Identifying and characterizing biological hotspots in the northern California Current

Reese, Douglas C.; Brodeur, Richard D.

doi:10.1016/j.dsr2.2006.01.014

Cited by 43 publications

(45 citation statements)

References 25 publications

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“…Although, again, less so than reported in Ainley et al (2005), the chlorophyll maximum depth, another indirect measure of prey availability at the larger scale (as is location of a front), was important for a few species. Not surprisingly considering this effect, Reese & Brodeur (2006) found that chlorophyll concentration was important in explaining patterns in fish occurrence in the study area. Thus, if chlorophyll maximum is a proxy for fish abundance, it is not surprising that this covariate declined somewhat in importance when direct measures of fish abundance were included.…”

Section: Interannual Differences In Patternsmentioning

confidence: 99%

“…echo integration) data using a raw ping rate of 4 pings s Analyses included here were limited to collections made during daylight hours, since this is the time period during which birds forage and day and night community structures may differ. Nekton abundance was then standardized for differences in effort between tows based on the volume of water filtered per trawl (see Reese & Brodeur 2006). Data analysis.…”

Section: Methodsmentioning

confidence: 99%

“…Since seabird surveys and fish trawls were not fully synchronized, fish density for each segment of the seabird surveys (see next paragraph) was estimated using geostatistical modeling techniques based on values obtained from trawl results. This method of determining spatial distributions of fish species and various community characteristics has been previously used and described in detail by Reese & Brodeur (2006). For each species we collected and calculated the abundance at specified sample locations.…”

Section: Micronekton and Macronekton -Acousticsmentioning

confidence: 99%

“…Repercussions would cascade up and down the trophic pyramid, especially if frontal or 'hotspot' structures had become altered in location and intensity; already limited in space, this is where predators or the act of predation itself concentrates prey (e.g. Hoefer 2000, Reese & Brodeur 2006.…”

Section: Introductionmentioning

confidence: 99%

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Association of predators and prey at frontal features in the California Current: competition, facilitation, and co-occurrence

Ainley¹,

Dugger²,

Ford³

et al. 2009

Mar. Ecol. Prog. Ser.

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We investigated variations in the small-to meso-scale abundance and distribution of the 6 most abundant seabird species in the northern California Current -black-footed albatross Phoebastria nigripes, sooty shearwater Puffinus griseus, pink-footed shearwater Puffinus creatopus, forktailed storm-petrel Oceanodroma furcata, common murre Uria aalge, and Cassin's auklet Ptychoramphus aleuticus -during the upwelling season of 2000 and 2002. Covariates (21 total), with importance assessed using logistic and generalized linear modeling and an information theoretic approach, included physical features such as sea surface temperature, dynamic height (apparent water-column pressure), and pycnocline depth; biological factors such as chlorophyll maximum; and food-web factors such as the density of 3 size classes of zooplankton, the density of potential piscine competitors, i.e. Pacific salmon Oncorhynchus spp., and abundance of fish prey such as zooplankton, northern anchovy Engraulis mordax, and the juveniles of salmon and demersal fishes. The most important factors explaining seabird occurrence changed from mesoscale physical features during a food-rich year (2002; exhibited over 15 to 30 km) to smaller-scale occurrence of actual prey patches during a food-poor year (2000; <1 km). Spatial overlap in occurrence of murres and shearwaters with adult salmon was interpreted as co-occurrence and, perhaps, competition for prey species; a negative spatial overlap between shearwaters and abundance of forage fish was interpreted as evidence for prey depletion (or predator-induced alteration of availability) by the birds and other co-occurring predators (salmon). Overall, results and other information indicated the value of adding spatially explicit data on predator and prey species abundance and predator-prey behavior to improve foodweb modeling.

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Section: Interannual Differences In Patternsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Micronekton and Macronekton -Acousticsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Association of predators and prey at frontal features in the California Current: competition, facilitation, and co-occurrence

Ainley¹,

Dugger²,

Ford³

et al. 2009

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…The GWR was designed to consider the location of points, so that spatially varying relationships could be explored [68,73,74] The second model, the hot-spot analysis, carried out using the Getis-Ord Gi statistic, was used to define the clustered regions and obtain a z-score output for every point [75]. The z-scores are measures of standard deviation that reflect the significance of the clustering.…”

Section: Geostatistics Analysis Modelsmentioning

confidence: 99%

Structural Changes of Desertified and Managed Shrubland Landscapes in Response to Drought: Spectral, Spatial and Temporal Analyses

et al. 2014

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Drought events cause changes in ecosystem function and structure by reducing the shrub abundance and expanding the biological soil crusts (biocrusts). This change increases the leakage of nutrient resources and water into the river streams in semi-arid areas. A common management solution for decreasing this loss of resources is to create a runoff-harvesting system (RHS). The objective of the current research is to apply geo-information techniques, including remote sensing and geographic information systems (GIS), on the watershed scale, to monitor and analyze the spatial and temporal changes in response to drought of two source-sink systems, the natural shrubland and the human-made RHSs in the semi-arid area of the northern Negev Desert, Israel. This was done by evaluating the changes in soil, vegetation and landscape cover. The spatial changes were evaluated by three spectral indices: Normalized Difference Vegetation Index (NDVI), Crust Index (CI) and landscape classification change between 2003 and 2010. In addition, we examined the effects of environmental factors on NDVI, CI and their clustering after successive drought years. The results show that vegetation cover indicates a negative ∆NDVI change due to a reduction in the abundance of woody vegetation. On the other hand, the soil cover change data indicate a positive ∆CI change due to the expansion of the biocrusts. These two trends are evidence for degradation processes in terms of resource conservation and bio-production. A considerable part of the changed area (39%) represents OPEN ACCESSRemote Sens. 2014, 6 8135 transitions between redistribution processes of resources, such as water, sediments, nutrients and seeds, on the watershed scale. In the pre-drought period, resource redistribution mainly occurred on the slope scale, while in the post-drought period, resource redistribution occurred on the whole watershed scale. However, the RHS management is effective in reducing leakage, since these systems are located on the slopes where the magnitude of runoff pulses is low.

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Nutrient supply, surface currents, and plankton dynamics predict zooplankton hotspots in coastal upwelling systems

Messié

Chávez

2017

Geophysical Research Letters

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A simple combination of wind‐driven nutrient upwelling, surface currents, and plankton growth/grazing equations generates zooplankton patchiness and hotspots in coastal upwelling regions. Starting with an initial input of nitrate from coastal upwelling, growth and grazing equations evolve phytoplankton and zooplankton over time and space following surface currents. The model simulates the transition from coastal (large phytoplankton, e.g., diatoms) to offshore (picophytoplankton and microzooplankton) communities, and in between generates a large zooplankton maximum. The method was applied to four major upwelling systems (California, Peru, Northwest Africa, and Benguela) using latitudinal estimates of wind‐driven nitrate supply and satellite‐based surface currents. The resulting zooplankton simulations are patchy in nature; areas of high concentrations coincide with previously documented copepod and krill hotspots. The exercise highlights the importance of the upwelling process and surface currents in shaping plankton communities.

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Identifying and characterizing biological hotspots in the northern California Current

Cited by 43 publications

References 25 publications

Association of predators and prey at frontal features in the California Current: competition, facilitation, and co-occurrence

Association of predators and prey at frontal features in the California Current: competition, facilitation, and co-occurrence

Structural Changes of Desertified and Managed Shrubland Landscapes in Response to Drought: Spectral, Spatial and Temporal Analyses

Nutrient supply, surface currents, and plankton dynamics predict zooplankton hotspots in coastal upwelling systems

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