NANFA-- farm ponds and you...

Dave Neely (
Fri, 22 Sep 2000 23:45:38 CDT

>This is personal experience only... From what I have seen, read, and >the
>tiny amount of research I've done myself, the impact of the small >stock
>pond is negligible at best. Even when considered as cumulative in
>effect. There are many reasons for this:

Menzel and Cooper (1992) noted that most farm ponds in the SE were built in
the last 50 years and represent 0.5% of the land surface, with over a
million (!) farm ponds on 1st and 2nd- order tributaries in the SE (streams
are classified on connectivity; 1st order streams are the first to appear on
a 7.5 minute topo map, two 1st order tribs connect to form a 2nd order
stream, etc.). Note that in contrast to Kansas, farm ponds in the SE are
usually built by impounding a small, sometimes intermittent stream.

Also in contrast to Kansas, most headwater streams in the SE were originally
shaded by a forest canopy, which affects headwater streams to a larger
degree than in larger streams: since the entire channel is shaded for most
or all of the day, average mean temperature is reduced, evaporation rates
are reduced, the capacity for primary production via photosynthesizing algae
is reduced, and there is a large input of organic matter in the form of leaf
fall and larger debris (sticks, pinecones, trees, etc.). This energy source
is utilized by fungi, bacteria, and macroinvertebrates that shred and
consume this material, promoting a downstream energy flow in the form of
fine pieces of organic matter (FPOM), dissolved organic carbon (DOC),
invertebrate drift and invertebrate feces.

Farm ponds break this cycle and have many of the same effects of large
impoundments (summarized in Burkhead et al. 1997): alteration or elimination
of natural hydrological patterns; concentration of pollutants and sediments;
provide a focal point for introduction of nonindigenous fishes (which is
significant- bluegills, green sunfish, and golden shiners are often the
dominant species immediately downstream of farm ponds in the SE); restrict
the movement of stream fishes (and isolating fishes in upstream areas);
thermally alter downstream stream segments; and perhaps most critically,
alteration of nutrient cycling and trophic webs.

Farm ponds are nowhere near as effective at removing organic wastes from
streams or systems as wetlands are- emergent and submerged vegetation in
wetlands provides a maximal amount of surface area available for the growth
of microbial and algal biofilms. These biofilms are amazingly effective at
sequestering organic carbon- in many cases, orders of magnitude more
efficient than the vascular plants that they grow on! If farmers were
interested in reducing nutrient inputs to stream systems on their
properties, they would likely be better served by constructing tiered
artifical wetlands rather than “settling ponds.”

Farmers should be just as inherently responsible for what they do to natural
systems as “big business,” whether it be large scale agribusiness, a
smelting plant, a sewage treatment plant, or a chemical manufacturing
facility. In principle, it should be easier for a small farmer to meet
these requirements; by fencing off riparian zones and streams from
livestock, in the sensible use of wetland areas to filter and treat
livestock effuent, in sensible use of chemicals, etc.

When I was an undergrad in Maryland, a professor there (who would become my
mentor and advisor for my MS) was doing surveys for the Maryland darter. He
may be the last person to see a live one- he saw a single individual in fall
of 1989 while snorkeling. That winter, a small dam holding liquid manure
broke on a small tributary to Deer Creek, sending a pulse of concentrated
shit down the stream, causing a fish kill (excuse me for my use of
profanity- there’s no better term to describe it) on the lower part of the
river. No Maryland darters have been seen in the decade since, despite
intensive surveys. Logperch, shield darters, fantail darters, and other
benthic species were dramatically reduced following the spill, but have
since recovered. This pattern gets repeated on a time frame that is way
too common; like J.R., I spend a lot of time out in the field (out of my
ivory tower?) collecting fish, and I see the direct effects of small farms
on fish abundance, diversity, and community structure every day. Farmers
may mean well, but in general, their actions are extremely damaging to small
stream fish communities, and perhaps more pervasive than the large polluters
that we usually think about… should they be responsible?

Just something to think about…

Burkhead, N.L., S.J. Walsh, B.J. Freeman, and J.D. Williams. 1997. Status
and restoration of the Etowah River, an imperiled southern Appalachian
ecosystem. Pages 375-445 in: G.W. Benz and D.E. Collins, eds. Aquatic fauna
in peril: the southeastern perspective. Sp. Pub. 1, SE Aquatic Res. Inst.,
Decatur, Georgia.

Menzel, R.G. and C.M. Cooper. 1992. Small impoundments and ponds. Pages
389-420 in: C.T. Hackney, S.M. Adams, and W.H. Martin, eds. Biodiversity of
the southeastern United States: Aquatic communities, Wiley and Sons, New

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