Pub Date : 2002-08-29DOI: 10.1201/9780203180594-22
P. Snelgrove, C. Smith
Deep-sea ecosystems are the most extensive and remote ecosystems on Earth. Perception of the deep-sea benthic environment has changed dramatically in the last century from one of an azoic, or at least species-poor habitat to one that is rich in species. The early misconception was created, in part, by evidence of vast, monotonous expanses of cold, dark sediment plains with little obvious spatial or temporal heterogeneity. Given that many species-rich ecosystems on Earth are obviously heterogeneous, it is surprising that some estimates of species numbers in the deep sea (e.g. ∼10 7 macrofaunal species) rival those for tropical rainforests. Although other estimates are more conservative (e.g. 5 x 10 5 macrofaunal species), it is clear that deep-sea benthic habitats contain many species. The paradox of high deep-sea diversity has generated a number of explanatory hypotheses, including some that are currently difficult to test and others that are the focus of ongoing study. Approaches include analyses of local, regional, and global patterns, and experimental manipulations within habitats. Mechanistic generalisations are difficult to make because experimentation and sampling coverage are spatially and temporally limited, but evidence to date suggests that small-scale habitat variability and patchy disturbance, as well as global and regional variability, may play roles in maintaining deep-sea diversity. The importance of small-scale habitat variability and patchy disturbance has been demonstrated for only a small subset of species, many of which are opportunists. Broad inferences from global and regional patterns of species diversity are debatable because many areas remain poorly sampled and causes of patterns are ambiguous. Nonetheless, our understanding of diversity patterns in the deep-sea benthos has increased dramatically in the last three decades. If the approaching decades hold even a portion of the surprises seen in the recent past, then science can expect very exciting discoveries from the deep ocean in the near future.
{"title":"A riot of species in an environmental calm: the paradox of the species-rich deep-sea floor","authors":"P. Snelgrove, C. Smith","doi":"10.1201/9780203180594-22","DOIUrl":"https://doi.org/10.1201/9780203180594-22","url":null,"abstract":"Deep-sea ecosystems are the most extensive and remote ecosystems on Earth. Perception of the deep-sea benthic environment has changed dramatically in the last century from one of an azoic, or at least species-poor habitat to one that is rich in species. The early misconception was created, in part, by evidence of vast, monotonous expanses of cold, dark sediment plains with little obvious spatial or temporal heterogeneity. Given that many species-rich ecosystems on Earth are obviously heterogeneous, it is surprising that some estimates of species numbers in the deep sea (e.g. ∼10 7 macrofaunal species) rival those for tropical rainforests. Although other estimates are more conservative (e.g. 5 x 10 5 macrofaunal species), it is clear that deep-sea benthic habitats contain many species. The paradox of high deep-sea diversity has generated a number of explanatory hypotheses, including some that are currently difficult to test and others that are the focus of ongoing study. Approaches include analyses of local, regional, and global patterns, and experimental manipulations within habitats. Mechanistic generalisations are difficult to make because experimentation and sampling coverage are spatially and temporally limited, but evidence to date suggests that small-scale habitat variability and patchy disturbance, as well as global and regional variability, may play roles in maintaining deep-sea diversity. The importance of small-scale habitat variability and patchy disturbance has been demonstrated for only a small subset of species, many of which are opportunists. Broad inferences from global and regional patterns of species diversity are debatable because many areas remain poorly sampled and causes of patterns are ambiguous. Nonetheless, our understanding of diversity patterns in the deep-sea benthos has increased dramatically in the last three decades. If the approaching decades hold even a portion of the surprises seen in the recent past, then science can expect very exciting discoveries from the deep ocean in the near future.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84419988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-01-01DOI: 10.1201/9780203180594-12
D. Thomas, G. Dieckmann
Antarctic sea ice at its maximum extent in winter covers 40% of the Southern Ocean in a frozen layer, on average, 1 m thick. Sea ice is not solid, rather it is an ice crystal matrix permeated by a labyrinth of brine filled channels and pores in which life thrives. Organisms are constrained by a set of physicochemical factors quite unlike anything they encounter in the plankton from where they are recruited. Because sea ice is increasingly viewed as a suitable proxy for life in previous periods of the Earth's history, and even for astrobiology, it is pertinent that the physicochemical constraints acting upon sea-ice biology are better understood. The, largely microbial, network that develops in the ice itself imparts a unique chemistry that influ- ences the nature and chemical composition of biogenic material released from the ice. This chemistry can result in the export of material to the sediments with distinctive chemical signa- tures that are useful tools for reconstructing past sea-ice cover of the oceans. This review synthesises information on inorganic nutrient, dissolved organic matter and dissolved gases from a variety of Antarctic ice habitats.
{"title":"BIOGEOCHEMISTRY OF ANTARCTIC SEA ICE","authors":"D. Thomas, G. Dieckmann","doi":"10.1201/9780203180594-12","DOIUrl":"https://doi.org/10.1201/9780203180594-12","url":null,"abstract":"Antarctic sea ice at its maximum extent in winter covers 40% of the Southern Ocean in a frozen layer, on average, 1 m thick. Sea ice is not solid, rather it is an ice crystal matrix permeated by a labyrinth of brine filled channels and pores in which life thrives. Organisms are constrained by a set of physicochemical factors quite unlike anything they encounter in the plankton from where they are recruited. Because sea ice is increasingly viewed as a suitable proxy for life in previous periods of the Earth's history, and even for astrobiology, it is pertinent that the physicochemical constraints acting upon sea-ice biology are better understood. The, largely microbial, network that develops in the ice itself imparts a unique chemistry that influ- ences the nature and chemical composition of biogenic material released from the ice. This chemistry can result in the export of material to the sediments with distinctive chemical signa- tures that are useful tools for reconstructing past sea-ice cover of the oceans. This review synthesises information on inorganic nutrient, dissolved organic matter and dissolved gases from a variety of Antarctic ice habitats.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88046011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-01-01DOI: 10.1201/9780203180594.ch5
B. Gillanders, M. Kingsford
Freshwater is scarce in many regions of the world. In some areas, water entitlements currently exceed the available water supply yet few proposals for regulating quantities extracted are scrutinised in terms of possible impacts or undergo any form of rigorous impact assessment. In addition, there is little understanding of the potential impacts. There is a growing need to understand better the impact of altered flows of fresh water on estuarine and open coastal marine systems. There is a perception that fresh water is lost when it enters the marine environment. We argue that freshwater-saltwater dynamics have profound influences on coastal ecosystems. The purpose of this paper is to review the nature of freshwater discharges and the effects of fresh water on the physical aspects of estuaries as well as estuarine and marine flora, fauna and habitats. Although the review focuses on decreased flows to marine systems, major increases in flow can also have a major impact on estuarine and coastal systems. Freshwater runoff is a function of numerous environmental variables, depending primarily on climate (precipitation and evaporation) and the physical characteristics of the drainage basin. Anthropogenic activities in catchments may result in diversions and reductions in freshwater flow, alterations of timing and rates of flow to estuarine and coastal systems, and/or adverse water quality conditions with major changes in nutrient loading. Sediment loads, pH, temperature, salinity, clarity, oceanography and nutrients are affected. Perturbations in coastal systems can be freshwater pulses (i.e. storms or opening of floodgates) or press scenarios (i.e. persistent flow of low variation from rivers or industry). Impacts on organisms can also be categorised as pulse events (where there is a rapid but not sustained change), or press events (where changes are sustained over long periods of time). Changes to freshwater input affect habitats and organisms within estuaries. The effects include mortality, changes in growth and development, and in some cases movement of organisms. Major mortalities are most likely during pulse events of freshwater input. There is considerable descriptive and small-scale experimental evidence to suggest that a variety of organisms may be affected by changes to freshwater input. Much of the experimental evidence focuses on single factor experiments and rarely have there been multifactorial experiments (an exception is seagrasses). In addition, there have been no large-scale experiments (e.g. size of sample unit 10's to 100's of metres), although it is acknowledged that such experiments will be difficult. We suggest that any changes in water management (e.g. removal of water for irrigation) should be treated as manipulative experiments and that estuarine and marine systems are monitored together with reference or control locations (where there has been no change) to determine the impact of such changes. At the large scale, finding suit
{"title":"Impact of changes in flow of freshwater on estuarine and open coastal habitats and the associated organisms","authors":"B. Gillanders, M. Kingsford","doi":"10.1201/9780203180594.ch5","DOIUrl":"https://doi.org/10.1201/9780203180594.ch5","url":null,"abstract":"Freshwater is scarce in many regions of the world. In some areas, water entitlements currently exceed the available water supply yet few proposals for regulating quantities extracted are scrutinised in terms of possible impacts or undergo any form of rigorous impact assessment. In addition, there is little understanding of the potential impacts. There is a growing need to understand better the impact of altered flows of fresh water on estuarine and open coastal marine systems. There is a perception that fresh water is lost when it enters the marine environment. We argue that freshwater-saltwater dynamics have profound influences on coastal ecosystems. The purpose of this paper is to review the nature of freshwater discharges and the effects of fresh water on the physical aspects of estuaries as well as estuarine and marine flora, fauna and habitats. Although the review focuses on decreased flows to marine systems, major increases in flow can also have a major impact on estuarine and coastal systems. Freshwater runoff is a function of numerous environmental variables, depending primarily on climate (precipitation and evaporation) and the physical characteristics of the drainage basin. Anthropogenic activities in catchments may result in diversions and reductions in freshwater flow, alterations of timing and rates of flow to estuarine and coastal systems, and/or adverse water quality conditions with major changes in nutrient loading. Sediment loads, pH, temperature, salinity, clarity, oceanography and nutrients are affected. Perturbations in coastal systems can be freshwater pulses (i.e. storms or opening of floodgates) or press scenarios (i.e. persistent flow of low variation from rivers or industry). Impacts on organisms can also be categorised as pulse events (where there is a rapid but not sustained change), or press events (where changes are sustained over long periods of time). Changes to freshwater input affect habitats and organisms within estuaries. The effects include mortality, changes in growth and development, and in some cases movement of organisms. Major mortalities are most likely during pulse events of freshwater input. There is considerable descriptive and small-scale experimental evidence to suggest that a variety of organisms may be affected by changes to freshwater input. Much of the experimental evidence focuses on single factor experiments and rarely have there been multifactorial experiments (an exception is seagrasses). In addition, there have been no large-scale experiments (e.g. size of sample unit 10's to 100's of metres), although it is acknowledged that such experiments will be difficult. We suggest that any changes in water management (e.g. removal of water for irrigation) should be treated as manipulative experiments and that estuarine and marine systems are monitored together with reference or control locations (where there has been no change) to determine the impact of such changes. At the large scale, finding suit","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82481160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-01-01DOI: 10.1201/9780203180594.ch4
S. Beaulieu
Phytoplankton blooms sometimes result in the mass sinking of phytodetritus through the water column to the sea floor. The accumulation of a phytodetrital fluff layer on the sea floor is an episodic or seasonal event in some marine environments. This review provides a comprehensive list of locations in the world where the accumulation of phytodetritus has been observed on the sea floor. The microscopic and chemical composition of phytodetritus sampled from the sea floor at shallow to abyssal depths is also summarised. In addition, this review provides an overview of the mechanisms leading to mass sinking events, rates of accumulation of fluff layers, the impact of phytodetritus on fluxes of dissolved and particulate matter at the sediment/water interface, and the fate of phytodetritus on the sea floor. More studies are needed to understand the importance of these ephemeral phenomena for the ecology of benthic organisms, benthic-pelagic coupling in the carbon cycle, and the geological record in marine sediments.
{"title":"Accumulation and fate of phytodetritus on the sea floor","authors":"S. Beaulieu","doi":"10.1201/9780203180594.ch4","DOIUrl":"https://doi.org/10.1201/9780203180594.ch4","url":null,"abstract":"Phytoplankton blooms sometimes result in the mass sinking of phytodetritus through the water column to the sea floor. The accumulation of a phytodetrital fluff layer on the sea floor is an episodic or seasonal event in some marine environments. This review provides a comprehensive list of locations in the world where the accumulation of phytodetritus has been observed on the sea floor. The microscopic and chemical composition of phytodetritus sampled from the sea floor at shallow to abyssal depths is also summarised. In addition, this review provides an overview of the mechanisms leading to mass sinking events, rates of accumulation of fluff layers, the impact of phytodetritus on fluxes of dissolved and particulate matter at the sediment/water interface, and the fate of phytodetritus on the sea floor. More studies are needed to understand the importance of these ephemeral phenomena for the ecology of benthic organisms, benthic-pelagic coupling in the carbon cycle, and the geological record in marine sediments.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87900243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-01-01DOI: 10.4324/9780203180525_the_origins_of_the_coastal_and
B. Morton, J. Britton
The Azores Archipelago is geologically young, and the nine islands are from 8 million (Santa Maria) yr old. Evidence of endemism among the Azorean marine and maritime biota is sparse and clearly apparent only with regard to the supralittoral, maritime, vegetation Probably no alga nor marine animal is endemic, although a few species in several phyla are currently recognised as having this status. The marine fauna shows little evidence of colonisation by species with an eastern Pacific origin following the closure of the Isthmus of Panama and the opening of the Bering Strait in the Late Pliocene. The majority of the Azorean coastal and marine biota is very modem and comprises species that have arrived predominantly from the eastern Atlantic, especially the area between southern Europe (Lusitanian Region) and northwest Africa (Mauretanian Region), including the Mediterranean, but also contains species from other Atlantic sources. Regardless of their geographic origin, most representatives of the coastal Azorean marine biota are chance survivors of recent chance immigrants probably delivered to these shores in a variety of ways. It is likely, however, that the majority, but unknown percentage, of species were delivered by currents. Species with teleplanic larvae, for example, are present from both the western and eastern Atlantic. It is also likely that some, especially representatives of the Hydroida and species exhibiting direct development, were delivered by rafting and there are some examples of possible delivery by migratory birds (phoresy) which may also be more significant with regard to inter-island transport and especially between wetland feeding and roosting sites. The majority of terrestrial plants, all mammals, reptiles, amphibians and freshwater fishes (except Anguilla anguilla) of the Azores were introduced by man. Some marine colonisers have received human assistance, particularly the maritime vegetation and other well known exotics but in the latter case, unlike elsewhere, their impacts appear minimal. Following a brief introduction to the Azores, the geology of the islands and the ocean currents by which they are influenced, the marine, especially intertidal, flora and fauna are discussed in terms of their origins and possible means of arrival. The algae are represented by >300 species, the fauna by some 2100. The depauperate marine biota is characterised by simple communities notably lacking significant numbers of suspension feeders, perhaps to be expected in mid-Atlantic waters and, thus, by just as simple food chains. The uniformity of shore types also limits recruitment, even of successful immigrants, and coastal diversity and sources of primary productivity are only enriched in a few significant wetlands.
{"title":"The origins of the coastal and marine flora and fauna of the Azores","authors":"B. Morton, J. Britton","doi":"10.4324/9780203180525_the_origins_of_the_coastal_and","DOIUrl":"https://doi.org/10.4324/9780203180525_the_origins_of_the_coastal_and","url":null,"abstract":"The Azores Archipelago is geologically young, and the nine islands are from 8 million (Santa Maria) yr old. Evidence of endemism among the Azorean marine and maritime biota is sparse and clearly apparent only with regard to the supralittoral, maritime, vegetation Probably no alga nor marine animal is endemic, although a few species in several phyla are currently recognised as having this status. The marine fauna shows little evidence of colonisation by species with an eastern Pacific origin following the closure of the Isthmus of Panama and the opening of the Bering Strait in the Late Pliocene. The majority of the Azorean coastal and marine biota is very modem and comprises species that have arrived predominantly from the eastern Atlantic, especially the area between southern Europe (Lusitanian Region) and northwest Africa (Mauretanian Region), including the Mediterranean, but also contains species from other Atlantic sources. Regardless of their geographic origin, most representatives of the coastal Azorean marine biota are chance survivors of recent chance immigrants probably delivered to these shores in a variety of ways. It is likely, however, that the majority, but unknown percentage, of species were delivered by currents. Species with teleplanic larvae, for example, are present from both the western and eastern Atlantic. It is also likely that some, especially representatives of the Hydroida and species exhibiting direct development, were delivered by rafting and there are some examples of possible delivery by migratory birds (phoresy) which may also be more significant with regard to inter-island transport and especially between wetland feeding and roosting sites. The majority of terrestrial plants, all mammals, reptiles, amphibians and freshwater fishes (except Anguilla anguilla) of the Azores were introduced by man. Some marine colonisers have received human assistance, particularly the maritime vegetation and other well known exotics but in the latter case, unlike elsewhere, their impacts appear minimal. Following a brief introduction to the Azores, the geology of the islands and the ocean currents by which they are influenced, the marine, especially intertidal, flora and fauna are discussed in terms of their origins and possible means of arrival. The algae are represented by >300 species, the fauna by some 2100. The depauperate marine biota is characterised by simple communities notably lacking significant numbers of suspension feeders, perhaps to be expected in mid-Atlantic waters and, thus, by just as simple food chains. The uniformity of shore types also limits recruitment, even of successful immigrants, and coastal diversity and sources of primary productivity are only enriched in a few significant wetlands.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89492557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The mortality of intertidal cirripedes","authors":"M. Barnes","doi":"10.1201/9781482298550-7","DOIUrl":"https://doi.org/10.1201/9781482298550-7","url":null,"abstract":"","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79726433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present review provides a framework within which the impact of dredging on biological resources that live on the sea bed ("Benthic" communities) can be understood, and places in perspective some of the recent studies that have been carried out in relation to aggregates dredging in European coastal waters. The impact of dredging works on fisheries and fish themselves, and on their spawning grounds is outside the scope of this review. We have, however, shown that empirical models for shelf waters such as the North Sea indicate that as much as 30% of total fisheries yield to man is derived from benthic resources, and that these become an increasingly important component of the food web in near-shore waters where primary production by seaweeds (macrophytes) and seagrasses living on the sea bed largely replaces that by the phytoplankton in the water column. Because dredging works are mainly carried out in near-shore coastal deposits, and these are the ones where benthic production processes are of importance in supporting demersal fish production, our review concentrates on the nature of ben thic communities, their sensitivity to disturbance by dredging and land reclamation works, and on the recovery times that are likely to be required for the re-establishment of community structure following cessation of dredging or spoils disposal. Essentially, the impact of dredging activities mainly relates to the physical removal of substratum and associated organisms from the seabed along the path of the dredge head, and partly on the impact of subsequent deposition of material rejected by screening and overspill from the hopper. Because sediment disturbance by wave action is limited to depths of less than 30m, it follows that pits and furrows from dredging activities are likely to be persistent features of the sea bed except in shallow waters where sands are mobile. Recent studies using Acoustic Doppler Current Profiling (ADCP) techniques suggest that the initial sedimentation of material discharged during outwash from dredgers does not, as had been widely assumed, disperse according to the Gaussian diffusion principles used in most simulation models, but behaves more like a density current where particles are held together during the initial phase of the sedimentation process. As a result, the principal area likely to be affected by sediment deposition is mainly confined to a zone of a few hundred metres from the discharge chute. Our review suggests that marine communities conform to well-established principles of ecological succession, and that these allow some realistic predictions on the likely recovery of benthic communities following cessation of dredging. In general, communities living in fine mobile deposits, such as occur in estuaries, are characterized by large populations of a restricted variety of species that are well adapted to rapid recolonization of deposits that are subject to frequent disturbance. Recolonization of dredged deposits is ini
{"title":"The impact of dredging works in coastal waters : A review of the sensitivity to disturbance and subsequent recovery of biological resources on the sea bed","authors":"L.J.Seiderer D.R.Hitchcock R.C.Newell","doi":"10.1201/B12646-16","DOIUrl":"https://doi.org/10.1201/B12646-16","url":null,"abstract":"The present review provides a framework within which the impact of dredging on biological resources that live on the sea bed (\"Benthic\" communities) can be understood, and places in perspective some of the recent studies that have been carried out in relation to aggregates dredging in European coastal waters. The impact of dredging works on fisheries and fish themselves, and on their spawning grounds is outside the scope of this review. We have, however, shown that empirical models for shelf waters such as the North Sea indicate that as much as 30% of total fisheries yield to man is derived from benthic resources, and that these become an increasingly important component of the food web in near-shore waters where primary production by seaweeds (macrophytes) and seagrasses living on the sea bed largely replaces that by the phytoplankton in the water column. Because dredging works are mainly carried out in near-shore coastal deposits, and these are the ones where benthic production processes are of importance in supporting demersal fish production, our review concentrates on the nature of ben thic communities, their sensitivity to disturbance by dredging and land reclamation works, and on the recovery times that are likely to be required for the re-establishment of community structure following cessation of dredging or spoils disposal. Essentially, the impact of dredging activities mainly relates to the physical removal of substratum and associated organisms from the seabed along the path of the dredge head, and partly on the impact of subsequent deposition of material rejected by screening and overspill from the hopper. Because sediment disturbance by wave action is limited to depths of less than 30m, it follows that pits and furrows from dredging activities are likely to be persistent features of the sea bed except in shallow waters where sands are mobile. Recent studies using Acoustic Doppler Current Profiling (ADCP) techniques suggest that the initial sedimentation of material discharged during outwash from dredgers does not, as had been widely assumed, disperse according to the Gaussian diffusion principles used in most simulation models, but behaves more like a density current where particles are held together during the initial phase of the sedimentation process. As a result, the principal area likely to be affected by sediment deposition is mainly confined to a zone of a few hundred metres from the discharge chute. Our review suggests that marine communities conform to well-established principles of ecological succession, and that these allow some realistic predictions on the likely recovery of benthic communities following cessation of dredging. In general, communities living in fine mobile deposits, such as occur in estuaries, are characterized by large populations of a restricted variety of species that are well adapted to rapid recolonization of deposits that are subject to frequent disturbance. Recolonization of dredged deposits is ini","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73859216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ecological impact of green macroalgal blooms","authors":"D. Raffaelli, J. Raven, L. J. Poole","doi":"10.1201/B12646-13","DOIUrl":"https://doi.org/10.1201/B12646-13","url":null,"abstract":"","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84798994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Coral/seaweed competition and the control of reef community structure within and between latitudes","authors":"Margaret W. Miller","doi":"10.1201/B12646-11","DOIUrl":"https://doi.org/10.1201/B12646-11","url":null,"abstract":"","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86251290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"ECOLOGY OF THE GREEN MACROALGA CODIUM FRAGILE (SURINGAR) HARIOT 1889: INVASIVE AND NON-INVASIVE SUBSPECIES","authors":"C. D. Trowbridge","doi":"10.1201/B12646-3","DOIUrl":"https://doi.org/10.1201/B12646-3","url":null,"abstract":"","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85654206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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