Environmental Engineering Reference
In-Depth Information
Biography 11.1. ROBERT WETZEL
Robert Wetzel (Fig. 11.14) has had a major influence in the
field of aquatic ecology. One of his many contributions has
been to demonstrate that primary production by periphyton
and macrophytes in lakes is often greater than that by phy-
toplankton. Many researchers incorrectly assumed that phy-
toplankton photosynthesis dominated in lakes because of
the large volume of water containing phytoplankton (see
Chapter 22). In addition to establishing the importance of
benthic producers, his research has documented the fate and
cycling of carbon in ecosystems. Perhaps his greatest influ-
ence has been through his textbook,
Limnology
(Wetzel, 1983). This topic has been
used to train innumerable aquatic ecologists. His most recent edition,
Limnology:
Lake and River Ecosystems
(2001), is even more comprehensive and will be the ba-
sic limnological reference for years to come.
Dr. Wetzel became interested in ecology because an inspiring high school biol-
ogy teacher took the time to show him the virtues of nature. From this start, he has
become one of the most respected aquatic ecologists in the world. He has more than
350 scientific publications and has received numerous awards and honors.
Wetzel finds an academic career extremely rewarding, and he deeply appreciates
the freedom to satisfy his intellectual curiosity. He has had adventures related to lim-
nology as well. For example, he recalls a time sampling alone on Borax Lake in a
rubber raft when a youth on shore with a rifle decided to try and shoot the raft out
from under him. Obviously, he survived the experience.
Wetzel cautions new students of aquatic ecology not to put too much stock in
simple explanations and to remember that biology is a complex and sophisticated
field of study. He suggests that an important area for future study is the regulation
of growth and the productivity of aquatic organisms by chemically mediated signals
among them (Wetzel, 1991).
FIGURE 11.14
Robert Wetzel.
O
2
concentration in streams can also vary over time (Fig. 11.13D) al-
lowing
in situ
measurement of photosynthetic rates (Method 11.2). O
2
variation over time can provide an index of the relative degree of system
productivity, with large diurnal swings in O
2
occurring in the more pro-
ductive systems. Information on O
2
dynamics can be used in ecosystem
analyses or as a management tool to assess effects of river pollution (Auer
and Effler, 1989). In rivers that receive a great deal of untreated sewage,
O
2
can disappear completely (Sidebar 11.2).
Variation occurs in O
2
over time in wetlands. This fact has been used
to estimate rates of primary production and respiration in the Everglades
(McCormick
et al.,
1997). The variation of O
2
was found to be extreme
in some areas that receive phosphorus pollution in the Everglades. The
water column was completely anoxic at night and fully saturated during
the day.
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