Is harbour development ecologically sustainable?

Abstract

Not one of the twelve harbours studied in this book was developed in an ecologically sustainable way. The data presented in this book quantify environmental impacts ranging from degradation to ecosystem collapse. A simple measure of the impact of harbours and urbanisation is the fisheries. In Tokyo Bay the total annual fish catch of fish decreased by a factor of ten, from 1×105tons y-1 in the 1950's to less than 5×104 tons yr-1 in the 1970's; this has not improved since even though environmental protection measures are being implemented. In the Changjiang Estuary, the biomass of Stolephorus, a traditional commercial fish species in the region, has been considerably reduced after 1990 and shows almost no landing records in last 5-10 years; the catch of Stolephorus decreased from 560 tons yr-1 in the 1960s to 5-10 tons yr-1 in 1990; and the commercial fishing for crabs in this region has shut-down after 1980s and all catches of crabs were banned in 1990 owing to a population crash. Fish kills are now occurring nearly routinely in the Pearl River Estuary and in Hong Kong waters from hypoxia and harmful algae blooms (HAB). Pearl Harbor is degraded but much less seriously; 99% of the oysters died in 1972; however fish and invertebrates survived into the 1990s when water quality improved. Bangkok estuarine waters can, in the dry season, become anoxic and inhospitable to fish; the situation is severe but not hopeless in the upper Gulf of Thailand; the catch per effort decreased by a factor of ten from about 290 kg hr-1 in 1963 to 20-30 kg hr-1 in the 1990s; fishery production declined greatly from 1986 to 1995. Fish stocks in Ho Chi Minh City estuarine waters have virtually collapsed and only aquaculture remains. In Manila Bay the trawl catch per unit effort decreased from 46 kg hr-1 in 1947 to 10 kg hr -1 in 1993; the demersal biomass decreased from 4.61 mt km -2 in 1947 to 0.47 mt km-2 in 1993. Hypoxia events are now reported in Klang Harbour, clearly inhospitable to fish. In Singapore waters, marine fish species composition between 1934 and 1973 showed no loss of species but definitely less abundance; wild fisheries are now negligible; occasional fish kills have occurred from spills and anoxia especially in Johor Strait. Jakarta Bay has very little intact fisheries; the remaining fisheries are comprised of more opportunistic fish species that can exist in the now heavily polluted waters. By comparison Darwin Harbour fisheries are still rich but they are completely non-managed in a free-for-all philosophy as if there was no tomorrow; in 2000, 37% of Darwin residents spent some of their time fishing and one in every five resident households owned a pleasure boat used at least partly for recreational fishing; the total number of hours fished annually in 2000 was estimated to be 540,481 hours; some fish spawning aggregations have disappeared; the resulting ecosystem impact is unknown and basically not studied, and this lack of data precludes sustainable management. There are other parameters of environmental degradation. These include in all harbours studied in this book some, but not all, of the following symptoms: harmful algae blooms, anoxia and hypoxia (oxygen depletion), and poisoning by fecal pollution, 4,4'-DDE and 4,4'-DDT, pesticides, PAHs and phenol, the production of toxins that accumulate through marine food chains to poison marine mammals, seabirds and humans. In extreme cases of grossly polluted, poorly flushed waters a parameter of pollution is simply gross stench. Another measure of environmental degradation is a decrease in biodiversity. In the Pearl and Changjiang estuaries for instance, the number of species of plankton and benthos has decreased dramatically, the community composition of plankton and benthos is now much simpler, and the biodiversity is degraded. In some cases such as the Changjiang Estuary the ecosystem has essentially collapsed; its historical role of providing multiple ecological services to society is changing to a simplified service system, e.g. the estuary essentially provides only land for settlement and waterways for transportation and trade. Protecting endemic species from invasive species is low on the priority list of port operators. Invasive species are increasingly common, mainly introduced through ballast water in large bulk cargo carriers and vessel fouling, especially of slow moving barges and dry docks. These can overwhelm some endemic species.