Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2018-08-21T13:55:57Z No. of bitstreams: 1 2010 - Joaquim Neto de Sousa Santos.pdf: 1864983 bytes, checksum: e70ed9f5ee68c8f365819e496dbb0176 (MD5) / Made available in DSpace on 2018-08-21T13:55:57Z (GMT). No. of bitstreams: 1 2010 - Joaquim Neto de Sousa Santos.pdf: 1864983 bytes, checksum: e70ed9f5ee68c8f365819e496dbb0176 (MD5) Previous issue date: 2010-05-21 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico, CNPq, Brasil. / Morphodynamism, extratification and seasonality are among the main factor to influence the composition and abundance of the macroinfauna in sandy beaches. The macroinfauna of two sandy beaches were sampled between winter-2005 and summer-2006 during low tide; one beach was protected (Flamengo beach) located in Guanabara bay, and the other was exposed to waves in the oceanic zone (Grumari beach). The hypothesis that the physical characteristics of the beaches determine the difference in composition and relative abundance of the macroinfauna was tested. Flamengo beach was characterized as dissipative and had comparatively higher t?xon richenes and lower biomass, when compared with Grumari beach that was classsified as reflective. In Flamengo beaches, higher abundance was recordded for Enoploides sp, and Emerita brasiliensis, whereas in Grumari beach Sacocirrus sp and E. brasiliensis were the most abundant taxons. The beaches showed highe dissimilarity in composition and relative abundance of the taxons (91.75%). Sacocirrus sp, Enoploides sp, Dispio uncinata, Scolelepis goodbobyi and E. brasiliensis explained 63.70% of the dissimilarity between the two beaches. In both beaches, we observed extratification in occurence and abundance of the macroinfauna in two seasons. Emerita brasiliensis occurred mainly in Grumary beach in the extrate 1 and Sacocirrus sp in extrate 2, while in Flamengo beach E. brasiliensis and Enoploides sp had the highest abundance in extrate 1 and S. goodbody and D. uncinata in extrate 3. The hypothesis that the macrofauna differs among extrate and beaches was accepted and the differences in composition and relative abundance of the macroinfauna were attributed to morphodynamism, althought other environmental factores can be influencing such differences. / O morfodinamismo, estratifica??o e a sazonalidade s?o os fatores mais importantes na determina??o da composi??o e abund?ncia da macroinfauna em praias arenosas. A macroinfauna de duas praias foi amostrada no inverno/2005 e ver?o/2006 durante a mar? baixa, sendo uma praia protegida (Flamengo) localizada na ba?a de Guanabara, e outra praia exposta localizada na zona oce?nica (Grumari). Foi testada a hip?tese que as caracter?sticas f?sicas das praias determinam diferen?as na composi??o e abund?ncia da macroinfauna. A praia do Flamengo foi caracterizada como dissipativa e apresentou maior riqueza de t?xons, e menor biomassa, quando comparada com a praia de Grumari classificada como refletiva. Na praia do Flamengo as maiores abund?ncias foram registradas para Enoploides sp, e Emerita brasiliensis, enquanto em Grumari foram Sacocirrus sp e E. brasiliensis. As praias apresentaram elevada dissimilaridade na composi??o e abund?ncia relativa dos t?xons (91.75%), Sacocirrus sp, Enoploides sp, Dispio uncinata, Scolelepis goodbobyi e E. brasiliensis explicaram 63.70% das diferen?as entre as praias. Em ambas as praias foram observadas estratifica??es na ocorr?ncia e abund?ncia da macroinfauna nas duas esta??es analisadas. Na praia de Grumari, E. brasiliensis ocorreu principalmente no estrato 1 e Sacocirrus sp no estrato 2, enquanto na praia do Flamengo E. brasiliensis e Enoploides sp apresentaram as maiores abund?ncias no estrato 1 e S. goodbodyi e D. uncinata no estrato 3. A hip?tese da varia??o na composi??o da macroinfauna entre os extratos foi aceita, e as diferen?as observadas na composi??o e abund?ncia da macroinfauna foram atribu?das ao morfodinamismo; no entanto, outros fatores ambientais podem estar relacionados com tais diferen?as.

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Early life stages of many marine and diadromous fish species use sandy beach surf zones, which occur along >50% of the world's marine coastlines. This extensive habitat can provide juvenile fishes with an abundant supply of potential prey and the ability to hide from predators in its shallow turbid waters. Chinook salmon is an anadromous species that migrates to the ocean during their first (subyearlings) or second (yearlings) year of life. The majority of subyearlings reside in estuaries during their first summer season; however, a small number of juveniles also use surf zones. Early marine residence is considered a critical period for Chinook salmon due to high mortality rates; however the role of surf zones in Chinook salmon life history is unclear. Therefore, I determined the distribution of juvenile Chinook salmon on beaches of the eastern North Pacific, compared the migration and growth patterns observed in surf zones and estuaries, identified the factors that accounted for variation in juvenile surf zone catch, explored the factors that influence growth rate variation in surf zones and estuaries, and modeled how growth rates in these coastal habitats may vary in the near future with predicted changes in climate. The majority (94%) of juveniles were caught in surf zones adjacent to estuaries with trough areas, which are beach sections where sand moved by currents and waves produce a trench-like shape. Surf zone fish were collected in significantly lower numbers than estuarine juveniles but entered brackish/ocean waters at similar sizes. Juveniles in surf zones consumed similar organisms (gammarid amphipods, crustacean larvae and insects) as in estuaries. Furthermore, stomach fullness indices (average = 2% of body weight) and growth rates (average = 0.4 mm day�����) were similar in surf zones and estuaries. At one surf zone, juvenile catch was positively correlated to short-term specific growth rates (14 days prior to capture). A bioenergetics modeling approach indicated that given current conditions, consumption rates accounted for more of the variation in growth than prey energetic content and temperature. Climate models predict future increases in fresh water temperature (1.5 to 5.8��C), sea surface temperature (1.2��C) and wave height (0.75 m) that could influence estuarine and surf zone use. Therefore, I developed a local mixing model based on these predictions to estimate future surf zone and estuarine water temperatures in two of the watersheds studied. Based on these temperature projections and the bioenergetics model, I predicted how juvenile specific growth rates would vary in both habitats. I determined that increases in water temperature in both habitats would reduce specific growth rates by 9 to 40% in surf zones and estuaries if diet composition and consumption rates remain similar to present conditions. To compensate for the decline in growth, juveniles may increase their consumption rates or consume more energetically rich prey, if available. If they are not able to compensate, their size at the end of the season may be reduced, which could reduce their overall survival. These results confirm that a small number of suyearling Chinook salmon use sandy beach surf zones, mostly adjacent to estuary mouths, where they experience growth conditions comparable to estuaries. My findings indicate that, in certain situations, juvenile Chinook salmon surf zone use can be influenced by surf zone growth conditions, while variation in growth rates are themselves most strongly influenced by variation in consumption rates in surf zones and estuaries. Predicted changes in coastal western North American climate will likely modify juvenile growth conditions in the next 50 years, and potentially reduce overall survival. Additional insights into the potential impacts of climate change on juvenile salmon will require estimates of changes in the composition, energetic quality and abundance of prey communities inhabiting coastal environments. / Graduation date: 2013