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Effects of heat stress and local human disturbance on the structure of coral reef ecosystems at multiple scales of biological organizationMagel, Jennifer 04 January 2019 (has links)
The world’s coral reefs are being impacted by myriad disturbances, from localized overfishing and nutrient pollution to global climate change-induced temperature increases and ocean acidification. Conservation of coral reefs in the face of increasing variability and uncertainty requires an understanding of the interacting effects of multiple stressors on the diverse components of these vital ecosystems. In this thesis, I use data from reefs around Kiritimati atoll (Republic of Kiribati) in the central equatorial Pacific Ocean to examine the effects of a severe pulse heat stress event and local human disturbance on two important components of the coral reef ecosystem – three-dimensional (3D) structural complexity and reef fish assemblages. Using 3D reef models constructed through structure-from-motion photogrammetry, I examined changes in reef structural complexity in the year following the 2015-2016 El Niño and mass coral bleaching event. I found that exposure to prolonged thermal stress and subsequent coral mortality resulted in declines in reef structural complexity, particularly reef surface rugosity and terrain ruggedness. Baseline levels of structural complexity were also negatively influenced by local human disturbance, while complexity was positively related to the densities of branching and massive coral growth forms. These findings have important implications for the maintenance of healthy reef ecosystems, as high levels of structural complexity are important for supporting diverse reef-associated fish assemblages. Next, using underwater visual censuses of reef fish assemblages, I quantified fish abundance, biomass, species richness, and assemblage structure before, during, and after the 2015-2016 El Niño. Total reef fish abundance, biomass, and species richness declined during the El Niño, suggesting that pulse heat stress events may have short-term, negative consequences for reef fish. Although these metrics did not vary substantially across the local human disturbance gradient, recovery of assemblages following the heat stress event was impeded by higher levels of local human disturbance. Reef fish assemblage structure was influenced by a more diverse array of factors, showing significant shifts in response to heat stress, human disturbance, and net primary productivity. Given the many important roles that fish play on coral reefs, declines such as those observed here may impair the ecological functioning of these ecosystems. Together, my results highlight the negative impacts of heat stress and local human disturbance on coral reefs, demonstrating ways in which these stressors may interact to limit reef resilience in the face of increasing anthropogenic pressures. / Graduate / 2019-12-07
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DistribuiÃÃo de recrutas e adultos de cinco espÃcies de peixes recifais do Atol das Rocas / Distribution of recruits and adults of five species of reef fishes of the RocasCarolina Cerqueira de Paiva 02 October 2008 (has links)
nÃo hà / O sucesso no recrutamento de peixes recifais depende do nÃmero de
indivÃduos que sobrevivem apÃs a entrada das larvas no ambiente recifal. Diversos
processos pÃs-recrutamento sÃo responsÃveis pela distribuiÃÃo de recrutas e
adultos e, conseqÃentemente, pela estruturaÃÃo da populaÃÃo destes. A partir da
realizaÃÃo de censos visuais subaquÃticos foi caracterizada a distribuiÃÃo dos
recrutas e adultos de Abudefduf saxatilis, Stegastes rocasensis, Thalassoma
noronhanum, Acanthurus chirurgus e Acanthurus coeruleus no Atol das Rocas.
Foram amostradas 13 estaÃÃes com caracterÃsticas contrastantes, formando cinco
categorias: nove piscinas, uma formaÃÃo de poÃas de marÃ, uma formaÃÃo de
recifes em mancha, um recife de arenito e uma crista algÃlica. As piscinas foram
classificadas em conectadas (Barretinha, Barreta Falsa e Podes Crer) e nÃo
conectadas (Farol 2, Garoupinha, CemitÃrio, Ãncoras, Abrolhos e Tartarugas)
permanentemente com o oceano. As piscinas nÃo conectadas, por sua vez, foram
classificadas em rasas (Farol 2, Garoupinha e CemitÃrio) e fundas (Ãncoras,
Abrolhos e Tartarugas). AnÃlises de variÃncia unifatoriais revelaram que as poÃas de
marà e as piscinas foram as categorias de maior preferÃncia entre os recrutas
enquanto as poÃas de marà foram evitadas pela maioria dos adultos. Testes-t
independente por grupos demonstraram que o tipo de conectividade das piscinas
com o oceano interferiu na distribuiÃÃo da maior parte dos recrutas, mas nem tanto
na dos adultos. JÃ a profundidade das piscinas nÃo conectadas influenciou a
distribuiÃÃo da maioria dos recrutas e de todos os adultos. Movimentos migratÃrios,
complexidade estrutural e cobertura do substrato, presenÃa de outros indivÃduos da
mesma espÃcie, disponibilidade de alimento e presenÃa de predadores sÃo os
processos pÃs-recrutamento que provavelmente influenciaram a distribuiÃÃo de
recrutas e adultos. AlÃm disso, a profundidade tambÃm pode ter exercido alguma
interferÃncia na distribuiÃÃo de A. chirurgus, dos recrutas de A. saxatilis e dos
adultos de A. coeruleus. NÃo foram observados recrutas de A. coeruleus / The success in the recruitment of reef fish depends on the number of
individuals who survive after larvae have entered in the reef environment. Different
post-recruitment processes are responsible for the distribution of recruits and adults
and consequently, for the structure of their populations. The distribution of Abudefduf
saxatilis, Stegastes rocasensis, Thalassoma noronhanum, Acanthurus chirurgus and
Acanthurus coeruleus recruits and adults were assessed through visual censuses in
the Atol das Rocas. 13 sample stations with contrasting features were pooled in five
categories: nine pools, a tidal pond formation, a patch reef formation, a sandstone
reef and an algae crest. Pools were classified as connected (Barretinha, Barreta
Falsa and Podes Crer) and non-permanently connected (Farol 2, Garoupinha,
CemitÃrio, Ãncoras, Abrolhos and Tartarugas) with the ocean. Non-connected pools
were classified in shallow (Farol 2, Garoupinha and CemitÃrio) and deep (Ãncoras,
Abrolhos and Tartarugas). Unifactorial analysis of variance revealed that tidal ponds
and pools were the most preferred categories among recruits, while the majority of
adults avoided tidal ponds. Independent t-tests per groups demonstrated that the
type of pool connectivity with the ocean affected the distribution of the largest part of
recruits, however to a much lesser extent in the case of adults. Non-connected pool
depth affected the distribution of most recruits and all adults. Migratory movements,
structural complexity, reef substrate coverage, the presence of conspecifics, food
availability and predator presence are post-recruitment processes that probably
affected recruit and adult distribution. Depth may have also influenced A. chirurgus,
A. saxatilis recruits and A. coeruleus adults to a certain extent. No A. coeruleus
recruits have been observed.
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Nocturnal parental care and the role of parents in hatching their eggs in the clown anemonefish Amphiprion perculaPacaro, Madison 17 March 2022 (has links)
Parental care is a critical component of many breeding systems that enhances both parent and offspring fitness. It is widely recognized that parental care varies in quality and quantity in response to variation in offspring need, parental condition, and ecological context. One context that has been underexplored, however, is the difference in parental care between day and night, with many parental care studies focused on diurnal care. To fully understand the evolution of parental care, the costs and benefits and the negotiations between parents, both diurnal and nocturnal care must be accounted for. Here, we show that nocturnal parental care exists in the clownfish Amphiprion percula, with males and females actively caring for offspring at night throughout embryo development and during hatching in a laboratory setting. At night, as during the day, males are the dominant caregivers and both parents increase care as embryos mature. At night, in contrast to the day, females provide substantially more care. This increase in energy expended by parents on care may be a mechanism to increase dissolved oxygen in the water at night, improving embryo survival. We also document the existence of three new nocturnal parental care behaviors, not previously seen during the day: vigorous fanning, vigorous mouthing, and anemone biting. These behaviors are particularly frequent during hatching, and although they are not necessary for hatching to occur, they may serve to enhance the embryos’ successful transition from the benthos to the water column. This study contributes to our understanding of parental care, demonstrating the importance of considering nocturnal care if we are to gain a complete understanding of the evolution of parental care. / 2023-03-16T00:00:00Z
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A detailed morphological, behavioural, and genetic characterization of the larval phase of the Red Sea clownfish, Amphiprion bicinctusJusto, Micaela 03 1900 (has links)
Coral reef fish are known to have a bipartite life cycle: a dispersive pelagic larval phase (DPL), where larvae ‘travel’ away from their parents to occupy new habitats, and a sedentary reef phase characterized by juveniles and adults. Study of the DPL is an essential prerequisite to understand how persistence, connectivity, and gene flow operate between populations. Clownfish have been the subject of considerably varied fields of research in recent decades, not only due to their economic value, but also because of their ease of maintenance in laboratory settings, regular spawning, and short DPL. Their life cycle is also defined as bipartite, with a DPL lasting around 15 days until settlement, and the fish exhibit a symbiotic relationship with sea anemones. The transitions between phases are associated with a series of morphological, behavioural, genetic, cellular and molecular changes. However, these changes are poorly characterized in some species of clownfish. Therefore, the Red Sea clownfish, Amphiprion bicinctus, was reared to fill the gap in the literature by investigating their i) morphology, ii) swimming abilities, and iii) differential gene expression (DGE) throughout ontogeny. The DPL was characterized in the preflexion, flexion and postflexion stages, according to flexion of the notochord, on 0, 2 and 10 days post hatch (dph), respectively. Metamorphosis was defined by a morphological transition between the DPL and juvenile phases, associated with the appearance of white stripes, on day 10 and until the end of the experiment, on day 14. Additionally, metamorphosis is followed by a behavioural change at 14 dph, called settlement, where larvae transition from free swimming in the water column to associating with the substrate. We also demonstrate that the larvae present active swimming from the moment they hatch, and the swimming speed increases throughout DPL. Overall, the development of A. bicinctus is similar to other clownfish species. This work provides a strong baseline on the development of A. bicinctus, which may open the door to a deeper understanding of the role of dispersal behaviours and enhance our ability to design effective marine reserve networks in the Red Sea.
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“Movers and Stayers” Movement Ecology of Yellowtail Snapper Ocyurus chrysurus and Horse-eye Jack Caranx latus Around Buck Island Reef National Monument, U.S. Virgin IslandsNovak, Ashleigh 09 July 2018 (has links)
When movement ecology of target species is coupled with spatial management approaches, such as marine protected areas (MPAs), the results can establish effective conservation outcomes. Nevertheless, a knowledge gap persists regarding how many marine organisms use specific environments over long, continuous periods of time. Acoustic telemetry arrays and fine-scale positioning systems are quickly pervading the marine environment as they can monitor animal movements on a near continuous basis, filling in many previous unknowns on spatial use patterns. Further, coupling fine-scale movement patterns and benthic habitat data provides a spatial framework foundation essential to understanding the intricacies of how habitats can drive movement ecology, and how organisms might link adjacent habitats and resources through movement. The first chapter of this thesis quantified both the broad- and fine-scale movement patterns of yellowtail snapper Ocyurus chrysurus (n = 8) around Buck Island Reef National Monument (BIRNM), St. Croix, U.S. Virgin Islands, an MPA managed by the National Park Service. High site fidelity and a clear affinity to the western shelf break characterized common broad-scale movements observed for this species. Two distinct contingents were detected by the positioning system suggesting individuals were using habitats in two unique, highly structured ways, however, this result requires further validation through an increased sample size. For the second chapter, I characterized the broad-scale movement ecology of horse-eye jack Caranx latus (n = 7), an understudied, but common predatory reef fish. Horse-eye jack are wide ranging, with most individuals visiting almost all receivers (n = 78) in the BIRNM array network. Comparatively, horse-eye jack made more frequent BIRNM boundary crossings into adjacent MPAs harboring various levels of protection. Taken together, these two case studies highlight how sympatric reef species differentially use space within BIRNM and highlight the necessity of evaluating MPA efficacy across species and over longer time scales. Constructing single species movement assessments is essential information, yet there is now a demonstrated need for community movement studies. The final chapter of this thesis highlights promising next steps for this project, including the proposal of a new hourly or sub hourly movement trajectory analysis, potentially capable of elucidating species interactions in near real-time. Together, this thesis not only fills data gaps on species deficient in ecological studies (horse-eye jack) but illuminates individuality in habitat and space use (yellowtail snapper), and how these analyses can be tied back in to developing stronger holistic community population assessments. With continued exploitation of marine environments and increasing anthropogenic demand of marine resources, the need for understanding processes driving species movements is essential in developing successful spatial management plans.
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La structuration des communautés de poissons de récif à différentes échelles : de la taxonomie aux fonctions / The assembly of reef fish communities across scales : from taxonomy to functionsBender Gomes, Mariana 28 March 2014 (has links)
Comprendre les mécanismes d'assemblages des communautés est l'une des principales questions en écologie et biogéographie. Elle est également essentielle pour prédire les conséquences des changements globaux sur la distribution future de la biodiversité. Les communautés écologiques sont la résultante de facteurs interagissant à plusieurs échelles spatiales et temporelles. En outre, ces processus peuvent affecter différemment les composantes taxonomique, fonctionnelle et phylogénétique de la biodiversité. Nous étudions ici les processus écologiques qui structurent les communautés de poissons de récif, l'un des assemblages de vertébrés les plus diversifié sur Terre. Les facettes taxonomique et fonctionnelle de ces assemblages ont été étudiées au travers de plusieurs échelles spatiales. Nos objectifs sont (i) d'identifier les facteurs structurant les assemblages de poissons de récif à différentes échelles (du régional au local), (ii) d'évaluer dans quelles mesures les processus structurant les groupes taxonomiques et fonctionnels sont consistants entre eux et (iii) de comprendre la distribution de la rareté fonctionnelle dans les assemblages de poissons de récif. Deux bases de données ont été utilisées : (1) une base de données sur les caractéristiques fonctionnelles et les distributions globales de plus de 6000 espèces de poissons dans six régions biogéographiques ; (2) un ensemble de données comprenant les occurrences de 1 474 espèces de poissons sur 9 681 échantillons obtenus le long de transects (comptages visuels en scaphandre autonome) de 40m² à travers 252 sites dans plusieurs régions biogéographiques. Dans l'océan Atlantique, la structure taxonomique et fonctionnelle des communautés de poissons a une signature biogéographique, avec une différence marquée entre les espèces des récifs biogènes riches (dans les Caraïbes et composée des petites espèces) et les régions périphériques dominées par des espèces plus grandes. L'environnement joue également un rôle important dans la structuration des assemblages dans d'autres domaines biogéographiques. Alors que la composition taxonomique des communautés est principalement liée à l'isolement des récifs, la structure fonctionnelle est influencée par la disponibilité de l'habitat à l'échelle locale. Encore une fois, il y a une plus grande contribution des petites espèces dans les sites les plus riches alors que les grandes espèces dominent en périphérie, suite à la plus forte capacité de colonisation des grandes espèces. Les assemblages présentent des structures fonctionnels emboîtées. Plus précisément les sites pauvres en diversité fonctionnelle, ici mesurée en nombre d'entités fonctionnelles différentes, sont des sous-ensembles des sites riches. Cette structure résulte de l'interaction entre les capacités de dispersion/colonisation des espèces et/ou des besoins en ressources, ainsi que des gradients d'isolement et de surface. Malgré la présence de groupes fonctionnels essentiels et de redondance dans les assemblages de poissons, la majorité des espèces dans les communautés sont rares. De plus, les espèces rares occupent une large proportion de la gamme de traits fonctionnels et effectuent souvent des fonctions uniques. Selon les scénarios simulant la perte d'espèces rares (de 8 à plus de 200 espèces rares / moyenne : 78,2 ± 62), il y aurait une perte élevée - 80 % dans un seul site - de la diversité fonctionnelle. Nos résultats révèlent que les processus au sein d'un domaine biogéographique sont responsables d'une structuration taxonomique et fonctionnelle. De plus, le rôle essentiel de la capacité de colonisation de l'espèce met en évidence l'importance de la connectivité pour le maintien de la structure fonctionnelle des communautés de poissons de récif. Enfin, la contribution des espèces rares à la diversité fonctionnelle montre que ces taxons doivent être protégés afin de maintenir l'ensemble des fonctions et services des écosystèmes. / Understanding the mechanisms of community assembly is one of the main questions in ecology and biogeography, and is essential for predicting the implications of future biodiversity loss. It is known that an array of processes operating at different spatial and temporal scales interact to produce ecological communities. These processes may affect differently the multiple components of communities: the taxonomic, functional and phylogenetic components. Here we investigate the patterns and processes structuring one of the most diverse vertebrate assemblages on Earth: reef fishes. Reef fish assemblages were assessed across multiple spatial scales, under a taxonomic and functional perspective. Our main objectives included: (i) the identification of determinants of structure in reef fish assemblages across scales (regional to local); (ii) assessing to which extent the processes behind assemblage structures are consistent for taxonomic and functional groups; (iii) understanding the patterns of functional rarity in reef fish assemblages at a global scale. Two databases were utilized: (1) an extensive database on the functional traits and the global distributions of over 6,000 reef fish species across six marine biogeographic regions; (2) a dataset comprising the occurrences of 1,474 fish species over 9,681 underwater visual transects of 40m2 across 252 sites, also throughout the major biogeographic regions. Within the Atlantic Ocean, the taxonomic and functional structure of reef fish assemblages exhibit a biogeographic fingerprint, with a marked discrimination between species rich biogenic reefs – primarily in the Caribbean, where communities were dominated by small invertebrate feeders – and poorer peripheral regions dominated by larger species with more diverse diets. At the regional scale, both historical events and environmental characteristics (coral reefs vs. periphery) have played a role in structuring both components of assemblages. The role of environment features also holds for the structure of assemblages in other biogeographic realms (i.e. Indo-Pacific and Tropical Eastern Pacific). While the taxonomic composition of assemblages is mainly related to reef isolation, the functional structure is influenced by local habitat availability. Again, there is a greater contribution of small-bodied species in the most species-rich locations; and large-bodied species prevailing in peripheral assemblages, a pattern related to species' colonization capacity. Reef fish assemblages across most regions depicted significantly functional nested structures, attributed to functional redundancy – different species constitute a number of key functional entities. The nested structure results from the interaction between species' dispersal/colonization capabilities and/or resource requirements, with isolation and area gradients. Despite the existence of key functional groups and redundancy, the majority of species are rare (low abundance or occupancy). Also, rare species fulfil much of the range of functional traits within reef fish communities and often perform unique roles. Under scenarios of rare species loss (from 8 to over 200 rare species/ mean: 78.2±62) there would be high functional diversity erosion in the majority of reef fish communities, this level reaching up to 80% of functional diversity in one location. However the extent to which these functional groups actually contribute to ecosystem functioning is unknown. Our results reveal that within-realm processes, such as evolutionary histories, have shaped the taxonomic and functional structure of assemblages in each realm. Moreover, the key role of species' colonization capacity highlights the importance of connectivity to the maintenance of the functional structure across reef fish communities. Finally, the contribution of rare species to functional diversity indicates that protecting these taxa is essential to maintain ecosystem functioning and services in reef fish communities.
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Relative Survival of Gags Mycteroperca microlepis Released Within a Recreational Hook-and-Line Fishery: Application of the Cox Regression Model to Control for Heterogeneity in a Large-Scale Mark-Recapture StudySauls, Beverly J. 01 January 2013 (has links)
The objectives of this study were to measure injuries and impairments directly observed from gags Mycteroperca microlepis caught and released within a large-scale recreational fishery, develop methods that may be used to rapidly assess the condition of reef fish discards, and estimate the total portion of discards in the fishery that suffer latent mortality. Fishery observers were placed on for-hire charter and headboat vessels operating in the Gulf of Mexico from June 2009 through December 2012 to directly observe reef fishes as they were caught by recreational anglers fishing with hook-and-line gear. Fish that were not retained by anglers were inspected and marked with conventional tags prior to release. Fish were released in multiple regions over a large geographic area throughout the year and over multiple years. The majority of recaptured fish were reported by recreational and commercial fishers, and fishing effort fluctuated both spatially and temporally over the course of this study in response to changes in recreational harvest restrictions and the Deepwater Horizon oil spill. Therefore, it could not be assumed that encounter probabilities were equal for all individual tagged fish in the population. Fish size and capture depth when fish were initially caught-and-released also varied among individuals in the study and potentially influenced recapture reporting probabilities. The Cox proportional hazards regression model was used to control for potential covariates on both the occurrence and timing of recapture reporting events so that relative survival among fish released in various conditions could be compared.
A total of 3,954 gags were observed in this study, and the majority (77.26%) were released in good condition (condition category 1), defined as fish that immediately submerged without assistance from venting and had not suffered internal injuries from embedded hooks or visible damage to the gills. However, compared to gags caught in shallower depths, a greater proportion of gags caught and released from depths deeper than 30 meters were in fair or poor condition. Relative survival was significantly reduced (alpha (underline)<(/underline)0.05) for gags released in fair and poor condition after controlling for variable mark-recapture reporting rates for different sized discards among regions and across months and years when individual fish were initially captured, tagged and released. Gags released within the recreational fishery in fair and poor condition were 66.4% (95% C.I. 46.9 to 94.0%) and 50.6% (26.2 to 97.8%) as likely to be recaptured, respectively, as gags released in good condition. Overall discard mortality was calculated for gags released in all condition categories at ten meter depth intervals. There was a significant linear increase in estimated mortality from less than 15% (range of uncertainty, 0.1-25.2%) in shallow depths up to 30 meters, to 35.6% (5.6-55.7%) at depths greater than 70 meters (p < 0.001, R2 = 0.917). This analysis demonstrated the utility of the proportional hazards regression model for controlling for potential covariates on both the occurrence and timing of recapture events in a large-scale mark-recapture study and for detecting significant differences in the relative survival of fish released in various conditions measured under highly variable conditions within a large-scale fishery.
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People and Fish in Fiji: an ethnobiological study of a coral reef ecosystemGordon, Andrew Ross Unknown Date
No description available.
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People and Fish in Fiji: an ethnobiological study of a coral reef ecosystemGordon, Andrew Ross 11 1900 (has links)
People are active participants in coral reef ecosystems. This ethnobiology study considers and contrasts folkbiological knowledge of people living in two groups of artisanal fishing villages in Kadavu Province, Fiji. The high level of biological diversity on the Astrolabe Reef provides insights into folk categorization and classification methods that include colour, shape, size, physical features, and habits of certain reef fish and marine animals. Surveying large numbers of experts and novices on defined groups of creatures yields more depth and range of responses allowing higher confidence levels in response accuracy. A comparison of the data with Berlins (1992) proposed principles yields mixed results. Sea cucumbers have high ecological salience and their identification requires attention to the affect of two centuries of trade on Fijian society. Effective ethnobiological research provides productive options to contribute to coral reef sustainability programs with long term benefits for local people and marine life. Key words: Kadavu, naming and classification of fish, coral reef ethnobiology.
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Dinâmica dos padrões sucessionais do macrofitobentos em áreas marinhas sob diferentes regimes de proteçãoSilva, Marianna Barbosa da 20 January 2014 (has links)
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Previous issue date: 2014-01-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Reefs ecosystems have high biological diversity, but they have suffered many
impacts resulting from human activities. These anthropogenic stressors may
promote particular impacts on reef benthic communities, which are often
structured by sessile organisms. Thus, knowledge about the community
structure of phytobenthos have been used as the basis for the assessment of
environmental impacts in many marine environments. In the case of reefs,
changes in nutrient concentrations, as well as overfishing, have been described
as the greatest responsible for the damages to the structure of this ecosystem.
Thus, several studies have been conducted in order to better understand the
role of herbivory and nutrient enrichment on the structure of seaweed
communities. In this context, the present study was to analyze the patterns of
colonization and succession of the phytobenthos, as well as the influence of
herbivory, especially the reef fish on these processes. Thus, this study was
divided into two chapters, the first being: "Assessment of patterns of
colonization and succession of the phytobenthos in reef communities in Paraíba
coast." The assay used artificial substrates, and was conducted within the
boundaries of a marine reserve (Parque Estadual Marinho de Areia VermelhaPEMAV)
and an adjacent location that has similar biotic characteristics; and
showed that the colonization of different groups over time is probably related
with biological characteristics of the species (life cycle, morphological structure
and reproductive strategies). The second chapter, entitled " The influence of
herbivorous fish species on patterns of colonization and succession of
phytobenthos in reef ecosystems," indicates that the group of herbivores did not
affect the structure of the phytobenthos community present in PEMAV, a
situation which is possibly related to overfishing and degradation of the coastal
reefs in Paraíba, which alter the structure of the fish and phytobenthic
communities. / Os recifes formam ecossistemas que apresentam grande diversidade biológica
e, no entanto, têm sofrido diversos impactos, resultantes de ações antrópicas.
Estes estressores antropogênicos podem promover um impacto especial sobre
as comunidades bentônicas dos recifes, que quase sempre são estruturadas
por organismos sésseis. Desta forma, conhecimentos a respeito da estrutura
das comunidades de fitobentos têm sido utilizados como base para a avaliação
de impactos ambientais em muitos ambientes marinhos. No caso dos recifes,
as alterações nas concentrações de nutrientes, assim como a sobrepesca, têm
sido apontados como os maiores responsáveis pelo comprometimento da
estrutura desse ecossistema. Assim, diversos estudos têm sido conduzidos
com o propósito de compreender melhor o papel da herbivoria e do
enriquecimento de nutrientes na estrutura das comunidades de algas marinhas.
Neste contexto, o presente estudo se propôs a analisar os padrões de
colonização e sucessão do macrofitobentos, bem como a influência da
herbivoria, em especial pela ictiofauna, sobre esses processos. Desta forma, o
presente trabalho foi dividido em dois capítulos, sendo o primeiro: “Avaliação
dos padrões de colonização e sucessão do macrofitobentos em comunidades
recifais do litoral paraibano”. O ensaio utilizou substratos artificiais e foi
conduzido dentro dos limites de uma reserva marinha (O Parque Estadual
Marinho de Areia Vermelha-PEMAV) e numa localidade adjacente que
apresenta características bióticas semelhantes; e evidenciou que a colonização
e sucessão dos diferentes grupos ao longo do tempo provavelmente está
relacionada às características biológicas das espécies (ciclo de vida, estrutura
morfológica e estratégias reprodutivas). Já o segundo capítulo, intitulado “A
influência da ictoufauna herbívora sobre os padrões de colonização e sucessão
do macrofitobentos em ecossistemas recifais”, verificou que o grupo dos
herbívoros não atuou de maneira a afetar a estrutura da comunidade do
macrofitobentos presente no PEMAV, o que provavelmente está relacionado à
degradação dos recifes costeiros paraibanos, que acaba por alterar a estrutura
das comunidades ícticas e fitobentônicas.
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