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Artificial reefs: Myth or reality?
Marine Pothaion Bulletin, Volume 18, No. 7, pp. 367-368, 1987. Pnnted in Great Britain.
Artificial Reefs: Myth or Reality? Among various systems of sea-farming, particular attention has been given to the installation, on the sea bottom, of artificial reefs for the increase of production. In fact, new surfaces are created for sessile organisms as well as new habitats for fish, cephalopods and crustaceans. The cavities constitute shelters and protection also for organisms at delicate biological stages (embryonic sacs of cephalopods, crustaceans in the moulting phase, etc.). On the sandy or detritus bottoms these new structures should therefore serve to attract and concentrate rocky bottom fish fauna so as to recycle the surplus energy concentrated near the coast and to create new fishing zones. Moreover, the artificial reefs protect the coastal fishing grounds against trawling in prohibited areas. This sea farming has been tried in many European and non-European countries, and it is even used for sport fishing in the United States. Initially various materials were used: old cars and street cars, old boats, used tyres, etc.; however the cars were abandoned almost immediately because they corroded rapidly, liberating toxic substances, and the tyres even if tied together and ballasted, were easily dragged away by trawl nets. In Japan and the United States experiments were tried with specially made concrete blocks; these have given much better results, being stable, heavy, and easy to assemble. They are made according to local requirements: with ample surfaces to facilitate larval fixation and with cavities and holes offering shelter; they can be developed vertically to allow the exploitation of different habitats according to photic or thermic slopes. A recent meeting organized by the General Fishing Council for the Mediterranean (GFCM) at Ancona (FAO Fisheries Report No. 357, 1986) gave an opportunity to take stock of the historical aspects and present situation in the context of coastal management and of the Mediterranean prospects opened by these activities. In France concrete and large-scale initiatives have been undertaken only recently, following a series of rather limited experiments. In Languedoc-Roussillon, in 1985, 15 000 m ~ of reefs were installed with the additional idea of deveiopment shellfish culture. On the Alpes Maritimes coast, a similar experiment is being conducted, which foresees by 1988 the installation of 20 000 m 3 of reefs, divided into three sections. These operations are part of a national programme, begun in 1984, which consists of a sedimentological and geotechnical study of immersion sites, a control of the modifications of the fish populations induced, presumably, by the presence of these structures, and a study of fish colonization dynamics. In Italy the first experiments were made in the middle Adriatic (Porto Recanati), starting with big pyramids composed of 14 blocks linked together by lines for mussel farming. Other reefs have been installed in
(1025-326X/87 $3.1)0+0.(10 1987 Pergamon Journals Ltd.
Liguria (Gulf of Rapallo) and along the coasts of Latium and Sicily. It is evident that these initiatives, if conducted in the proper places and on a scientific basis, can lead to remarkable benefits. Apart from the protection against trawling and the attraction of numerous species of commercial interest, the presence of an artificial reef permits the development of shellfish culture, thanks to an increase of colonization surface and to energy recycling. The most positive experience in Italy is that of Porto Recanati; the reefs constructed as above mentioned, of cement blocks according to precise rules, on soft bottoms and in waters rich in nutrients, have led to a new community of hard bottoms with a notable increase in production of fish, mussels, and gastropods. This is demonstrated not only by comparative statistical data from the National Research Council (CNR) laboratory in Ancona but, above all, by the request from fishermen to convert their present trawling methods to fixed equipment in protected zones. Other experiences are not as positive, at least at the present, and show contradictory results. We have seen in fact many local initiatives without a coordinated programme with a return in certain cases to the use of old automobile bodies and used tyres (as was done at Varazze in Liguria) in the hope of increasing sport fishing but also to get rid of useless junk. In other cases, reefs were built to protect, in some unexplained way, the Posidonia and hard bottom communities. In Sicily it seems to have been an increase in fish production only on the reefs in the Gulf of Castellamare, where the waters show a certain degree of nutrients. For other zones of the island there is no precise documentation about the advantages brought by artificial reefs. As to the Latium experiences, the reefs installed near the mouth of the Tiber were initially colonized by a large number of mussels. The population however has steadily been reduced, probably because of the presence of inert suspended matter from the river. Even though from a scientific viewpoint, some experiments are interesting and have scientific validity for studying the modalities of colonization, there are no direct comparative data available for ascertaining whether the possible quantitative increase in fish fauna and the reappearance of some species are really due to the presence of the reefs or, more simply, to the protection of the area. It is a question which we must ask ourselves, for example, in the case of the experiments off the coast of Monaco and in the Gulf of Rapallo in areas adjacent to hard bottoms and in oligotrophic waters. The experience of marine parks teaches us, on the other hand, that the conservation of natural environments is obtained without the use of artificial structures. On this point the Italian law 979/1982 regarding the realization of marine parks is clear: it excludes any changes in the natural environment of the protected areas. On the contrary, the law 41/1982 provides expressly for artificial reefs but with the exact aim of increasing fishery in suitable places. It is therefore a question of two entirely distinct purposes. Given the favourable prospects that this technique (if well conducted) can offer for sea-farming, the construc367
Marine Pollution Bulletin
tion of reefs must not be left to improvization and superficiality. It is clear that to avoid useless waste it is imperative to assess whether the ecological characteristics of a particular area guarantee a good probability of success, in close collaboration with fishermen, administrators, and researchers. In many cases it does
Marine Pollution Bulletin, Volume 18, No. 7, p. 368. 1987. Printed in Great Britain.
Inventory Management for Pollution Control Contaminants are often introduced into the environment unnecessarily because of poor agricultural, forestry and industrial practices. Malpractices in agriculture that lead to losses of soil, fertilizers and pesticides to adjacent waters are legion. One of my early experiences, however, was with pest control in the forest industry. It had to do with infestation of freshly cut logs by the ambrosia beetle, Trypodendron spp. These beetles bore into the green sapwood where they introduce a fungus to feed their newly hatched larvae. The fungus creates a stain in the wood which renders it unacceptable, or at least of much lower value, as a peeler log for plywood production. Freshly cut logs that were subject to attack by the ambrosia beetle were often held in log booms in coastal bays and inlets until they were ready to be taken to a plywood mill. The method of control that was being tested by the forest industry was spraying with a formulation of benzene hexachloride (BHC; more accurately, hexachlorocyclohexane). My involvement was to determine if BHC was persistent in seawater, as DDT had been found to be earlier. Other scientists examined its toxicity to salmon. It was found that the BHC formulation was toxic to coho salmon, Oncorhynchus kisutch, but only at a relatively short distance (up to 0.3 m) below the sprayed log booms (Jackson, K. J., 1959, Can. Fish. Culturist 27, 33-42). Our work on the persistence of BHC in seawater showed that it was comparatively unstable (Werner, A. E. & Waldichuk, M., 1961, J. Fish. Res. Bd. Can. 18, 287-289). There was no strong argument against using this pesticide in seawater, provided fish were not in the area at the time of the spraying. After all factors were considered, however, the forest
368
not seem that these norms have been observed. The EEC rightly requires, before giving financial support, that the plans must be underwritten by a research organization which guarantees the necessary basic studies. G. COGNETTI
O025-326X/87 S3.o0+0.00 © 1987 Pergamon Journals Ltd.
industry entomologist working on the project recommended that no spraying be done but that log booming be managed differently. By avoiding storage of newly cut logs in log booms when swarming of the ambrosia beetle was most intense, the problem of infestation of logs held in water would not arise. Spraying water on logs stored on land effectively prevented beetle damage (Richmond, H. A., & Nijholt, W. W., 1972, Water misting for log protection from ambrosia beetles in B.C., Environment Canada, Forestry Service, Pacific Forest Research Centre, Victoria, B.C.). This strategy for controlling infestation of freshly cut logs has been quite effective, and there has been no need to spray them with a pesticide and thus introduce it into the environment. Logging introduces ecological problems in coastal waters through storage and transportation (see Mar. Pollut. Bull. 10, 33-34). A major impact of logs in coastal waters stems from dumping them from vehicles on land into the water. This practice has been largely abandoned. Easy let-down devices are being used to lower logs into the water. Dry sorting on land is taking over from log booming and sorting in coastal waters. Among recommendations made on water transportation and storage of logs (Sedell, J. R., & Duval, W. S., 1985, General Technical Report PNW-186, USDA Forest Service Anadromous Fish Habitat Program, Pacific Northwest Forest and Range Experiment Station, Portland, Ore.), one states: "The inventory of logs in water for any purpose should be kept to the lowest possible number for the shortest possible time". Clearly, inventory management in the forest industry can play an important role in minimizing water pollution. No doubt it can do the same in other industries as well. MICHAEL WALDICHUK
Artificial Reefs: Myth or Reality? Among various systems of sea-farming, particular attention has been given to the installation, on the sea bottom, of artificial reefs for the increase of production. In fact, new surfaces are created for sessile organisms as well as new habitats for fish, cephalopods and crustaceans. The cavities constitute shelters and protection also for organisms at delicate biological stages (embryonic sacs of cephalopods, crustaceans in the moulting phase, etc.). On the sandy or detritus bottoms these new structures should therefore serve to attract and concentrate rocky bottom fish fauna so as to recycle the surplus energy concentrated near the coast and to create new fishing zones. Moreover, the artificial reefs protect the coastal fishing grounds against trawling in prohibited areas. This sea farming has been tried in many European and non-European countries, and it is even used for sport fishing in the United States. Initially various materials were used: old cars and street cars, old boats, used tyres, etc.; however the cars were abandoned almost immediately because they corroded rapidly, liberating toxic substances, and the tyres even if tied together and ballasted, were easily dragged away by trawl nets. In Japan and the United States experiments were tried with specially made concrete blocks; these have given much better results, being stable, heavy, and easy to assemble. They are made according to local requirements: with ample surfaces to facilitate larval fixation and with cavities and holes offering shelter; they can be developed vertically to allow the exploitation of different habitats according to photic or thermic slopes. A recent meeting organized by the General Fishing Council for the Mediterranean (GFCM) at Ancona (FAO Fisheries Report No. 357, 1986) gave an opportunity to take stock of the historical aspects and present situation in the context of coastal management and of the Mediterranean prospects opened by these activities. In France concrete and large-scale initiatives have been undertaken only recently, following a series of rather limited experiments. In Languedoc-Roussillon, in 1985, 15 000 m ~ of reefs were installed with the additional idea of deveiopment shellfish culture. On the Alpes Maritimes coast, a similar experiment is being conducted, which foresees by 1988 the installation of 20 000 m 3 of reefs, divided into three sections. These operations are part of a national programme, begun in 1984, which consists of a sedimentological and geotechnical study of immersion sites, a control of the modifications of the fish populations induced, presumably, by the presence of these structures, and a study of fish colonization dynamics. In Italy the first experiments were made in the middle Adriatic (Porto Recanati), starting with big pyramids composed of 14 blocks linked together by lines for mussel farming. Other reefs have been installed in
(1025-326X/87 $3.1)0+0.(10 1987 Pergamon Journals Ltd.
Liguria (Gulf of Rapallo) and along the coasts of Latium and Sicily. It is evident that these initiatives, if conducted in the proper places and on a scientific basis, can lead to remarkable benefits. Apart from the protection against trawling and the attraction of numerous species of commercial interest, the presence of an artificial reef permits the development of shellfish culture, thanks to an increase of colonization surface and to energy recycling. The most positive experience in Italy is that of Porto Recanati; the reefs constructed as above mentioned, of cement blocks according to precise rules, on soft bottoms and in waters rich in nutrients, have led to a new community of hard bottoms with a notable increase in production of fish, mussels, and gastropods. This is demonstrated not only by comparative statistical data from the National Research Council (CNR) laboratory in Ancona but, above all, by the request from fishermen to convert their present trawling methods to fixed equipment in protected zones. Other experiences are not as positive, at least at the present, and show contradictory results. We have seen in fact many local initiatives without a coordinated programme with a return in certain cases to the use of old automobile bodies and used tyres (as was done at Varazze in Liguria) in the hope of increasing sport fishing but also to get rid of useless junk. In other cases, reefs were built to protect, in some unexplained way, the Posidonia and hard bottom communities. In Sicily it seems to have been an increase in fish production only on the reefs in the Gulf of Castellamare, where the waters show a certain degree of nutrients. For other zones of the island there is no precise documentation about the advantages brought by artificial reefs. As to the Latium experiences, the reefs installed near the mouth of the Tiber were initially colonized by a large number of mussels. The population however has steadily been reduced, probably because of the presence of inert suspended matter from the river. Even though from a scientific viewpoint, some experiments are interesting and have scientific validity for studying the modalities of colonization, there are no direct comparative data available for ascertaining whether the possible quantitative increase in fish fauna and the reappearance of some species are really due to the presence of the reefs or, more simply, to the protection of the area. It is a question which we must ask ourselves, for example, in the case of the experiments off the coast of Monaco and in the Gulf of Rapallo in areas adjacent to hard bottoms and in oligotrophic waters. The experience of marine parks teaches us, on the other hand, that the conservation of natural environments is obtained without the use of artificial structures. On this point the Italian law 979/1982 regarding the realization of marine parks is clear: it excludes any changes in the natural environment of the protected areas. On the contrary, the law 41/1982 provides expressly for artificial reefs but with the exact aim of increasing fishery in suitable places. It is therefore a question of two entirely distinct purposes. Given the favourable prospects that this technique (if well conducted) can offer for sea-farming, the construc367
Marine Pollution Bulletin
tion of reefs must not be left to improvization and superficiality. It is clear that to avoid useless waste it is imperative to assess whether the ecological characteristics of a particular area guarantee a good probability of success, in close collaboration with fishermen, administrators, and researchers. In many cases it does
Marine Pollution Bulletin, Volume 18, No. 7, p. 368. 1987. Printed in Great Britain.
Inventory Management for Pollution Control Contaminants are often introduced into the environment unnecessarily because of poor agricultural, forestry and industrial practices. Malpractices in agriculture that lead to losses of soil, fertilizers and pesticides to adjacent waters are legion. One of my early experiences, however, was with pest control in the forest industry. It had to do with infestation of freshly cut logs by the ambrosia beetle, Trypodendron spp. These beetles bore into the green sapwood where they introduce a fungus to feed their newly hatched larvae. The fungus creates a stain in the wood which renders it unacceptable, or at least of much lower value, as a peeler log for plywood production. Freshly cut logs that were subject to attack by the ambrosia beetle were often held in log booms in coastal bays and inlets until they were ready to be taken to a plywood mill. The method of control that was being tested by the forest industry was spraying with a formulation of benzene hexachloride (BHC; more accurately, hexachlorocyclohexane). My involvement was to determine if BHC was persistent in seawater, as DDT had been found to be earlier. Other scientists examined its toxicity to salmon. It was found that the BHC formulation was toxic to coho salmon, Oncorhynchus kisutch, but only at a relatively short distance (up to 0.3 m) below the sprayed log booms (Jackson, K. J., 1959, Can. Fish. Culturist 27, 33-42). Our work on the persistence of BHC in seawater showed that it was comparatively unstable (Werner, A. E. & Waldichuk, M., 1961, J. Fish. Res. Bd. Can. 18, 287-289). There was no strong argument against using this pesticide in seawater, provided fish were not in the area at the time of the spraying. After all factors were considered, however, the forest
368
not seem that these norms have been observed. The EEC rightly requires, before giving financial support, that the plans must be underwritten by a research organization which guarantees the necessary basic studies. G. COGNETTI
O025-326X/87 S3.o0+0.00 © 1987 Pergamon Journals Ltd.
industry entomologist working on the project recommended that no spraying be done but that log booming be managed differently. By avoiding storage of newly cut logs in log booms when swarming of the ambrosia beetle was most intense, the problem of infestation of logs held in water would not arise. Spraying water on logs stored on land effectively prevented beetle damage (Richmond, H. A., & Nijholt, W. W., 1972, Water misting for log protection from ambrosia beetles in B.C., Environment Canada, Forestry Service, Pacific Forest Research Centre, Victoria, B.C.). This strategy for controlling infestation of freshly cut logs has been quite effective, and there has been no need to spray them with a pesticide and thus introduce it into the environment. Logging introduces ecological problems in coastal waters through storage and transportation (see Mar. Pollut. Bull. 10, 33-34). A major impact of logs in coastal waters stems from dumping them from vehicles on land into the water. This practice has been largely abandoned. Easy let-down devices are being used to lower logs into the water. Dry sorting on land is taking over from log booming and sorting in coastal waters. Among recommendations made on water transportation and storage of logs (Sedell, J. R., & Duval, W. S., 1985, General Technical Report PNW-186, USDA Forest Service Anadromous Fish Habitat Program, Pacific Northwest Forest and Range Experiment Station, Portland, Ore.), one states: "The inventory of logs in water for any purpose should be kept to the lowest possible number for the shortest possible time". Clearly, inventory management in the forest industry can play an important role in minimizing water pollution. No doubt it can do the same in other industries as well. MICHAEL WALDICHUK