EFFECTS OF HEATED EFFLUENTS
87
ported (Naylor, 1957a; Elton, 1958) warm water immigrants which
have been recorded from artificially heated conditions in temperate
European waters (see Table I and Fig. 8) include the crabs Rhithropanopeus harrisi (Wolff, 1954), Brachynotus sexdentatus Risso (Naylor,
1957b,c) and Neopanope texana sayi (Smith) (Naylor, 1960), the barnacle
Balanus amphitrite var. denticulata (Crisp and Molesworth, 1951 ;
Naylor, 1958, 1965), the kamptozoan Loxosoma kefersteinii (Claparhde)
(Ryland and Austin, 1960), the bryozoan Bugula neritina (L.) (Ryland,
1960) the mollusc Venus mercenaria (Heppel, 1961 ; Ansell, 1963 ;
Ansell et al., 1964a), the isopod Limnoria tripunctata (Eltringham and
Hockley, 1958 ; Jones, 1963), the serpulid polychaetes Mercierella
enigmatica Fauvel (Fauvel, 1922 ; Monro, 1924 ; Tebble, 1956 ; Naylor,
1959, 1965 ; Markowski, 1962 ; Gee, 1963) and Hydroides incrustans
Monro (Monro, 1938 ; Naylor, 1965, Gee, 1963), and perhaps also the
fish Atherina boyeri (Risso) (Bowers and Naylor, 1964). The methods
by which various species are transported will clearly vary according to
their habits. Apart from deliberate introductions such as oysters and
clams, and species introduced accidentally with those species (see
Elton, 1958), sessile species could also travel amongst ship fouling
(Bishop, 1951 ; Kuhl, 1963). However, large free living forms would only
be able to travel on the hulls of ships if fouling was very thick and provided a suitable foothold. Alternative methods of travel for these
species might be as larvae or adults in seawater ballast tanks (Peters
and Panning, 1933 ; Rees and Cattley, 1949 ; Wolff, 1954) or as adults
under the grids covering sea inlet valves (Naylor, 1957b). There is no
reason to suppose that tropical or subtropical species could not tolerate
at least a summer voyage into temperate waters and become established
by any of these methods. Warm-water species which have also been
introduced into Europe by human agencies, but which do not appear
to have become established in heated localities, include a cladoceran
Penilia (Cattley and Harding, 1949), the crabs Pachygrapsus transversus Gibbs (Bertelson and Ussing, 1936 ; Bull, 1962), Pilumnoides
perlatus (Poeppig) (Marine Biological Association, 1957), Planes
minutus Leach (Wolff, 1954) and Callinectes sapidus (Wolff, 1954).
Whereas such species apparently died off during the winter months they
could perhaps have thrived near warm water effluents and should be
considered as likely replacement species in addition to those known to
occur already. Similarly several warm stenothermal species, introduced
naturally by warm currents, should also be considered as possible
replacement species. For example, Huntsman and Reid (1921) and Fish
and Johnson (1937) have shown that certain fish, medusae, amphipods
and chaetognaths seldom spawn in the Bay of Fundy, and the popula-
87
ported (Naylor, 1957a; Elton, 1958) warm water immigrants which
have been recorded from artificially heated conditions in temperate
European waters (see Table I and Fig. 8) include the crabs Rhithropanopeus harrisi (Wolff, 1954), Brachynotus sexdentatus Risso (Naylor,
1957b,c) and Neopanope texana sayi (Smith) (Naylor, 1960), the barnacle
Balanus amphitrite var. denticulata (Crisp and Molesworth, 1951 ;
Naylor, 1958, 1965), the kamptozoan Loxosoma kefersteinii (Claparhde)
(Ryland and Austin, 1960), the bryozoan Bugula neritina (L.) (Ryland,
1960) the mollusc Venus mercenaria (Heppel, 1961 ; Ansell, 1963 ;
Ansell et al., 1964a), the isopod Limnoria tripunctata (Eltringham and
Hockley, 1958 ; Jones, 1963), the serpulid polychaetes Mercierella
enigmatica Fauvel (Fauvel, 1922 ; Monro, 1924 ; Tebble, 1956 ; Naylor,
1959, 1965 ; Markowski, 1962 ; Gee, 1963) and Hydroides incrustans
Monro (Monro, 1938 ; Naylor, 1965, Gee, 1963), and perhaps also the
fish Atherina boyeri (Risso) (Bowers and Naylor, 1964). The methods
by which various species are transported will clearly vary according to
their habits. Apart from deliberate introductions such as oysters and
clams, and species introduced accidentally with those species (see
Elton, 1958), sessile species could also travel amongst ship fouling
(Bishop, 1951 ; Kuhl, 1963). However, large free living forms would only
be able to travel on the hulls of ships if fouling was very thick and provided a suitable foothold. Alternative methods of travel for these
species might be as larvae or adults in seawater ballast tanks (Peters
and Panning, 1933 ; Rees and Cattley, 1949 ; Wolff, 1954) or as adults
under the grids covering sea inlet valves (Naylor, 1957b). There is no
reason to suppose that tropical or subtropical species could not tolerate
at least a summer voyage into temperate waters and become established
by any of these methods. Warm-water species which have also been
introduced into Europe by human agencies, but which do not appear
to have become established in heated localities, include a cladoceran
Penilia (Cattley and Harding, 1949), the crabs Pachygrapsus transversus Gibbs (Bertelson and Ussing, 1936 ; Bull, 1962), Pilumnoides
perlatus (Poeppig) (Marine Biological Association, 1957), Planes
minutus Leach (Wolff, 1954) and Callinectes sapidus (Wolff, 1954).
Whereas such species apparently died off during the winter months they
could perhaps have thrived near warm water effluents and should be
considered as likely replacement species in addition to those known to
occur already. Similarly several warm stenothermal species, introduced
naturally by warm currents, should also be considered as possible
replacement species. For example, Huntsman and Reid (1921) and Fish
and Johnson (1937) have shown that certain fish, medusae, amphipods
and chaetognaths seldom spawn in the Bay of Fundy, and the popula-