Diversity of Benthic Biofilms Along a Land Use Gradient in Tropical Headwater Streams, Puerto Rico

Abstract. Long-term data series (1996–2009) for eleven acidic headwater streams (< 10 km2) in Sweden were analyzed to determine factors controlling concentrations of trace metals. In-stream chemical data as well climatic, flow, and deposition chemistry data were used to develop models predicting concentrations of chromium (Cr), lead (Pb), and zinc (Zn). Data were initially analyzed using partial least squares to determine a set of variables that could predict metal concentrations across all sites. Organic matter (as absorbance) and iron related positively to Pb and Cr, while pH related negatively to Pb and Zn. Other variables such as conductivity, manganese, and temperature were important as well. Multiple linear regression was then used to determine minimally adequate prediction models which explained an average of 35% (Cr), 52% (Zn), and 72% (Pb) of metal variation across all sites. While models explained at least 50% of variation in the majority of sites for Pb (10) and Zn (8), only three sites met this criterion for Cr. Investigation of variation between site models for each metal revealed geographical (altitude), chemical (sulfate), and land-use (silvaculture) influences on predictive power of the models. Residual analysis revealed seasonal differences in the ability of the models to predict metal concentrations as well. Expected future changes in model variables were applied and results showed the potential for long-term increases (Pb) or decreases (Zn) for trace metal concentrations at these sites.

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Influence of temperature, precipitation, and cloud cover on diel dissolved oxygen ranges among headwater streams with variable watershed size and land use attributes

Aquatic Sciences ◽

10.1007/s00027-020-00756-6 ◽

2020 ◽

Vol 82 (4) ◽

Author(s):

Ryan M. Utz ◽

Bethany J. Bookout ◽

Sujay S. Kaushal

Keyword(s):

Land Use ◽

Dissolved Oxygen ◽

Cloud Cover ◽

Headwater Streams ◽

Influence Of Temperature ◽

Watershed Size

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SYSTEMS-BASED LAND-USE EVALUATION AT THE SOUTH COAST OF PUERTO RICO

Applied Engineering in Agriculture ◽

10.13031/2013.19367 ◽

1998 ◽

Vol 14 (2) ◽

pp. 191-200 ◽

Cited By ~ 5

Author(s):

J. W. Hansen ◽

F. H. Beinroth ◽

J. W. Jones

Keyword(s):

Land Use ◽

Puerto Rico ◽

South Coast ◽

The South

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Effects of land-use/land-cover changes on land crab,Cardisoma guanhumi, abundance in Puerto Rico

Journal of Tropical Ecology ◽

10.1017/s0266467408005130 ◽

2008 ◽

Vol 24 (4) ◽

pp. 417-423 ◽

Cited By ~ 6

Author(s):

Yogani Govender ◽

Alberto M. Sabat ◽

Elvira Cuevas

Keyword(s):

Land Use ◽

Puerto Rico ◽

Land Cover ◽

Soil Temperature ◽

Surface Soil ◽

Negative Relationship ◽

Land Use Land Cover ◽

Land Crab ◽

Cardisoma Guanhumi ◽

Crab Abundance

AbstractThe land crabCardisoma guanhumipopulations have been on the decline in Puerto Rico for the last three decades. While some studies suggest overexploitation and pesticides as causing the observed population declines, the effect of land-use/land-cover (LULC) changes have not been investigated. In this study we compared the abundance and size ofCardisoma guanhumiin five different LULC types (mangroves, grasslands, forest, urban and industrial), and investigated the relationship between differences in physical microhabitat conditions among the LULC types with crab abundance and size. Although no significant differences in size were found among the different LULC types, crabs were significantly less abundant in grassland sites. Surface soil temperature, depth to groundwater and air temperature were found to vary significantly among the LULC types. Of these, only surface soil temperatures had a significant negative relationship with crab abundance. It appears that high variation in soil temperature and a high groundwater table observed in the grasslands is most detrimental to crabs. Interestingly, during the time when land crab populations declined there was corresponding change of LULC from agriculture to grasslands.Cardisoma guanhumiis resilient to changes in LULC, however, changes that alter their access to groundwater and escape from high soil temperature reduce their habitat.

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Effect of land use on mayfly assemblages structure in Neotropical headwater streams

Anais da Academia Brasileira de Ciências ◽

10.1590/0001-3765201420130516 ◽

2014 ◽

Vol 86 (4) ◽

pp. 1735-1747 ◽

Cited By ~ 9

Author(s):

ANA EMILIA SIEGLOCH ◽

MARCIA SURIANO ◽

MARCIA SPIES ◽

ALAÍDE FONSECA-GESSNER

Keyword(s):

Land Use ◽

Tropical Rainforest ◽

Headwater Streams ◽

Environmental Indicators ◽

Semideciduous Forest ◽

Analysis Of Similarity ◽

Negative Effect ◽

Water Ph ◽

Partial Redundancy Analysis ◽

Partial Redundancy

The aim of this study was to test the effect of agricultural and forestry land use on the structure of mayfly assemblages in low-order streams. Twenty-nine headwater streams were investigated in the state of São Paulo. We analyzed 15 streams in pristine areas (mixed tropical rainforest, semideciduous forest and dense tropical rainforest), and 14 streams covered with sugarcane, eucalyptus and pasture. Mayfly richness obtained by rarefaction curves was higher in pristine areas (21 genera), especially in mixed and semideciduous forest when compared to land use (9 genera), where values were particularly low in sugarcane plantation (3 genera). The non-metric multidimensional scaling (NMDS) ordination showed clear difference in mayfly assemblages between land uses and pristine areas, supported by analysis of similarity (R=0.67, p=0.001). In partial redundancy analysis (pRDA), the environmental descriptors that best explained differences in assemblage structure were Riparian, Channel and Environmental Inventory (RCE) index score, percentage of fine sediment stream substrate, water pH and land elevation. Our results show that agricultural and forestry land use has a strong negative effect on the structure of mayfly assemblages. These results also support the use of mayflies as environmental indicators, as some genera were sensitive to changes in land use, while others responded to naturally occurring changes in the study area.

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