From: Scientific forum on fish and fisheries
[mailto:[log in to unmask]]On Behalf Of Maurice Crawford
Sent: 14 August 2002 01:29
To: [log in to unmask]
Subject: Monitoring non-native species in estuaries.
Hello Fish Ecologists,
The National Estuarine Research Reserve System (USA) recently completed
a report on broad-scale invasion monitoring programs, based on a
held in January 2002. We've pasted the executive summary below and the
complete document can be downloaded as a pdf from:
Kerstin Wasson and Maurice Crawford
NON-NATIVE SPECIES IN OUR NATION'S ESTUARIES: A FRAMEWORK FOR AN
INVASION MONITORING PROGRAM
National Estuarine Research Reserve Technical Report Series 2002: 1
Wasson, K., Lohrer, D., Crawford, M., and Rumrill, S.
Invasions of non-native species are now recognized as being second only
to anthropogenic habitat destruction as a cause of global extinctions.
distribution of the world's biota is being altered to an unprecedented
degree, largely through human transport. Estuaries are among the most
vulnerable ecosystems in the world to anthropogenically-facilitated
invasions, in part because entire coastal planktonic assemblages are
moved between distant estuarine ports in ballast water of international
vessels. Hundreds of non-native aquatic species have become established
in U.S. estuaries, and some of them have been shown to have dramatic
negative impacts on native biological communities, habitat structure,
and ecosystem processes.
Very few attempts have been made to monitor estuarine invasions at a
broad spatial scale. Yet standardized, repeated, quantitative measures
multiple sites are the best way of determining the correlates of
invasion success, and would shed light both on attributes of species
that make them likely to invade and have negative impacts, and on
characteristics of the recipient environments that make them resistant
or vulnerable to invasion. Monitoring would also facilitate early
detection of new invasions, within the window of opportunity where
eradication efforts may be successful. By simultaneously carrying out
monitoring across estuaries for invaders and native species, along with
physical and chemical characterization, scientists could also determine
how ecological impacts vary geographically,
and attempt to identify the mechanisms behind observed differences. A
nationally coordinated invasion monitoring program in estuarine habitats
would thus allow coastal managers and resource agencies to better devise
and implement effective strategies for preserving regionally distinct
The National Estuarine Research Reserve System (NERRS) is a network of
protected areas established to study and improve the health of U.S.
estuaries and coastal habitats. With 25 reserves on all three coasts of
the continental U.S., in addition to those in Alaska, Puerto Rico, and
the Great Lakes, the reserve system has outstanding spatial coverage to
detect and track range expansions of exotic species. Furthermore, every
reserve participates in system-wide monitoring, consistently collecting
meteorological data and carrying out baseline water quality measurements
that would complement any biological monitoring program. The reserves
also have strong management, education, and restoration programs
excellently suited to an integrated approach to estuarine invasions.
A recent survey of the NERRS revealed that most reserves have been
significantly affected by biological invasions, and that non-native
species are a medium to high priority for future research funding. Over
85 problematic non-native species were identified by the reserve system,
with concerns associated primarily with negative impacts on native
species, communities, or habitat structure. More than half the reserves
are already monitoring the spread of a non-native aquatic plant of
concern, and many are tracking crab invasions.
In January 2002, the NERRS sponsored a workshop to devise a framework
for a national estuarine invasion monitoring program, with funding from
the Aquatic Nuisance Species Task Force and NOAA. The workshop brought
together over 40 participants -- invasion biologists, reserve system
representatives, and partner organizations -- to envision elements of an
ideal monitoring program for estuarine invasions.
Eleven invasion biologists made recommendations on strategies and
protocols for developing a national invasion monitoring program. Some
themes raised by many included: 1) the importance of carrying out
biological monitoring across estuaries, targeting native and non-native
species, 2) the power of linking biological data with physical
variables to explain observed patterns, 3) the value of a central
database for monitoring data, 4) the necessity for taxonomic expertise,
and 5) the challenges and rewards of question-driven monitoring.
Workshop participants identified and prioritized questions to drive a
national invasion monitoring program. The top two questions concerned
patterns of species richness and abundance, which comprise basic
biological monitoring. Three additional high-ranking questions focused
more specifically on invasions, and involved environmental correlates of
invasion success, early detection of new invaders, and impacts of
non-native species. Examples of monitoring programs for each of the top
four questions were developed, including appropriate taxa, methods, and
likely scientific and management benefits to answering them.
Participants identified estuarine habitat types and taxa to consider as
the focus of invasion monitoring. Marshes, submerged aquatic
vegetation, and shellfish beds received the highest ranking overall,
because they are ecologically relevant across a broad geographic range,
because they are tractable for monitoring, and because they are critical
for sustaining key estuarine resources, yet potentially fragile in the
face of anthropogenic threats. The top taxa that emerged were plants,
macroalgae, mammals and fish. These rose to the top because of their
tractability as study organisms, their potential to influence the
ecology of estuaries they invade, and the likelihood that they could be
eradicated if necessary. Most other taxa were considered difficult to
identify for non-experts, and difficult to control. Participants found
it difficult to prioritize habitats and taxa without a specific context
(scientific question, funding source, user group).
A national invasion monitoring program would best be built of
partnerships. Links between various agencies and organizations would
increase the geographic coverage and bring greater resources that would
allow an increased scope of any program. Academic involvement in agency
monitoring programs would be fruitful for the academics, and would
enhance the scientific value of the monitoring. Partnerships with local
communities would help to raise the profile of estuarine invasions, and
could complement any national invasion monitoring program.
The workshop has resulted in a broad blueprint for national invasion
monitoring, which can be used to guide future reserve system efforts or
those by other agencies. Critical questions about invasions have been
identified, and potential approaches illustrated. More generally, the
workshop has highlighted the scientific value and management benefits of
carrying out biological monitoring consistently at a broad geographic
scale. The NERRS, perhaps in collaboration with partners, is poised to
institute such a national program.
Dr. Kerstin Wasson, Research Coordinator
Elkhorn Slough National Estuarine Research Reserve
tel: 831 728 5939 fax: 831 728 1056
email: [log in to unmask]
Dr. Maurice Crawford, Science Coordinator
NOAA's Ocean Service
National Estuarine Research Reserve System
Tel: 301.713.3155 ext. 165
E-mail: [log in to unmask]
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