EPA's Vessel General Permit and Small Vessel General

threat to listed species. Toxicity of copper to aquatic organisms is dependent on pH, temperature,
alkalinity, hardness, and concentrations of bicarbonate, sulfide, and organic ligands. Synergistic
toxicity is suggested for mixtures of copper and aluminum, iron, zinc, mercury, anionic
detergents, or various organophosphorus insecticides (Eisler 2000).
In the BE, EPA describes effects of copper from studies that directly measure changes to
survival, growth, and reproduction. In addition to these endpoints, exposure to contaminants may
result in sublethal effects to aquatic and aquatic-dependent wildlife that may affect a species’
fitness, either alone or in combination with other physiological or environmental stressors. In
many cases, these effects have been found to occur at concentrations lower than those that
directly affect survival, growth, or reproduction. They may also be lower than criteria that have
been deemed protective of aquatic life. In the case of copper, effects upon chemoreception and
behavior have been particularly well-studied and documented in aquatic species. Though absent
from the BE, EPA acknowledges and describes these effects in its report to Congress:
“At relatively low concentrations, copper is toxic to a wide range of aquatic organisms,
not just fouling organisms (CRWQCB, 2005). Concentrations as low as 5 to 25 μg/L can
be lethal for marine invertebrates (Chambers et al., 2006). Elevated copper levels affect
growth, development, feeding, reproduction, and survival at various life stages of fish,
mussels, oysters, scallops, crustaceans, and sea urchins. High copper levels also change
the types of phytoplankton that thrive in boat basins (Calabrese et al., 1984). Low levels
of dissolved copper affect the olfactory capabilities in juvenile Coho salmon, which is
critical for homing, foraging, and predator avoidance (Baldwin et al., 2004). The effect
of copper on olfaction of juvenile salmonids suggests that copper might affect other fish
species, too. Most effects on fish are sublethal (e.g., they may hinder metabolic
processes, reproduction, development, activity levels and behavior). Thus, the damage is
chronic and less noticeable than, for example, fish kills caused by sudden oxygen
depletion (Evans et al., 1994).“
Hecht and colleagues compiled data on sensory effects to juvenile salmonids exposed to
dissolved copper (Hecht et al. 2007). In their analysis, benchmark concentrations ranged from
0.18 – 2.1 μg/L, corresponding to reductions in predator avoidance behavior from approximately
8 – 57%. Recent work is consistent with previous observations (Baldwin et al. 2011, McIntyre et
al. 2012). These effects can manifest over a period of minutes to hours and can persist for
weeks. In aquatic systems, chemoreception is one of oldest and most important sensory systems
used by animals to collect information on their environment and generate behaviors involved in
growth, reproduction, and survival (Pyle and Mirza 2007). These behaviors include recognition
of conspecifics, mates and predators, food search, defense, schooling, spawning and migration.
Stimuli are perceived by sensory structures and converted to electrical signals that are conducted
to the central nervous system where the information is integrated and appropriate behavioral
responses are generated (Baatrup 1991). Detection of chemical signals involves not only
recognition of a spectrum of unique compounds or mixtures but also their spatial and temporal
distribution in the medium (Atema 1995). Sensory receptors are in direct contact with the
environment, and therefore pollutants may disrupt normal chemosensory function by masking or
counteracting biologically relevant chemical signals or by causing direct morphological and
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