal plate, largest epiplastron, and the pectoral girdle. Hitherto, Stupendemys geographica (from the Pliocene of Venezuela) and Archelon ischyros (from the Lower Cretaceous of North America) were regarded as largest known turtles with about 220 cm long shell. However, Megalochelys from Myanmar involves much larger specimens, suggesting this is a true largest known turtle.

Megalochelys: gigantic tortoise from the Neogene of Myanmar

Background. The genus Megalochelys is the largest known testudinid (family Testudnidae) found from the upper Miocene to lower Pleistocene of India to Indonesian Islands. The maximum length of the shell in this genus has been estimated as up to about 2 m long based on a specimen from the lower Pleistocene of Java Island, Indonesia. Recently, joint paleontological expeditions of Japan and Myanmar led by M. Takai have unearthed abundant fossils of this genus from the Neogene since 2003. These materials shed new light on this unique gigantic tortoise. Methods. All materials of Megalochelys were found from the Lower Irrawaddy Beds in poor preservation except for one nearly complete shell. The shell lengths from the fragmentary materials were estimated by using those of medium to large–sized testudinids. Results. Postcranial materials, including twenty-five epiplastra, one cervical vertebra, appendicular skeletons, and one nearly complete shell (about 180 cm long) have been discovered from the Lower Irrawaddy Beds in narrow area near Pauk Township. They are associated with terrestrial mammals such as Stegodon, suggesting that the age of the fossil bearing beds are attributed to the late Miocene to the early Pliocene. Of these, the epiplastra in two morphological states appear to be derived from sexual dimorphism of this genus as seen in several testudinids and noted previously by second author on the relevant materials. A huge distal portion of the humerus (ca. 31 cm long) suggests that its original length was about 75 cm. Discussion. A nearly complete shell is about 180 cm long, although this seems a rather young male individual of Megalochelys based on its rather slender epiplastral morphology, which is nearly as large as given estimation of the maximum shell length from Java material. On the other hand, the largest humerus, estimated as 75 cm in original length, suggests its shell was about 270 cm long. This estimation seems to be supported by other isolated materials such as the nuchal plate, largest epiplastron, and the pectoral girdle. Hitherto, Stupendemys geographica (from the Pliocene of Venezuela) and Archelon ischyros (from the Lower Cretaceous of North America) were regarded as largest known turtles with about 220 cm long shell. However, Megalochelys from Myanmar involves much larger specimens, suggesting this is a true largest known turtle.

Diversity, Distribution Pattern, Morphometric of Box Mussel Septifer bilocularis (Linnaeus, 1758) on the Reef Flat in Cape Lampangi, South Minahasa

Septifer bilocularis (Linnaeus, 1758) is a suspension feeder organisms which are found live clustered on dead coral . This study aims to estimate the average density, analyzes the distribution patterns and analyze morphometric aspects of a long-high (thick) relation, length-total weight relation and length-weight index without shell relation of S. bilocularis at that location. Sampling method using transect squares method, with the length of each line is 50m, on each transect placed 10 squares (measuring 1m x 1m). Based on the data analysis of the average density in both transect was 214 individuals with a clustered deployment pattern, with a maximum shell length of 29,64mm. The relation between length and high of shell shows that the growth is allometri negative, length and total weight shell relationships is allometri negative, where the contents of the weight index does not increase with increasing length but declined. Box mussel Septifier bilocularis live clustered with very dense aggregations in intertidal reef flat area on the intertidal zone are exposed at the lowest tide at Cape Lampangi. Keywords : box mussel, morphometric, Cape Lampangi, South Minahasa ABSTRAK Septifer bilocularis (Linnaeus, 1758) merupakan organisme pemakan suspensi yang banyak ditemukan hidup secara mengelompok pada rataan terumbu karang mati. Penelitian ini bertujuan untuk menduga kepadatan rata-rata, menganalisis indeks dispersi atau pola sebaran dan menganalisis aspek morfometrik berupa hubungan panjang-tinggi (tebal), panjang-berat dan panjang-indeks berat tubuh tanpa cangkang dari S. bilocularis di lokasi tersebut. Pengambilan sampel menggunakan metode transek kuadrat, dengan panjang setiap garis 50 meter, pada masing-masing transek diletakkan 10 kuadrat (berukuran 1m x 1m). Berdasarkan analisis data kepadatan rata-rata secara keseluruhan (kedua transek) adalah 214 individu dengan pola penyebaran mengelompok, dengan panjang cangkang maksimum 29,64mm. Hubungan pertumbuhan panjang dan tinggi cangkang ‘allometri negatif’, hubungan panjang cangkang dan berat total ‘allometri negatif’, di mana pertambahan indeks isi tidak sejalan dengan pertambahan panjang tetapi menurun. Kerang kotak Septifier bilocularis hidup mengelompok dengan agregasi yang sangat padat di daerah intertidal rataan terumbu pada zona intertidal yang terekspos pada saat surut terendah di Tanjung Lampangi. Kata kunci : karang kotak, morfometrik, Tanjung Lampangi, Minahasa Selatan

Differences on allocation of available resources, in growth, reproduction, and survival, in an exotic gastropod of Physidae compared to an endemic one

Physa acuta Draparnaud, 1805 is an invasive gastropod that can affect local species. In Argentina, it is widespread and abundant, even in environments inhabited by the native species Stenophysa marmorata Guilding, 1828. Its predominance raises the question whether this could be explained by a more successful energy allocation in functional requirements (growth, reproduction and survival) compared to S. marmorata. This study was aimed at comparing growth rates, as well as survival and fecundity, between both species under laboratory conditions. Individuals born on the same day were grouped in four per aquaria and kept under controlled conditions of food, light, and temperature. Snails were weekly measured (maximum shell length), and growth rates were calculated using the Von Bertalanffy's equation. The number of eggs and survivors were grouped by week. Stenophysa marmorata was larger at birth than Physa acuta and invested more energy in growth, delaying sexual maturity. This resulted in a disadvantage in fecundity and survival compared to P. acuta, which had a lower growth rate but matured earlier and survived longer. Furthermore, the growth of P. acuta was not affected by reproduction, its reproductive period was longer, consequently with more eggs laid than S. marmorata.

Ecological considerations and niche differentiation between juvenile and adult black limpets (Cymbula nigra)

The endangered patellid limpet Cymbula nigra is present in the extreme western Mediterranean, yet the species has rarely been the subject of study in this region. The aim of the present research is to describe the ecology, distribution and population structure of the species in an area of the Mediterranean coast of North Africa (Ceuta). Results indicate that the species prevails in waters that have an important Atlantic influence. Furthermore, different shell morphologies are distinguished, and in consequence, a statistical analysis is carried out based on morphometric data. Based on maximum shell length, height/length coefficients and shell morphology, a total of three significantly different morphologies are described. Furthermore, considering physical parameters such as height over seawater level and average substratum inclination, juveniles resulted to be clearly segregated from the two other groups. Additionally, no differences were found regarding the topography of the substrate used by juvenile and adult individuals, although the colonized surfaces are significantly smoother than those where Patella ferruginea is present.