Introduction
5
loss or truncation at the upper or inner shore because of embankments
for agriculture and aquaculture, industry, airports, residents, and as coastal
protection measures, whilst dredging and dumping activities, particularly in
estuaries, hard coastal defence structures and replenished beach sand on open
coasts and fishery operations, may all create strong physical disturbance.
The widespread introduction of species across biogeographic barriers
from coast to coast is irreversible. This trans-oceanic exchange of species
occurs unintentionally with shipping, either fouling or in ballast water, and
with aquaculture (Carlton and Geller 1993). Only a few of the introduced
species have turned into massive invaders transforming the dynamics and
structure of the recipient ecosystem. The cumulative effect is to bring about a
sameness between distant coasts which previously had no species in common, except for humans.
The exploitation of living resources on sedimentary shores affected primarily the upper trophic levels: mammals, birds and fish (Wolff 2000a,b). Gray
whales have been exterminated from the coastal lagoons of the North
Atlantic, and a re-introduction would require whales from the Pacific population. Dugongs and manatees have likewise become rare in parts of their
former range and hunting has reduced populations of seals and birds. The
latter suffered particularly from harvesting of eggs, a similar problem for sea
turtles. More recently, nature conservation has allowed for a partial recovery
of coastal bird populations. Overfishing and partly habitat degradations at
coasts and rivers lead to declines in a variety of large anadromic fish. Some
species of rays with a late and low reproductive output ended as by-catch in
the fisheries and became rare and functionally extinct on the coast. Oysters
became overexploited (i.e., Rothschild et al. 1994). It seems likely that on the
intensively harvested tidal flats of the East-Asian coasts, the entire sizespectrum of benthic invertebrates became truncated at its upper range.
Particularly in densely populated areas around embayments and semienclosed seas, eutrophication and toxic pollutants have changed coastal ecosystems. Eutrophication primarily increased primary production (Schramm
and Nienhuis 1996), but seagrasses have adapted to oligotrophic waters. These
rooted plants give way to fast-growing algae when nutrient levels increase.
Mats of green algae cover intertidal sediments enriched with nitrogen, with
detrimental effects on the benthic fauna underneath. There is also evidence
that eutrophication has increased benthic zoomass in estuaries (Beukema
1991). Toxic pollutants often occur at the same sites where nutrient levels have
increased, and the opposite effects of these two components may mask one
another. Global warming and the concomitant sea-level rise will interact with
most of the factors mentioned above. Whilst anthropogenic effects on the
biota of sedimentary shores is not a main focus of this Volume, the widespread occurrence of such effects means that they become an integral part of
the comparisons; nowhere can the footprint of human activity be ignored.
5
loss or truncation at the upper or inner shore because of embankments
for agriculture and aquaculture, industry, airports, residents, and as coastal
protection measures, whilst dredging and dumping activities, particularly in
estuaries, hard coastal defence structures and replenished beach sand on open
coasts and fishery operations, may all create strong physical disturbance.
The widespread introduction of species across biogeographic barriers
from coast to coast is irreversible. This trans-oceanic exchange of species
occurs unintentionally with shipping, either fouling or in ballast water, and
with aquaculture (Carlton and Geller 1993). Only a few of the introduced
species have turned into massive invaders transforming the dynamics and
structure of the recipient ecosystem. The cumulative effect is to bring about a
sameness between distant coasts which previously had no species in common, except for humans.
The exploitation of living resources on sedimentary shores affected primarily the upper trophic levels: mammals, birds and fish (Wolff 2000a,b). Gray
whales have been exterminated from the coastal lagoons of the North
Atlantic, and a re-introduction would require whales from the Pacific population. Dugongs and manatees have likewise become rare in parts of their
former range and hunting has reduced populations of seals and birds. The
latter suffered particularly from harvesting of eggs, a similar problem for sea
turtles. More recently, nature conservation has allowed for a partial recovery
of coastal bird populations. Overfishing and partly habitat degradations at
coasts and rivers lead to declines in a variety of large anadromic fish. Some
species of rays with a late and low reproductive output ended as by-catch in
the fisheries and became rare and functionally extinct on the coast. Oysters
became overexploited (i.e., Rothschild et al. 1994). It seems likely that on the
intensively harvested tidal flats of the East-Asian coasts, the entire sizespectrum of benthic invertebrates became truncated at its upper range.
Particularly in densely populated areas around embayments and semienclosed seas, eutrophication and toxic pollutants have changed coastal ecosystems. Eutrophication primarily increased primary production (Schramm
and Nienhuis 1996), but seagrasses have adapted to oligotrophic waters. These
rooted plants give way to fast-growing algae when nutrient levels increase.
Mats of green algae cover intertidal sediments enriched with nitrogen, with
detrimental effects on the benthic fauna underneath. There is also evidence
that eutrophication has increased benthic zoomass in estuaries (Beukema
1991). Toxic pollutants often occur at the same sites where nutrient levels have
increased, and the opposite effects of these two components may mask one
another. Global warming and the concomitant sea-level rise will interact with
most of the factors mentioned above. Whilst anthropogenic effects on the
biota of sedimentary shores is not a main focus of this Volume, the widespread occurrence of such effects means that they become an integral part of
the comparisons; nowhere can the footprint of human activity be ignored.