REVIEWS AND RECORDS

Summerhayes, C. P., Hofmeyr. P. K. &; Rioux, R. H. 1974. Seabirds off the southwestern coast of Africa. Ostrich 45: 83–109.

The distribution of seabirds off the southwestern coast of Africa was observed during April. May and November, and observed south of Africa in March. Most seabirds off the west coast were concentrated near to the coast or over the edge of the continental shelf. These are sites where forms of upwelling bring water rich in nutrients to the surface of the sea. The most birds were seen in March, April and May, the least in November. Most common over the shelf-edge were, in order of abundance, Blackbrowed Albatross, Cape Hens, Shy Albatross, Yellownosed Albatross, Wilson's Storm Petrels, Cape Gannets, Common/Arctic Terns, and Antarctic Skuas. Seasonal shifts in their ranges and population densities probably reflect the influence of breeding and migration.

Comparable concentrations of seabirds were only seen as the cold, nutrient-rich waters of the Subantarctic were approached south of Africa. Here turbulence breaks up the front of the Subtropical Convergence and, in moving large masses of cold water northwards, provides a “corridor” which Southern Ocean species may follow to reach Africa.

(Contribution No. 2687 of the Woods Hole Oceanographic Institution).     

The behaviour of seabirds foraging at fishing boats around Shetland

Among the different types of fishing vessels around Shetland, whitefish trawlers attract the largest numbers of scavenging seabirds and provide the most food. Offal was almost all consumed by seabirds, predominantly by Fulmars Fulmarus glacialis , which excluded other species by their aggression. Fulmars generally ignored discarded whole fish, which were mainly taken by Great Black-backed Gulls Larus marinus , Gannets Sula bassana and Great Skuas Catharacta skua . Although flatfish were usually ignored because seabirds found them difficult to swallow and they sank faster, most discarded roundfish were consumed. Herring Gulls L. argentatus , Lesser Black-backed Gulls L. fuscus and Kittiwakes Rissa tridactyla were rarely able to obtain offal or discards. Herring Gulls and Lesser Black-backed Gulls spent much time on the periphery of feeding flocks while Kittiwakes rarely attempted even to join these. Most of the birds at trawlers were in adult plumage, and it is suggested that the low proportion of immature birds present was a further reflection of the highly competitive feeding conditions at trawlers. We suggest that likely changes in fishing practice and seabird population sizes in the immediate future may result in Herring Gulls, Lesser Black-backed Gulls and Great Skuas finding feeding on waste around trawlers increasingly difficult, so they may be further displaced by Fulmars, Gannets and Great Black-backed Gulls.     

BREEDING NOMADISM IN SOUTHERN AFRICAN SEABIRDS-CONSTRAINTS,CAUSES AND CONSERVATION

Crawford, R.J.M., Dyer, B.M. & Brooke, R.K. 1994. Breeding nomadism in southern African seabirds-constraints, causes and conservation. Ostrich 65:231-246.

Fourteen species of seabirds representing three orders and five families breed in southern Africa. Nomadism in the breeding populations of 13 of these seabirds is examined. African Penguins Spheniscus demersus, Cape Gannets Morus capensis. Bank Cormorants Phalacrocorax neglectus, Whitebreasted Cormorants P. carbo and White Pelicans Pelecanus onocrotalus show strong fidelity to specific localities. Caspian Terns Sterna caspia change breeding localities at a low frequency; Cape Cormorants P. capensis, Hartlaub's Gulls Larus hartlaubii and Swift S. bergii and Roseate S. dougallii Terns at a higher frequency. At some localities, Bank Cormorants remain at the same breeding sites for extended periods, whereas Crowned Cormorants P. coronatus, Whitebreasted Cormorants, Kelp Gulls L. dominicanus, Hartlaub's Gulls, Damara Terns S. balaenarum, Swift Terns and Roseate Terns all alter breeding sites. Where space is not limiting, African Penguins may also change sites. Constraints on nomadism include strong attachment to traditional breeding localities, unwillingness to roost at non-breeding localities, and lack of suitable alternative nesting localities. Amongst causes of nomadism are excessive disturbance by humans and South African Fur Seals Arctocephalus pusillus and competition for breeding space, which have resulted in even the least nomadic of the species changing their breeding locations. Regularly nomadic species are likely to respond to environmental cues that enable them either to reduce cost of breeding or to increase reproductive output. Therefore, they are potentially useful indicators of ecological health. Nomadic breeders additionally have the ability to establish new breeding colonies. Some species have used artificial structures to expand their breeding range, and probably also to increase their overall populations. However, nomadic tendencies complicate the conservation of breeding activities. By contrast, breeding species with strong fidelity to traditional localities are more easily protected.     

LONG DISTANCE OFFSHORE MOVEMENTS OF BOTTLENOSE DOLPHINS1

Despite recent progress defining the morphological and genetic characteristics of forms of the bottlenose dolphin inhabiting offshore waters, little is known of their behavior or ranging patterns. Reports suggest that an “offshore form” exists between the 200- and 2,000-m isobaths in distinct Gulf of Mexico and western North Atlantic stocks, while one or more coastal forms inhabit the waters inshore. Two opportunities to track rehabilitated adult male bottlenose dolphins with satellite-linked transmitters occurred in 1997. “Rudy” stranded in NW Florida and was released in the Gulf of Mexico off central west Florida. He moved around Florida and northward to off Cape Hatteras, NC, covering 2,050 km in 43 d. “Gulliver” stranded near St. Augustine and was released off Cape Canaveral, FL. He moved 4,200 km in 47 d to a location northeast of the Virgin Islands. Gulliver swam through 5,000-m-deep waters 300 km offshore of the northern Caribbean islands, against the North Equatorial Current. These records expand the range and habitat previously reported for the offshore stock of bottlenose dolphins inhabiting the waters off the southeastern United States, underscore the difficulties of defining pelagic stocks, illustrate the success of rehabilitation efforts, indicate the value of follow-up monitoring of rehabilitated and released cetaceans, and expand our understanding of the long-range movement capabilities of a dolphin species more commonly thought of as a resident in coastal waters.     

SUMMER DISTRIBUTION OF PELAGIC BIRDS OFF THE COAST OF ARGENTINA

Eighteen species of sea–birds were observed from CSS 'Hudson' in the South Atlantic between the Rio de la Plata and Tierra del Fuego in late January and late February 1970. Major feeding areas were noted off Mar del Plata, the Valdes Peninsula and Tierra del Fuego, Argentina, the first two in rich modified or unmodified water of the subantarctic Falkland Current, associated with upwelling. The southernmost area had most birds, the northernmost fewest. A temperate–latitude assemblage including Yellow–nosed Albatross and Cory's Shearwater occurred off Mar del Plata in warmed water of subantarctic (Falkland Current) origin. South of 39°S these two species were replaced by Black–browed Albatross and Great Shearwater in cold offshore water of the Falkland Current. Off the Valdes Peninsula Black–browed Albatross, Great and Sooty Shearwaters, White–chinned Petrels and family groups of Magellanic Penguins occurred near the edge of highly–productive water of the Falkland Current. The largest feeding area, east of Tierra del Fuego, had Magellanic and Rockhopper Penguins, Great Shearwaters, King Cormorants, South American Terns and jaegers, but no oceanographic information is available. At 50°S prions and diving petrels appeared for the first time, marking a possible oceanographic discontinuity or proximity to colonies on the Falkland Islands. Several common species of the South Atlantic were not seen on the transect including Cape Pigeon, Southern Fulmar, Soft–plumaged Petrel, Schlegel's Petrel and Pediunker. Kelp Gull, South American Tern, Manx Shearwater and jaegers were rare or absent far from land. New southern limits for the western South Atlantic Ocean were established for Cory's and Manx Shearwaters, and the Great Shearwater was observed for the first time in Chilean waters.     

Trans‐equatorial migration,staging sites and wintering area of Sabine’s Gulls Larus sabini in the Atlantic Ocean

The migrations and winter distributions of most seabirds, particularly small pelagic species, remain poorly understood despite their potential as indicators of marine ecosystem health. Here we report the use of miniature archival light loggers (geolocators) to track the annual migration of Sabine’s Gull Larus sabini, a small (c. 200 g) Arctic‐breeding larid. We describe their migratory routes and identify previously unknown staging sites in the Atlantic Ocean, as well as their main Atlantic wintering area in the southern hemisphere. Sabine’s Gulls breeding in northeast Greenland displayed an average annual migration of almost 32 000 km (n = 6), with the longest return journey spanning close to 39 000 km (not including local movements at staging sites or within the wintering area). On their southern migration, they spent an average of 45 days in the Bay of Biscay and Iberian Sea, off the coasts of France, Spain and Portugal. They all wintered in close association with the cold waters of the Benguela Upwelling, spending an average of 152 days in that area. On their return north, Sabine’s Gulls staged off the west African coast (Morocco, Mauritania, Senegal), spending on average 19 days at this site. This leg of migration was particularly rapid, birds travelling an average of 813 km/day, assisted by the prevailing winds. Sabine’s Gulls generally followed a similar path on their outbound and return migrations, and did not exhibit the broad figure‐of‐eight pattern (anti clockwise in the southern hemisphere and clockwise in the northern hemisphere) seen in other trans‐equatorial seabirds in the Atlantic and Pacific oceans.     

Calcareous dinoflagellate cyst distributions in surface sediments from upwelling areas off NW Africa, and their relationships with environmental parameters of the upper water column

Only very few studies have focussed on the spatial distribution and ecology of calcareous dinoflagellate cysts (dinocysts) in upwelling areas. Here, distributions of individual calcareous dinocyst species in surface sediment samples from the coastal upwelling zone off NW Africa and their relationships with known environmental parameters of the (sub-)surface waters have been analysed in order to enhance our knowledge on their modern distribution patterns and to determine the ecological significance and palaeoenvironmental reconstruction potential of each calcareous dinocyst species within this exemplary high-productivity region. In addition to calculating relative cyst abundances, well-constrained sedimentation rates have allowed the calculation of dinocyst accumulation rates (cysts cm^− 2 ka^− 1) for most of the surface sample positions, thus providing a much more accurate estimation of actual calcareous dinocyst production in the upper water column than could be warranted in similar studies so far. Distinct differences in the geographic distribution patterns of nine species were observed. In general, high accumulation rates of calcareous dinocysts were found around and south of 29°N and offshore the westernmost Canary Island La Palma, with slightly lower accumulation rates in the upwelling-influenced areas off Cape Yubi and in the upwelling filament area off Cape Ghir. Multivariate ordination techniques were applied in order to compare the cyst accumulation rates of individual species with physical parameters (temperature, salinity, density, mixed layer depth) and the trophic state (nitrate, phosphate and chlorophyll concentrations) of the overlying (sub-)surface waters. All species were found to relate significantly to one or more of the environmental parameters, partly confirming previous results on cyst ecology but also providing new information which will be useful for future palaeoenvironmental reconstructions within upwelling areas.     

Interannual variability (1988-1991) of siliceous phytoplankton fluxes off northwest Africa

Four years of observations (1988–1991) of downward fluxesof diatoms and silicoflagellates at a trap site off Cape Blanc(ca. 20°N, 20°W), northwest Africa, are presented. Significantvariations in flux and species composition were observed aswell as a marked drop in the export of biogenic opal (and diatoms)from 1988 to 1989; fluxes remained low thereafter. We hypothesizethat this diminution might be related to decreased coastal upwellingintensity and offshore spreading of the typical chlorophyllfilament, and/or a lesser silicate content of upwelling watersoff Cape Blanc. In addition, the more seaward positioning ofthe mooring may have influenced the fluxes. At all times, diatomswere the most prominent contributors to the biogenic opal flux,and diatom fluxes closely paralleled total mass flux fluctuations.Although species composition varied seasonally, no significantqualitative variations were observed from year to year. In general,the dominance of neritic diatoms, such as Thalassionema nitzschioidesvar. nitzschioides, resting spores of Chaetoceros and Cyclotellalitoralis, reflected the continuous offshore influence of coastalupwelling at the Cape Blanc trap site, with stronger intensityin spring/summer. In contrast, the occurrence of pelagic diatoms(e.g. Nitzschia bicapitata, N. interruptestriata, T. nitzschioidesvar. parva and Fragilariopsis doliolus), and high silicoflagellatefluxes (mainly Dictyocha messanensis) were linked to inshoretransport of oceanic waters, generally in winter. With the exceptionof some fragile, pelagic diatoms, dominant species found inthe settled material also occurred in the underlying sediments,suggesting that diatom thanatocoenosis downcore (Organisms preservedfrom the top to the bottom in sediment core) can be used asa reliable indicator of the intensity and persistence of theoffshore spreading of coastal upwelling.     

ORNITHOLOGICAL TRANSECTS IN THE NORTH ATLANTIC

An analysis is presented of observations made in the North Atlantic from 14 August to 10 September 1966, and comparisons are made with previously published data relating to this area. The majority of the records were obtained during transects along latitudes 55° N. and 58° N., but other data were collected in Labrador and Newfoundland coastal waters. During the period spent at sea 30 species were recorded, including five passerine species that came aboard ship. Manx Shearwaters were seen in Newfoundland waters where there have been few previous records. The record of a Balearic Shearwater appears to be the most northerly to date. Some evidence of correlation was found between the numbers of Great Shearwaters seen and the surface water temperature, but there was little evidence of correlation in the case of the Fulmar. Other points of interest are the records of moult in the Great Shearwater, and the records of Grey Phalaropes and Sabine's Gulls. An analysis of the skua movements suggests that the Arctic Skuas seen originated from Scandinavia, the Great Skuas from Iceland and the Pomarine and Long-tailed Skuas from the Canadian arctic.     

A further contribution on the biology of the Antarctic flea,Glaciopsyllus antarcticus (Siphonaptera: Ceratophyllidae)

Summary Experiments showed that adult Antarctic Fleas Gladopsyllus antarcticus preferred dark over light conditions, dry over wet conditions, and fine substrate over coarse substrate. Examination of seabird chicks and collections of nest material indicated that the Southern Fulmar Fulmarus glacialoides, is the major host species of the Antarctic Flea, while Snow Petrels Pagodroma nivea, Cape Petrels Daption capense, Antarctic Petrels Thalassoica antarctica, and Wilson's Storm-Petrels Oceanites oceanicus are minor hosts. This is the first report of Antarctic Fleas occuring on either Antarctic Petrels or Wilson's Storm-Petrels. No fleas were found associated with Southern Giant Petrels Macronectes giganteus, Antarctic Skuas Catharacta maccormicki, or Adelie Penguins Pygoscelis adeliae. No live fleas were found in Southern Fulmar nest material during their period of dispersal over the winter months, supporting the hypothesis that Antarctic Fleas survive the winter period by remaining on their seabird host.     

SEA-BIRDS AT LAGOS AND IN THE GULF OF GUINEA

Regular observations of sea-birds were made in the vicinity of Lagos, southwest Nigeria, between October 1967 and June 1971. Records in the Gulf of Guinea were obtained in April 1969 and, together with others from Ghana and Sierra Leone, were used to complement this study. While few large populations of sea-birds are supported, the diversity of species occurring at Lagos and over offshore deep water was great. The occurrence of nine species of sea-bird new to Nigeria was established or confirmed; most of these were also new to West Africa southeast of Gambia. Details are given of fluctuations in numbers these and a further 16 species.
All coastal habitats at Lagos supported a large population of immature Black Terns, and groups of immatures made up a high proportion of observations of other Palaearctic terns and of Royal Terns, which breed only in northwest Africa. In contrast, the Lesser Black-backed Gulls and Damara Terns reaching Lagos (from breeding grounds almost two continents apart) were mainly adults; both these species are amongst those showing a current increase in numbers. A pronounced spring passage was observed among species including Royal and Sandwich Terns, but adult movements in autumn were not elucidated. The occurrence of the European race of the Little Tern in southwest Nigeria was confirmed, it is at least a regular spring migrant. The frequency of vagrants in January and February was linked to local climate as much to general distribution. Brief comment is also given on immature plumages, and the growing exploitation and pollution of coastal waters.     

The relationship between plankton-feeding Bonaparte's and Mew Gulls and tidal upwelling at Active Pass, British Columbia

The food habits of Bonaparte's (Larus Philadelphia) and MewGulls (L. canus) were studied at Active Pass, British Columbia,in relation to upwelling of zooplankton. Bonaparte's Gulls fedmostly on planktonic crustaceans during September-November andagain during April-May, while Mew Gulls foraged there chieflyin February and March. Both species ate predominantly the euphausiid,Thysanoessa raschii, in spring, while Bonaparte's Gulls fedmainly on the amphipods, Parathemisto pacifica and Calliopiuslaeviusculus, in fall. Year-round sampling of zooplankton andcollection of temperature and salinity data showed gull numbersto correlate with times of maximum upwelling and abundance ofzooplankton prey in surface waters. Outside the upwelling zonein Active Pass, Bonaparte's and Mew Gulls fed mostly on fishesand intertidal organisms, but also on zooplankton along tidelines.     

Mesoscale advection of Upogebia pusilla larvae through an upwelling filament in the Canaries Coastal Transition Zone (CTZ)

Larval transport has a strong influence on marine populations and ecosystem function. Traditional hypotheses establish that larvae of coastal species are swept offshore during strong upwelling periods producing low recruitment rates; however, recent studies have demonstrated that this hypothesis is not supported by larval distribution data. The present study examines the influence of upwelling filaments on larval advection and wastage. During August 1993, the transport of Upogebia pusilla was analysed in relation to an offshore filament off Northwest Africa. This mesoscale structure was generated by a trapped, quasi-permanent cyclonic eddy located between the Canary Islands and the African shelf and extended 150?km westward into the oligotrophic open ocean waters. The horizontal distribution depicted by U. pusilla larvae was strongly influenced by the oceanographic features of the Canaries Coastal Transition Zone (CTZ). Specifically, the larvae were closely associated with upwelling front and filament position, showing that these neritic larvae can be advected 10–100s of kilometres offshore through the filament. However, the low larval densities observed in the samples suggest that many larvae might remain close to the coast, thus avoiding seaward transport. This implies that filaments probably do not significantly affect the recruitment success of intertidal invertebrates such us U. pusilla in upwelling systems.     

PHYLOGENETIC RELATIONSHIPS OF BRYDE'S WHALES IN THE WESTERN NORTH PACIFIC AND ADJACENT WATERS INFERRED FROM MITOCHONDRIAL DNA SEQUENCES1

To clarify phylogenetic relationships of Bryde's whales, we examined the nucleotide sequence of the mitochondrial control region and cytochrome b gene in 33 animals: 12 from offshore waters of the western North Pacific, five from off the Solomon Islands, and 16 from the East China Sea and coastal waters of Kochi in southwestern Japan. For reference purposes, homologous sequences from four Balaenoptera species including four Bryde's whales collected in the eastern Indian Ocean were added. We found whales from the three sampling areas to be genetically distinct. The control region sequences suggested that the whales from the three areas separate at higher than the populational level from one another. The cytochrome b data indicated that genetic differences between whales off the Solomon Islands and animals in the other two areas are equivalent to values found among recognized Balaenoptera species, although such a relationship was not observed between the other two areas. We conclude that whales in the East China Sea and coastal waters of Kochi separate from Bryde's whales in offshore waters of the western North Pacific at higher than the populational level but lower than the specific level (i. e., at the subspecific level) and that whales off the Solomon Islands do not belong genetically to the Bryde's whale as previously recognized.     

A simulation of the distribution of Acartia clausi during Oregon Upwelling, August 1973

The distribution of the estuarine copepod Acartia clausi incoastal waters off Oregon during an upwelling period in August1973 is simulated. A time dependent, two dimensional (x, z,t) model relates maximum offshore extent of the copepod's fourlife stages (egg, nauplius, copepodite, and adult) to intensityof the wind stress driving the upwelling circulation, stagedevelopment time, and mortality. Realistic solutions are obtainedby using actual intermittent wind forcing recorded by an anemometerat Newport. Offshore transport is overestimated when the circulationmodel is driven by theoretical continuous winds, suggestingzooplankton may be washed out of coastal upwelling zones (e.g.off Northwest Africa) which undergo periods of prolonged upwelling. With an accurate model of offshore transport and stage developmenttime, the mismatch between predicted and observed distributionsmay be used to estimate field mortality of the various stages.     

Rapid palaeoceanographic changes in the Benguela Upwelling System for the last 160,000 years as indicated by abundances of planktonic foraminifera

Two sediment cores retrieved from the continental slope in the Benguela Upwelling System, GeoB 1706 (19°33.7′S 11°10.5′E) and GeoB 1711 (23°18.9′S, 12°22.6′E), reveal striking variations in planktonic foraminiferal abundances during the last 160,000 years. These fluctuations are investigated to assess changes in the intensity and position of the upwelling centres off Namibia. Four species make up over 95% of the variation within the core, and enable the record to be divided into episodes characterized by particular planktonic foraminiferal assemblages. The fossil assemblages have meaningful ecological significance when compared to those of the modern day and the relationship to their environment. The cold-water planktonic foraminifer, Neogloboquadrina pachyderma sinistral [N. pachyderma (s)], dominates the modern-day, coastal upwelling centres, and Neogloboquadrina pachyderma dextral and Globigerina bulloides characterize the fringes of the upwelling cells. Globorotalia inflata is representative of the offshore boundary between newly upwelled waters and the transitional, reduced nutrient levels of the subtropical waters. In the fossil record, episodes of high N. pachyderma (s) abundances are interpreted as evidence of increased upwelling intensity, and the associated increase in nutrients. The N. pachyderma (s) record suggests temporal shifts in the intensity of upwelling, and corresponding trophic domains, that do not follow the typical glacial-interglacial pattern. Periods of high N. pachyderma (s) abundance describe rapid, discrete events dominating isotope stages 3 and 2. The timing of these events correlates to the temporal shifts of the Angola-Benguela Front (Jansen et al., 1997) situated to the north of the Walvis Ridge. Absence of high abundances of N. pachyderma (s) from the continental slope of the southern Cape Basin indicates that Southern Ocean surface water advection has not exerted a major influence on the Benguela Current System. The coincidence of increased upwelling intensity with the movement of the Angola-Benguela Front can be interpreted mainly by changes in strength and zonality of the trade wind system.     

Environmental fungal diversity in the upwelling ecosystem off central Chile and potential contribution to enzymatic hydrolysis of macromolecules in coastal ecotones

Even though occurrence of fungi in several marine environments has been documented, their inclusion within the marine microbial loop is not fully recognized. A major constraint is whether fungi in coastal waters are truly marine or represent transient microorganisms transported from terrestrial environments. We approached this issue by analyzing ambient fungal composition and hydrolytic activity of culturable fungi along a nearshore-offshore gradient in the upwelling ecosystem off central Chile, a region of high marine productivity strongly influenced by river discharges. We detected different communities of fungi in nearshore and offshore waters, with near estuary strains hydrolyzing proteins and carbohydrates faster than those from offshore sites. We conclude that coastal waters off central Chile comprise distinct fungal communities representative of offshore and nearshore environments, and provide new evidence for fungi processing organic matter in coastal ecotones, opening a fresh perspective for disappearance of organics carried by rivers in the coastal ocean.     

High Complexity Food Webs in Low-diversity Eastern Pacific Reef–Coral Communities

Community-wide feeding interrelationships in a low-diversity coral reef off the Pacific coast of Panamá (Uva Island reef) demonstrate complex pathways involving herbivore, strong corallivore, and carnivore interactions. Four trophic levels with 31 interguild links are identified in a generalized food web, and documented feeding interrelationships with 287+ species links are portrayed in a coral–corallivore subweb. The importance of trophic groups changes greatly with time, from unknown causes over annual to decadal-scale periods, and during very strong El Niño–Southern Oscillation events such that intermittent intense herbivory by echinoids (Diadema) and corallivory by gastropod mollusks, the crown-of-thorns sea star Acanthaster, hermit crabs, and fishes result in high levels of coral mortality and bioerosion of reef substratum. Intraregional differences in species composition and abundances affecting food-web interactions are briefly described for nonupwelling (Uva Island) and upwelling areas (Pearl Islands) in Panamá. Seasonal upwelling in the Pearl Islands results in high plankton productivity, which likely augments production in invertebrates, fishes, marine mammals, and seabirds, but these pathways still remain largely unquantified. The corallivore Acanthaster is absent from upwelling centers in Panamá and from upwelling and nonupwelling areas in the southern and central Galápagos Islands, and the highly destructive, facultative corallivore Eucidaris galapagensis occurs only in the latter offshore islands and at Cocos Island. Relatively recent declines in the abundances of manta rays, sharks, and spiny lobsters are correlated with, but not necessarily causally linked to, increasing fishing activities in the late 1970s to early 1980s. The extent to which the complex yet highly unstable Uva Island food web is representative of other eastern Pacific coral reef ecosystems remains to be investigated.     

Responses by four seabird species to a fluctuating availability of Cape Anchovy Engraulis capensis off South Africa

In recent years, Cape Anchovy Engraulis capensis has been the most important food for four seabirds breeding in South Africa–African Penguin Spheniscus demersus, Cape Gannet Morus capensis, Cape Cormorant Phalacrocorax capensis and Swift Tern Sterna bergii. Between 1984 and 1992, biomass of spawning anchovy fluctuated between about 0.5 and 1.75 million tons. Abundance of anchovy was significantly related to numbers of chicks fledged by African Penguins, occurrence of anchovy in the diet of Cape Gannets and numbers of Cape Cormorants and Swift Terns that attempted to breed. Numbers of African Penguins and Cape Gannets that attempted breeding probably also were influenced by abundance of anchovy. African Penguins and Cape Cormorants abandoned nests when anchovy were scarce and deferred breeding until anchovy became more plentiful. Survival of immature African Penguins in a period of anchovy scarcity was enhanced by availability of South African Sardine Sardinops sagax as an alternative food. When anchovy abundance was low, Cape Gannets fed on sardine.     

The rehabilitation of Swift Terns Sterna bergii incapacitated by marine foam on Robben Island,South Africa

One-hundred-and-three incapacitated Swift Terns Sterna bergii were captured on Robben Island on 15 December 2003; 93 (90%) were released between 28 December 2003 and 4 February 2004, having been treated at the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) facility in Cape Town. The rehabilitation procedure is described. This is the first incident involving the admission of a large group of Swift Terns to SANCCOB and the first time birds have been known to be incapacitated by marine foam, generated by a combination of wave action, kelp mucilage and phytoplankton. Seven had been ringed as chicks; three were from Robben Island, three from other offshore islands of the Western Cape and one from Lüderitz, Namibia, 855km to the north.