Higher Average Richness Research Articles

Spatial and temporal changes of subtidal benthic communities in Antofagasta Bay (SE Pacific) stressed by permanent human disturbances

Human activities have impacted the coastal area of Antofagasta Bay for decades, particularly miners’ activities (loading of mineral concentrates of Cu, Zn, Pb, and Mg), port operations, tourism, desalination plants, artisanal fishing, and sewage discharge. Subtidal coastal benthic communities were assessed in 7 sectors with different magnitudes of anthropogenic disturbances between the years 2008 to 2011 at Antofagasta Bay. Transennella pannosa, Incatella cingulata, Crassilabrum crassilabrum, and Leukoma thaca dominated the communities in all years of study. Based on the type of feeding behavior, the highest biomass was evidenced for the suspensivore group in all years of study, followed by the carnivore species. The highest average richness and average Shannon diversity were observed in sectors with medium and high levels of disturbances. In contrast, the highest average species dominance was registered in a sector with low disturbances. Community structure differed significantly between the seven sectors over the four years. The analysis of classification and ordination showed the conformation of three groups of sectors based on their dissimilarities. The differences were best explained by the sectors with low and high disturbances and by the presence of bivalves, ascidians, gastropods, and algae. It was demonstrated that the reduction or absence of fishing pressure could explain species’ high richness and diversity. Likewise, the sectors under low disturbance pressure showed the highest biomass and dominance of species. The information obtained in the current work could be used to design management strategies for conservation, monitoring, and restoration programs.

Caracterización ecológica de una turbera ombrogénica en Magallanes: hacia una propuesta de bioindicadores de monitoreo ambiental

Ombrogenic peat bogs are ecologically extreme ecosystems, where the restrictive conditions such as anoxia, high acidity and low availability of nutrients allow a gradual accumulation of the organic substrate known as peat. This substrate is of great commercial interest because it is exploited for horticultural purposes and energy biomass. The exploitation of peat, however, involves the removal of vegetation, which has an important effect on secondary succession and ecosystem resilience. The flora and vegetation of peat bogs in the Brunswick Peninsula (Magallanes), in an area susceptible to mining exploitation, was studied to characterize ecological indicators. Phytosociological surveys were carried out to determine attributes of composition and structure at the community and landscape scale. This information was collated with satellite images and analyzed by univariate procedures (e.g. KW, Pearson) and multivariate (e.g. NMDS, ISA, ANOSIM). The following types of ombrogenic peat bogs were differentiated: graminoid, chamaephytic, Sphagnum and pulvinated peat bogs, which were associated with a terrestrialization to paludification gradient, and decomposition. The highest average richness was recorded in the pulvinated peat bogs. The chamaephytic and graminoid bogs has the largest areas, while the pulvinated were distributed in a few hectares. Diagnostic species (e.g. Caltha appendiculata, Donatia fascicularis, Drosera uniflora, Myrteola nummularia) were associated with one or another type of vegetation, showing ecological preferences. No exotic species were recorded. This information can help define critical levels of resilience and propose management and restoration strategies in post-disturbance abandoned peatlands.

Predicting wildlife distribution patterns in New England USA with expert elicitation techniques

Understanding the impacts of landscape change on species distributions can help inform decision-making and conservation planning. Unfortunately, empirical data that span large spatial extents across multiple taxa are limited. In this study, we used expert elicitation techniques to develop species distribution models (SDMs) for harvested wildlife species (n = 10) in the New England region of the northeastern United States. We administered an online survey that elicited opinions from wildlife experts on the probability of species occurrence throughout the study region. We collected 3396 probability of occurrence estimates from 46 experts, and used linear mixed-effects methods and landcover variables at multiple spatial extents to develop SDMs. The models were in general agreement with the literature and provided effect sizes for variables that shape species occurrence. With the exception of gray fox, models performed well when validated against crowdsourced empirical data. We applied models to rasters (30 × 30 m cells) of the New England region to map each species’ distribution. Average regional occurrence probability was highest for coyote (0.92) and white-tailed deer (0.89) and lowest for gray fox (0.42) and moose (0.52). We then stacked distribution maps of each species to estimate and map focal species richness. Species richness (s) varied across New England, with highest average richness in the least developed states of Vermont (s = 7.47) and Maine (s = 7.32), and lowest average richness in the most developed states of Rhode Island (s = 6.13) and Massachusetts (s = 6.61). Our expert-based approach provided relatively inexpensive, comprehensive information that would have otherwise been difficult to obtain given the spatial extent and range of species being assessed. The results provide valuable information about the current distribution of wildlife species and offer a means of exploring how climate and land-use change may impact wildlife in the future.

Land use influences harvestman diversity in northern Spain: a case study involving secondary grasslands and forest plantations (Arachnida: Opiliones)

Harvestmen have a general distribution pattern with more species and higher abundance in forests than in open habitats, as previously verified in mountain Cantabrian areas of northern Spain, of the Orocantabrian Province. The study of harvestmen of the low Cantabrian areas of the adjacent biogeographic Cantabro-Atlantic Province is highly appropriate to determine the influence of biogeographic position on the main diversity parameters and the effect of different land uses on harvestman assemblages. The main types of managed habitats (forest plantations and secondary grasslands), together with natural forests, non-planted young forests, shrublands and habitat boundaries were continuously sampled with seven pitfall traps during 1 year at 28 sites. The harvestman assemblages were classified using six different analyses, and indicator species were identified. The spatial patterns of harvestman diversity in low areas differed from those of mountain areas, although they have 15 species in common. Remarkably, higher average harvestman species richness was measured in low Cantabrian areas than in mountain areas. Shrublands and boundaries were the most species-rich habitats. Forested areas were the poorest in abundance, and were not the habitats richest in harvestman species, though they had higher average richness than mountain Cantabrian forests. Grasslands had a unique harvestman composition with significant extraordinary abundances, in particular of Homalenotus quadridentatus (indicator species of this habitat) and H. laranderas. Interestingly, H. laranderas, Paroligolophus agrestis and Ischyropsalis hispanica, indicator species of some open habitats in low Cantabrian areas, have recently been shown to be indicators of shady forests in mountain Cantabrian territories.

Phytoplankton in Coqueiro Lake (Pantanal de Poconé, Mato Grosso, Brazil)

Studies on floristic composition are key to understand qualiquantitative changes on phytoplankton assemblages over the year. Spatial-temporal variation in composition, richness, frequency of occurrence, and abundance (semi-quantitative) of the phytoplankton community was analyzed monthly (from April 2002 to May 2003), at 3 stations, in Coqueiro Lake (Pantanal, Mato Grosso, Brazil). We registered 256 taxa, mainly represented by Zygnematophyceae (36%), Chlorophyceae (21%), and Euglenophyceae (14%). The highest abundance occurred at the limnetic station (2), but Bacillariophyceae, Cyanophyceae, Chlorophyceae, and Zygnematophyceae prevailed at the 3 stations. The highest average richness was obtained at the littoral station (3), but this station showed a significantly lower abundance (p < 0.05) than the 2 limnetic stations. The system was characterized for higher contributions of Chlorophyceae in the falling water period, Bacillariophyceae in the low waters, Cyanophyceae in the rising waters and Zygnematophyceae in the high waters, and, on average, the highest richness and abundance were registered in the drought (Aulacoseira spp., Coelastrum spp., Anabaena spp., Aphanocapsa minutissima, Planktolyngbya spp. and Eutetramorus fottii). The attributes of phytoplankton community showed spatial and temporal variations, influenced by the presence of macrophytes, but defined, above all, by seasonal hydrologic changes, caused by the flooding pulse.

Diversity and structure of microcrustacean assemblages (Cladocera and Copepoda) and limnological variability in perennial and intermittent pools in a semi-arid region, Bahia, Brazil

Temporary wetlands undergo recurrent drought due to the scarcity of water, which disrupts the hydrological connectivity with adjacent aquatic systems. However, some environments retain water for longer periods, allowing greater persistence of the community. The current study evaluated differences in the microcrustacean assemblages and limnological variability between perennial and intermittent pools in a semi-arid region of Brazil. The abiotic features (water temperature, pH, total alkalinity, electrical conductivity and depth) of intermittent pools were affected more than perennial pools due to loss of water volume. This may have contributed to a higher average richness and diversity index in some intermittent pools and differences in the structure of the assemblages. The lowest species richness and diversity were recorded where physical factors, such as a large quantity of suspended solids and variability in the electrical conductivity of the water and pH, make the environment unsuitable for these organisms. These results suggest that community development in intermittent pools is interrupted by the dry season; when the water returns, due to rainfall or rising groundwater, each pond undergoes a different process of colonization. In these circumstances, the biological importance of temporary aquatic environments is clear, since such pools provide shelters and have an important role in the maintenance of the regional diversity of aquatic environments.