Ulrich Saint-Paul

Fish communities in central Amazonian white- and blackwater floodplains.

In Amazonian floodplains, the flood cycle of the river is becoming the dominant seasonal factor, and fish communities are found to fluctuate greatly over the year. During inundation, fish migrate into floodplain forests to feed on fruits and seeds, in an area more than 300 000 km2 in size. To document patterns of species diversity, distribution, abundance and temporal dynamics and in order to describe the ecological importance of the inundated forest, floodplain fish were captured using variously sized gill nets in white and black water areas inside and outside the floodplain forests during low, rising, high and falling water level in 1990 and 1991. Dominance varies to some extent in white water between floodplain forest (0.06) and open water (0.11) while it is unchanged in black water (0.04). Black water fish communities were more diverse. Most abundant among white water fish were Liposarcus pardalis, Pygocentrus nattereri, and Pellona flavipinnis, for example, or Plagioscion squamsissimus, Serrasalmus rhombeus, and Serrasalmus manueli in black water. Among the most abundant white water fish, Colossoma macropomum, Mylossoma duriventre and Osteoglossum bicirrhosum occurred almost exclusively in inundated forests. Of the black water species there were a large number of species which were captured only in inundated forest, such as Geophagus cf. altifrons, Hoplias malabaricus, Osteoglossum bicirrhosum and Uaru amphiacanthoides. Catches varied with sample site, water level and direction of water level change. The average CPUE in white and black water was 190 and 41 g fish m−2 and day, respectively, with maximum yields at low water and minimum yields at high water. Comparing rising and falling water levels, a significantly higher quantity of fishes was captured at falling water level. In black water, fish catches from the floodplain forest exceeded the open water catch by 183 to 550%, depending on season. Differences in respect of white water are smaller (106–281%). Fish communities in the area under investigation seem to be stochastically assembled, with significant differences between white and black water only. Many fishes move into the floodplain forest not only to feed but probably also for other reasons – to seek shelter, for example.

Observations of fish migration in a macrotidal mangrove channel in Northern Brazil using a 200-kHz split-beam sonar

A 200-kHz split-beam echosounder (BioSonics, DT6000) with a 6° circular-beam transducer was applied in a mangrove channel in Northern Brazil to study the migratory patterns of intertidal fish. Acoustic sampling was conducted horizontally across the channel perpendicular to the tidal current during two lunar cycles in the dry season 2000 and the wet season 2001. The complex acoustic environment of the mangrove channel was characterized by small target sizes (juvenile fish), multiple targets (aggregated fish), high reverberation and background noise levels due to sediment loads, plankton and mangrove litter transport. Dry seasons provided less noisy acoustic conditions resulting in clearer echo data than wet seasons. Neap tide data were less complex than spring tide data. During a tidal cycle, low water provided the clearest acoustic conditions. Mangrove leaves generated fish-like echoes. Analysis of two dry season wax moon cycles revealed fish flux maxima at low water, flood start and high water in the daytime and the night cycle. Night fish fluxes were significantly higher than at daylight. Throughout the tidal cycles, 60% of the fish traveled with the tide and 40% against, suggesting active foraging against the tide to be a major component of fish movements. Resident mangrove fish entered the intertidal creeks at early flood tide, leaving at late ebb tide at fairly shallow-water depths. Estuarine fish required a minimum water depth (about 2 m) for tidal migration. Since time delays during spring tides between immigration of resident and estuarine fish were reduced, foraging time and habitat accessibility would be enhanced and fish catches and fishes’ feeding success would be greater.

Diurnal distribution and behavioral responses of fishes to extreme hypoxia in an Amazon floodplain lake

SynopsisBecause of the need for surface access for aquatic surface respiration (ASR), fish density increases were demonstrated for the open water of a floodplain lake during severe hypoxia. This indicates an O2-induced diurnal pattern of horizontal migrations between the zone of macrophyte cover and open water. Supplemental experimental investigations seem to suggest that species such as characoids,Colossoma macropomum andSchizodon fasciatum, deviate from this pattern. During long periods of oxygen depletion, they return to the region of macrophyte growth and survive there without displaying the usual kind of ASR. Mortality studies in net cages exposed in natural water bodies confirmed that only these two species are able to survive severe hypoxia beneath macrophyte cover. The possibility of an O2-input through the root system of plants is discussed. The O2-concentration has a significant influence on the locomotory behavior and the frequency of opercular movement in characoids. There is significantly less locomotory activity beneath the macrophytes during periods of oxygen depletion among those species not forced to migrate than among those in the open water regions, where normal ASR behavior is possible.

Spatial and temporal distribution of Myrophis punctatus (Ophichthidae) and associated fish fauna in a northern Brazilian intertidal mangrove forest

The mangrove forest along the northern Brazilian coast is not inundated during low tide. However, many fish species stay in the mangrove forest during this time. Tidal behaviour strategies are described for fish species that linger in the mangrove forest during low tide. The samples were taken at the end of the dry season (December 1996) and at the end of the rainy season (July 1997). Fish were captured using an ichthyotoxic plant extract (Ichthyotere cunabi). Spatial and temporal fish density and biomass were analyzed statistically. Thirty-six samples were taken with a total density of 2.8 ind m-2 and a total biomass of 17.4 g m-2 distributed among seven families and 14 species. Myrophis punctatus was the most important species in number (1.66 ind m-2) and weight (12.68 g m-2) of all catches. The total fish densities were not significantly different among areas and between months, although, total biomass differed significantly in time and space. The densities and biomass for the three most dominant species (M. punctatus, Poecilia spp. and Gobionellus smaragdus) differed significantly among species. Only the biomass of these species showed significant monthly differences. The only significant main effect on variance in the densities and biomass of M. punctatus were encountered between months. In addition, the factor area was significantly different for the variable number of species.

Mangrove dynamics and management in North Brazil

PART I: Introduction 1. The Need for a Holistic Approach in Mangrove Research and Management U. Saint-Paul and H. Schneider 2. MADAM, Concept and Reality U. Saint-Paul PART II: Geography and Biogeochemistry 3. Geography of the Braganca Region G. Krause 3.1. Background and Scope 3.2. Spatial Boundaries 3.3. Principal Features of the Natural and Social System 3.4. Co-Evolutionary Outcomes of the Natural and Social Dynamics References 4. Palaeoenvironmental Reconstruction H. Behling, M. Cohen, R.J. Lara, and V. Vedel 4.1. Coastal Region of Northern Brazil 4.2. Holocene Environmental Changes 4.3. Model of Braganca Mangrove Development 4.4. Holocene Coastal Dynamics References 5. The Biogeochemistry of the Caete Mangrove-Shelf System B. Koch, T. Dittmar, and R.J. Lara 5.1. Introduction and Overview 5.2. Sediment Processes 5.3. The Outwelling of Detritus and Decomposition Products into Coastal Waters 5.4. The Fate of Mangrove-Outwelling on the Continental Shelf 5.5. Concluding Remarks References PART III: Floristic and Faunistic Studies in Mangroves 6. Mangrove Vegetation of the Caete Estuary U. Mehlig, M.P.M. Menezes, A. Reise, and E. Medina 6.1. Floristics and Forest Structure 6.2. Litterfall and Phenology 6.3. Dendrochronological Studies of Rhizophora mangle Tree 6.4. Soil-Vegetation Nutrient Relations 6.5. Concluding Remarks and Outlook References 7. Mangrove Infauna and Sessile Epifauna C.R. Beasley, M.E.B. Fernandes, E.A.G. Figueira, D.S. Sampaio, K.R. Melo, and R.S. Barros 7.1. Introduction 7.2. The Infauna of the Mangrove Forest at the Furo Grande Tidal Creek 7.3. Comparison of the Benthic Fauna among Sites with Differing Degrees of Degradation 7.4. Settlement of the Tidal Creek Epifauna in the Caete Mangrove Estuary 7.5. Differences in Settlement of Epibenthos between Mangrove and Tidal Creek Habitats 7.6. Conclusions References PART IV: Dynamics in the Mangrove System 8. Drivers of Temporal Changes in Mangrove VegetationBoundaries and Consequences for Land Use R.J. Lara, M. Cohen, and C. Szlafsztein 8.1. Introduction 8.2. Influence of Inundation Frequency and Sediment Salinity on Wetland Structure 8.3. Changes in Current Vegetation Units: Boundaries, Ecotone Shifts and Consequences for Land Use References 9. System Processes and Forest Development U. Berger and M. Wolff 9.1. The Interlink between the Modelling Approaches 9.2. Trophic Pathways 9.3. Forest Dynamics under Different Natural Disturbance Regimes 9.4. Conclusions References 10. Synoptic Analyses of Mangroves for Coastal Zone Management G. Krause and M. Bock 10.1. Background and Scope 10.2. Research strategy 10.3. Change Dynamics 10.4. Classification of Mangrove Patterns 10.5. Potential Contributions to Coastal Zone Management References PART V: Ecology and Fishery of Fin-Fish in the Mangrove System 11. Distribution Pattern of Fish in a Mangrove Estuary M. Barletta and U. Saint-Paul 11.1. Seasonal Changes in the Caete Estuary 11.2. Fish Assemblage Patterns References 12. Dynamics in Mangrove Fish Assemblages on a Macrotidal Coast U. Krumme and U. Saint-Paul 12.1. Introduction 12.2. Environmental Setting 12.3. Nekton Sampling in Macrotidal Environments 12.4. Trends in Species Richness, Biomass and Density along a Shoreline Gradient 12.5. Composition of Transients 12.6. Tidal Movements 12.7. Tidal and Diel Changes in The Intertidal Fish Assemblages 12.8. Tide-to-Tide, Weekly, Fortnightly and Monthly Variation in Abundance, Catch Weight and Species Richness of Transients 12.9. Patterns in Feeding 12.10. Spatial Patterns in the Intertidal Fish Fauna 12.11. Implications for Future Research and Long-Term Monitoring References 13. An Evaluation of the Larval Fish Assemblage A. Barletta-Bergan 13.1. Value of Mangroves and Estuaries as Nurseries 13.2. First Ichthyoplankton Survey 13.3. A North Brazilian Larval Fish Community in Relation to Mangroves Worldwide References 14. Molecular Phylogenetic and

Nursery Habitat Shifts in an Estuarine Ecosystem: Patterns of Use by Sympatric Catfish Species

The seasonal and spatial distribution (density and biomass) of five size classes of two catfish species (Cathorops spixii and Cathorops agassizii) were studied along an estuarine ecocline to test the relative importance of the nursery function of each habitat. Seasonal vs. area interactions were significant for all size classes of both species. During the early rainy season, the middle estuary is an important nursery habitat for juveniles of both species. When environmental conditions change during the late rainy season, the C. spixii primary nursery habitat shifts to the lower estuary. During this period, juveniles of C. agassizii remain in the middle estuary. Another important ecological area is the upper estuary, which becomes a breeding, spawning and hatchery area during the late dry season for both species. The nursery function of habitats shifts according to the seasonal fluctuation of salinity and dissolved oxygen, and each species responds differently to this change.

An integrated approach to mangrove dynamics and management

The main objective of the MADAM project (Mangrove Dynamics and Management) is to generate the scientific basis enabling the sustainable stewardship of the resources of the Caeté mangrove estuary in Northeast Brazil in the sense of integrated coastal (zone) management. To achieve this, it is necessary to acquire in-depth knowledge of natural processes as well as of the relevant institutional, cultural, economic, social and political dynamics. Causal linkages within the ecosystem, as well as between ecosystem, economy and society, are analysed and explained via dynamic and trophic modelling. Scenario construction is intended to forecast the effects of acute or chronic interference on utilized resources, and to answer wider, management-related questions (e.g. restoration of destroyed areas, utilization potential for aquaculture). This paper describes the project strategy as developed and modified in the context of research results from the initial 2-yr project phase. It is argued that a continuous discussion process is essential to assess the validity of the strategies formulated at the beginning of a medium-time project, particularly if the project is of interdisciplinary nature.

Simulating harvesting scenarios towards the sustainable use of mangrove forest plantations

Mangrove forests appear among the most productive ecosystems on earth and provide important goods and services to tropical coastal populations. Thirty-five percent of mangrove forest areas have been lost worldwide in the last two decades. Management measures could be an option to combine human use and conservation of mangroves. These measures can be improved if their impacts are assessed before they are performed. By doing so, the best management option out of a set of all potential options can be selected in advance. The mangrove model—KiWi—has been proven to be suitable for analyzing mangrove forest dynamics in the neotropics. Here, the model was applied to mangrove management scenarios. For this, the model was parameterized to Rhizophora apiculata, one of the most common mangrove species planted in Asia for timber production. It is thus the first simulation model describing Asian mangrove plantations. The recently developed Pattern Oriented Modelling approach was used to find those parameters fitting best density patterns and dbh (diameter at breast height) size classes reported in literature. The results demonstrated that the KiWi model was able to: (1) reproduce the growth patterns of a mono-specific plantation of R. apiculata in terms of forest density and size class distribution and (2) can provide criteria for the selection of a thinning strategy within a harvesting cycle.

Mitochondrial DNA reveals population structuring in Macrodon atricauda (Perciformes: Sciaenidae): a study covering the whole geographic distribution of the species in the southwestern Atlantic.

Abstract We investigated the genetic structure and diversity of M. atricauda, based on 266 specimens collected off the coast of southern Brazil and Argentina at seven locations, covering the whole geographic distribution of this species. A DNA sequence alignment of 904 base pairs of the mitochondrial Control Region revealed a total of 85 haplotypes. FST analyses suggest that M. atricauda does not comprise a single demographic stock. Two different genetic units are identified, which possibly are related to ecological adaptations of the species within its range. Genetic diversity, Bayesian analysis of population structure, and significant negative results for the D and FS tests indicate that M. atricauda populations have undergone recent expansion. The spatial distribution of genetic variation seems to be related to historical colonization from south to north, followed by expansion.

Deep-sea shrimps Aristaeomorpha foliacea and Pleoticus robustus (Crustacea: Penaeoidea) in the Colombian Caribbean Sea as a new potential fishing resource

In the Colombian Caribbean Sea a shallow water commercial shrimp fishery has been developed, targeting mainly Farfantepenaeus notialis . Yet, similarly to so many fisheries around the world, the exploitation of this shrimp is not regulated, and a significant depletion has resulted. This study investigates new fishing areas, exploring the poorly understood deep-sea habitats in the Colombian Caribbean Sea, to determine the potential for a viable deep shrimp fishery, studying their abundance and spatial distribution. We found high abundances for giant red shrimp ( Aristaeomorpha foliacea ) and royal red shrimp ( Pleoticus robustus ), both important commercially. The higher biomass of these two deep-sea shrimp species were found mainly in the northern zone of the Colombian Caribbean Sea, where the local oceanography is modulated by the seasonal upwelling with high productivity. The size-structure following depth strata showed that A. foliacea increase in size with the depth and the contrary for P. robustus . The majority of adult individuals in these two deep-sea shrimp species reflect the non-fished populations in the study area. However, more scientific assessment is necessary to determine life cycle population parameters of deep-sea shrimps and associated biodiversity before initiating a new commercial shrimp fishery.