Southwest Biological Science Center

Aquatic Ecosystems

Filter Total Items: 36
Date published: January 18, 2017
Status: Active

Uncovering the Base of the Food Web: Primary Production Dynamics in the Colorado River

Algae, phytoplankton, and rooted macrophytes represent the base of many aquatic food webs and are known as primary producers. Through photosynthesis, these organisms convert sunlight energy into chemical energy (i.e., carbon) that in turn fuels the growth of animals such as macroinvertebrates and fish. This project uses high frequency measurements of dissolved oxygen, which is a by-product of...

Date published: December 30, 2016
Status: Active

River Sediment Dynamics

Sediment controls the physical habitat of river ecosystems.  Changes in the amount and areal distribution of different sediment types cause changes in river-channel form and river habitat.  The amount and type of sediment suspended in the water column determines water clarity.  Understanding sediment transport and the conditions under which sediment is deposited or eroded from the various...

Date published: December 30, 2016

Southwestern Riparian Zones, Tamarisk Plants, and the Tamarisk Beetle

Introductions of bio-control beetles (genus Diorhabda) are causing defoliation and dieback of exotic Tamarix spp. in riparian zones across the western U.S., yet the factors that determine the plant communities that follow Tamarix decline are poorly understood. In particular, Tamarix-dominated soils are often higher in nutrients, organic matter, and salts than nearby soils, and these soil...

Date published: December 23, 2016
Status: Active

Population Dynamics of Endangered Humpback Chub in Grand Canyon

Construction of Glen Canyon Dam has led to large changes in environmental conditions of the downriver Colorado River. Whereas the pre-dam Colorado River experienced large seasonal variation in temperature and discharge and was highly turbid, the post-dam Colorado River is far less variable in terms of temperature and discharge and is frequently clear. Many nonnative fish species had already...

Date published: December 23, 2016
Status: Active

Understanding Factors Influencing Rainbow Trout Growth in the Colorado River

Rainbow trout is a desirable sport fish that has been introduced in many locations around the world. Although introductions of rainbow trout and other nonnative fishes provide recreational fishing opportunities, they also pose threats to native fish populations. The Glen Canyon Dam Adaptive Management Program has tasked scientists and managers with identifying management options that allow...

Date published: December 22, 2016
Status: Active

SBSC Scientist Directory

Click on "Science" to go to the SBSC scientist directory. When you click on a scientist's name (you may need to scroll down to see all the names), you will be taken to that scientist's professional page and contact information. 

Date published: December 22, 2016
Status: Active

Connectivity of Sand Resources Along the Colorado River in Grand Canyon

We study the links among different geomorphic processes that affect river valley landscapes in the Colorado River downstream from Glen Canyon Dam, Arizona. Dam-released flows affect the deposition and retention of sandbars that serve as sources for other sand resources, such as windblown sand dunes, throughout the Colorado River ecosystem. The degree to which the landscapes are differentially...

Date published: December 21, 2016
Status: Active

Effects of Water Clarity on Survival of Endangered Humpback Chub

Introduced rainbow trout and brown trout are considered a threat to the endangered humpback chub in the Colorado River in Grand Canyon. These introduced species eat native fish, but impacts are difficult to assess because predation vulnerability depends on the physical conditions under which predation takes place. We studied how predation vulnerability of juvenile humpback chub changes in...

Contacts: David Ward
Date published: December 20, 2016
Status: Active

Riparian Remote Sensing in the Colorado River and Grand Canyon Region

Riparian vegetation has increased dramatically along the Colorado River downstream of Glen Canyon Dam since the closure of the dam in 1963. The spatial patterns and temporal rates of vegetation increase occur due to changes in river hydrology, dam operations, and climate. The increase in vegetation, particularly onto otherwise bare sandbars, has impacted recreational, geomorphological,...

Date published: December 15, 2016
Status: Active

Status of Northern Leopard Frogs in the Southwest

Although it is not listed on the Federal Endangered Species list, there is considerable concern over northern leopard frog declines in western North America. It is listed as a “special concern” species by some state wildlife agencies (e.g., Arizona Game and Fish Department 1996) and declines have been reported in Arizona, Colorado, New Mexico, and other areas across the west.  Leopard frogs...

Contacts: Charles Drost
Date published: December 15, 2016
Status: Active

Economics of Outdoor Recreation

Economic research at Grand Canyon Monitoring and Research Center is used to determine economic benefits of outdoor recreation in Glen Canyon National Recreation Area below Glen Canyon Dam and in Grand Canyon National Park, as affected by operation of Glen Canyon Dam. This research identifies recreationists’ preferences for attributes associated with their trips, spending that occurs regionally...

Contacts: Lucas Bair
Date published: December 13, 2016

Measuring Water Requirements Of Riparian Regions in the Southwestern U.S. Compared with Drylands in Australia

Floodplain red gum forests are sites of high biodiversity in arid regions of south Australia. They depend on periodic floods from rivers, but dams and diversions have reduced flood frequencies, leading to deterioration of the trees. We determined the water requirements of red gum trees so environmental flows can be used to restore and maintain the forests. We used measurements of transpiration...

Contacts: Pamela Nagler