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ENVIROMENTAL RISK ASSESSMENT OF MARINE 3
INVASIVE SPECIES CARRIED BY BALAST WATER

ENVIROMENTAL RISK ASSESSMENT OF MARINE
INVASIVE SPECIES CARRIED BY BALAST WATER

Oktay Eren TUREYEN*
*Istanbul Technical University

ABSTRACT

Ballast water carried by ships is a significant vector to transfer of marine organisms beyond their natural
ecoregions, resulting in economic, social and environmental negative impacts. The aim of this study is to
investigate the risks of environmental negative impacts of marine invasive species by environmental risk
assessment method and identify the high-risk invasive species, vessels and voyages for prioritization of
inspections, compliance tests and monitoring activities. All marine species investigated for the risk
assessment are chosen from Turkish coasts and the new method for risk classification is developed and
specified for local risk assessments of marine invasive species carried by ballast water.
Keywords: Invasive species, Ballast water, risk assessment, risk classification

1. Introduction

Over two-thirds of the world’s surface is covered by water and oceans serving as an important
transportation route for both people and merchandise and more than 90% of all worldwide trade
goods are carried by ships on the ocean [1]. All ships are carefully designed to carry those goods
and people all around the world. However ships don’t always travel with cargo or full cargo, so
they have to take some weight to operate safely through the water with enough depth. Ballast is
defined as any solid or liquid material that is taken into a vessel to increase the draft, change the
trim, and regulate the stability or to maintain stress loads within acceptable limits. After
steel-hulled ships and developed pumping technology, sea water converted the major ballast of
selection. Ballast water is taken to ballast tanks of ships at source port while unloading cargo
and at destination port new cargo is taken on board while ballast water discharging to new port.

While taking ballast water into the ballast tanks, large number of organisms from source port is
also taken to the tanks from different species and different life stages such as eggs, cysts, spores
or adults. Organisms taken from source port generally will be invasive species for destination
port so that they became introduced or invasive species for the new ecosystem [2].

Even habitats with similar conditions, like same depth, salinity and temperature regimes, from
different part of world, can have very different kind of species. Ecological barriers provide an
isolation of biogeographic regions from each other. Those ecological barriers started to get
cracked by anthropogenic activities such as transportation and shipping. By shipping,
organisms can be carried widely beyond their native areas and they are introduced to new
regions, where they can become established and spread if the conditions of the new environment
are suitable [3].

Invasive species can be extremely dangerous for any environment by displacing native species
with outcompeting or preying on those native species, besides they can change all food web and
alter basic physical activities such as nutrient cycling and sedimentation [4]. For example the
North American comb jellyfish, Mnemiopsis leidyi was released with ballast water to the Black
Sea in 1980s and affected all the ecosystem [5]. Vibrio cholerae introduced in Peru in 1991, was
the reason of nearly a million people’s diseases and the death of more than ten thousand by

Sayı 5, 2016 GiDB|DERGi