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The role of stress; sources and degrees, in
bringing on and solving marine livestock disease is not often fully
appreciated. Weakening of specimens occurs most drastically in the
course of wild collection, and holding, handling, and shipping of all
livestock. What can we all do in our various roles as purveyors and
custodians of this life? The purpose of this essay is to familiarize you
with the nature of stress; its most common inputs, and address what you
can and should do to ameliorate stressful conditions.
Starting in 1982, I have presented talks on “three sets of factors that
determine livestock health” at scientific gatherings, dozens of club and
national gatherings, as well as three years of the University of New
England “Fish Health Conference” in Biddeford, Maine.
As you can see, the second “set” of these
factors entails “suitability of the environment”; all deviations of
which can be accounted as sources of stress: Environmental, Social, And
Nutritional and more with many subdivision therein.
The complete “three sets” model other factor sets are “initial state”
and “presence and degree of pathogenicity of disease-causing organisms”.
These three factor sets interplay to determine livestock health. For
here, this essay, we will limit our discussion to the role of stress in
this fluid equation. Introduction of Stress: Capture, Handling,
Shipping
Think about when outbreaks of disease are most likely to occur: during
introduction of new livestock, particularly newly-arrived
(wild-collected or captive-produced) stock is purchased. Indeed, all
newly acquired livestock should be considered as carriers of infectious
and parasitic diseases; and quarantined, perhaps prophylactically
treated to avoid introducing troubles in your main display/s.
I cannot over-emphasize the higher importance of everyone in “chain of
custody” of livestock doing their part to reduce stress. Alternatively,
chemical treatments for (induced) infectious and parasitic disease
likely result in more deaths than cures. Put another way; once aquatic
life, particularly marine, is over-stressed, there is little one can do
to effectively recover its health. Pathogenic Disease in the Wild
Of course, nothing comes from nowhere; wild populations of fishes and
invertebrates, plants and algae have resident bacteria, protozoan and
more fauna that can become health threatening; though most exist in a
balance that usually result in no symptoms of disease. Indeed,
successful “symbionts” (“living together”) must need “get along” with
their hosts/sponsors, less they both perish.
On the positive side, aquatic organisms generally have enormous natural
resistance (immunity) through their physiology; which in turn is mostly
dependent on environmental factors. Divers do occasion naturally
diseased life underwater in the wild, but by and large wild populations
remain healthy due to their immunological defenses.
The breakdown in the balance of health versus disease is mainly a matter
of a shift in environmental conditions that weaken host life in favour
of opportunistic endo- and ecto-organisms, as well as an increase in
susceptibility to predation in nature. Biological Diseases in Captivity
Comparing life on land and freshwater environments, one finds that
marines are far more susceptible to environmental variability. This
makes sense intuitively as terrestrial organisms and freshwater biota
live and have evolved in far more change-able worlds than the vast ocean
realms. Though seawater habitats do indeed change; their shifts are
almost always small and over long periods of time. Put in aquarist
terms: sea life has little tolerance for environmental change; variances
resulting in stress and loss of immunity. There are several principal sources of stress
that marine life encounters in our care: exposure to concentrated
metabolites, low dissolved oxygen and RedOx, vacillating temperature, pH
and specific gravity; poor and lack of nutrition, social traumas, and
physical damage from handling….
The worst of these insults occurs in the process of collection in the
wild, and processing (handling and shipping) of collected and cultured
stocks.
More specifically, different sources of stress occur when livestock is:
Having been in the trade for decades and reviewing the scant useful
accounts of others observations on receiving livestock I will attest to
the wide range of health in just-received shipments. Especially with
long hauls (more than a day in the bag) and poor weather exposure the
livestock may be outright mostly dead or on its way; all shipments
experience light to severe physiological stress.
Time spent in small volumes of water in bags during transport is most
damaging; and careful consideration must be made in maximizing these
variables versus the cost of space and weight in shipping cost. I have
encountered pHs in the low sixes, and ten and more parts per million of
ammonia. My stance and urging of the industry and hobbyists who are
involved in long haul shipping of livestock to engage “guerilla
acclimation” has also spanned decades of article writing and live
presentations. Matching shipping water pH with water of no metabolite
content and slowly dripping it to overflow to flush out metabolite
before raising pH is absolutely critical in avoiding deadly hemolysis
and gill burn. Optimal and Stabilized Environment Is Key:
Water quality values to shoot for include: pH of 8.2-8.4;
alkalinity2.5-4 meq/l. No detectable ammonia or nitrite, Nitrate of ten
or less ppm, esp. for reef life; high (7-8 ppm) and consistent dissolved
oxygen; similar for RedOx (300-300 micro-Siemens/cm.); a specific
gravity 1.025-26 (a bit higher for Red Sea, and sometimes artificially a
bit lower for Fish Only systems).
Other environmental factors to consider: Décor suitable and arranged to
provide sufficient psychological cover and territorial relief; taking
care to allow room for all and not stocking incompatible species, sex
ratios or intolerant sizes of livestock. Avoid too-sudden changes in
light/dark conditions.
Nutritional considerations: Take care to assure all livestock is being
“nitrified”; not just fed… as non-nutritious foods or wrong formats may
lead to deficiency syndromes and further stress. Environmental Manipulation versus Chemical
Treatment Therapies:
As mentioned to above; more often than not earnest “medicine”
administration for marines proves toxic or inefficacious. Alternatively,
simple environmental manipulation (pH adjusted freshwater dips/baths),
raising pH….) will affect cures in not-too-far gone circumstances. In
particular I find aggravating the continuing sale of unlabeled
ingredient “cure-alls” and unscientifically proven “holistic” fixes that
have no proven value as marine remedies. The Power of Careful Observation
There is nothing, no fancy test gear, no automated make up; high
technology filtration or lighting that compares with the value of your
observing your livestock and their behavior. Every time you’re near your
systems you should be checking to see that all seems okay. Each time you
feed your livestock or are working on the tank, is an opportunity to
assure that all are present and doing well.
Stress is a part of life, including those in our clear boxes of water;
but too much stress leads to moribund organisms and their deaths. Note
that there are always signs that something is going amiss in advance of
real loss. The onus is upon you to catch such problems before they
become deadly. Cloze:
The awareness and accomplishment of preventing undue stress in your
livestock pays big dividends in assuring its health. Most new organisms
are compromised to a degree from elements of their handling and shipping
prior to acquiring them. To the extent that you are able to ameliorate
sources of stress, your new and existing captive biota will thrive or
fall prey to infectious, parasitic, nutritional, even simple
environmental over-stress. As conscientious consumers we should do our
part at all levels of distribution to investigate what species, from
what areas do best; and further to do what we can once the livestock is
in our care; observation and rest through quarantine; and if perceived
necessary, treatment.
I recall Stephen Spotte (1973) making a comment that seawater life forms
were “physiological extensions” of their environment. Bear this in mind
when casting your votes for buying, acclimating and placing new
livestock. Bibliography/Further Reading: Fenner, Bob. Undated.
Acclimating Marine Livestock for Home Hobbyists & Commercial/Guerilla
Acclimation Technique. WetWebMedia
http://wetwebmedia.com/acclimat.htm
Fenner, Bob. 2006. The three sets of factors
that determine livestock health. TFH 11/06.
http://wetwebmedia.com/mardisease.htm Spotte, Stephen. 1973. Marine Aquarium
Keeping. Wiley Interscience, NY. 171 pp. |
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