Stemming the tide of invasive species in Great Lakes
Bi-national regulation of ballast water has reduced invasion risk by 85%
since 2008

Date:
March 11, 2022
Source:
McGill University
Summary:
New research shows that a bi-national regulation targeting ships
entering the Great Lakes since the mid-2000s has been remarkably
effective in reducing a large proportion of the invasive species
in the world's largest freshwater ecosystem.



FULL STORY ========================================================================== Ballast water release from ocean vessels has introduced hundreds
of invasive species to coastal ecosystems worldwide, causing major
disruptions to fisheries and biodiversity. Attempts to control aquatic invasions have met with mixed success in general. However, a new study
suggests that a bi-national regulation targeting ships entering the Great
Lakes since the mid-2000s has been remarkably effective in reducing a
large proportion of the invasive species inthe world's largest freshwater ecosystem. The study by Anthony Ricciardi, (Professor of Biology in
the Redpath Museum and Bieler School of Environment, McGill University)
and co-author Hugh MacIsaac (Professor and Canada Research Chair in the
Great Lakes Institute for Environmental Research, University of Windsor)
was recently published in Conservation Letters.


==========================================================================
"I'm aware of no other documented case in which the invasion rate
of a large aquatic system has been suppressed through a management intervention,"said Ricciardi. "This layer of protection is clearly
beneficial. There are many highly invasive freshwater species in Europe,
for example, that could be delivered in ballast water and would almost certainly proliferate in the Great Lakes. The regulation is likely
preventing their introduction." The world's most invaded freshwater
ecosystem No other freshwater ecosystem on Earth has been invaded as
much, or as frequently, as the Great Lakes basin. Nearly 190 non-native
species of fish, invertebrates, plants, plankton, and microbes have
established populations in the basin over past two centuries. Nearly
65% of invaders recorded since the opening of the St Lawrence seaway in
1959 were transported to the Great Lakes in the ballast tanks of ships
from overseas ports. These include notorious stowaways such as the zebra mussel, the quagga mussel, the spiny water flea, and the round goby --
each among the most ecologically and economically damaging invaders in
the basin.

Between 1959 and the mid-2000s, one new invader was discovered established
in the Great Lakes every 6-7 months.

This onslaught prompted a move by Canada and the USA to harmonize
regulations and mandate flushing saltwater through ballast tanks of
all ships while they were still in open ocean, before entering the St
Lawrence seaway bound for the Great Lakes. Saltwater flushing has been
shown in experiments to cause a massive reduction in the abundance and
variety of freshwater organisms carried in ballast tanks.

Empirical evidence of an abrupt reduction in invasion risk The true
test of such a regulation is its effect on the observed rate of species invasion. Since 2008, invasions reported in the Great Lakes basin have
declined by 85% and are now at their lowest rate in two centuries. Other factors could have contributed to the abrupt decline in the invasion
rate, but empirical evidence points to ballast water regulation as the overwhelming primary cause.

Although the Great Lakes remain vulnerable to invasions from poorly
regulated sources, such as trade in living organisms (e.g. aquarium pets,
live bait, ornamental garden plants, food markets), this study highlights
the potential benefit of an internationally coordinated, evidence-based
control strategy.


========================================================================== Story Source: Materials provided by McGill_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Anthony Ricciardi, Hugh J. MacIsaac. Vector control reduces the
rate of
species invasion in the world's largest freshwater ecosystem.

Conservation Letters, 2022; DOI: 10.1111/conl.12866 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220311140624.htm

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