Johannes 1970 sedim reefs.pdf

How to kill a Coral Reef--I
S e d i m e n t a t i o n and flooding due to p o o r land m a n a g e m e n t , and the release of h e a t e d and hypersaline industrial effluents are injuring or destroying coral r e e f c o m m u n i t i e s in various parts of the world. By itself this s t a t e m e n t is perhaps n o t likely to arouse m u c h concern; so m a n y b e t t e r known, m o r evisible environments are being stressed or d e s t r o y e d b y man. I shall therefore begin by indicating briefly w h y the welfare of the reefs should be w o r t h y of concern. To say that coral c o m m u n i t i e s provide some of the loveliest scenery on earth and some of the m o s t exciting recreation is just a beginning. T h e y are also a m o n g the m o s t biologically p r o d u c t i v eo f all natural c o m m u n i t i e s , produchag more new living material per unit area, with no help from man, than a carefully and expensively cultivated field o f sugar cane receiving the same a m o u n t o f sunlight. A m o n g the most extensive o f all shallow water cornmunities, coral reefs yield high quality p r o t e i n in the form o f fish and shellfish to millions o f people in thecoastal tropics where terrestrial sources o f protein are characteristicallyinadequate. A l t h o u g h reef c o m m u n i t i e s are h i d d e n beneath the surface o f the sea, some o f their effects are clearly visible on land. Present day reefs are key agents in the creation and preservation of the beaches and c o n t o u r s of m o r e t h a n 400 atolls, n u m e r o u s other tropical islandsand thousands of miles o f continental coastline. The w h i t e or pink sand beaches in these areas are c o m p o s e d o f the f r a g m e n t e d calcareous skeletons o f reef organisms. The characteristic line of surf breaking offshore marks the natural selfrepairing breakwater thrown up b y the lime-secreting inhabitants o f the reef, providing t h e land with an effective buffer against theocean, In addition coral reefs are a m o n g the m o s t biologically diverse o f all c o m m u n i t i e s , t e e m i n g with animals and plants o f great interest to scientist and l a y m a n for a continually e x p a n d i n g variety of reasons. R e e f organisms for example, contain m a n y pharmacologically active c o m p o u n d s . The essential ingredient for an ' u l t i m a t e 'birth control pill, one that can be taken the 'day after' has b e e n f o u n d in the tissues o f a coral and is just one o f t h e c o m p o u n d s o f reef origin currently under intensive study b y the drug industry, Coral reefs thus c o n s t i t u t e a vast, richly e n d o w e d , multi-purpose resource. But like m o s t o t h e r shallow water communities, t h e y are vulnerable to variouspollutants. The damage so far, although p o o r l y d o c u m e n t e d , is clearly serious, as I shall a t t e m p t to show. While abused environments o f m u c h smaller p r o p o r t i o n s and lesser value to m a n have received considerable a t t e n t i o n f r o m conservationists, coral reefs have received little; this article is p r o b a b l y the first ever published on the general p ro b l e m s of coral reef pollution, There are vivid red plumes in the bright blue sea downcurrent f r o m every stream m o u t h ' . On west Molokai, Hawaii, extensive soil erosion followed the i n t r o d u c t i o n o f livestock, pineapple farming and axis deer. In c o n s e q u e n c e the shoreline has advanced across the reef flat more than a mile in some areas b u r y i n g the reef c o mm u n i t i e s in red silt. Kaneohe Bay is the largest bay in the Hawaiian Islands and its extensive, sheltered, colourful reefs are accessible to more people for skin diving and commercial and sports fishing than any o t h e r reefs in the islands. In addition the m o s t extensive coral reef research p r o g r a m m e in the Pacific is centred on the bay at the Hawaii Institute of Marine...