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Book ChapterDOI

6. Benthic Communities

About: The article was published on 2013-03-15. It has received 8 citations till now. The article focuses on the topics: Benthic zone.
Citations
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Book ChapterDOI
23 Mar 2013
TL;DR: Close and highly efficient tree-microbe-soil interrelationships are a major factor in explaining why mangroves are highly productive forests in oligotrophic environments.
Abstract: The interactions of mangrove trees with soil and associated microorganisms are complex. Mangrove trees must cope with a harsh, waterlogged environment, being anchored in soils colonized by highly abundant, productive, and diverse microbial assemblages. The soil horizons are usually dominated by biogenic structures, usually crab burrows and deep tree roots, and are often pockmarked with cracks and fissures. These structures and their activities, coupled with drainage and recharge of interstitial water by tides, foster spatially complex patterns of organic matter decomposition within the forest floor. Except for biogenic structures, oxygen penetrates only a few millimeters into the soil, so anaerobic processes dominate early diagenesis. Sulfate reduction is often the major anoxic process, occurring to a soil depth of at least 1 m and relating to root uptake and exudation of dissolved materials. Recent evidence suggests that iron and manganese reduction may be important in close association with roots and crab activities. Mangrove soils are a source of microbially mediated gases, such as CO2, CH4, N2, and N20. The driving factor of plant-soil relations in mangrove forests is the high nutrient and water requirements needed to fuel high rates of tree photosynthesis. Close and highly efficient tree-microbe-soil interrelationships are a major factor in explaining why mangroves are highly productive forests in oligotrophic environments.

66 citations

Journal ArticleDOI
TL;DR: Tidal creek nekton assemblages were compared among mangrove forests impacted by Typhoon Sudal and differing in stand structure to indicate that studies of structural complexity and neKton densities may be better served when individual species are compared and that diverse mangroves tree assemblage will support diverse nektons that may be more resilient to disturbance.
Abstract: Structurally complex mangrove roots are thought to provide foraging habitat, predation refugia, and typhoon protection for resident fish, shrimp, and crabs. The spatially compact nature of Micronesian mangroves results in model ecosystems to test these ideas. Tidal creek nekton assemblages were compared among mangrove forests impacted by Typhoon Sudal and differing in stand structure. Structurally complex Rhizophora spp. stands were predicted to support higher densities and different communities of nekton and to provide greater protection from typhoons compared to less complex Sonneratia alba/Bruguiera gymnorrhiza stands. Lift net data revealed that structural complexity did not support greater nekton densities, but did support significantly different nekton assemblages. The cardinalfish Apogon ceramensis and goby Oxyurichthys lonchotus had significantly higher densities in S. alba/B. gymnorrhiza mangrove creeks, whereas the silverside Atherinomorus lacunosus and diogenid crabs had significantly higher densities in Rhizophora spp. creeks. Similar nekton densities 17 and 4 months after the typhoon in Rhizophora spp. creeks provided indirect evidence that structural complexity increased protection for resident nekton from disturbances. Findings indicate that studies of structural complexity and nekton densities may be better served when individual species are compared and that diverse mangrove tree assemblages will support diverse nekton assemblages that may be more resilient to disturbance.

25 citations

Journal ArticleDOI
TL;DR: There was a shift in species composition, abundance and biomass of mollusc assemblages for all faunal types (infauna, epifauna and arboreal fauna) as forest age increased, correlated with the changes in vegetation and above-ground biomass.
Abstract: We compared the mollusc assemblages of planted mono-specific Rhizophora mangroves of known different ages. As forest age increased, there was a shift in species composition, abundance and biomass of mollusc assemblages for all faunal types (infauna, epifauna and arboreal fauna). This shift was correlated with the changes in vegetation (increasing forest cover and above-ground biomass) and sediment characteristics (increasing organic matter and decreasing sand content). Some species dominate in young plantations ( 15 years; Terebralia sulcata, Nerita planospira). The two former groups of species are mostly species of infaunal and epifaunal habitats, while the latter group is mainly composed of arboreal species. The shift in mollusc species composition and dominance may serve as a useful indicator of restoration patterns in planted mangroves.

17 citations

Journal ArticleDOI
TL;DR: Baseline community assemblages and diversity of macrozoobenthic infauna in soft-bottomed intertidal flats at Bodo Creek on the upper reaches of the Andoni-Bonny estuarine system were determined spatially and in relation to sediment particle characteristics for two years from May 2006 to April 2008 as mentioned in this paper.
Abstract: Baseline community assemblages and diversity of macrozoobenthic infauna in soft-bottomed intertidal flats at Bodo Creek on the upper reaches of the Andoni–Bonny estuarine system were determined spatially and in relation to sediment particle characteristics for two years from May 2006 to April 2008. Interstitial water temperature, pH, dissolved oxygen and conductivity varied, while biological oxygen demand at the sites was similar. A total of 7 742 specimens belonging to 47 genera and 29 families of macrofauna were recovered from the samples. Density ranged between 8 and 1 583 m−2, while Shannon–Wiener diversity varied from 0.102 to 1.052. A Hutcheson t-test revealed significant inter-site diversity differences, except for Station 2 vs Station 5 and Station 4 vs Station 5. Canonical correspondence analysis (CCA) revealed that the nature of substratum accounted for 34% of the taxa distribution and abundance in the study area; variances for the first and second axes were 77.8% and 21.2%, respectively. The CC...

16 citations

Journal ArticleDOI
TL;DR: It is suggested that tree-species composition and tidal flooding level can have a significant effect on the habitat partitioning of sexes and sizes of the mangrove crab U. cordatus both during and outside the breeding season.
Abstract: Environmental factors strongly affect mangrove crabs, and some factors modulate population structure and habitat partitioning during the crabs’ life cycle. However, the effect of these environmental factors on habitat selection by mangrove crabs is still unknown. We evaluated habitat selection by the mangrove crab Ucides cordatus in mangrove forests with different degrees of predominance of Rhizophora mangle, Laguncularia racemosa or Avicennia schaueriana, two tidal flooding levels (less- and more-flooded), and two biological periods (breeding and non-breeding seasons). Sampling was conducted in four mangrove forests with different influences of these biotic and abiotic parameters. We used the data for sex ratio to explain environmental partitioning by this species. Females predominated in R. mangle mangroves, independently of the biological period (breeding or non-breeding seasons), and males predominated only in the less-flooded L. racemosa mangroves. The flooding level affected the sex ratio of U. cordatus, with a predominance of males in less-flooded mangroves, independently of the biological period; and a gender balance in the more-flooded mangroves only during the breeding season. Outside the breeding season, the largest specimens were recorded in the R. mangle mangroves, but in the breeding season, the largest crabs were recorded in the L. racemosa mangroves with a higher level of flooding. These results suggest that tree-species composition and tidal flooding level can have a significant effect on the habitat partitioning of sexes and sizes of the mangrove crab U. cordatus both during and outside the breeding season.

13 citations

References
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Book ChapterDOI
TL;DR: Mangroves are trees or bushes growing between the level of high water of spring tides and a level close to but above mean sea-level and the land animals found in mangrove forests include roosting flocks of fruit bats, fishing and insectivorous birds, and many insects are conspicuous.
Abstract: Publisher Summary Mangroves are trees or bushes growing between the level of high water of spring tides and a level close to but above mean sea-level Very few species of mangrove are deep rooted, or have persistent tap roots Almost all are shallow rooted but the root systems are often extensive and may cover a wide area Rhizophoraceous trees have seedlings with a long radicle which would seem well suited to develop into a tap root, but as soon as the seedling becomes established in the mud the radicle develops little further Trees of Avicennia and of Sonneratia develop several different kinds of roots The main rooting system consists of large cable roots which give off anchoring roots downwards and aerial roots or pneumatophores upwards These pneumatophores in their turn produce a large number of nutritive roots which penetrate the mineral-rich subsurface layers of the soil The land animals found in mangrove forests include roosting flocks of fruit bats, fishing and insectivorous birds, and many insects are conspicuous Of the marine animals, crabs and molluscs live permanently in the forest, and prawns and fishes come in on the tide to feed on the apparently abundant nutriment provided by the mangrove soils In South East Asia man uses mangrove areas for the establishment of ponds for the culture of fish and prawns, and for timber

881 citations

Journal ArticleDOI
TL;DR: It appears that burrowing affects soil aeration which in turn affects the productivity and reproductive output of Rhizophora, and it remains to be seen if the roles played by grapsid crabs are as important elsewhere as in Australia.
Abstract: The density of the burrowing crab fauna in a mangrove forest was reduced, using pitfall traps, to test the hypothesis that decreased burrowing would lead to: (1) increased soil sulphide concentrations; (2) altered nutrient concentrations; and (3) decreased forest productivity and growth. Experiments were conducted in Rhizophora -dominated forests in north Queensland, Australia, over a 12-month period. Crabs were trapped and removed from the experimental plots during 1 week each month for a year. Soil chemical and forest growth parameters were measured at monthly intervals in the experimental and appropriate control plots. Over the course of the experiment, soil sulphide and ammonium concentrations increased to levels which were significantly higher in plots from which crabs were being removed in comparison to controls. No differences were observed for either phosphate or nitrate plus nitrite. Cumulative forest growth, as measured by stipule fall, was significantly less in removal plots than in controls. Additionally, trees in the removal plots had significantly less reproductive output than did trees in control plots. These results support the hypothesis that burrowing by crabs is an important process in Australian Rhizophora forests. It appears that burrowing affects soil aeration which in turn affects the productivity and reproductive output of Rhizophora . Knowledge of the ecology of grapsid crabs from other continents, however, is very limited. It remains to be seen if the roles played by grapsid crabs are as important elsewhere as in Australia. This is particularly true for the Caribbean region from which many of our paradigms concerning mangrove forest ecology were developed.

343 citations

Journal ArticleDOI
TL;DR: The results show that an earlier attempt to measure detrital export from mangrove forests in northeastern Australia over-estimated export by at least 22% by ignoring leaf removal by crabs, and indicate that current models of energy flow in mangroves must be altered to include the leaf litter → crab trophic link in order to describe accurately the food chains of mangroVE forests in the Indo-West Pacific region.

321 citations

Journal ArticleDOI
TL;DR: An account is given of 114 new or otherwise interesting species of benthic marine flagellates from Fiji, Northern Australia (Queensland), Hawaii, Panama and Brazil.
Abstract: An account is given of 114 new or otherwise interesting species of benthic marine flagellates from Fiji, Northern Australia (Queensland), Hawaii, Panama and Brazil. Most species are heterotrophs drawn from the euglendis, dinoflagellates, kinetoplastids, bicosoecids, heteroloboseids, and a variety of taxa of uncertain affinities. The work emphasizes the rich variety of protist taxa in marine benthic sites. New names are Amphidinium corrugatum, Anisonema glaciale, Bodo cephalophorus, B. platyrhynchus, B. saliens, Bordnamonas tropicana, Cafeteria ligulifera, C. marsupialis, C. minuta (Ruinen, 1938) nov. comb., Cryptaulax elegans, Dinematomonas inaequalis = Dinema inaequale, Dinematomonas maculata (= Dinema maculatum), Dinematononas valida (= Dinema validum), Diplonema ambulator, Diplonema metabolicum, Discocelis punctata, Dolium sedentarium, Goniomonas amphinema, Goniomonas pacifica, Gyrodinium oblongum, Heteronema exaratum, H. splendens, H. vittatum, Mastigamoeba psammobis, M. skujae nom. nov., Massisteria ...

316 citations

Journal ArticleDOI
TL;DR: High microbial biomass and very high rates of bacterial productivity coupled with low densities of meiofaunal and macroinfaunal consumers observed in earlier studies suggest that microbes may be a sink for carbon in intertidal sediments of tropical mangrove estuaries.
Abstract: Bacterial productivity ((3)H-thymidine incorporation into DNA) and intertidal microbenthic communities were examined within five mangrove estuaries along the tropical northeastern coast of Australia. Bacteria in mangrove surface sediments (0-2 cm depth) were enumerated by epifluorescence microscopy and were more abundant (mean and range: 1.1(0.02-3.6)×10(11) cells·g DW(-1)) and productive (mean: 1.6 gC·m(-2)· d(-1)) compared to bacterial populations in most other benthic environments. Specific growth rates (¯x=1.1) ranged from 0.2-5.5 d(-1), with highest rates of growth in austral spring and summer. Highest bacterial numbers occurred in winter (June-August) in estuaries along the Cape York peninsula north of Hinchinbrook Island and were significantly different among intertidal zones and estuaries. Protozoa (10(5)-10(6)·m(-2), pheopigments (0.0-24.1μg·gDW(-1)) and bacterial productivity (0.2-5.1 gC·m(-2)·d(-1)) exhibited significant seasonality with maximum densities and production in austral spring and summer. Algal biomass (chlorophylla) was low (mean: 1.6μg·gDW(-1)) compared to other intertidal sediments because of low light intensity under the dense forest canopy, especially in the mid-intertidal zone. Partial correlation analysis and a study of possible tidal effects suggest that microbial biomass and bacterial growth in tropical intertidal sediments are regulated primarily by physicochemical factors and by tidal flushing and exposure. High microbial biomass and very high rates of bacterial productivity coupled with low densities of meiofaunal and macroinfaunal consumers observed in earlier studies suggest that microbes may be a sink for carbon in intertidal sediments of tropical mangrove estuaries.

255 citations