An Ecologist’s Perspective
By Gerald Z. Jacobi
A Santa Fe resident for over 30 years, Gerald Z. Jacobi is Professor Emeritus of Environmental Science and Management at New Mexico Highlands University. He has also worked for state and federal resource agencies and is currently engaged in research projects with the New Mexico Department of Game and Fish, New Mexico Environment Department, U. S. Forest Service, and Trout Unlimited. He is a member of the Santa Fe River Commission.
I have been fortunate in my life and professional career to have spent most of my time observing and investigating freshwater ecosystems such as rivers, lakes, and ponds. My interest has not diminished since my curiosity as a child first took me to the banks of a living river in a small town along the front range of Colorado over 60 years ago. Moving water dominated my time. I raced toy boats, trying to avoid back currents and large rocks which might slow the downstream drift. I spent hours lying on the banks looking into the water at aquatic insects as they moved their gills while trying to maintain position against the current. Several times I collected them in jars to take home to observe, later getting up during the night to see if they were still alive (they weren’t), only to conclude they needed flowing water to survive (not knowing about respiration at the time). Fishing next caught my fancy, not only the thrill of catching an unknown, but to see what fish were eating. I examined stomach contents only to realize that insects and other invertebrates were important components in the diet of fish. I then tried to catch fish with artificial flies that I tied to imitate the immature and adult stages of insects, finally ascertaining that these two life stages were interconnected.
This early exposure to the aquatic natural world eventually led me to university teaching and research where I extolled the attributes of aquatic systems and the need for healthy rivers and watersheds in our lives. I exposed students to environmental ethics and encouraged them to pursue careers in environmental science. My professional career continues as a research biologist investigating the interconnectedness of the physical, chemical, and biological processes of freshwater ecosystems. I still look at flowing waters with wonder knowing they are extremely complex systems but can be enjoyed and appreciated without involving the details.
A living river is one which has an environmental flow satisfying all aspects of the riparian and instream biological community and is a constant reminder of the health of the watershed because activities upstream are manifest downstream. It contains a flow that provides water through time and space by mimicking the natural flow (hydrograph) and reflects the physical, chemical and biological integrity of the region. A river such as the Santa Fe River during pre-dam time may have been perennial some years and ephemeral others (with interrupted surface flow), but probably had reaches connected through sub-surface flow. Continuous perennial surface flows connected to the Rio Grande allowed native Rio Grande cutthroat trout and other fish to colonize upper reaches.
Presently in the high desert landscape of the southern Sangre de Cristo Mountains, rivers that reach the Rio Grande are few due to the vagaries in the weather and the multiple demands of humans on the water supply. In small freeflowing reaches such as the upper Santa Fe River, the natural water year begins with high spring flushing flows due to the melting of snow that accumulated during the winter. This increased flow wets the edge of the stream, flooding riparian vegetation like cottonwoods, willows, and grasses, and providing water that infiltrates and is stored in the flood plain for eventual slow release back into the channel later in the year. Beaver dams further enhance the storage capacity of the flood plain. Higher flows give dimension and pattern to the stream and redefine the channel. Vegetative debris and sediments that accumulated the previous year are redistributed downstream and to the edges of the stream to build up the banks so that grasses and woody vegetation gain a stronghold to further buffer succeeding floods.
The increase in discharge and warming water temperature during the spring rejuvenate surface algae, diatoms, mosses, vascular plants, and biofilms. During this time, the emergence of many aquatic insects such as mayflies, stoneflies, caddisflies, midges, and crane flies is triggered. These organisms complete their life cycles as reproducing aerial adults that disperse along the watercourse to eventually deposit eggs in the water to begin a new generation. Some of these insects will become food for fish and for riparian birds, mammals, amphibians, and other insects attracted to the aquatic habitat and the riparian vegetation. An increase in spring stream flow is also a signal for spawning by salmonids such as the Rio Grande cutthroat trout, which utilize cleaned stream bottom gravels.
Discharge begins to taper off after a few weeks of spring runoff. Summer flows generally are more stable, but can be interrupted by occasional floods. Monsoon rains later in the summer may cause temporary increases in volume. Flow and temperature decrease in late fall as precipitation decreases. Leaves falling into the water accumulate to form the food base for many aquatic organisms sustaining them through the winter. Snow accrued in the winter eventually melts in the spring to begin the runoff cycle again.
In an urban setting such as Santa Fe, summer rain and subsequent flooding is usually short lived, dramatic, and often times devastating. The impervious and built upon watershed acts as a shield, allowing the water to rush downstream through the previously dry and poorly vegetated arroyos and river channel. It is only when rushing water reaches the Santa Fe River Rural Protection Zone (originally the Santa Fe River Preserve) several miles downstream (below the City of Santa Fe Waste Water Treatment Plant discharge) that the riparian vegetation and expansive flood plain function as a cushion, buffering the flow. Here, high flows are absorbed and diverted throughout the bosque to later appear, diminished but sustained, to augment flow to the river downstream. Today, this phenomenon does not occur along the dry Santa Fe River near the downstream city limits of Santa Fe.
Through rivers, a variety of ecological communities are connected by the flow from headwater to lower elevations. In Santa Fe County, diverse neighborhoods, each with specific and perhaps different relationships to the river, are also intertwined. For most of the year the Santa Fe River through town and downstream is a dry remnant of its former self, visited and enjoyed by only a few. One only has to look to the community events celebrating the river when it occasionally flows in spring and summer to see how running water is cherished and appreciated. The river blessing at San Ysidro Crossing in Aqua Fria and the fishing derby and river festival within Santa Fe are well attended. A year round living Santa Fe River could provide an environment for play and exploration of the outdoors, linking neighborhoods through parks and the river trail and providing sustenance to nature. Once a living Santa Fe River is re-established, I would like to be involved in ecological studies. I want to take friends old and new to the river to turn over a few stones to see signs of the return, and encourage continuation of the numerous school projects showing our young people various positive aspects of the river. I hope such experiences will spur others to be as fascinated as I have always been with the life found in a river.