O comportamento natatório de larvas de peixes na fase da primeira alimentação de Rachycentron canadum e Epinephelus marginatus foi descrito usando imagens de câmeras de alta frequência (60 a 2000 quadros por segundo) pelas técnicas de imageamento: microscopia de campo claro, sistema de filtros pareados e holografia. Oito métricas comportamentais foram registradas na presença de náuplios de copépodes; rotíferos Brachionus sp. e; sem alimento: natação rotineira (1 a 2,9 vezes o comprimento do corpo por segundo, CP s-¹); natação explosiva (3 a 40 CP s-¹); recuo; distâncias percorridas; batimentos do complexo caudal na natação e manutenção da posição (40 b s-¹); contrações rápidas do corpo em formato de C (de 0,16 a 0,40 s) e S (0,009 a 0,17 s); repouso; e comportamento alimentar (visualização das presas e tentativa de captura). As larvas alteraram a velocidade de natação na presença de presas e aumentaram em função da idade. Os maiores valores alcançados do número de Reynolds foram na presença de presas, para natação rotineira foi 200. As contrações da musculatura e mudanças na velocidade de natação indicam relação com aspectos ecológicos dos organismos, como busca por alimento e interações intra e interespecíficas. / The swimming behavior of first feeding fish larvae Rachycentron canadum and Epinephelus marginatus was described using images acquired with high-speed cameras (60 to 2000 frames per second) by the imaging techniques: bright field microscopy, matched filters system and holography. Eight behavioral metrics were recorded in the presence of copepod nauplii; rotifer Brachionus sp.; and unfed: routine swimming (1 to 2.9 body lengths per second, BL s-¹); burst swimming (3 to 40 BL s-¹); backward swimming; distance traveled; caudal beat frequency of swimming and maintaining of the position (about 40 b s-¹); fast C-turns (0.16 to 0.40 s) and S-turns (0.009 to 0.17 s); rest; and feeding behavior (observation of prey and attempts to capture). The larvae altered their swimming velocity in the presence of prey and incresead according to age. The highest values of the Reynolds number were reached in the presence of prey, to routine swimming was < 20, and to bust swimming > 200. Muscles contractions and changes in the swimming showed a relation to ecological aspects of organisms, like food searching and intra and interspecific interactions.

Στόχο της παρούσας διατριβής αποτέλεσε η διερεύνηση των αβιοτικών και βιοτικών παραγόντων που ελέγχουν τη χωροχρονική κατανομή δύο βασικών συστατικών του πλαγκτικού συστήματος στο βορειοανατολικό Αιγαίο, του μεσοζωοπλαγκτού και των ιχθυονυμφών. Η περιοχή μελέτης παρουσιάζει ιδιαίτερο ενδιαφέρον καθώς χαρακτηρίζεται από αυξημένα επίπεδα παραγωγικότητας, συγκριτικά με τον ολιγότροφο χαρακτήρα της ανατολικής Μεσογείου, και ως εκ τούτου υψηλή συγκέντρωση ιχθυοαποθεμάτων (κυρίως μικρών πελαγικών ψαριών). Τα χαρακτηριστικά αυτά θεωρείται ότι σχετίζονται με την τοπογραφία της περιοχής (εκτεταμένη υφαλοκρηπίδα), την εισροή ποταμών αλλά κυρίως με την έντονη μέσης κλίμακας υδρολογική πολυπλοκότητα (μέτωπο Λήμνου, αντικυκλώνας Σαμοθράκης), που επάγει η εισροή και κυκλοφορία του χαμηλής αλατότητας νερού της Μαύρης Θάλασσας (<30 psu), στα 20-30 επιφανειακά μέτρα της υδάτινης στήλης. Η μελέτη της κατανομής και σύνθεσης του μεσοζωοπλαγκτού (σε κατακόρυφη και οριζόντια διάσταση) πραγματοποιήθηκε σε ένα εκτεταμένο δίκτυο σταθμών κατά τη διάρκεια τριών περιόδων θερμοστρωμάτωσης (Ιούλιος 2003– Σεπτέμβριος 2003 – Ιούλιος 2004), ενώ των ιχθυονυμφών κατά το μήνα Ιούνιο των ετών 2003 έως 2006. Σύμφωνα με τα αποτελέσματα της έρευνας, το απόθεμα του μεσοζωπλαγκτού στο Β.Α. Αιγαίο βρέθηκε μεγαλύτερο σε σχέση με εκείνο που αναφέρεται για άλλα ελληνικά πελαγικά νερά (Ιόνιο, νότιο Αιγαίο), κλειστούς και ημίκλειστους κόλπους καθώς και για ορισμένες παράκτιες και πελαγικές περιοχές της Δυτικής Μεσογείου. Σημαντικό κομμάτι της βιοκοινότητας, ειδικά στο επιφανειακό στρώμα επίδρασης του νερού της Μαύρης Θάλασσας, αποτέλεσαν ηθμοφάγες ομάδες όπως τα κλαδοκεραιωτά, οι κωπηλάτες και τα βυτιοειδή. Το Σεπτέμβριο 2003 η αλατότητα στην περιοχή βρέθηκε υψηλότερη κατά δύο μονάδες σε σχέση με τον Ιούλιο του ίδιου έτους, αντανακλώντας ενδεχομένως τη μικρότερη εισροή του νερού της Μαύρης Θάλασσας (πλούσιο σε διαλυτό οργανικό άνθρακα), και η αφθονία των ηθμοφάγων ομάδων ήταν σημαντικά μειωμένη την περίοδο αυτή σε σχέση με τον Ιούλιο 2003. Η χρονική αυτή διακύμανση στο απόθεμα του μεσοζωοπλαγκτού φάνηκε να σχετίζεται τόσο με τη διαφοροποίηση της επίδρασης του νερού της Μαύρης Θάλασσας στην περιοχή, όσο και με τα χαρακτηριστικά της βιολογίας των οργανισμών (π.χ. εποχικός κύκλος). Τον Ιούλιο 2004 το νερό της Μαύρης Θάλασσας περιορίστηκε κυρίως στο ανατολικό τμήμα της θρακικής υφαλοκρηπίδας, εγκλωβιζόμενο σε μια αντικυκλωνική δομή γύρω από τη Σαμοθράκη περίπου 50 km διαμέτρου, και οι τιμές αφθονίας και βιομάζας βρέθηκαν ιδιαίτερα αυξημένες (διπλάσιες έως και τριπλάσιες) συγκριτικά με το 2003. Σημαντικό παράγοντα διαφοροποίησης των ποσοτικών χαρακτηριστικών του μεσοζωοπλαγκτού (αφθονία & βιομάζα) αλλά και διαμόρφωσης διακριτών συναθροίσεων ειδών κωπηπόδων και κλαδοκεραιωτών αποτέλεσε το βάθος. Τα επιφανειακά νερά, που δέχονταν την άμεση επιρροή του νερού της Μαύρης Θάλασσας, εμφανίστηκαν περισσότερο παραγωγικά με ιδιαίτερη σύνθεση ειδών, των οποίων οι συναθροίσεις αποτέλεσαν ευαίσθητους δείκτες της οριζόντιας ωκεανογραφικής ετερογένειας. Αλλαγές στην παροχή και κυκλοφορία του νερού της Μαύρης Θάλασσας φάνηκε να προκαλούν μέσης κλίμακας υδρολογική (μέτωπα, στρόβιλοι) και βιολογική πολυπλοκότητα στην περιοχή, η οποία βρέθηκε να αντανακλάται περαιτέρω στη δομή και κατανομή των ζωοπλαγκτικών συναθροίσεων τόσο στο οριζόντιο επίπεδο όσο και στο κατακόρυφο. Συγκεκριμένα, τα υδρολογικά μέτωπα αποτέλεσαν περιοχές αυξημένων τιμών φθορισμού και μεσοζωοπλαγκτικής βιομάζας και ο αντικυκλώνας της Σαμοθράκης αποτέλεσε ιδιαίτερο βιογεωχημικό ενδιαίτημα, χαρακτηριζόμενο από αυξημένες τιμές συνολικής αφθονίας και ιδιαίτερη σύνθεση βιοκοινότητας μεσοζωοπλαγκτού. Εκτός από τη σημασία των φυσικών παραγόντων στην κατανομή του μεσοζωοπλαγκτού, βιολογικές αλληλεπιδράσεις, όπως ο ανταγωνισμός και η θήρευση φάνηκε επίσης να παίζουν σημαντικό ρόλο στη διαμόρφωση των παρατηρούμενων προτύπων κατανομής. Η χωρική ετερογένεια στην κατανομή των πληθυσμών του μεσοζωοπλαγκτού φάνηκε να αντικατοπτρίζει τη σημασία των οικοφυσιολογικών χαρακτηριστικών των ειδών και του εύρους μεγέθους των τροφικών σωματιδίων. Σε αντίθεση με το μεσοζωοπλαγκτόν, η μέση αφθονία του συνόλου των ιχθυονυμφών καθώς και των μεμονωμένων ταξινομικών κατηγοριών τους στην περιοχή του Β.Α. Αιγαίου κατά την διάρκεια της τετραετούς έρευνας (2003-2006), δεν παρουσίασε σημαντική χρονική διαφοροποίηση. Οι ιχθυονύμφες των επιπελαγικών ειδών αποτέλεσαν το σημαντικότερο συστατικό της βιοκοινότητας, με κυρίαρχο είδος το Engraulis encrasicolus (γαύρος), είδος του οποίου η κορύφωση ωοτοκίας συμπίπτει χρονικά με την περίοδο δειγματοληψίας. Η οριζόντια κατανομή των ιχθυονυμφών στην περιοχή ήταν ετερογενής και φάνηκε να ελέγχεται από τη συνεργιστική δράση παραμέτρων που επιδρούν στο απόθεμα των γεννητόρων καθώς και φυσικών και βιολογικών διαδικασιών που επιδρούν στη πλαγκτική φάση των απογόνων τους. Ιδιαίτερα σημαντικό ρόλο στη διαμόρφωση των παρατηρούμενων ιχθυονυμφικών προτύπων κατανομής βρέθηκε να παίζουν εξελικτικές προσαρμογές των ειδών σε μεγάλη κλίμακα χρόνου, όπως είναι η στρατηγική αναπαραγωγής και το περιβάλλον διαβίωσης. Ως εκ τούτου, το βάθος αλλά και ενδείξεις των τροφικών συνθηκών στην κολώνα του νερού (π.χ. συγκέντρωση ζωοπλαγκτού, φθορισμός) εξήγησαν σε σημαντικό βαθμό τη χωρική διαφοροποίηση της σύνθεσης της βιοκοινότητας των ιχθυονυμφών. Η κυκλοφορία επίσης του νερού της Μαύρης Θάλασσας φάνηκε σε πολλές περιπτώσεις να επηρεάζει σημαντικά τη διαμόρφωση της οριζόντιας κατανομής τους, είτε συμβάλλοντας στην κατακράτηση τους κοντά στα πεδία ωοτοκίας, ή, προκαλώντας τη διασπορά τους μακριά από αυτά. Η αντανάκλαση της οριζόντιας ωκεανογραφικής ετερογένειας στις συναθροίσεις των συγκεκριμένων μεροπλαγκτικών οργανισμών, παρότι λιγότερο έντονη σε σχέση με τις ολοπλαγκτικές ομάδες του μεσοζωοπλαγκτού, ήταν επίσης εμφανής. Η υψηλή συμμετοχή στη βιοκοινότητα των ιχθυονυμφών, πελαγικών ειδών, που κατά την ενήλικη φάση είναι άμεσα επηρεαζόμενα από μεταβολές που πραγματοποιούνται στο ανώτερο στρώμα της υδάτινης στήλης (όπου επιδρά το νερό της Μαύρης Θάλασσας), φαίνεται να είχε σημαντική συμβολή σε αυτό. / The main aim of the present study was directed towards an understanding of the agents (abiotic and biotic) that shape the spatiotemporal distribution patterns of two fundamental components of the northeastern Aegean Sea (NEA) planktonic food web, namely mesozooplankton and fish larvae. The study area is of great scientific interest due to its relatively increased local productivity levels, comparatively to the highly oligotrophic eastern Mediterranean, hence its importance as a fishing ground, especially for fisheries targeting small pelagic fish. These characteristics are considered to be associated with local topographic features (extended continental shelf), riverine inflow, but mainly the high hydrological complexity (development of fronts and eddies) which is induced by the inflow and advection of low salinity Black Sea waters (BSW) at the upper part of the water column (surface 20-30 m). Mesozooplankton group composition and distribution patterns were examined both in horizontal and vertical plane in an extended sampling grid, during three stratification periods (July 2003 – September 2003 – July 2004). Four broad scale ichthyoplankton surveys were carried out (June 2003, 2004, 2005, 2006) over a station grid similar to that of mesozooplankton sampling, in order to investigate the major distribution and abundance patterns of fish larvae in the area. According to this study, the overall mesozooplankton standing stock in the NEA was found higher than those typically reported for other Mediterranean ecosystems, including hellenic pelagic waters and various closed or semi-closed gulfs as wells as some western Mediterranean pelagic and coastal regions. During all sampling periods, filter feeding taxa i.e. cladocerans, doliolids, appendicularians consisted an important element of mesozooplankton group composition particularly at the upper water column (directly influenced by the BSW). In September 2003, when surface salinity was 2 psu higher than July 2003 (probably reflecting lower BSW inflow in the area), the abundance values of these zooplankters decreased considerably. This temporal variation seemed to be related not only to differentiation in BSW (rich in dissolved organic carbon) influence, but also to species specific biological characteristics (e.g. seasonal cycle). In July 2004, BSW circulation was mainly restricted in the eastern part of the Thracian shelf and the abundance and biomass values in the area were significantly increased (2-fold up to 3-fold increase) compared to the previous surveys. Sampling depth played an important role in the differentiation of quantitive mesozooplankton characteristics (in terms of abundance and biomass values) but also in the formation of different copepod and cladoceran species assemblages. Surface waters, under the direct influence of BSW, were more productive and their species assemblages were sensitive tracers of horizontal oceanographic variability. Changes in the supply and flow of BSW into the NEA induced mesoscale hydrographic (fronts, eddies) and biological variability which was reflected on the structure and distribution of mesozooplankton assemblages in the horizontal and vertical plane. Frontal zones (e.g. southeastern of Lemnos) were characterized by increased fluorescence values and mesozooplankton biomass. The anticyclonic eddy over the Thracian shelf, where BSW is entrapped (Samothraki gyre), seemed to serve as a distinguished biochemical habitat with increased mesozooplankton abundance values and distinctive group composition. Besides the importance of physical parameters for zooplankton distribution in the NEA, biological interactions (e.g. competition, predation) may have played a significant role in shaping the observed distribution patterns. The hydrological heterogeneity induced by the advection of the BSW seemed to influence the qualitative and quantitative characteristics of the lower trophic levels. In turn, mesozooplankton populations presented spatial heterogeneity that reflected the importance of food size spectra and species-specific ecophysiological characteristics. Contrary to mesozooplankton community, mean abundance values of fish larvae (either as a total or for each separate taxonomic category) did not show any significant interannual difference during the four year study in the area of NEA (2003-2006). Fish larvae of epipelagic species consisted the major component of community, while a dominance of anchovy larvae was also observed due to the coincidence of the sampling period with the intensive spawning of this species. Fish larvae horizontal distribution was heterogenous and seemed to be controlled by the coupling between agents acting on the spawning stock and physical and biological processes influencing the planktonic phase of their offsprings. Fish larvae distributional patterns seemed to highly depend on species specific evolutionary adaptations, like reproduction strategy and the living habitat of the adults. Sampling depth as well as indications of water column trophic conditions (e.g. zooplankton concentration, fluorescence), explained significantly the spatial differentiation of fish larvae assemblages during all sampling periods. The circulation pattern of BSW seemed to be an important determinant of the taxonomic composition and abundance of larval fish assemblages, contributing either on larval retention near the spawning grounds, or inducing their dispersion. The assemblages of these meroplanktonic early-life stages also reflected the horizontal oceanographic heterogeneity in NEA, though less intensively comparing to other holoplanktonic zooplankters. The domination of local larval fish community by larvae of pelagic fish, that in the adult phase are directly influenced by changes taking place in the upper part of the water column (influenced by the BSW), may have contributed to this reflection.

A distribuição horizontal e vertical das larvas de peixes mesopelágicos de Phosichthyidae foi descrita a partir de dados amostrados desde a superfície até 200 m de profundidade, e em 5 estratos na coluna de água. As coletas foram realizadas no verão e inverno de 2002, em radiais perpendiculares à costa Sudeste do Brasil, entre o cabo de São Tomé (RJ) e a ilha de São Sebastião (SP). A abundância das larvas (larvas.m²) foi estimada para o material amostrado pela rede Bongô (333 cm) e a densidade (larvas.m³) para a Multi Plankton Sampler (300 cm). No total foram coletadas 538 larvas de Phosichthyidae no verão e 146 no inverno. Duas espécies foram identificadas, Pollichthys mauli e Vinciguerria nimbaria, ambas apresentaram-se distribuídas, preferencialmente, na região oceânica da área de estudo com maiores densidades entre 60 e 80 m de profundidade, onde a temperatura e a salinidade foram superiores a 20°C e 36, respectivamente, estando diretamente relacionados à massa de Água Tropical, transportada pela Corrente do Brasil. Todas as fases de desenvolvimento larval foram capturadas, entretanto, a maioria das larvas estava em pós-flexão da notocorda. Em relação à variação diária, as larvas foram mais abundantes durante a noite. / Horizontal and vertical distribution of mesopelagic Phosichthyidae fish larvae was described based on data sampled collected from the surface up to 200 m depth, and at five stratums on the water column. The sampling was performed in summer and winter, 2002, on perpendiculars transects in southeastern Brazilian Bight, between São Tomé Cape (RJ) and São Sebastião Island (SP). The abundance of larval (larvae.m²) was estimated from sample of Bongo net (333 cm) and the density (larvae.m³) from sample of Multi Plankton Sampler (300 cm). A total of 538 larvae of Phosichthyidae was collected during summer, and 146 in the winter. Two species, Pollichthys mauli and Vinciguerria nimbaria, were identified; both were mainly distributed in the oceanic region of the study area and were more abundant between 60 and 80 m depth, where temperature and salinity were higher than 20°C and 36, respectively, which are directly related with the Tropical Water mass, transported by Brazil Current. All larval stages of development were caught, however, the majority was in postflexion stage. In relation to diel variation, larvae were more abundant during the night.

A distribuição horizontal e vertical das larvas de peixes mesopelágicos de Phosichthyidae foi descrita a partir de dados amostrados desde a superfície até 200 m de profundidade, e em 5 estratos na coluna de água. As coletas foram realizadas no verão e inverno de 2002, em radiais perpendiculares à costa Sudeste do Brasil, entre o cabo de São Tomé (RJ) e a ilha de São Sebastião (SP). A abundância das larvas (larvas.m²) foi estimada para o material amostrado pela rede Bongô (333 cm) e a densidade (larvas.m³) para a Multi Plankton Sampler (300 cm). No total foram coletadas 538 larvas de Phosichthyidae no verão e 146 no inverno. Duas espécies foram identificadas, Pollichthys mauli e Vinciguerria nimbaria, ambas apresentaram-se distribuídas, preferencialmente, na região oceânica da área de estudo com maiores densidades entre 60 e 80 m de profundidade, onde a temperatura e a salinidade foram superiores a 20°C e 36, respectivamente, estando diretamente relacionados à massa de Água Tropical, transportada pela Corrente do Brasil. Todas as fases de desenvolvimento larval foram capturadas, entretanto, a maioria das larvas estava em pós-flexão da notocorda. Em relação à variação diária, as larvas foram mais abundantes durante a noite. / Horizontal and vertical distribution of mesopelagic Phosichthyidae fish larvae was described based on data sampled collected from the surface up to 200 m depth, and at five stratums on the water column. The sampling was performed in summer and winter, 2002, on perpendiculars transects in southeastern Brazilian Bight, between São Tomé Cape (RJ) and São Sebastião Island (SP). The abundance of larval (larvae.m²) was estimated from sample of Bongo net (333 cm) and the density (larvae.m³) from sample of Multi Plankton Sampler (300 cm). A total of 538 larvae of Phosichthyidae was collected during summer, and 146 in the winter. Two species, Pollichthys mauli and Vinciguerria nimbaria, were identified; both were mainly distributed in the oceanic region of the study area and were more abundant between 60 and 80 m depth, where temperature and salinity were higher than 20°C and 36, respectively, which are directly related with the Tropical Water mass, transported by Brazil Current. All larval stages of development were caught, however, the majority was in postflexion stage. In relation to diel variation, larvae were more abundant during the night.

Six rivers within the upper Mumbidgee catchment were sampled for larval and juvenile fish. The rivers represented both regulated and unregulated flow regimes and varied widely in size. There was wide variation in the larval fish communities supported by each river, both in terms of the species diversity and total abundance of fish sampled. The highly regulated reach of the Mumbidgee River sampled during this study had the highest numbers of native species and native individuals of any river sampled. In the two rivers selected for further study, the Murmmbidgee and Goodradigbee, there was a high level of inter-annual consistency in the species composition within the reaches sampled, despite considerable change in the temperature and flow regimes of both rivers. This indicates that at least some spawning of those species sampled may occur each year, regardless of environmental conditions. Estimates of the relative abundance of each species sampled changed markedly between years, and it is argued, on the basis of growth information contained in the otoliths, that differential survival of larvae and juveniles was largely responsible for this shift in relative abundance. Otolith microstructure provided information on the date of spawning and early growth patterns of all species sampled in the upper Mumumbidgee catchment. In addition to determining the age and thus 'birth-date' of an individual, the effect of a particular event or series of events has on growth, and subsequent survival, is permanently recorded in the otolith microstructure. This enables accurate back-calculation and correlation to management actions or natural events. No other research tool has this ability to retrospectively assess, on a daily basis, the impacts of management actions on condition and subsequent survival of fish larvae. Species sampled could be separated into three groups based on spawning requirements; those linked with flow, those linked with temperature and generalist species that appear to have river independent cues, such as photoperiod or moon phase. Patterns in growth rate during the early life history stages enabled quantification of the consequences of variation in environmental conditions on the survival and recruitment of various species. Growth was not always highly correlated with water temperature, in fact, for mountain galaxias, high temperatures appear to negatively affect larval condition and subsequent survival. Conversely, carp exhibited a strategy more consistent with common perceptions, with growth and survival increasing with increasing temperature. The study uncovered spawning and growth patterns that were unexpected. Age analysis of western carp gudgeon demonstrated that they had undertaken a mid-winter spawning, when the water temperature in the main channel was far lower than that at which spawning was previously recorded for this species. Redfin perch from the unregulated Goodradigbee River exhibited growth rates exceeding the published upper limits for this and other closely related species. This growth could not be correlated with either temperature or flow, indicating that there are additional factors that dominate growth rates of redfin perch in the Goodradigbee River. The proportion and abundance of native species alone is not necessarily indicative of a 'healthy' or pristine system; some native species may be positively affected by river regulation, at least as juveniles. Comparison of the current larval fish community with likely pre-European fish communities does provide an indication of change to the system. The results of this study suggest that larval fish growth rates can be strongly influenced by environmental conditions, thus providing a powerful tool for monitoring future change and the factors which cause it. This study has demonstrated the value of larval and juvenile fish age and growth information, derived from otolith microstructure techniques, for many aspects of river management. Current river management priorities for which these techniques provide unique information include the determination of environmental flow regimes and the control of undesirable exotic species such as carp.

Η οικολογία και η δυναμική της εγκατάστασης εξετάστηκαν για τέσσερα μεσογειακά παράκτια είδη: Diplodus vulgaris, Diplodus sargus, Oblada melanura και Diplodus annularis. Η διερεύνηση τους έγινε με υποδιαίρεση της βενθικής ιχθυονυμφικής τους φάσης σε έξι οντογενετικά στάδια βάσει χρωματικών πρότυπων που εμφάνιζαν διαδοχή και ήταν χαρακτηριστικά για κάθε είδος. Η συλλογή δεδομένων έγινε για κάθε οντογενετικό στάδιο με στρωματοποιημένη δειγματοληψία, με τις στρώσεις να αποτελούν συνδυασμό τύπου υποστρώματος και βάθους στην παράκτια περιοχή ανατολικά των εκβολών του Αχελώου, από βάθος 0 έως 5m. Τα δεδομένα συλλέχθηκαν με απ’ ευθείας παρατηρήσεις με χρήση καταδυτικής συσκευής. Υπολογίστηκαν οι πυκνότητες κάθε οντογενετικού σταδίου στους διάφορους τύπους υποστρώματος και βάθη μέσα στο έτος. Η κατανομή των πυκνοτήτων αυτών έδωσε στοιχεία για τις οικολογικές προτιμήσεις των βενθικών ιχθυονυμφών και των νεαρών, καθώς και για τους ρυθμούς μεταμόρφωσης κάθε είδους. Επίσης ελέγχθηκε το πρότυπο συμπεριφοράς των ιχθυονυμφών του μελανουριού κατά την εγκατάσταση τους, μ’ επινόηση ειδικής μεθοδολογίας κι ενός δείκτη που απέδωσε ποσοτικά τις διάφορες εκφάνσεις της συμπεριφοράς. Σύμφωνα με τ’ αποτελέσματα της εργασίας, φάνηκε ότι ο σαργόπαπας και ο σαργός εγκαθίστανται την κρύα περίοδο του έτους, ενώ το μελανούρι και ο σπάρος τη θερμή. Όλα τα είδη εμφάνισαν γρηγορότερο ρυθμό μεταμόρφωσης κατά τα πρώτα στάδια, ενώ τα είδη που εγκαταστάθηκαν το καλοκαίρι είχαν συνολικά γρηγορότερους ρυθμούς μεταμόρφωσης από τα χειμερινά. Τα είδη εμφάνισαν διαφοροποίηση στη χρονική και χωρική κατανομή τους ώστε να ελαττώνονται οι ανταγωνιστικές δράσεις. Το είδος με τη μακρύτερη χρονική παρουσία ήταν ο σαργόπαπας (10 μήνες), ο οποίος εμφάνισε ευρύτητα ως προς τις οικολογικές του απαιτήσεις διασπειρόμενος σ’ όλο το εύρος βάθους και τύπους υποστρώματος, εκτός του αμμώδους. Στον αντίποδα, το μελανούρι είχε τη μικρότερη συνολική παρουσία (4 μήνες) και απόλυτη εξάρτηση από σκληρό υπόστρωμα. Ο σαργός κι ο σπάρος έδειξαν ενδιάμεσες οικολογικές απαιτήσεις με προτίμηση στα σκληρά υποστρώματα και στα φανερόγαμα αντίστοιχα. Κανένα είδος δεν έδειξε προτίμηση σε αμμώδεις βυθούς. Ιδιαίτερο οικολογικό ρόλο εμφάνισε το ρηχότερο τμήμα της παράκτιας ζώνης και οι μεταβατικές ζώνες διαφορετικών υποστρωμάτων. Οι βενθικές ιχθυονύμφες του μελανουριού επέδειξαν τάση παραμονής για μέρες με μικρές ομάδες σε σημεία του υποστρώματος. Στα επόμενα στάδια σχημάτισαν μεγάλες ομάδες με μικρότερη εξάρτηση από το υπόστρωμα. / The ecology and dynamics of settlement process were studied for four sparids (Diplodus vulgaris, D. sargus. D. annularis and Oblada melanura), in a coastal littoral in western Hellas. The benthic larval phase of each species was divided in six ontogenetic stages, according to specific patterns in appearance that followed a sequence. Preliminary observations showed non homogeneous distribution of the larvae in the area, so stratified sampling was applied. Strata represented the different substratum types accounted in each of the three depth zones of 0-1m, 1-2m and 2-5m. Data concerned abundances of each ontogenetic stage in each stratum during a 15 month interval and they were collected by visual census. Moreover, data on site-attachment ontogenetically depended behavior of benthic larvae of O. melanura were also collected. The later behavior was studied via an index devised for quantifying different expressions of residence behavior. Two of the studied species (D. vulgaris and D. sargus), settled during the cold period of the year while the other two settled during summer. Metamorphosis rates were faster at the first ontogenetic stages for all species, while they were faster in total for the summer species. Temporal and spatial distribution of the species was arranged in order to minimize competition. D. vulgaris and D. sargus settled in the same substratum types in different periods and O. melanura and D. annularis settled during the same period in different substrata. D. vulgaris remained in the nursery area the longest period, exhibiting the broadest ecological requirements, being distributed in different substrata and depths. O. melanura remained half as long in the nursery area, exhibiting the narrowest ecological requirements, staying always over hard substratum in shallow waters. The other two species exhibited intermediate conditions, with D. sargus preferring hard substratum and D. annularis, seagrass beds. None of the studied species preferred soft substratum. The shallowest part of the littoral appeared to be very important for three species (D. vulgaris, D. sargus, O. melanura) and the transition zones (between two different substrata), for all four of them. Benthic larvae of Oblada melanura commenced settlement in small shoals that resided for varying number of days in specific sites over stones or rocky substratum. Gradually as metamorphosis proceeded they became more kinetic forming larger shoals that expanded their home range.

Murray cod Maccullochella peelii peelii is an iconic freshwater angling species that has suffered declines in abundance and is now listed as a nationally vulnerable species. Despite recognition of the need for biological knowledge to provide future management directions, little is known of its ecology. This thesis examines that ecology to provide new knowledge and recommendations for improved conservation management. (For complete abstract open document)

Made available in DSpace on 2017-07-10T18:13:30Z (GMT). No. of bitstreams: 1 Patricia S da Silva.pdf: 3404031 bytes, checksum: 5e4338885b036077d4619e4525d56526 (MD5) Previous issue date: 2011-08-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this study was to analyze spatial and temporal patterns of ichthyoplankton in tributaries (Aguapeí, Verde, Pardo and Anhanduí) of Porto Primavera Reservoir, Upper Paraná River, Brazil, and its relation to some environmental variables. Specifically we sought to (I) assess whether the tributaries have similar abiotic characteristics, (II) verify that abiotic factors have more influence in the spawning of the species, (III) investigate if the species have preference for tributaries, and (IV) analyze whether the tributaries of the Porto Primavera Reservoir are really suitable environments for reproduction of fish species, especially long-distance migratory drastically affected by impoundments. Samples were taken monthly during three spawning seasons (October to March from 2007 to 2010), through horizontal hauls on the water surface at dusk, with a plankton net. The principal component analysis (PCA) was used to ascertain whether the abiotic variables differed among the tributaries. The influence of environmental variables (water temperature, pH, electrical conductivity, dissolved oxygen, turbidity, water level and discharge) in the abundance of eggs and larvae was determined using the Bioenv procedure. The Kruskal-Wallis (KW) was applied to verify spatial (tributaries: rivers Aguapeí, Verde, Pardo and Anhanduí; and habitats: main channel and lagoon) and temporal distribution patterns (month: October, November, December, January, February, and March, and spawning seasons: 1 =2007/2008, 2=2008/2009, and 3=2009/2010). The characteristic taxa of each tributary were identified through Indicator Species Analysis (IndVal). A total of 49,072 eggs, 63,857 larvae were captured. The variable that best correlated with the distribution and abundance of ichthyoplankton was the water discharge. The highest densities of eggs were noted for the Verde river, however larvae did not differ significantly among the tributaries. Eggs had the highest densities in the main channel and while larvae in lagoons. High catches of ichthyoplankton were observed from November to January, but with a peak in December. Abundance of eggs were higher in the 2009/2010 spawning season, however the larvae did not differ among spawning season. The species composition varies along the tributaries and each river has a group of indicator species. In main channel of the rivers were mainly found larvae of migratory species of short distance and long-distance and in the lagoons mainly sedentary or migratory species of short distances. The tributaries assessed are spawning grounds for many fish species and can be considered suitable for the reproduction of many long-distance migratory species. Establishment and enlargement of Conservation Units in tributaries of Porto Primavera reservoir, can help preserve habitats identified as essential spawning and nursery areas, and can be key to the maintenance and conservation of the fish species in the upper Paraná River basin. / O objetivo deste trabalho foi analisar padrões espaciais e temporais do ictioplâncton em tributários (Aguapeí, Verde, Pardo e Anhanduí) do reservatório de Porto Primavera, alto rio Paraná, Brasil, e sua relação com algumas variáveis ambientais. Especificamente procurou se (I) Avaliar se os tributários apresentam características abióticas similares, (II) Verificar que fatores abióticos exercem maior influência na desova das espécies, (III) Averiguar se há preferência das espécies de peixes quanto aos tributários, e (IV) Analisar se os tributários do reservatório de Porto Primavera realmente são ambientes adequados à reprodução das espécies de peixes, em especial as migradoras de longa distância drasticamente afetadas pelos represamentos. As amostragens foram realizadas durante três estações reprodutivas sucessivas (outubro a março de 2007 a 2010), ao anoitecer com rede de plâncton. A análise de componentes principais (ACP) foi empregada para averiguar se as variáveis abióticas diferiam entre os tributários. A influência das variáveis ambientais (temperatura da água, pH, condutividade elétrica, oxigênio dissolvido, turbidez, nível e vazão) na abundância de ovos e larvas foi determinada através do procedimento Bioenv. O teste de Kruskall Wallis (K-W) foi aplicado para verificar padrões de distribuição espacial (tributários: rios Aguapeí, Verde, Pardo e Anhanduí; e habitats: rio e lagoa) e temporal (meses: outubro, novembro, dezembro, janeiro, fevereiro e março; e estações reprodutivas: 1 = 2007/2008, 2 = 2008/2009 e 3 = 2009/2010). Os táxons característicos de cada tributário foram identificados por meio da Análise de Espécies Indicadoras (IndVal). Um total de 49.072 ovos, 63.857 larvas foi capturado. A variável que melhor se correlacionou com a distribuição e abundância do ictioplâncton foi a vazão. As maiores densidades de ovos foram verificadas para o rio Verde, porém as de larvas não diferiram significativamente entre os tributários. Ovos apresentaram maiores densidades nos rios e as larvas nas lagoas. Capturas elevadas do ictioplâncton foram observadas de novembro a janeiro, porém com pico em dezembro. As capturas de ovos se sobressaíram na estação reprodutiva de 2009/2010, no entanto, as de larvas não diferiram entre as estações reprodutivas. A composição das espécies ao longo dos tributários varia e cada rio apresenta um grupo de espécies indicadoras. Nos rios foram encontrados principalmente larvas de espécies migradoras de curta e longa distância e nas lagoas principalmente de espécies sedentárias ou migradoras de curta distância. Os tributários analisados atuam como área de desova de várias espécies de peixes e podem ser considerados propícios para a reprodução de várias espécies migradoras de longa distância. A criação e ampliação de Unidades de Preservação Permanente nos tributários do reservatório de Porto Primavera podem auxiliar na preservação dos habitats identificados como áreas essenciais para a desova e berçário, e pode ser a chave para a manutenção e conservação das espécies de peixes na bacia do alto rio Paraná.

This study determined the effect of hypoxia on air-breathing onset and physiological and morphological characters in larvae of the air breathing fishes Trichopodus trichopterus and Betta splendens. Larvae were exposed intermittently (12/12 h daily) to 20, 17, and 14 kPa of PO2 from 1 to 40 days post-fertilization. Survival, onset of air breathing, wet body mass, O2, Pcrit were measured every 5 dpf. Hypoxia advanced by 4 days, and delayed by 9 days, the onset of air breathing in Betta and Trichopodus, respectively. Hypoxia increased larval body length, wet mass, and labyrinth organ respiratory surface of Betta, but did not affect these factors in Trichopodus. Hypoxic exposure increased O2 by 50-100% at each day throughout larval development in Betta, but had no effect on larval Trichopodus. Hypoxia decreased Pcrit in Betta by 37%, but increased Pcrit in Trichopodus by 70%. Larval Betta reared in hypoxia showed a modified heart rate:opercular rate ratio (3:1 to 2:1), but these changes did not occur in Trichopodus. Compared to Betta, the blood of Trichopodus had a higher P50 and much smaller Bohr and Root effects. These interspecific differences are likely due to ecophysiological differences: Betta is a non- obligatory air-breather after 36 dpf with a slow lifestyle reflected in its low metabolism, while Trichopodus is an obligatory air-breather past 32 dpf with an athletic fast lifestyle and accompanying high metabolism.