Faunal Biomass Research Articles

Prey versus substrate as determinants of habitat choice in a feeding shorebird

Many shorebirds on their non-breeding grounds feed on macrobenthic fauna which become available at low tide in coastal intertidal flats. The Eastern Curlew Numenius madagascariensis in Moreton Bay Australia, varies greatly in density among different tidal flats. This study asks: how important is the abundance of intertidal prey as a predictor of this variation? We quantified feeding curlews’ diet across 12 sites (different tidal flats, each re-visited at least eight times), through 970 focal observations. We also estimated the abundance of total macrobenthic fauna, potential prey taxa and crustacean prey on each tidal flat; measured as the number of individuals and a relative biomass index per unit substrate surface area obtained from substrate core samples. We estimated curlew density at each site using low-tide surveys from every site visit. Curlew density showed a strong positive association with both the density and biomass of fauna and of potential prey ( r values all around 0.70) across the 12 flats. Associations with crustacean density and biomass were also statistically significant (r values both 0.60). However, these variables also showed a strong negative correlation with a measure of substrate resistance (based on the amount of hard material in the substrate core), which was the best predictor of curlew density ( r = −0.82). Curlews were most abundant at sites with the least resistant substrate, and these sites also generally had the highest faunal density and biomass. When the effect of substrate resistance was statistically removed, curlew density was no longer significantly correlated with fauna density and biomass. This suggests that macro-scale habitat choice by Eastern Curlew on their non-breeding grounds is more strongly influenced by prey availability (which is higher when substrate resistance is lower) than by prey density or biomass, although in Moreton Bay a positive correlation across sites meant that these factors were synergistic.

Distribution, habitat use and ecology of deepwater Anemones (Actiniaria) in the Gulf of Mexico

Abstract The distribution of deepwater Actiniaria is poorly known. Rarely are these organisms identified to family, as this requires both well-preserved specimens and taxonomic expertise. Ecological information is similarly lacking. From the results of a comprehensive surveying program in the deep Gulf of Mexico, we report the occurrence of nine species of Actiniaria. For the most abundant four of these, we plot distributions and discuss habitat use, morphological variation, and feeding strategies. Actiniaria in the Gulf appear to have broad, basin-wide distributions with little depth preference. Faunal biomass is highest in the NE Gulf within submarine canyons or at the base of slope escarpments. Attachment mode is mostly opportunistic on various types of hard substrata, including trash. Sediment-dwelling forms are very abundant at an organically rich site within a large submarine canyon.

Trophic interactions under stress: hypoxia enhances foraging in an estuarine food web

Ecosystem-level effects of stressors are critical to understanding community regulation, and environmental stress models are useful in describing such effects. Hypoxia is an important stres- sor in aquatic ecosystems that usually decreases abundance and biomass of benthic fauna. In field surveys, predator abundance is low in hypoxic areas, and in lab experiments, predators reduce their feeding rates under hypoxic conditions, leading to the hypothesis that consumer stress models (CSMs), rather than prey stress models (PSMs), apply to the systems. We tested predictions from these models with manipulative field experiments wherein we varied predator access to marked Macoma balthica clams at deep and shallow sites in the York River, Chesapeake Bay, before (June) and during (August) hypoxic episodes. In June, dissolved oxygen in deep and shallow sites was normoxic (>2 mg l -1 ) for most of the experiment. In August, the shallow zone remained normoxic, while the deep zone experienced several hypoxic episodes. During hypoxia, predation rates in hypoxic sites were more than twice those in normoxic sites, whereas mortality due to physical stress did not differ between time periods or depths. Ambient clam densities were lower at the deep sites than at the shallow sites, and in August than in June. We conclude that hypoxia increased the suscep- tibility of benthic prey to predation, enhancing infaunal secondary production available to predators, but concurrently reducing the resilience of the benthic community. These findings are inconsistent with the predictions of CSMs, indicating that PSMs better describe this system.

Distribution and diversity of sipunculan fauna in high Arctic fjords (west Svalbard)

Sipuncula is a relatively species poor and generally rarely investigated phylum; nonetheless, it may play a considerable role in the ecosystem. During this study sipunculan species distribution patterns in four fjords of west Spitsbergen (Kongsfjorden, Hornsund, Isfjorden and van Mijenfjorden) were examined. Material was collected during ten cruises undertaken from 1997 to 2006. A total of 381 samples were taken at 132 stations located in the four fjords and, a total number of 920 sipunculans specimens were found in 114 of those samples. The highest sipunculan species richness was observed in Hornsund (six species), followed by Kongsfjorden and Isfjorden (Wve species in each fjord). Sipunculan fauna in all fjords was strongly dominated by GolWngia vulgaris (80% of all sipunculan individuals in Kongsfjorden), and GolWngia margaritacea (84% in van Mijenfjorden and 40% in Hornsund) or Nepha- soma diaphanes (54% in Isfjorden). Locally, sipunculans were found in high densities (max. 62 ind. 0.1 m i2 and up to 11% of macrobenthic densities) and biomass (max. 110.87 g 0.1 m i2 and up to 80% of total fauna biomass). At such sites, sipunculans may play an important role in bioturbation of sediments and as a food source for higher trophic levels. Sipunculans did not occur within close proximity of the gla- cier where they might be eliminated due to high sedimenta- tion rate and low amounts of organic matter. Because of their importance in benthic systems, a need to include sipunculans in routine macrobenthic surveys is emphasized.

Effects of water exchange and vegetation on the macroinvertebrate fauna composition of shallow land-uplift bays in the Baltic Sea

Shallow bays with soft sediment bottoms are common habitats along the Swedish and Finnish Baltic Sea coastline. These bays undergo a process of geomorphometric evolution with the natural isostatic land-uplift process, whereby open bays and sounds decrease in depth and are gradually isolated from the sea, forming bays with narrow openings. This study tested the relationship between the morphometric isolation of the bays from the sea and the macroinvertebrate fauna community of these bays. Additionally, we tested the specific role of the submerged vegetation as an indicator of the macroinvertebrate fauna community. We chose two environmental factors for the analyses, water exchange of the bays and the taxon richness of the macroflora in the bays. We found a hierarchical relationship between water exchange, flora taxon richness, and fauna biomass and taxon richness using structural equation modelling: decreased biomass and taxon richness of fauna were related to decreased flora taxon richness, which in turn was related to decreased water exchange. Using multivariate redundancy analysis, the two environmental factors included in the model were found to explain 47.7% of the variation in the fauna taxon composition and 57.5% of the variation in the functional feeding groups of the fauna. Along the morphometric isolation gradient of the bays, the fauna assemblages changed from a community dominated by gastropods, bivalves, and crustaceans, to a community mainly consisting of a few insect taxa. Moreover, the proportion of predators, gathering collectors, and shredders increased while that of filtering collectors and scrapers decreased. Our results indicate that the density and taxon richness of macroinvertebrate fauna are higher in less morphometrically isolated bays than in more isolated bays in the Baltic Sea. Furthermore, we suggest that the taxon richness of macroflora can serve as an indicator of the fauna community.

Low biomass of macrobenthic fauna at a tropical mudflat: An effect of latitude?

The macrobenthic animal biomass of the intertidal area of the Sembilang peninsula of South Sumatra, Indonesia, has been studied in 2004. Each month (March–August) 21 core samples were taken at each of six sampling stations. Macrobenthic fauna were identified at the lowest taxonomical level possible and counted. Biomass was measured as ash-free dry mass (afdm). The average biomass over all stations and months was 3.62 g afdm m −2, the highest biomass (47.45 g afdm m −2) found at a station in one month was due to abundant occurrence of the bivalve Anadara granosa. Low biomass of macrobenthic fauna at Sembilang peninsula cannot easily be explained but is in line with low biomasses found elsewhere in the tropics. For that reason we analyzed a data set of 268 soft-bottom intertidal biomasses collected world-wide to look for a relationship with latitude. It was shown that average biomass of intertidal macrobenthic fauna in the tropics was significantly ( p < 0.05) lower than that at non-tropical sites. A significant second-order relationship between biomass of macrobenthic fauna and latitude was established.

CHANGES IN THE BIODIVERSITY OF MUSSEL ASSEMBLAGES INDUCED BY TWO METHODS OF CULTIVATION

Mussel cultivation involves collecting mussel spat or transplanting mussels that typically harbor complex assemblages of associated species, into more favorable growing sites. The biodiversity associated with cultivated mussel assemblages thus depends partly on the source of the mussels and on the new habitat created by the method of cultivation. The aim of the current study was to make a quantitative comparison of the macrofaunal communities associated with natural intertidal seed beds and with cultivated mussels grown either on the seabed or on ropes, particularly in relation to the structure of the mussel populations. Core samples (79 cm 2 ) were collected from rope-grown and subtidal bottom-cultured populations and from natural intertidal mussel beds using a nested ANOVA design. The size distribution, biomass and density of the mussel populations and the macrofauna associated with each type of population were quantified. The biomass of macrofauna associated with mussels was significantly greater within rope-grown mussel assemblages than on mussel beds. There were significantly fewer individuals among bottom-cultured mussels than either rope-grown or naturally occurring intertidal mussels. Positive correlations between mussel biomass and associated faunal biomass existed at certain sites but not others. There was a shift from oligochaete to polychaete dominated worm communities caused by mussel cultivation. Sessile polychaetes were most abundant among rope-grown mussels whereas highly motile polychaetes were most abundant at the bottom-culture sites. Fewer amphipod crustaceans were found under both types of cultivation. To maintain or enhance the abundance and biomass of mussel-associated fauna relative to the intertidal beds, suspended culture is preferable to on-bottom cultivation. Positive mussel and associated-macrofaunal biomass correlations are species dependent; cultivation sites could thus be selected to minimize detrimental impacts of mussel farming or even increase the biomass of mussel-associated macrofauna.

Isotopic detection of recent photosynthate carbon flow into grassland rhizosphere fauna

In this study, we measured the incorporation of recent photosynthate-C inputs into active rhizosphere fauna (earthworms, enchytraeids, mites and collembolans) in an upland grassland soil under natural environmental conditions. This was achieved by means of a 13CO 2 pulse-chase experiment made during the growing season, followed by a 20-day dynamic sampling of soil fauna for 12C/ 13C analysis by IRMS. The effect of post- 13C labelling defoliation (cutting) on fauna 12C/ 13C ratios was also examined. Results showed that earthworms made up over 93% of the extracted fauna biomass, while mites, collembolans and enchytraeids together accounted for less than 7%. All fauna groups showed evidence of tracer 13C in their tissues within a week of 13CO 2 pulse labelling in both control and cut treatments. Cutting significantly increased the amount of tracer 13C entering the organisms ( P = 0.0002 ). Similarly, the fauna group also had a significant effect ( P = 0.0001 ). Time did not have any effect on fauna 13C content between groups as differences were only significant at the last sampling occasion. The interaction time×animal group, however, had a significant effect ( P = 0.0054 ). Collembolans accounted for most of the tracer 13C measured within the fauna biomass, i.e. mean±standard deviation of 44.78±12.75% and 44.29±14.69% of fauna 13C in control and cut treatments, respectively. Mites and earthworms contained between 22.13% and 28.45%, and enchytraeids less than 6% of the tracer 13C. We conclude that, during the growing season, there was a rapid incorporation of recent photosynthate-C into rhizosphere mesofauna. This carbon transfer was most significantly increased by defoliation in mites and collembolans ( P < 0.01 ). These results provide evidence that soil foodweb carbon dynamics are not solely underpinned by detrital decomposition but are also affected by short-term plant rhizodeposition patterns.

Effects of water exchange and abiotic factors on zooplankton and epibenthic fauna in shrimp ponds

Assemblages of zooplankton and epibenthic invertebrates were collected from a commercial Penaeus monodon (Fabricius) pond at fortnightly intervals over an entire grow-out season. The pond inlet and outlet water were also sampled intensively over three 1-week periods throughout the season. Before stocking the ponds with shrimp postlarvae, copepods dominated the zooplankton. Immediately after the ponds were stocked, there was a rapid decline in zooplankton numbers, particularly the dominant larger copepods, suggesting heavy predation by shrimp postlarvae. For the rest of the season, barnacle nauplii were the dominant zooplankton component in the pond. Pond water exchanges had little detectable influence on the composition or density of the zooplankton assemblage. Instead, the dominance of barnacle nauplii appeared to have been maintained by steady recruitment due to barnacle reproduction in the pond. While changes in the biomass of pond zooplankton were not correlated with physico-chemical characteristics, changes in density were positively correlated with temperature, and negatively correlated with pH, dissolved oxygen and secchi disc readings. Epibenthic faunal density peaked at the end of the season, while the biomass peaked during the middle part of the season. Sergestids (Acetes sibogae Hansen) were the most abundant epibenthic taxa. No correlations were found between physico-chemical parameters and epibenthic fauna biomass or density. Abundances of epibenthic fauna were not related to zooplankton densities, suggesting that trophic interactions between these assemblages is not important. No Acetes were captured in samples of outlet water, and only on a single occasion were large numbers captured in the inlet water; after this, there was a notable increase in the number of Acetes in the pond. This evidence, together with the lack of an increase in the size of Acetes during the season, suggests that water exchange is an important but unpredictable source of recruitment of epibenthic fauna into the pond. The results emphasize the benefits of ensuring that appropriate zooplankton assemblages have been introduced into the ponds, when they are filled, to support the shrimp immediately after stocking. This will depend on the initial inoculum and may be difficult to manipulate with water exchanges once established. Assemblages of epibenthic fauna appear more likely to change with exchanges and may need to be monitored across the season, particularly if their presence reduces production through adverse impacts such as competition with postlarvae, introduction of disease or deteriorated water quality.

Ecological contrasts across an Antarctic land–sea interface

Abstract We report the composition of terrestrial, intertidal and shallow sublittoral faunal communities at sites around Rothera Research Station, Adelaide Island, Antarctic Peninsula. We examined primary hypotheses that the marine environment will have considerably higher species richness, biomass and abundance than the terrestrial, and that both will be greater than that found in the intertidal. We also compared ages and sizes of individuals of selected marine taxa between intertidal and subtidal zones to test the hypothesis that animals in a more stressed environment (intertidal) would be smaller and shorter lived. Species richness of intertidal and subtidal communities was found to be similar, with considerable overlap in composition. However, terrestrial communities showed no overlap with the intertidal, differing from previous reports, particularly from further north on the Antarctic Peninsula and Scotia Arc. Faunal biomass was variable but highest in the sublittoral. While terrestrial communities were depauperate with low biomass they displayed the highest overall abundance, with a mean of over 3 × 105 individuals per square metre. No significant differences in ages of intertidal and subtidal individuals of the same species were found, with bryozoan colonies of up to 4 years of age being present in the intertidal. In contrast with expectation and the limited existing literature we conclude that, while the Antarctic intertidal zone is clearly a suboptimal and highly stressful habitat, its faunal community can be well established and relatively diverse, and is not limited to short‐term opportunists or waifs and strays.

Primate and Dung Beetle Communities in Secondary Growth Rain Forests: Implications for Conservation of Seed Dispersal Systems

Conservation efforts are often aimed at one or a few species. However, habitat sustainability relies on ecological interactions among species, such as seed dispersal. Thus, a community-scale conservation strategy may be more valuable in some settings. We describe communities of primary (primates) and secondary (dung beetles) seed dispersers from 5 sites in the Brazilian Amazon. We estimate community biomass of these taxa and, using multivariate ordination, examine the potential for natural reforestation at each site, given the communities of seed dispersers present. Since disturbed habitat is increasingly common and increasingly the focus of conservation efforts, we also examine differences among seed disperser communities between primary forest and secondary growth at each site. Analyses of faunal biomass in different localities and habitats indicate that secondary growth receives nearly as much use by primates as primary forest; given the dominant groups of dung beetles in secondary growth, disturbed habitat should show a pattern of seed burial that is clumped and deep. Areas with high biomass of Alouatta spp. and the large nocturnal dung beetle species may have the greatest potential for natural reforestation of secondary growth particularly for large seeded species. The data suggest that knowledge of the biomass of primary and secondary dispersing fauna facilitates predictions for the likelihood of disturbed habitat to regenerate and comparisons of sites in broader geographical areas e.g., Neotropical vs. Paleotropical forests.

Biogeographical patterns in the fauna associated with southern African mussel beds

Macrofauna communities colonizing intertidal mussel beds were sampled at seven sites between Swakopmund (Namibia) and Salt Rock (KwaZulu-Natal). Mean mussel cover, length, biomass and bed depth were all low in the southeast (former Transkei). Faunal abundance and biomass were minimal along the south coast, increasing up both west and east coasts. Species diversity and richness showed the reverse trends, peaking at south coast sites and dropping off to the west and east. Multivariate analysis grouped the faunal communities into four distinct clusters, corresponding to the recognized Namib, Namaqua, Agulhas and Natal biogeographical provinces. The low mussel biomass and cover in the Eastern Cape can be attributed to intense human exploitation, but the low faunal abundance and biomass along the south coast was unexpected, as was the negative correlation between faunal abundance and diversity. Over recent decades intense exploitation has resulted in marked declines in mussel cover along the east coast, while the M. galloprovincialis invasion has resulted in dramatic increases in mussel cover to the west. The results given here indicate how these changes might have affected the wider intertidal communities in these regions.

Invertebrate prey of the bark-foraging insectivore Phascogale tapoatafa: distribution of biomass amongst alternative foraging substrates within south-western Australian woodlands

The bark of trees is an important foraging substrate for a range of vertebrate insectivores. This study aimed to investigate the distribution of food resources available to the bark-foraging insectivore Phascogale tapoatafa, and to compare prey biomass on bark versus the litter layer. We conducted nocturnal sampling for arthropods on tree trunks and litter in a forest in south-western Australia. The bark fauna biomass was dominated by spiders, with cockroaches, beetles and ants also well represented. In contrast, the litter was dominated by orthopterans. Invertebrate biomass was much greater in the litter layer than on tree trunks. Prey items in bark were more plentiful in Melaleuca swamps than in the surrounding dry sclerophyll woodland. Within swamps, trees with the highest invertebrate densities had thin trunks or loose bark, whilst in woodland it was trees with thick bark. Water availability may increase the prey resource used by bark-foraging insectivores.

Floods and drought: Response of earthworms and potworms (Oligochaeta: Lumbricidae, Enchytraeidae) to hydrological extremes in wet grassland

Summary The population dynamics of earthworms and potworms (Oligochaeta: Lumbricidae, Enchytraeidae) were recorded in three floodplain meadows differing in soil type in Northern Germany during 2 years of contrasting hydrological extremes: 2002 with high precipitation, extended winter inundations and summer floods in two of the sites, and 2003 with an extraordinarily dry summer. In all sites, earthworms dominated the biomass of soil fauna, the dominant species being Octolasion tyrtaeum in marsh soil, Octolasion cyaneum in peat soil, Allolobophora chlorotica in gley soil, and Lumbricus rubellus in all three sites. The enchytraeid communities composed of 7–10 species, differed widely between sites. While the summer flood of 2002 reduced annelid populations in peat soil to zero, in gley soil only enchytraeids were sharply reduced. The earthworms there probably were less affected because of shorter duration of the flood, the lower air temperatures and SOM contents and the diapause of the dominant A. chlorotica . During summer drought in 2003, earthworms and enchytraeids were absent from gley soil, while they had maximum abundances in peat soil. The marsh soil, structured by a microrelief of shallow ditches and ridges, had highest densities of annelids. As it was not subjected to summer flooding in 2002, populations of both earthworms and potworms were stable. The drought in 2003 led to a sharp decrease in earthworm abundance in July, while the enchytraeids reached maximum values. Dynamics and survival strategies of different annelid species are discussed. The water holding capacity as well as the organic matter content of the soil are important factors for annelids in sites subjected to such hydrological extremes. To promote terrestrial annelids, controlled flooding should be kept short, especially in winters following natural summer floods. If possible, recovery times for annelids should be guarenteed, that is 2–3 months without inundations for enchytraeids and about half a year for earthworms. A microrelief with drier refuge sites can be judged as favourable for earthworms. An artificially raised groundwater table will favour annelids during drought periods.

Factors influencing flamingo (Phoenicopterus roseuis) distribution in the Pulicat Lagoon ecosystem, India

The shallow (1.5 m) Pulicat Lagoon in India supports a variety of migratory birds (125 species), especially flamingos and storks. Flamingo populations in this area are dominated by Phoenicopterus roseuis, and they are densely distributed in shallow areas and fringes of the lake where the water level is below 40 cm. Eighteen flamingo groups are distributed around the lagoon with ~750 individuals per group. Flamingo populations are greatest in places where fish, algal, and benthic faunal biomass are highest. Physiological adaptations and morphology of flamingo are important criteria for selecting feeding locations.

Bacterial traits, organism mass, and numerical abundance in the detrital soil food web of Dutch agricultural grasslands

AbstractThis paper compares responses to environmental stress of the ecophysiological traits of organisms in the detrital soil food webs of grasslands in the Netherlands, using the relationship between average body massMand numerical abundanceN. The microbial biomass and biodiversity of belowground fauna were measured in 110 grasslands on sand, 85 of them farmed under organic, conventional and intensive management. Bacterial cell volume and abundance and electrophoretic DNA bands as well as bacterial activity in the form of either metabolic quotient (qCO2) or microbial quotient (Cmic/Corg) predicted the response of microorganisms to stress. For soil fauna, the logarithm of body mass log(M) was approximately linearly related to the logarithm of numerical abundance log(N) with slope near −1, and the regression slope and the proportion of predatory species were lower in intensive agroecosystems (more reduced substrates with higher energy content). Linear regression of log(N) on log(M) had slope not far from −3/4. The approach to monitoring data illustrated in this paper could be useful in assessing land‐use quality.

Living conditions, abundance and biomass of under-ice fauna in the Storfjord area (western Barents Sea, Arctic) in late winter (March 2003)

The under-ice habitat and fauna were studied during a typical winter situation at three stations in the western Barents Sea. Dense pack ice (7–10/10) prevailed and ice thickness ranged over <0.1–1.6 m covered by <0.1–0.6 m of snow. Air temperatures ranged between −1.8 and −27.5°C. The ice undersides were level, white and smooth. Temperature and salinity profiles in the under-ice water (0–5 m depth) were not stratified (T=−1.9 to −2.0°C and S=34.2–34.7). Concentrations of inorganic nutrients were high and concentrations of algal pigments were very low (0.02 μg chlorophyll a l−1), indicating the state of biological winter. Contents of particulate organic carbon and nitrogen ranged over 84.2–241.3 and 5.3–16.4 μg l−1, respectively, the C/N ratio over 11.2–15.5 pointing to the dominance of detritus in the under-ice water. Abundances of amphipods at the ice underside were lower than in other seasons: 0–1.8 ind. m−2 for Apherusa glacialis, 0–0.7 ind. m−2 for Onisimus spp., and 0–0.8 ind. m−2 for Gammarus wilkitzkii. A total of 22 metazoan taxa were found in the under-ice water, with copepods as the most diverse and numerous group. Total abundances ranged over 181–2,487 ind. m−3 (biomass: 70–2,439 μg C m−3), showing lower values than in spring, summer and autumn. The dominant species was the calanoid copepod Pseudocalanus minutus (34–1,485 ind. m−3), contributing 19–65% to total abundances, followed by copepod nauplii (85–548 ind. m−3) and the cyclopoid copepod Oithona similis (44–262 ind. m−3). Sympagic (ice-associated) organisms occurred only rarely in the under-ice water layer.

Soil macrofauna in SE Mexican pastures and the effect of conversion from native to introduced pastures

Abstract A large area in the Gulf Coast region of Mexico is pastureland, generally dominated by native grass species, yet little is known of the physical, chemical and biological characteristics and limitations of soils beneath them. Furthermore, nothing is known of the effect of converting native to introduced grasses on the soil ecosystem in Mexican pastures. Over the last 30 years 60 samples were taken in 21 sites throughout SE Mexico to evaluate soil macrofauna communities. Of these, 15 samples were taken at five sites in the state of Veracruz, Mexico, taken during the dry (April–May) and/or wet (September–October) seasons of 1998 and 1999, to specifically compare soil macrofauna present in native and introduced pastures. These sites were located in a N–S transect including three biogeographic regions, separated by the transverse Neo-volcanic axis. Taking data from all sites, earthworms, ants and termites dominated in terms of density, while earthworms dominated the soil fauna biomass, commonly surpassing the weight of the grazing cattle per hectare. Of a total of 15 comparisons of soil fauna populations in native and introduced pastures, important differences in the communities were observed on nine occasions, using multivariate analyses. These differences, however, depended on the site sampled, season, and sample year, and tended to be more evident in the rainy season, when populations were at their maximum numbers. Earthworm communities were different between the two pasture types; twice as many species on average were found in native (four species) than in introduced (two species) pastures. Most species were native to Mexico, only a few exotics being found, indicating slow exotic species invasion rates or little replacement of natives by exotics. In conclusion, the present study showed that large communities of soil macrofauna are present in SE Mexican pastures and that, depending on the site’s characteristics and the management practices implemented, the conversion of native to introduced pastures can significantly alter the diversity and abundance of soil-dwelling macro-invertebrates. However, further studies must be undertaken in other pastures, particularly well-managed introduced pastures with or without legume associations, to assess whether these results hold true under a wider range of management situations and sites.

Abundance, Biomass and Diversity of Soil Fauna at Different Ecosystems in Jakenan, Pati, Central Java

The assessment of soil fauna in three different ecosystems namely teak forest, home garden and fallow paddyfield hadbeen studied in Pati, Central Java. The soil fauna was collected using a soil corer of 20 cm diameter to the depth of 0-15 cmfrom 5 randomized points in the above ecosystems. The soil fauna was t$en extracted in a Berlese funnel extractor. Soil faunain the home garden showed a highest abundance (2 940 individual m--), followed by teak forest (2 340 individual m-?) and fallow paddy (1 790 individual m-?). Home garden had also a higher soil fauna diversity (2.06) compared to the teak forest (1.82) and fallow paddy (1.67). In terms of soil fauna biomass, teak forest had a higher value (961 mg m-3 compared to the home garden (368 mg m-3 and fallow paddy (309 mg m"). In these three ecosystems, two fauna groups, i.e. Collembola and Acari were the most abundant animals. Poor vegetation cover tend to reduce the population of soil fauna in the fallow paddj. field, whereas vegetation found in the home garden and teak forest protected the soil surface from direct sunshine and maintained soil moisture. This condition presumably provided a more favourable habitat for soil fauna. Thus, vegetation cover appears important to maintain soil moisture and soil living-organisms.

The response of macrofauna communities and shorebirds to macrophyte wrack subsidies on exposed sandy beaches of southern California

To investigate the influence of marine macrophyte wrack subsidies on community structure, relationships between community attributes, including species richness, abundance, and biomass of macrofauna and abundance of shorebirds, and a variety of factors, including the standing crop of wrack and beach morphodynamics, were examined on 15 exposed sandy beaches on the southern California coast. The beaches sampled were primarily modally intermediate morphodynamic types, and three were groomed regularly. Species richness, abundance, and biomass of the macrofauna were high compared to values reported for similar beach types in other regions and were not predicted by morphodynamics or other physical factors. Overall species richness and abundance, and the species richness, abundance, and biomass of wrack-associated fauna and selected taxa were significantly correlated with the standing crop of macrophyte wrack. Wrack-associated macrofauna, such as amphipods, isopods, and insects, made up an average of >37% of the species on ungroomed beaches and comprised 25% or more of the total abundance on half of those beaches. The abundance of two shorebird species, plovers that forage using visual cues, was positively correlated with the standing crop of wrack and with the abundance of wrack-associated invertebrates. Significant differences in community structure, including depressed species richness, abundance, and biomass of macrofauna, especially for wrack-associated taxa, were associated with beach grooming and provided strong evidence for the bottom-up effects of wrack subsidies. Grooming also reduced the prey available to vertebrate predators, such as shorebirds. Substantial ecological effects of the large-scale disturbance and removal of organic material, food resources, and habitat are associated with beach grooming. These results suggest that macrophyte wrack subsidies strongly influence macrofaunal community structure, higher trophic levels, and ecological processes on exposed sandy beaches. The supply of macrophyte wrack should be considered as a factor in ecological studies of exposed sandy beaches, particularly where macrophyte production is high.