The nature and role of chimneys as a mode of open-ocean winter convection in the Greenland Sea are reviewed, beginning with a brief summary of Greenland Sea circulation and of observations of convection and of the resulting water structure. Then recent observations of long-lived chimneys in the Greenland Sea are described, setting them within the context of earlier observations and models. The longest-lived chimney yet seen in the world ocean was discovered in March 2001 at about 75°N 0°W, and subsequent observations have shown that it has survived for a further 26 months, having been remapped in summer 2001, winter 2002, summer 2002, and April-May 2003. The chimney has an anticyclonically rotating core with a uniform rotation rate of f/2 to a diameter of 9 km; it passes through an annual cycle in which it is uniform in properties from the surface to 2500 m in winter, while being capped by lower-density water in summer (primarily a 50-m-thick near-surface layer of low salinity and a 500-m-thick layer of higher salinity). The most recent cruise also discovered a second chimney some 70 km NW of the first, and accomplished a tightly gridded survey of 15,000 km 2 of the gyre centre, effectively excluding the possibility of further chimneys. The conclusion is that the 75°/0°chimney is not a unique feature, but that Greenland Sea chimneys are rare and are probably rarer than in 1997, when at least four rotating features were discovered by a float survey. This has important implications for ideas about chimney formation, for deepwater renewal in the Greenland Sea, and for the role of Greenland Sea convection in the North Atlantic circulation.
{"title":"Convective chimneys in the greenland sea: a review of recent observations","authors":"P. Wadhams","doi":"10.1201/9780203507810-3","DOIUrl":"https://doi.org/10.1201/9780203507810-3","url":null,"abstract":"The nature and role of chimneys as a mode of open-ocean winter convection in the Greenland Sea are reviewed, beginning with a brief summary of Greenland Sea circulation and of observations of convection and of the resulting water structure. Then recent observations of long-lived chimneys in the Greenland Sea are described, setting them within the context of earlier observations and models. The longest-lived chimney yet seen in the world ocean was discovered in March 2001 at about 75°N 0°W, and subsequent observations have shown that it has survived for a further 26 months, having been remapped in summer 2001, winter 2002, summer 2002, and April-May 2003. The chimney has an anticyclonically rotating core with a uniform rotation rate of f/2 to a diameter of 9 km; it passes through an annual cycle in which it is uniform in properties from the surface to 2500 m in winter, while being capped by lower-density water in summer (primarily a 50-m-thick near-surface layer of low salinity and a 500-m-thick layer of higher salinity). The most recent cruise also discovered a second chimney some 70 km NW of the first, and accomplished a tightly gridded survey of 15,000 km 2 of the gyre centre, effectively excluding the possibility of further chimneys. The conclusion is that the 75°/0°chimney is not a unique feature, but that Greenland Sea chimneys are rare and are probably rarer than in 1997, when at least four rotating features were discovered by a float survey. This has important implications for ideas about chimney formation, for deepwater renewal in the Greenland Sea, and for the role of Greenland Sea convection in the North Atlantic circulation.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89571089","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 : 2004-01-01DOI: 10.1201/9780203507810.ch6
M. Thiel, L. Gutow
Rafting has been inferred as an important dispersal mechanism in the marine environment by many authors. The success of rafting depends critically on the availability of suitable floating substrata. Herein currently available information on floating items that have been reported to carry rafting organisms is summarised. Floating items of biotic origin comprise macroalgae, seeds, wood, other vascular plants, and animal remains. Volcanic pumice (natural) and a diverse array of litter and tar lumps (anthropogenic) are the main floating items of abiotic origin. Macroalgae, wood, and plastic macrolitter cover a wide range of sizes while pumice, microlitter, and tar lumps typically are <10 cm in diameter. The longevity of floating items at the sea surface depends on their origin and likelihood to be destroyed by secondary consumers (in increasing order): nonlignified vascular plants/animal carcasses < macroalgae < driftwood < tar lumps/skeletal remains < plastic litter < volcanic pumice. In general, abiotic substrata have a higher longevity than biotic substrata, but most abiotic items are of no or only limited food value for potential rafters. Macroalgae are most abundant at mid-latitudes of both hemispheres, driftwood is of major importance in northern and tropical waters, and floating seeds appear to be most common in tropical regions. Volcanic pumice can be found at all latitudes but has primarily been reported from the Pacific Ocean. Plastic litter and tar lumps are most abundant near the centres of human population and activities. In some regions of abundant supply or zones of hydrography-driven accumulation, floating items can be extremely abundant, exceeding 1000 items km -2 . Temporal supply of floating items is variable, being seasonal for most biotic substrata and highly sporadic for some items such as volcanic pumice. Most reported velocities of floating items are in the range of 0.5-1.0 km h -1 , but direct measurements have shown that they occasionally are transported at much faster velocities. Published trajectories of floating items also coincide with the main oceanic currents, even though strong winds may sometimes push them out of the principal current systems. Many studies hint toward floating items to link source regions with coastal sinks, in some cases across long distances and even entire ocean basins. Fossil evidence suggests that rafting has also occurred in palaeo-oceans. During recent centuries and decades the composition and abundance of floating items in the world's oceans have been strongly affected by human activities, in particular logging, river and coastline regulation, and most importantly oil exploitation and plastic production. The currently abundant supply and the characteristics of floating items suggest that rafting continues to be an important dispersal mechanism in present-day oceans.
{"title":"The ecology of rafting in the marine environment. I: The floating substrata","authors":"M. Thiel, L. Gutow","doi":"10.1201/9780203507810.ch6","DOIUrl":"https://doi.org/10.1201/9780203507810.ch6","url":null,"abstract":"Rafting has been inferred as an important dispersal mechanism in the marine environment by many authors. The success of rafting depends critically on the availability of suitable floating substrata. Herein currently available information on floating items that have been reported to carry rafting organisms is summarised. Floating items of biotic origin comprise macroalgae, seeds, wood, other vascular plants, and animal remains. Volcanic pumice (natural) and a diverse array of litter and tar lumps (anthropogenic) are the main floating items of abiotic origin. Macroalgae, wood, and plastic macrolitter cover a wide range of sizes while pumice, microlitter, and tar lumps typically are <10 cm in diameter. The longevity of floating items at the sea surface depends on their origin and likelihood to be destroyed by secondary consumers (in increasing order): nonlignified vascular plants/animal carcasses < macroalgae < driftwood < tar lumps/skeletal remains < plastic litter < volcanic pumice. In general, abiotic substrata have a higher longevity than biotic substrata, but most abiotic items are of no or only limited food value for potential rafters. Macroalgae are most abundant at mid-latitudes of both hemispheres, driftwood is of major importance in northern and tropical waters, and floating seeds appear to be most common in tropical regions. Volcanic pumice can be found at all latitudes but has primarily been reported from the Pacific Ocean. Plastic litter and tar lumps are most abundant near the centres of human population and activities. In some regions of abundant supply or zones of hydrography-driven accumulation, floating items can be extremely abundant, exceeding 1000 items km -2 . Temporal supply of floating items is variable, being seasonal for most biotic substrata and highly sporadic for some items such as volcanic pumice. Most reported velocities of floating items are in the range of 0.5-1.0 km h -1 , but direct measurements have shown that they occasionally are transported at much faster velocities. Published trajectories of floating items also coincide with the main oceanic currents, even though strong winds may sometimes push them out of the principal current systems. Many studies hint toward floating items to link source regions with coastal sinks, in some cases across long distances and even entire ocean basins. Fossil evidence suggests that rafting has also occurred in palaeo-oceans. During recent centuries and decades the composition and abundance of floating items in the world's oceans have been strongly affected by human activities, in particular logging, river and coastline regulation, and most importantly oil exploitation and plastic production. The currently abundant supply and the characteristics of floating items suggest that rafting continues to be an important dispersal mechanism in present-day oceans.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74000642","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 : 2004-01-01DOI: 10.1201/9780203507810.ch8
C. Griffiths, L. Sittert, P. Best, A. C. Brown, B. M. Clark, P. Cook, R. Crawford, J. David, B. R. Davies, M. Griffiths, K. Hutchings, A. Jerardino, N. Kruger, S. Lamberth, R. Leslie, R. Melville‐Smith, R. Tarr, C. Lingen, R. Gibson, R. Atkinson, J. Gordon
This review provides a historical overview of human activities in the Benguela and documents their effects on marine animal life. Considered are the activities of conventional industrial and inshore fisheries but also nonfishery activities, such as mariculture, regulation of river flow, introduction of marine invasive species, marine contruction and mining, pollution and climate change. Human influences may conveniently be divided into four epochs: aboriginal (c. 10,000 before present (BP)-c, 1652), preindustrial (c. 1652-c. 1910), industrial (c. 1910-c. 1975) and postindustrial (c. 1975-present). The aboriginal epoch is characterised by low levels of mainly intertidal exploitation; the preindustrial epoch by intense exploitation of few large, accessible species; the industrial epoch by technological development and a subsequent massive escalation in catches; and the postindustial epoch by improved resource management and stabilisation of catches, but increasing nonfishery impacts on the system. Over 50 million t of biomass has been extracted from the system over the past 200 yr, resulting in significant changes in community structure. Extraction rates peaked at over 1.3 million t yr -1 in the 1960s and have subsequently declined by over 50%. Populations of whales, seals and pelagic and demersal fishes are recovering from historical overexploitation, while those of inshore stocks, particularly abalone, rock lobster and inshore linefishes, remain severely depressed.
{"title":"Impacts of human activities on marine animal life in the Benguela: A historical overview","authors":"C. Griffiths, L. Sittert, P. Best, A. C. Brown, B. M. Clark, P. Cook, R. Crawford, J. David, B. R. Davies, M. Griffiths, K. Hutchings, A. Jerardino, N. Kruger, S. Lamberth, R. Leslie, R. Melville‐Smith, R. Tarr, C. Lingen, R. Gibson, R. Atkinson, J. Gordon","doi":"10.1201/9780203507810.ch8","DOIUrl":"https://doi.org/10.1201/9780203507810.ch8","url":null,"abstract":"This review provides a historical overview of human activities in the Benguela and documents their effects on marine animal life. Considered are the activities of conventional industrial and inshore fisheries but also nonfishery activities, such as mariculture, regulation of river flow, introduction of marine invasive species, marine contruction and mining, pollution and climate change. Human influences may conveniently be divided into four epochs: aboriginal (c. 10,000 before present (BP)-c, 1652), preindustrial (c. 1652-c. 1910), industrial (c. 1910-c. 1975) and postindustrial (c. 1975-present). The aboriginal epoch is characterised by low levels of mainly intertidal exploitation; the preindustrial epoch by intense exploitation of few large, accessible species; the industrial epoch by technological development and a subsequent massive escalation in catches; and the postindustial epoch by improved resource management and stabilisation of catches, but increasing nonfishery impacts on the system. Over 50 million t of biomass has been extracted from the system over the past 200 yr, resulting in significant changes in community structure. Extraction rates peaked at over 1.3 million t yr -1 in the 1960s and have subsequently declined by over 50%. Populations of whales, seals and pelagic and demersal fishes are recovering from historical overexploitation, while those of inshore stocks, particularly abalone, rock lobster and inshore linefishes, remain severely depressed.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82829504","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 : 2004-01-01DOI: 10.1201/9780203507810-11
J. Claydon
Many coral reef fishes migrate to form short-lived aggregations at predictable sites and times in order to spawn. For the purposes of this review, such spawning aggregations are defined as any temporary aggregations formed by fishes that have migrated for the specific purpose of spawning. Spawning aggregations are known to be formed by 164 species from 26 families of coral reef fishes, but the actual number is likely to be much higher. Aggregative spawners share a number of common features. (1) All except one species release pelagic eggs. (2) They tend to have large body sizes. (3) They are more abundant in some phylogenetic groups, such as the Labridae, Scaridae, Serranidae, Acanthuridae, and Lutjanidae, although they are relatively uncommon in all but the least speciose families of Albulidae, Chanidae, Gerreidae, and Scombridae. (4) They are more likely to come from large populations with high densities. However, these features are not independent and their relative importance is not easily assessed. Known spawning aggregations form at the same sites over successive, predictable spawning seasons. However, from the limited data presently available, spawning aggregations do not appear to form consistently on predictable reef structures. The periodicity of spawning aggregations can differ greatly for the same species with relatively small degrees of spatial separation. A number of hypotheses have been proposed to explain why, when, and where spawning aggregations are formed. These include those that predict that the phenomenon of aggregative spawning (1) reduces predation on spawning adults and their eggs (the predator satiation hypothesis), (2) increases the degree of mate selectivity, and (3) allows individuals to assess sex ratios of populations and make decisions on sex change accordingly. Other hypotheses predict that the location and timing of spawning aggregations (1) reduce predation on both eggs (the egg predation hypothesis) and spawning adults (the predator evasion hypothesis), (2) increase the probability that larvae will settle on reefs (the egg dispersal hypothesis and the larval retention hypothesis), and (3) enhance the survival of larvae during their pelagic phase (the pelagic survival hypothesis). However, very little quantitative research addressed at an appropriate scale has been conducted to distinguish among these hypotheses, many of which make common predictions. Spawning aggregations of commercially important coral reef fishes have been lost in many locations throughout the tropics because unsustainable fishing targets the spawning aggregations themselves. The live reef food-fish trade has proven to be unsustainable in almost all locations in which it has operated, leading to widespread impoverishment and eradication of spawning aggregations. Appropriate management, legislation, and enforcement are essential to protect the stocks of commercially important aggregative spawners, as is a more comprehensive understanding of the
{"title":"Spawning aggregations of coral reef fishes: characteristics, hypotheses, threats and management","authors":"J. Claydon","doi":"10.1201/9780203507810-11","DOIUrl":"https://doi.org/10.1201/9780203507810-11","url":null,"abstract":"Many coral reef fishes migrate to form short-lived aggregations at predictable sites and times in order to spawn. For the purposes of this review, such spawning aggregations are defined as any temporary aggregations formed by fishes that have migrated for the specific purpose of spawning. Spawning aggregations are known to be formed by 164 species from 26 families of coral reef fishes, but the actual number is likely to be much higher. Aggregative spawners share a number of common features. (1) All except one species release pelagic eggs. (2) They tend to have large body sizes. (3) They are more abundant in some phylogenetic groups, such as the Labridae, Scaridae, Serranidae, Acanthuridae, and Lutjanidae, although they are relatively uncommon in all but the least speciose families of Albulidae, Chanidae, Gerreidae, and Scombridae. (4) They are more likely to come from large populations with high densities. However, these features are not independent and their relative importance is not easily assessed. Known spawning aggregations form at the same sites over successive, predictable spawning seasons. However, from the limited data presently available, spawning aggregations do not appear to form consistently on predictable reef structures. The periodicity of spawning aggregations can differ greatly for the same species with relatively small degrees of spatial separation. A number of hypotheses have been proposed to explain why, when, and where spawning aggregations are formed. These include those that predict that the phenomenon of aggregative spawning (1) reduces predation on spawning adults and their eggs (the predator satiation hypothesis), (2) increases the degree of mate selectivity, and (3) allows individuals to assess sex ratios of populations and make decisions on sex change accordingly. Other hypotheses predict that the location and timing of spawning aggregations (1) reduce predation on both eggs (the egg predation hypothesis) and spawning adults (the predator evasion hypothesis), (2) increase the probability that larvae will settle on reefs (the egg dispersal hypothesis and the larval retention hypothesis), and (3) enhance the survival of larvae during their pelagic phase (the pelagic survival hypothesis). However, very little quantitative research addressed at an appropriate scale has been conducted to distinguish among these hypotheses, many of which make common predictions. Spawning aggregations of commercially important coral reef fishes have been lost in many locations throughout the tropics because unsustainable fishing targets the spawning aggregations themselves. The live reef food-fish trade has proven to be unsustainable in almost all locations in which it has operated, leading to widespread impoverishment and eradication of spawning aggregations. Appropriate management, legislation, and enforcement are essential to protect the stocks of commercially important aggregative spawners, as is a more comprehensive understanding of the","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75881551","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 : 2004-01-01DOI: 10.1201/9780203507810.ch4
J. Ott, M. Bright, Silvia Bulgheresi
A high diversity of thiotrophic symbioses is found in sulphide-rich marine habitats, involving several phyla of protists and invertebrates, as well as several subdivisions of the Proteobacteria. Whereas some of the better-known symbioses are highly evolved endosymbioses, the more primitive ectosymbioses are less well known. The sulphur-oxidising chemolithotrophic nature of the bacteria and their nutritive importance to the eukaryote host have been demonstrated for the ciliates Kentrophoros spp. and Zoothamnium niveum, the nematode subfamily Stilbonematinae, and the carid shrimp Rimicaris exoculata. For a number of other regular bacteria-eukaryote associations, such a symbiotic relationship has been hypothesised based on ecological, morphological, physiological or molecular data, but is still inconclusive.
{"title":"Marine microbial thiotrophic ectosymbioses","authors":"J. Ott, M. Bright, Silvia Bulgheresi","doi":"10.1201/9780203507810.ch4","DOIUrl":"https://doi.org/10.1201/9780203507810.ch4","url":null,"abstract":"A high diversity of thiotrophic symbioses is found in sulphide-rich marine habitats, involving several phyla of protists and invertebrates, as well as several subdivisions of the Proteobacteria. Whereas some of the better-known symbioses are highly evolved endosymbioses, the more primitive ectosymbioses are less well known. The sulphur-oxidising chemolithotrophic nature of the bacteria and their nutritive importance to the eukaryote host have been demonstrated for the ciliates Kentrophoros spp. and Zoothamnium niveum, the nematode subfamily Stilbonematinae, and the carid shrimp Rimicaris exoculata. For a number of other regular bacteria-eukaryote associations, such a symbiotic relationship has been hypothesised based on ecological, morphological, physiological or molecular data, but is still inconclusive.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79591644","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}
Species lists have been compiled for all the major groups of Southern Ocean benthic marine invertebrates, eliminating synonymies where possible and providing a subjective estimate of completeness and reliability for each group. Antarctic marine diversity (pelagic and benthic) is relatively high at the phylum and class level, with the gaps mostly comprising minor, meiofaunal or parasitic groups. Most benthic diversity data come from the continental shelves, with relatively few samples from deeper water. Even for the continental shelves, however, sampling is highly patchy with some areas hardly investigated at all. Over 4100 benthic species have been reported from the Southern Ocean, with the most speciose groups being polychaetes, gastropods and amphipods. Comparison with tropical and temperate regions suggest that decapods, bivalves and teleost fishes are poorly represented in the Southern Ocean benthic marine fauna, whereas pycnogonids, echinoderms and many suspension feeding groups are rich and diverse. Some groups that are currently low in diversity were previously well represented in the Antarctic shallow water marine fauna, notably decapods and many fishes. Other groups have undergone marked radiations in the Southern Ocean, including pycnogonids, amphipods, isopods and teleost fishes; in all cases, however, it is only some lineages that have diversified. This indicates that evolutionary questions concerning the origin, diversification or extinction of the Southern Ocean marine fauna will have no single answer; the evolutionary history of each group appears to reflect a different response to the tectonic, climatic and oceanographic changes to which they have been subject through history. The disposition of southern hemisphere continents makes it difficult to assess whether there is a latitudinal dine in shallow-water marine diversity to mirror that known from the northern hemisphere. Within Antarctica, many species appear to have circumpolar distributions, and the long established biogeographical division into continental Antarctic, Antarctic Peninsula and sub-Antarctic regions have not been challenged by recent sampling. For most groups the frequency distribution of species per genus ratios is typical, though none is well described by the predictions from current evolutionary or null models. Where data are available, size spectra indicate that many Southern Ocean taxa are small, a few spectacular examples of gigantism notwithstanding, and species abundance plots are normal. Knowledge of the Southern Ocean benthic marine fauna has reached a stage where we can now ask powerful evolutionary questions, and the development of new molecular techniques provides the mechanism for answering them.
{"title":"Antarctic marine benthic diversity","authors":"A. Clarke, N. Johnston","doi":"10.1201/9780203180570-8","DOIUrl":"https://doi.org/10.1201/9780203180570-8","url":null,"abstract":"Species lists have been compiled for all the major groups of Southern Ocean benthic marine invertebrates, eliminating synonymies where possible and providing a subjective estimate of completeness and reliability for each group. Antarctic marine diversity (pelagic and benthic) is relatively high at the phylum and class level, with the gaps mostly comprising minor, meiofaunal or parasitic groups. Most benthic diversity data come from the continental shelves, with relatively few samples from deeper water. Even for the continental shelves, however, sampling is highly patchy with some areas hardly investigated at all. Over 4100 benthic species have been reported from the Southern Ocean, with the most speciose groups being polychaetes, gastropods and amphipods. Comparison with tropical and temperate regions suggest that decapods, bivalves and teleost fishes are poorly represented in the Southern Ocean benthic marine fauna, whereas pycnogonids, echinoderms and many suspension feeding groups are rich and diverse. Some groups that are currently low in diversity were previously well represented in the Antarctic shallow water marine fauna, notably decapods and many fishes. Other groups have undergone marked radiations in the Southern Ocean, including pycnogonids, amphipods, isopods and teleost fishes; in all cases, however, it is only some lineages that have diversified. This indicates that evolutionary questions concerning the origin, diversification or extinction of the Southern Ocean marine fauna will have no single answer; the evolutionary history of each group appears to reflect a different response to the tectonic, climatic and oceanographic changes to which they have been subject through history. The disposition of southern hemisphere continents makes it difficult to assess whether there is a latitudinal dine in shallow-water marine diversity to mirror that known from the northern hemisphere. Within Antarctica, many species appear to have circumpolar distributions, and the long established biogeographical division into continental Antarctic, Antarctic Peninsula and sub-Antarctic regions have not been challenged by recent sampling. For most groups the frequency distribution of species per genus ratios is typical, though none is well described by the predictions from current evolutionary or null models. Where data are available, size spectra indicate that many Southern Ocean taxa are small, a few spectacular examples of gigantism notwithstanding, and species abundance plots are normal. Knowledge of the Southern Ocean benthic marine fauna has reached a stage where we can now ask powerful evolutionary questions, and the development of new molecular techniques provides the mechanism for answering them.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80822318","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 : 2003-07-31DOI: 10.1201/9780203180570-23
L. Airoldi
Sedimentation is a widespread and increasing process on most rocky coasts. The literature on its effects is reviewed and support is found for the general conclusion that sedimen- tation is an important ecological factor for hard bottom organisms. Sediments deeply affect the composition, structure and dynamics of rocky coast assemblages, and increased sediment load as a consequence of anthropogenic activities can be a threat to their diversity and functioning. Sediments that accumulate on rocky substrata are important agents of stress and disturbance. They can cause burial, scour and profound modifications to the characteristics of the bottom surface, and interact with other important physical and biological processes. The effects of sedi- mentation are complex, because they involve both direct outcomes on settlement, recruitment, growth or survival of individual species and indirect outcomes through mediation of competitive and/or predator-prey interactions. Not all species and assemblages are equally affected by sedi- mentation and responses vary over space and time, depending on the characteristics of the depo- sitional environment, life histories of species and the stage of development of individuals and assemblages, and in relation to variable physical factors, including hydrodynamics, light intens- ity and bottom topography. Recent studies have much improved our ability to detect and under- stand the effects of sedimentation on rocky coast assemblages. However, little is still known about the underlying mechanisms. Overall, our present ability to make generalisations and pre- dictions is limited by a paucity of quantitative and experimental research, and by the scant atten- tion devoted to measuring the regime of perturbation by sediments and responses of organisms at relevant spatial and temporal scales. Predicting the magnitude of the effects that different sed- imentation regimes have on rocky coast organisms and the critical levels above which detrimen- tal effects become manifest remains a key issue for the ecology of rocky coasts and a challenge for future studies.
{"title":"THE EFFECTS OF SEDIMENTATION ON ROCKY COAST ASSEMBLAGES","authors":"L. Airoldi","doi":"10.1201/9780203180570-23","DOIUrl":"https://doi.org/10.1201/9780203180570-23","url":null,"abstract":"Sedimentation is a widespread and increasing process on most rocky coasts. The literature on its effects is reviewed and support is found for the general conclusion that sedimen- tation is an important ecological factor for hard bottom organisms. Sediments deeply affect the composition, structure and dynamics of rocky coast assemblages, and increased sediment load as a consequence of anthropogenic activities can be a threat to their diversity and functioning. Sediments that accumulate on rocky substrata are important agents of stress and disturbance. They can cause burial, scour and profound modifications to the characteristics of the bottom surface, and interact with other important physical and biological processes. The effects of sedi- mentation are complex, because they involve both direct outcomes on settlement, recruitment, growth or survival of individual species and indirect outcomes through mediation of competitive and/or predator-prey interactions. Not all species and assemblages are equally affected by sedi- mentation and responses vary over space and time, depending on the characteristics of the depo- sitional environment, life histories of species and the stage of development of individuals and assemblages, and in relation to variable physical factors, including hydrodynamics, light intens- ity and bottom topography. Recent studies have much improved our ability to detect and under- stand the effects of sedimentation on rocky coast assemblages. However, little is still known about the underlying mechanisms. Overall, our present ability to make generalisations and pre- dictions is limited by a paucity of quantitative and experimental research, and by the scant atten- tion devoted to measuring the regime of perturbation by sediments and responses of organisms at relevant spatial and temporal scales. Predicting the magnitude of the effects that different sed- imentation regimes have on rocky coast organisms and the critical levels above which detrimen- tal effects become manifest remains a key issue for the ecology of rocky coasts and a challenge for future studies.","PeriodicalId":54693,"journal":{"name":"Oceanography and Marine Biology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87523702","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}
Within the context of Europe, numerical modelling of coastal and shelf seas exhibits a range of diversity and a level of maturity reflecting global developments in this field. Results from a detailed survey distributed to researchers across Europe, supplemented by a literature search, indicates the variety of models and modelling techniques that are presently used. An inventory of models is assembled. Each aspect of the hydrodynamics, the boundary conditions and included processes such as waves, biology and sediments, are investigated in turn. This study helps to identify areas where consensus, or lack of consensus, exist. Thus, possible future model developments that suggest future trends are indicated. Uniquely, the European context provides a forum that fosters collaborative projects including model inter-comparisons. A list of projects relevant to modelling is given. At present such projects help to define the performance of individual models. However, they may eventually lead to a convergence and rationalisation of numerical model schemes or the establishment of community models that address not just the physics but also the salinity, temperature, chemical and biological aspects of shelf seas. Present and future progress towards such goals is indicated. The desirability of rationalisation, as discussed in the literature, is assessed. Present and future modelling challenges are indicated.
{"title":"Coastal and shelf-sea modelling in the European context","authors":"J. Jones","doi":"10.1201/9780203180594-7","DOIUrl":"https://doi.org/10.1201/9780203180594-7","url":null,"abstract":"Within the context of Europe, numerical modelling of coastal and shelf seas exhibits a range of diversity and a level of maturity reflecting global developments in this field. Results from a detailed survey distributed to researchers across Europe, supplemented by a literature search, indicates the variety of models and modelling techniques that are presently used. An inventory of models is assembled. Each aspect of the hydrodynamics, the boundary conditions and included processes such as waves, biology and sediments, are investigated in turn. This study helps to identify areas where consensus, or lack of consensus, exist. Thus, possible future model developments that suggest future trends are indicated. Uniquely, the European context provides a forum that fosters collaborative projects including model inter-comparisons. A list of projects relevant to modelling is given. At present such projects help to define the performance of individual models. However, they may eventually lead to a convergence and rationalisation of numerical model schemes or the establishment of community models that address not just the physics but also the salinity, temperature, chemical and biological aspects of shelf seas. Present and future progress towards such goals is indicated. The desirability of rationalisation, as discussed in the literature, is assessed. Present and future modelling challenges are indicated.","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":"78153814","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}
P. Woodworth, C. Provost, L. Rickards, G. Mitchum, M. Merrifield
This paper reviews the developments in tide gauge networks during the World Ocean Circulation Experiment (WOCE) and provides an overview of the resulting contributions to the scientific aims of the programme. The 1990s saw the rapid development of the satellite radar altimetry technique (results from which have been reviewed elsewhere), which played the major role in the measurement of ocean circulation variability during WOCE. This paper describes the complementary roles of altimetric and conventional in situ methods of sea-level recording by gauges which have evolved during the programme. In addition, it highlights those areas of research in which tide gauges (or bottom pressure recorders) have played a particularly important role. A final section looks to the future age of altimetry wherein the sea level and ocean circulation community must strive to construct an efficient, unified, global tide gauge-plus-altimetry system for application to a range of scientific objectives.
{"title":"A review of sea-level research from tide gauges during the World Ocean Circulation Experiment","authors":"P. Woodworth, C. Provost, L. Rickards, G. Mitchum, M. Merrifield","doi":"10.1201/9780203180594-4","DOIUrl":"https://doi.org/10.1201/9780203180594-4","url":null,"abstract":"This paper reviews the developments in tide gauge networks during the World Ocean Circulation Experiment (WOCE) and provides an overview of the resulting contributions to the scientific aims of the programme. The 1990s saw the rapid development of the satellite radar altimetry technique (results from which have been reviewed elsewhere), which played the major role in the measurement of ocean circulation variability during WOCE. This paper describes the complementary roles of altimetric and conventional in situ methods of sea-level recording by gauges which have evolved during the programme. In addition, it highlights those areas of research in which tide gauges (or bottom pressure recorders) have played a particularly important role. A final section looks to the future age of altimetry wherein the sea level and ocean circulation community must strive to construct an efficient, unified, global tide gauge-plus-altimetry system for application to a range of scientific objectives.","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":"76098520","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 : 2002-08-29DOI: 10.1201/9780203180594-26
N. Andrew, Y. Agatsuma, E. Ballesteros, A. G. Bazhin, E. P. Creaser, D. Barnes, L. Botsford, A. Bradbury, A. Campbell, J. Dixon, S. Einnarsson, P. Gerring, K. Hebert, M. Hunter, S. Hur, C. Johnson, M. A. Juinio-Meñez, P. Kalvass, Robert J. Miller, C. Moreno, J. S. Palleiro, D. Rivas, S. M. Robinson, S. Schroeter, R. Steneck, R. Vadas, D. Woodby, Z. Xiaoqi
World production of sea urchins peaked in 1995, when 120 306 t were landed. Chile dominates world production, producing more than half the world's total landings of 90 257 t in 1998. Other important fisheries are found in Japan, Maine, British Columbia, California, South Korea, New Brunswick, Russia, Mexico, Alaska, Nova Scotia, and in a number of countries that produced less than 1000 t in 1998. Aside from the Chilean fishery for Loxechinus albus, most harvest is of Strongylocentrotus spp., particularly S. intermedius, S. franciscanus, and S. droebachiensis. Only a small minority of fisheries have been formally assessed and in the absence of such assessments it is difficult to determine whether fisheries are overfished or whether the large declines observed in many represent the "fish down" of accumulated biomass. Nevertheless, those in Chile, Japan, Maine, California and Washington and a number of smaller fisheries, have declined considerably since their peaks and are likely to be overfished. Fisheries in Japan, South Korea and the Philippines have been enhanced by reseeding hatchery-reared juveniles and by modifying reefs to increase their structural complexity and to promote the growth of algae. Sea urchin fisheries have potentially large ecological effects, usually mediated through increases in the abundance and biomass of large brown algae. Although such effects may have important consequences for management of these and related fisheries, only in Nova Scotia, South Korea and Japan is ecological knowledge incorporated into management.
世界海胆产量在1995年达到顶峰，当年的产量为120306吨。智利在世界产量中占主导地位，1998年全球总产量90257吨，占全球总产量的一半以上。其他重要的渔场分布在日本、缅因州、不列颠哥伦比亚省、加利福尼亚、韩国、新不伦瑞克、俄罗斯、墨西哥、阿拉斯加、新斯科舍省以及1998年产量不足1000吨的一些国家。除了智利渔业的白纹Loxechinus albus，大多数收获是圆梭菌属，特别是S. intermedius, S. franciscanus和S. droebachiensis。只有一小部分渔场进行了正式评估，在没有这种评估的情况下，很难确定渔场是否过度捕捞，或者在许多渔场观察到的大量减少是否代表累积生物量的“减少”。然而，智利、日本、缅因州、加利福尼亚和华盛顿以及一些较小的渔场的鱼类数量自峰值以来已大幅下降，很可能被过度捕捞。日本、韩国和菲律宾的渔业已通过重新播种孵化场饲养的幼鱼和修改珊瑚礁以增加其结构复杂性和促进藻类生长而得到加强。海胆渔业具有潜在的巨大生态效应，通常通过增加大型褐藻的丰度和生物量来调节。虽然这种影响可能对这些和有关渔业的管理产生重要影响，但只有在新斯科舍省、南朝鲜和日本才将生态知识纳入管理。
{"title":"Status and management of world sea urchin fisheries","authors":"N. Andrew, Y. Agatsuma, E. Ballesteros, A. G. Bazhin, E. P. Creaser, D. Barnes, L. Botsford, A. Bradbury, A. Campbell, J. Dixon, S. Einnarsson, P. Gerring, K. Hebert, M. Hunter, S. Hur, C. Johnson, M. A. Juinio-Meñez, P. Kalvass, Robert J. Miller, C. Moreno, J. S. Palleiro, D. Rivas, S. M. Robinson, S. Schroeter, R. Steneck, R. Vadas, D. Woodby, Z. Xiaoqi","doi":"10.1201/9780203180594-26","DOIUrl":"https://doi.org/10.1201/9780203180594-26","url":null,"abstract":"World production of sea urchins peaked in 1995, when 120 306 t were landed. Chile dominates world production, producing more than half the world's total landings of 90 257 t in 1998. Other important fisheries are found in Japan, Maine, British Columbia, California, South Korea, New Brunswick, Russia, Mexico, Alaska, Nova Scotia, and in a number of countries that produced less than 1000 t in 1998. Aside from the Chilean fishery for Loxechinus albus, most harvest is of Strongylocentrotus spp., particularly S. intermedius, S. franciscanus, and S. droebachiensis. Only a small minority of fisheries have been formally assessed and in the absence of such assessments it is difficult to determine whether fisheries are overfished or whether the large declines observed in many represent the \"fish down\" of accumulated biomass. Nevertheless, those in Chile, Japan, Maine, California and Washington and a number of smaller fisheries, have declined considerably since their peaks and are likely to be overfished. Fisheries in Japan, South Korea and the Philippines have been enhanced by reseeding hatchery-reared juveniles and by modifying reefs to increase their structural complexity and to promote the growth of algae. Sea urchin fisheries have potentially large ecological effects, usually mediated through increases in the abundance and biomass of large brown algae. Although such effects may have important consequences for management of these and related fisheries, only in Nova Scotia, South Korea and Japan is ecological knowledge incorporated into management.","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":"86727115","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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