OCEANOGRAPHIC PROCESSES IN THE COSTAL SEAS

AROUND DEVELOPING COUNTRIES

Location: Watson Building G23 LTA

Location of Poster: Bridge Poynting/Watson

Saturday 24 July AM

Presiding Chair: S.V. Durvasula, (Kuwait Institute of Scientific Research, Kuwait)

PW1/E/04-A6 0900

MULTI-PHASE DISTRIBUTION OF ORGANIC MICROPOLLUTANTS IN XIAMEN HARBOUR, CHINA

J.L. Zhou*, Z. Zhang+, K. Maskaoui+ and H. Hong+ School of Ocean Sciences, University of Wales Bangor, Menai Bridge, Anglesey LL59 5EY, UK+Environmental Science Research Centre, Xiamen University, Xiamen 361005, P.R. China

Abstract 2. Xiamen Harbour, In Xiamen Special Economic Zone of the People’s Republic of China, was studied for its water and sediment quality, by determining the levels of 16 polycyclic aromatic hydrocarbons (PAHs), 12 polychlorinated biphenyls (PCBs) and 18 organochlorine insecticides in water, porewater and sediment samples from nine stations in the Harbour. Total PAH concentrations varied from 106 to 945 ng/l in water, 0 to 3548 ng/l in porewater, and 247 to 480 ng/g dry weight in surficial sediments. Total PCB levels varied from 0.12 to 1.69 ng/l in water, 2.67 to 34.80 ng/l in porewater, and 0 to 0.32 ng/g dry weight in sediments. The levels of all insecticides were in the range 6.60 - 19.56 ng/l (water), 11.93 - 78.53 ng/l (porewater), and 0 - 0.58 ng/g dry weight (sediment). The levels of total hexachlorocyclohexane (HCHs) in sediments varied from 0 to 0.14 ng/g dry weight, and those of total DDTs were in the range 0 - 0.06 ng/g dry weight. The micropollutants were present in higher levels in porewater than in surface water, due to the preference of these hydrophobic compounds for sedimentary phase than for water. Such a concentration gradient imply a potential flux of pollutants from sediments to overlying water. The levels of pollutants in sediments were one to several orders of magnitude lower than those in 1993, suggesting their decreased inputs in recent years and possible degradation over a period of time. Further work is needed to quantify the levels of these contaminants in suspended particulate matter, which are currently below the limits of detection.

PW1/W/05-A6 0920

TROPICAL REGIONS OF FRESHWATER INFLUENCE

ALEJANDRO J. SOUZA (Centre for Coastal & Marine Sciences, Proudman Oceanographic Lab, Bidston Observatory, Birkenhead, L43 7RA, UK email:ajso@ccms.ac.uk) and John H. Simpson (School of Ocean Sciences, Menai Bridge, Anglesey, LL59 5EY, UK).

The processes involve in the dynamics of Regions of Freshwater Influence (ROFIs) have been studied for some time in the first world countries, this has lead to basic understanding of this systems. But the Mayor ROFIs are located in tropical regions and predominatly third world countries in America, Asia and Africa, most of these systems are little studied and insitu data is scarce or non existant. The study of tropical ROFIS is of great importance to the global ecology as is here that there is great diversity of marine organisms live or develope, at the same time these regions are subject to important fisheries and in some cases are subject to large inputs of agreochemicals, as in the case of west Mexico and Mozambique. This calls for a knowledgable mangement of the Tropical ROFIs, which only be possible if the knowledge aquired in developed countries is transfered to underdeveloped countries.

PW1/P/01-A6 0940

MANGROVE DENUDATION AND ECOLOGICAL CHANGES IN A BAY-ESTUARY SYSTEM ON THE EAST COAST OF INDIA

Raman A.V., Frank Dehairs*, Chandramohan, P., Dipti Raut, Murthy, N.V. S. S., Rohini, T. and Satyanarayaiia, B. (Marine Biological Laboratory, Department of Zoology, Andhra University, Visakhapatnam-530 003, India, email: pcmavr@md2.vsnl.net.in) *Department of Analytical Chemistry (ANCH), Virje Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium, email: fdehirs@vub.ac.be)

Kakinada Bay, a shallow (<5 m) bar-built water body on the east coast of India, underwent many topographical changes attributable to port expansion programmes and industrial development recently. The Bay which covers an area of approximately 132 sq.km. is surrounded by extensive estuarine areas with enormous mangrove vegetation mainly, Avicennia, Excoecaria, Rhizophora, Aegiceras, Lumnitzera, Ceriops and others. In recent years, there has been a spurt in shrimp farming activity in this area which resulted in the destruction of much of this vegetation, the impingement being very severe in some localities. Investigations during the last three years (1994-1997) revealed appreciable changes in water quality and organisms in the Bay and tributaries, Coringa and Gaderu, as a result of these activities. In Coringa-Gaderu region close to shrimp farms, a several fold increase in nitrate (max. 83.52 µg.at/1) and phosphate (max. 41.6 µg.at/1) levels was noticed. Several species of phytoplankton notably Navicula, Skeletonema costatum,

Pleurosigma angulatum and Nitzschia closterium occur here often in bloom proportions (8,000 cells/ml). Within the Bay, regions once supported dense assemblages of benthic organisms (molluscs) Anadara, Placuna, Tonna and Turritella have now given place to different species owing to changes in sediment nature. Over the years, population size of these species decreased as a result of over exploitation commercially. The paper purports to draw comparisons between this study with those conducted in 1959-1964 attributing changes to anthropogenic effects during the intervening years.

PW1/W/02-A6 1000

OVERTURNING LENGTH SCALE AS AN INDICATOR OF THE WASTEWATER NEAR FIELD

Vlado MALACIC (Marine Biological Station, National Institute of Biology, Piran, 6330, Slovenia, email: malacic@nib.si)

During a period of calm weather and stratified water column of a shallow (depth = 21 m) semi-enclosed sea, six surveys of the wastewater near-field of two adjacent submarine diffuser outfalls, with a low sewage ouflow rate (usually less than 220 l/s), were conducted with a fine-scale CTD probe. The survey area of 780m_740m was monitored with the free-falling probe at 30-31 stations. Vertical velocity of the probe was nearly constant, 1 m/s, and the data was retrieved at a frequency of 50 Hz, providing a vertical resolution of 2.5 cm.

When using a fine-scale CTD it has been observed that from the vertical distribution of 'virtual' displacements (Thorpe displacements) of particles with a sampled density, by which each particle would gain a statically stable position, the length scale of overturning events could be estimated, through an appropriate averaging process.

Within the turbulent wastewater field the fluctuations of temperature were of the order of 0.1 oC, and of salinity less than 0.05 psu, generating overturning. The vertical extent of the overturning events could well be determined using the maximum vertical displacement, or the Thorpe length scale. Both scales also indicate the thickness of the neutrally buoyant subsurface wastewater field. Distribution of these length-scales over the diffussors show a clear picture of the wastewater field(s) of a thickness smaller than 1m in windless, stratified conditions, which is otherwise hard to obtain without costly experiments (dye tracers).

PW1/P/03-A6 1120

OCEANOGRAPHIC PROCESSES AND IMPACT OF HUMAN ACTIVITY ON COASTAL EROSION:A CASE STUDY FROM KARNATAKA, INDIA

K S JAYAPPA (Marine Geology Faculty, Mangalore University, Mangalagangotri-574199, Karnataka, India, email:jayappa@mnglr.ernet.in)

Complex nearshore processes change continually and derive their energy from waves and currents. Variations in energy distribution within the surf zone cause transport of sediment alongshore and offshore. Beach erosion in Karnataka has become a severe problem since last two decades. It is estimated that out of 290 km, 80 km is vulnerable to erosion during SW monsoon. The factors which are responsible for erosion of this coast are: storm waves, tidal and longshore currents, wave refraction (all natural), construction of ports, harbours, breakwaters, seawalls, damming of rivers and sand mining (all man-made). Of these, the man-made erosion and steps taken for its prevention are important ones to be attended immediately. In recent years, coastal communities are inhabiting newly developed coastal landforms. Beach erosion is part of a cyclic process and maintains a seasonal balance between erosion and accretion, but in some cases net erosion or accretion takes place. Erosion of beaches could be minimised by preventing (1) human interference with coastal processes, (2) inhabitation of fragile zones, and (3) sand mining from beaches and estuaries.

Seawalls which are used as erosion management tools, often complicate the erosion problem or shift the erosional sites to adjacent areas. In general, the cost of seawall construction and maintenance is greater than the value of the property saved. In some cases they have been destroyed by huge waves thereby recreational potentials of beaches are lost and posed a severe threat for shore-based fishing activity.

PW1/E/02-A6 1140

ON THE ISTRIAN COASTAL COUNTERCURRENT

Nastjenjka Supic (Centre for Marine Research, Rudjer Boskovic Institute, G. Paliaga 5, 52210 Rovinj, Croatia, email: supic@cim.irb.hr) Mirko ORLIC (Andrija Mohorovicic Geophysical Institute, email orlic@olimp.irb.hr) Danilo Degobbis (Centre for Marine Research, Rudjer Boskovic Institute, email: degobbis@cim.irb.hr)

By computing the relative (with respect to the 30 dbar surface) and absolute geostrophic currents and net transports from hydrographic data collected monthly to seasonally at six stations of the Po-Rovinj profile in the northern Adriatic, we demonstrate the existence of a descending current which usually appears in August along the Istrian coastal line and runs counter to the general Adriatic-wide cyclonic flow. We name it Istrian Coastal Countercurrent (ICCC). The current is found to be confined to the surface (of a 10 m depth) and coastal boundary (of a 10 km width) layers. Its mean relative speed is high, 7 cm/s (relative currents at the profile on average stay below 5 cm/s in winter and below 8 cm/s in summer), inducing a net geostrophic outflow near the Istrian coast. The ICCC was strong in 1968, 1977, 1983, 1984, 1988, 1989, 1991, 1992, 1996 and 1997, weak or absent in 1971, 1972, 1973, 1982, 1986, 1993, 1994 and 1995. Whenever the ICCC was well pronounced, a strong northerly flow was observed in the central part of the northern Adriatic profile, whereas a thick surface or subsurface layer of low density was found in the open waters off Rovinj. This points to a possible existence of a cyclonic gyre east of the Po delta and/or anticyclonic gyre off Rovinj. The existence of ICCC is confirmed by direct current measurements, which show that the descending coastal current was intense in 1977 and 1983, and that it did not develop in 1976, 1978 and 1987. The August intensity of the ICCC significantly correlates with the sea surface temperature (SST) recorded in preceding March in the northeastern Adriatic. Using a polynomial fit of the ICCC speed on the northeastern Adriatic SST a weak or non-existent ICCC is hindcasted for 1976 and 1987. It seems that a high intensity of ICCC coincides with oceanographic conditions which favour near anoxia or mucilage events, observed in 1988, 1989, 1991 and 1997.

PW1/W/03-A6 1200

INTERNAL WAVES AND ACOUSTIC FIELDS IN THE SHELF ZONE OF SEA

Vadim V. NAVROTSKY, Alexander N. Rutenko (Pacific Oceanological Institute, 43 Baltiyskaya Str., Vladivostok, 690041, Russia, email: navr@online.vladivostok.ru)

Some results of experimental investigation of internal waves and their influence on the characteristics of acoustic fields in the shelf zone of the Japanese Sea are presented. In our field experiments we used continuous signals with sinusoidal frequency modulation in the range 306- 328 Hz. Simultaneous measurements of acoustic parameters and water temperature fluctuations at different levels were made with the help of a measuring system, placed at distance of 250 m from the emmitor with the site depth of 38 m. It is shown, that intensities of acoustic signals with 4% difference of frequencies have rather different variations in time, sometimes in counterphase. The differences are maximum at levels, where the interference minimum is observed. Half-day tides cause 3 Hz displacements of the minimum in the interference structure of the measured acoustic field. The statistical analysis of temperature fluctuations at different levels was made. It was shown that in the range of short internal waves the most pronounced effects are due to resonant interactions of acouctic waves with sound velocity inhomogeneities, registered by temperature sensors. The main result of such interactions is redistribution of acoustic energy among normal modes with general flow of energy into higher modes and phase randomization.

PW1/E/01-A6 1220

ANTHROPOGENIC DISCHARGES INTO THE MOZAMBIQUE CHANNEL

U.ASWATHANARAYANA (c/o Ministry for the Coordination of Environmental Affairs, C.P. 1947, Maputo, Mozambique. Email : anarayan@zebra.uem.mz)

Mozambique Channel receives two kinds of anthropogenic discharges:

(i) Discharges (accidental or deliberate) from about 200 ships (mostly tankers) that pass through the Mozambique Channel daily - no discharge data is available in this regard, and (ii) anthropogenic discharges from the coast - these are studied along four principal coastal towns from south to north, namely, Maputo, Beira, Quelimane and Pemba.

In the case of Maputo and Beira, the industrial discharges into the sea are due to the port, oil installations, food and beverage processing, batteries, edible oils and soaps,textiles, fishing and canning, tourism, animal farms, etc. Municipal sewerage, with human faeces, is discharged into the sea untreated, with the consequence that the seawater is heavily contaminated with E.Coli ( x 1000/100 mL). In the case of Quelimane and Pemba, the industrial discharges into the sea are minimal, but the biological pollution of the sea is serious, as a good part of the population defaecate in the mangroves or on the beach. The human faeces get washed into the sea at high tide, and end up in fish which people consume. If there are cholera pathogens in the human faeces, cholera epidemic results. The cholera epidemic caused by ENSO-induced flooding along the east coast of Africa, killed an estimated 5000 people last year.

Saturday 24 July PM

Presiding Chair: S.V. Durvasula, Kuwait Institute of Scientific Research, Kuwait

PW1/W/06-A6 1400

STABILITY AND MORPHOLOGY OF THE COASTAL CONTOURS FROM SEDIMENTOLOGICAL LIFTING IN THE FORTALEZA-CE AREA, BRAZIL

Prof Agenor Cunha da Silva

This work was generated from studies required to the Directorate of Hydrography and Navigation of the Brazilian Navy by the National Union State Secretariat of the Ministery of the Treasury in order to analyse the evolution of coastal features in the municipalities of Fortaleza, Aquiraz, Caucaia and São Gonçalo do Amarante, Ceará State, Brazil, with views to determine the real mean high water line to charge taxes. The mean high water line was referred initially by the mean sea level in 1831, and it must be corrected because of the possible changes in that line. It includes granulometry and analysis of the sediments collected along the coast, between September 28 and October 02, 1993. The stability and contours of Northeastern and Southeastern beaches of Ceará, Brazil were researched. In addition, the intensity and evolution of the coastal process were examined in order to make a diagnosis, with the use of sedimentology, of areas where the contour mobility may imply loss of accuracy in cartographic works.

PW1/P/02-A6 1420

THE FUTURE PROSPECTS OF OCEANOGRAPHIC RESEARCH IN THE MEDITERRANEAN AND RED SEAS BY THE SURROUNDING DEVELOPING COUNTRIES

S.H. SHARAF EL DIN, Oceanography Department, Faculty of Science Alexandiua University

POEM is a multi-national co-operative research program initiated and carried out by scientists in both the regional oceanography and the potential of the eastern Mediterranean to provide a laboratory basin for global processes. In the past, some of the developing countries surrounding the eastern Mediterranean shared with a limited efforts in the various studies. More recently, several developing countries such as Egypt, Israel, Lebanon, Syria and Libya started to increase their scientific activities in the eastern Mediterranean. In Egypt, a lot of studies have been done on the management of the Egyptian Mediterranean coastal areas. Recently, study of the effect of some environmental factors on the distribution of the phytoplankton in the banias region on the Syrian coast has been taken place, In Lebanon, a model was constructed as a useful tool for the rehabilitation, protection and development of the Lebanese coast. Also, the status and solution of Beirut Bay wastewater problem was

studied extensively. In Lybia, the marine science activities were devoted more recently to the fisheries, pollution and coastal zone management.

In the Red Sea area, most of the work carried out in Suez, Bay, was mainly pollution and coastal zone management. In Aquba Gulf, most of the work done by a group of scientists from USA, Egypt and Israel. The project was mainly devoted to study the biological and environmental parameters in the Gulf. In the Red Sea, the research projects are still limited to the regional boundaries.

PW1/E/06-A6 1420

CZM AND THE COASTAL SEA: THE NEED TO ASSESS COASTAL ZONE VULNERABILITY AND APPLY LONG TERM STRATEGIC MEASURES

A. N. BALCHAND (Department of Physical Oceanography, Cochin University of Science and Technology, Fine Arts Avenue, Cochin 682 016, India, email: oceans@md3.vsnl.net.in)

The interaction between the land and oceans has been recognized as an important surface process of short and long term time scales. The dynamic properties and functional attribute of the coastal zone are the results of cumulative global environmental change - sea level changes, landscape alterations, marine ecosystem changes, trends in sedimentary behavioral patterns, hydrological factors and so forth. Of immediate concern is the coastal zone vulnerability arising due to climate change, subsidence and recession of coastlines, mining activities, water abstraction and large changes in wetland management. Study subjects often chosen relates to areas at change and related population at risk, agricultural production at change and ecosystem losses. The sensitive tropical coastal regions (mostly in low lying lands) which are highly productive and densely populated are currently threatened by above stated changes. Thus the need to assess coastal zone vulnerability based on information gathered on the physical environment, geomorphological setup, evaluation of varying trends of both natural and anthropogenic influences is relevant. The evaluation methodology shall aim at assessing the extent of damage already inflicted to the region, the response pattern, the remedial measures adopted and thus help us to deduce better understanding on the development of the fragile coastal sea. A suitable database covering land water uses and practices, development of wetlands, their functions and resources along with risk estimation and hazard evaluation would lead to the right application of long term strategic measures.

PW1/E/07-A6 1500

IMPACT OF RIVER DIVERSION IN SOUTHERN IRAQ ON THE HYDROBIOLOGY OF THE NORTHERN ARABIAN GULF

FAIZA AL-YAMANI Kuwait Institute for Scientific Research, P.O. Box 1638, Salmiyah-22017, Salmiyah, Kuwait.

The Arabian Gulf is a semi-enclosed body of water located in a climatically arid region with an average depth of 35 m, with a maximum depth of 120 m. Its only source of freshwater is seasonal and from the Shatt al-Arab in the north. High evaporation rates in excess of precipitation and river discharge result in high salinity (~ 42 psu). Frequent northwesterly winds mix the northern Gulf's shallow waters contributing to the resuspension of particulate matter and high turbidity from the silt-laden waters of the Shatt al-Arab. Freshwater enters the northern Gulf via the Shatt al-Arab, with an estimated annual discharge rate of 5 to 100 km3/yr. The Shatt al-Arab watershed and associated marshes are the main sources of nutrients that sustain a high productivity in the northern Gulf. Recently, Iraq completed its diversion of the Euphrates River to a man-made canal named the Third River which flows to the northwestern part of the Gulf. Additionally, more than 60% of the marshes in southern Iraq have been drained. Such developments as well as the ongoing Southeast Anatolia Project in Turkey, will exert a great impact, particularly in the northern Gulf. Comparison of recent data (1995-1998) with the earlier showed : a) a decrease in salinity in the northwestern Gulf to 25.60-33.00 psu, b) elevation of nutrients to higher ranges (6-15 mg-at/l nitrates, 0.4-0.9 mg-at/l phosphates, and 26-43 mg-at/l silicates). This is attributable to the impact of additional river runoff from the diversion. Additionally, higher turbidity levels (58-174 NTU), and higher phytoplankton biomass were recorded for the northern waters. Changes in the marine ecosystem resulting from alteration of flow regimes and water quality of the Shatt al-Arab waterway will probably have a major impact on the fishery resources of the northern Gulf. Especially the economically important species such as the shrimp-Metapenaeus affinis, the pomfret Pampus argenteus, and the suboor Tenualosa ilisha which are known to directly depend on freshwater inflow for spawning or nursery habitat. Additionally, indirect effects, operating through changes in the food web, may further impact population abundances, species diversity and imbalances amongst species.

PW1/W/01-A6 1520

THE HEAT BUDGET OF A TIDAL BAY

SHIGALLA B. MAHONGO Tanzania Fisheries Research Institute P.O. Box 9750 Dar es Salaam Tanzania

Atmospheric, sea surface temperature and sea level data were collected for a 23-day period at Chwaka bay (Zanzibar Island)in 1996. The data were used to calculate the turbulent fluxes of heat and moisture from a bulk aerodynamic method. The net radiative (long-wave and short-wave) heat fluxes were computed from records of incoming and outgoing short-wave radiation, and net all-wave radiation. An independent method was used to calculate the advective heat flux, and results conformed with a qualitative analysis of net surface heat flux in relation to the tidal phase, and to the water temperature variability. The effect of water-sediment heat conduction was basically a net transfer of heat from sediments to inundating water layers. The heat budget of the bay involves a near balance between heating by solar radiation, and cooling by evaporation and advective exchange with the open ocean. Maximum net surface heating occurs at around noon, while maximum net surface cooling takes place immediately after sunset.