Cephalopods become one of the most important commercial marine resources worldwide. The knowledge of the basic biology and population dynamics of these resources is the way to ensure the resource to be utilized properly. In Taiwan, cephalopods are traditionally used and prized as foods with high market price. Sepioteuthis lessoniana is an important fishery species. Its distribution is concentrated around the northeastern and the southern coasts of Taiwan, and the Peng-Hu Island. Although there are some investigations on the statolith of the adults, studies on early stages are scarce. In this study, we use the known-age statoliths incubated in the different conditions to relate with those factors, i.e., temperature, salinity, and photoperiod, which influenced the ring formations during the embryonic and larval stages. From April to September, several clusters of bamboos, 3 ~ 4 m long, 1 ~ 2 m wide, were set on the sea bed at a depth of 16 to 20 m to attract their spawning, and the egg-strings were then transported to the laboratory. When the development of the embryo reached stage 24, iris of eyes being prominent as a colour circle and statolith being formed, they were transferred into different rearing conditions, i.e., 20, 25, 30, 35 o/oo and 15, 20, 25, 30 oC. The durations from stage 24 to hatching were different among all different rearing conditions. The statoliths were extracted and mounted in Crystal Bond thermoplastic cement for reading their growth rings. In the normal condition (25 oC and 35 o/oo), the duration from stage 24 to hatching is 9 ~ 16 days. Although the rings can be counted in each specimen, the numbers do not match between the embryonic rings and the developmental duration. Changes on the shape of the statolith were observed among different incubated conditions. The shape of the statolith at hatching had obvious differences among different embryonic developmental conditions. The statolith developed in the colder environment had smaller dorsal dome, thinner and shorter rostrum than that developed in the warmer condition. Using the shape of this embryonic ring was to be applied to measure the variation of the shape of the statolith. This is a useful tool to know the temperature factor during embryonic development by comparing with the shape of the hatchling¡¦s statolith. After hatching, squid hatchlings were separated to incubate in two different photoperiod regimes, 12 hr: 12 hr and 24 hr constant light conditions. Squid larvae were maintained as long as possible. Although the trend which older squids have more increments on the statolith than younger squids is consistent, the slope between the increments and survival days is less than one. The time required to form one ring on the statolith is needed for more than one day. Bell-shaped distributions can be found in several analyses in this study, especially with large sample size in 25 oC at 35 o/oo. If the sample size was small, the bell-shaped distribution would be obscure. This may result in oversimplification in interpretating the result. Sometimes this kind of problem could be inevitable because collecting large enough sample size was difficult or impossible. In any validation exercise, it would be difficult to obtain data for the whole life cycle. This study indicated that the hypothesis of daily-increment for the whole life history required further verification with larger sample size and wider size ranges of the tropical squids in future.

Range expansion events of the Humboldt squid reveal our inadequate understanding of populations of this species. Despite recent hatching, reproductive, tagging, genetic and dietary studies of Dosidicus gigas, much speculation remains concerning geographic migration, stock assessment and habitat preferences. This study provides evidence that statolith trace elemental variations can be useful in distinguishing among geographic populations. Specimens were collected from the Galapagos Islands, southern California, and Washington State. A dissection method was recorded and published. By using laser ablation methods, discrete measurements of 10 elements were collected at 6 to 7 ablation sites covering embryonic, paralarval, juvenile and adult stages. Analysis of Variance revealed important ontogenic elemental variations among ablation locations. Multivariate Analysis of Variance, ordination techniques and discriminant function analysis with permutation testing were all utilized to compare and characterize the variations found in elemental concentrations. Significant ontogenic variations were found for 8 out of the 10 focus elements; this is the first report for 5 of these elements for this species. The geographic populations were effectively classified as distinct group for the first time using these methods. Elemental fingerprint signatures were found to be significantly different at multiple ontogenic growth regions of the statolith. Seattle and California paralarvae exhibited similar elemental signatures despite significant differences in those found in the embryonic core and juvenile regions of the statolith. These methods are a useful tool in providing stock assessment and can be improved for use in future population dynamics models.

Ocean acidification is predicted to lead to global oceanic decreases in pH of up to 0.3 units within the next 100 years. However, those levels are already being reached currently in coastal regions due to natural CO2 variability. Squid are a vital component of the pelagic ecosystem, holding a unique niche as a highly active predatory invertebrate and major prey stock for upper trophic levels. This study examined the effects of a range of ocean acidification regimes on the early life history of a coastal squid species, the Atlantic longfin squid, Doryteuthis pealeii. Eggs were raised in a flow-through ocean acidification system at CO2 levels ranging from ambient (400ppm) to 2200ppm. Time to hatching, hatching efficiency, and hatchling mantle lengths, yolk sac sizes, and statoliths were all examined to elucidate stress effects. Delays in hatching time of at least a day were seen at exposures above 1300ppm in all trials under controlled conditions. Mantle lengths were significantly reduced at exposures above 1300 ppm. Yolk sac sizes varied between CO2 treatments, but no distinct pattern emerged. Statoliths were increasingly porous and malformed as CO2 exposures increased, and were significantly reduced in surface area at exposures above 1300ppm. Doryteuthis pealeii appears to be able to withstand acidosis stress without major effects up to 1300ppm, but is strongly impacted past that threshold. Since yolk consumption did not vary among treatments, it appears that during its early life stages, D. pealeii reallocates its available energy budget away from somatic growth and system development in order to mitigate the stress of acidosis.

Since the studies of plant gravitropism by Charles Darwin, the identity of specific sensors of gravity in plants has been uncertain. To this date, statoliths - starch granules in the root tips - are considered to play a key role in gravity sensing. The role of statoliths as organelles that mediate the gravity sensing ability of plant roots is based on research that uses plants which have severely impaired ability to synthesize starch in general or have their cells that contain statoliths removed or damaged. This represents methodical imperfections that give rise to alternative explanations, like disturbed auxin flow due to heavy damage to the root tip or unknown involvement of starch from other parts of the plant in gravity perception. Thanks to advances in the field of CRISPR/Cas9 technology, we are now able to produce tissue-specific mutants that might help with clarification of whether starch granules in the root tip are involved in sensing gravity and if so, how significant is this involvement. This diploma thesis aimed to answer these questions by adapting the tissue-specific CRISPR/Cas9 system and using it for the creation of mutants that are starchless specifically in the columella cells. Using this approach, we generated one tissue non-specific mutant line and three tissue-specific mutant...

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Σκοπός της παρούσας διατριβής, ήταν α) η μελέτη της συστηματικής των Κεφαλοπόδων και ειδικώτερα της κατανομής και των συναθροίσεών τους στο Θρακικό πέλαγος και τους κόλπους Στρυμωνικό, Συγγιτικό, Τορωναίο, Θερμαϊκό και β) η μελέτη του βιολογικού κύκλου των ειδών Loligo vulgaris (καλαμάρι), Illex coindetii (θράψαλο) και Sepietta oweniana. Το υλικό που χρησιμοποιήθηκε προήλθε κυρίως από 8 δειγματοληψίες (9/91 – 12/93) που πραγματοποιήθηκαν από το EΛ.ΚΕ.Θ.Ε., με τράτα βυθού, σε βάθη 17- 400 m. Για τη μελέτη της βιολογίας των 2 Τευθοειδών το υλικό συμπληρώθηκε με μηνιαία λήψη δειγμάτων (2/92 – 6/93) από την επαγγελματική αλιεία στο ΒΑ Αιγαίο. Συνολικά προσδιορίστηκαν 28 είδη Κεφαλοπόδων, από 8 διαφορετικές οικογένειες: Enoploteuthidae (1 είδος), Histioteuthidae (1 είδος), Loliginidae (3 είδη), Ommastrephidae (3 είδη), Sepiidae (3 είδη), Sepiolidae (9 είδη), Argonautidae (1 είδος) και Octopodidae (7 είδη). Πολυπαραγοντικές αναλύσεις των λογαριθμικά τροποποιημένων δεδομένων αφθονίας των ειδών ανά δειγματοληπτική σύρση, έδειξαν διαφοροποιήσεις στη δομή των συναθροίσεων των Κεφαλοπόδων κατά κύριο λόγο με το βάθος και σε μικρότερο βαθμό με την εποχή και τη γεωγραφική περιοχή δειγματοληψίας. Στα είδη I. coindetii και S. oweniana διαπιστώθηκε αναπαραγωγική δραστηριότητα καθόλη τη διάρκεια του χρόνου, με μέγιστη ένταση αντίστοιχα το φθινόπωρο και χειμώνα – άνοιξη. Η αναπαραγωγική περίοδος για το νηριτικό L. vulgaris ήταν σχετικά πιό περιορισμένη (μέσα χειμώνα - αρχές φθινοπώρου) με μέγιστη ένταση την άνοιξη. Η ηλικία των 2 τευθοειδών, που εκτιμήθηκε απο την ανάγνωση των αυξητικών δακτυλίων σε στατολίθους, δεν ξεπερνά τους 14 μήνες ενώ ο ημερήσιος ρυθμός αύξησης του μανδύα φτάνει για το καλαμάρι τα 2-2,5 mm και για το θράψαλο τα 0,5-0,6 mm. Οι Οστειχθείς και τα Κεφαλόποδα αποτελούσαν τις πιο συχνά εμφανιζόμενες λείες στο στομαχικό περιεχόμενο των δύο Τευθοειδών, ενώ τα Καρκινοειδή την προτιμώμενη λεία για το είδος S. oweniana. / The twofold aim of this study was: firstly to contribute to the knowledge of the cephalopod species taxonomy in the Greek Seas, focusing particularly on faunistic composition at the N. Aegean (ΝΕ Mediterranean), and secondly to investigate the life history patterns of the species Loligo vulgaris, Illex coindetii and Sepietta oweniana. Faunistic study was based on samples collected from the N. Aegean Sea (N>39ο 50΄) during eight trawl surveys (9/91 – 12/93), carried out at depths 17 - 400 m. For the study of the two squid species biology, additional monthly samples were collected from commercial fishery in NE Aegean Sea during the period February 1992 - June 1993. In all, 28 species of cephalopods belonging to 8 families were identified including Enoploteuthidae (1 species), Histioteuthidae (1 species), Loliginidae (3 species), Ommastrephidae (3 species), Sepiidae (3 species), Sepiolidae (9 species), Argonautidae (1 species) and Octopodidae (7 species). To detect zonation patterns in cephalopod community structure, multivariate analyses of species abundance data per haul were performed. Considerable variability was shown in assemblage structure, determined primarily by depth, and to a lesser extent, by geographical location and season. Intermittent terminal spawning pattern has been shown for all 3 examined species. Spawning occurs throughout the year for I. coindetii and S. oweniana in the N. Aegean Sea, peaking respectively in autumn and winter-spring, as indicated by minimum ML50 values. The breeding season of neritic L. vulgaris extends from late winter to early autumn, with spawning intensity varying among years, due to variation in temperature and population age structure. Age of both teuthoid species, estimated by growth increment counts on statoliths, did not exceed 14 months. Daily growth rate (DGR) reached 2-2,5 mm in L. vulgaris and 0,5-0,6 mm in I. coindetii. L. vulgaris and I. coindetii feed primarily on fishes and cephalopods in the N. Aegean Sea, whereas S. oweniana on crustacean and fishes.