Diel vertical migration and feeding of chaetognaths in coastal waters of the eastern Mediterranean

This study investigates the diel vertical distribution and the diet of the most important chaetognath species found in the 0–50 m surface layer of a coastal area in the eastern Mediterranean during a 24-hour period in July 2004. Among the recorded chaetognaths, Sagitta enflata was the most abundant species (41.6%), followed by S. minima (32.5%) and S. serratodentata (20.8%). Those three species exhibited a “twilight migration” pattern, with only small differences among them. Vertical separation was found between S. enflata and S. minima. Both species preyed mainly on cladocerans, although copepods were the most abundant group in the zooplankton assemblage. The chaetognath species followed partially the diel vertical migration of their prey. S. enflata showed high feeding intensity at different times in both day and night, while S. minima fed more intensively at midday (12:00) and at dusk (20:00), and S. serratodentata in the morning (08:00). It seems that in order to coexist in an area of low productivity the chaetognath species follow the basic ecological rules of space, time and food-type separation, in order to reduce the inter- and intra-specific competition. The high preference of S. minima and especially of S. enflata for the cladocerans made them probably the most important predators of cladocerans during summer.     

Diet composition,feeding niche partitioning and trophic organisation of large pelagic predatory fishes in the eastern Arabian Sea

Information on the ecology and feeding behaviour of the large oceanic predatory fishes is crucial for the ecosystem approaches to fisheries management models. Co-existing large pelagic predators in the open oceans may avoid competition for the limited forage by resource partitioning on spatial, temporal or trophic levels. To test this, we studied the prey species composition, diet overlap, trophic level, and trophic organisation of 12 large predatory fishes co-existing in the eastern Arabian Sea. Stomach contents of 1,518 specimens caught by exploratory longline operations in the Indian Exclusive Economic Zone during the years 2006–2009 were analysed. Finfishes were dominant prey of all species except blue marlin (Makaira nigricans) and yellowfin tuna (Thunnus albacares), which fed mainly on cephalopods, and long-snouted lancetfish (Alepisaurus ferox) and pelagic stingray (Pteroplatytrygon violacea), which fed mainly on crustaceans. Common dolphinfish (Coryphaena hippurus) and yellowfin tuna fed on a wider variety of prey than the other species, while the diets of lancetfish and black marlin (Istiompax indica) were narrowest. Pelagic stingray and great barracuda (Sphyraena barracuda) fed on species occupying epipelagic waters, whereas the contribution of mesopelagic prey was higher in the diets of swordfish (Xiphias gladius) and pelagic thresher (Alopias pelagicus). Trophic levels of these fishes ranged from 4.13 to 4.37. Diet overlap index revealed that some of the large pelagic predatory fishes share common prey species. Cluster analysis of the diets revealed four distinct trophic guilds namely ‘flyingfish feeders’ (common dolphinfish and great barracuda); ‘mesopelagic predators’ (pelagic thresher and swordfish); ‘crab feeders’ (lancetfish, pelagic stingray and silky shark) and ‘squid feeders’ (yellowfin tuna, Indo-Pacific sailfish (Istiophorus platypterus), skipjack tuna (Katsuwonus pelamis), black marlin and blue marlin). Large predatory fishes of the eastern Arabian Sea target different prey types, and limit their vertical extent and time of feeding to avoid competing for prey.     

Feeding activity and food habits of the shad, Ethmalosa fimbriata (Bowdich), in the coastal waters of Cape Coast, Ghana

The monthly feeding activity and food habits of populations of Ethmalosa fimbriata occurring in the sea and an estuary in Cape Coast, Ghana district were investigated during a 14-month period. The juvenile fish, whose total length (T.L.) ranged from 5.3 to 14.7 cm, occur in the estuary and appeared to be more active feeders than the marine samples which measured 15.0–30.4 cm. The peak feeding activity in the marine population coincided with the onset of'upwelling' in the sea, which period is characterized by high salinities, decreasing temperatures and high zooplankton production. The species is primarily a plankton feeder. The stomachs of the marine samples contained mainly protozoa, crustacea, molluscan larvae and a considerable amount of detritus while the stomachs of the estuarine fish contained mainly phytoplankton, protozoa, sand grains and organic detritus. These observations have been discussed in relation to other reports on populations occurring along the West African coast.     

Distribution and ecology of tintinnids in the plankton of Lebanese coastal waters (eastern Mediterranean)

The tintinnids of Jounieh Bay in Lebanon were identified andtheir numerical abundance determined in horizontal and verticalnet samples from February 1979 to December 1980. Large fluctuationsin abundance and composition of the tintinnid fauna occurredduring the period of investigation. Two distinct peaks werenoted, a major one in May–June and a minor one in November–December.The first followed the main phytoplankton peak, suggesting apositive nutritional relationship between the two populations.The most abundant species were Tintinopsis beroidea and Eutintinnuslusus-undae. A few other species showed great abundance duringshorter periods. In all, 121 species were recorded during thisperiod, and of these 12 belong to the genus Tintinnopsis and11 to Eutintinnus.     

The feeding habits of Alestes baremose and Hydrocynus forskali (Pisces) in Lake Albert, East Africa

The stomach contents of 1922 Alestes baremose Joannis and 1184 Hydrocynus forskali Cuvier caught in Lake Albert, East Africa were examined. The fish were caught in gill nets in three main different types of habitat; in lagoons, inshore in the main body of the lake and offshore. Zooplankton, ephemeropteran imagines and higher plant species constituted almost the whole diet of A, baremose , although the relative importance of these three items varied with habitat. In the lagoons and inshore Hydrocynus forskali was mainly piscivorous, but offshore where the largest specimens occur it was feeding mainly on Caridina nilotica. The role of Hydrocynus species as predators in Lake Albert is discussed and it is shown that in this lake predation intensity bythis genus must be considered entirely in terms of H.forskali .     

Distribution and abundance of blackflies (Diptera: Simuliidae) in relation to impoundments in the Buffalo River, eastern Cape, South Africa

1. The abundance of blackfly species along the length (140 km) of the multiply impounded Buffalo River, eastern Cape, South Africa, was studied between 1986 and 1988. 2. Twenty-three species of blackflies were recorded, most of which (95%) were usually found 5–10 km from the source. 3. Impoundments favoured five lower-reach (pest) blackfly species at the expense of two upper-reach (non-pest) species. Impoundments have therefore shifted the distribution of blackfly species ‘upstream’, and have increased the distribution of pest blackflies. 4. The smallest impoundment, situated in the Upper Foothill Stony Run Zone, had the greatest effect on blackfly distribution. 5. There was no typical filter-feeding guild below impoundments. Possible reasons for this included the discharge of toxic algae from impoundments, the lack of compensatory releases, the sudden drying of impoundment tailwaters and the paucity of natural lakes in southern Africa which precludes a pre-adapted ‘outlet’ fauna.     

A contribution to the moss flora of the Cape Provinces (South Africa)

Abstract

Several first records of mosses are reported for continental sub-Saharan Africa, Southern Africa or the Cape Provinces as well as the occurrence of subterranean tuberous stolons in Pleuridium ecklonii and rhizoidal tubers in four acrocarpous mosses, viz. Archidium globiferum, Ditrichum difficile, Fissidens beckettii and Pleuridium nervosum.     

Brachymesophalangia V in Hottentot and “Cape Colored” children in Namibia (South West Africa) and South Africa

In order to determine the incidence of Brachymesophalangia V, an inspectional and metrical analysis was made of radiographs of 67 Nama-speaking Hottentots aged 2 to 17.5 years, and 210 Rehoboth Basters (in Namibia) and Cape Colored children (near Cape Town) aged 1.5 to 21 years. None of the children displayed cone-shaped epiphysis or early union, and none showed Brachymesophalangia V. It was confirmed that the incidence of Brachymesophalangia V is considerably higher in Mongoloid populations than in Caucasoid or Negroid groups, including Hottentots.     

Alternative life-history traits associated with reproduction in Oreochromis mossambicus (Pisces: Cichlidae) in small water bodies of the eastern Cape,South Africa

Synopsis Four wild populations of Oreochromis mossambicus were investigated to examine the effects of environmental factors on reproductive biology in contrasting habitats. Age at maturity, spawning-season length, spawning frequency, clutch size and nesting behaviour were influenced by the prevailing conditions for feeding, breeding and refuge. Even under a temperature regime that approached lethal limits during winter, and erratically fluctuating water levels, O. mossambicus demonstrated an ability to adopt a precocial life-history style in some habitats. In more hostile water bodies an increasingly altricial style was followed.     

Floristic diversity in the Cape Flora of South Africa

Comprising a land area of ca 90000 km2, less than 4% of the total land area for the Southern African subcontinent, the Cape Floristic Province is one of the world's richest areas in terms of botanical diversity for its size. An estimated 8650 species of vascular plants occur in this area, about 65% of which are endemic. This is about 42% of the estimated total for all of southern Africa. The number of species packed into so small an area is remarkable for the temperate zone, and compares closely with species totals for areas of comparable size in the wet tropics. The Cape Region consists of a mosaic of sandstone and shale substrates that give rise to soils of quite different types, and in addition local areas of limestone add to the edaphic diversity. Climates across the region are extremely variable, and the predominant orographic rainfall pattern ranges from 2000mm locally to less than 100mm, often with extremely steep gradients, the result of a mountainous landscape. The edaphic diversity resulting from a mosaic of different soils is compounded by sharp local gradients in precipitation that creates an unusual number of local habitats. A feature of the some of the soils in the Region is low nutrient levels and many of the plants on such soils have low seed dispersal capabilities, a factor important in explaining the high levels of local endemism. Species richness in the Cape Region is hypothesized to have resulted from the presence of a complex mosaic of diverse habitats and steep ecological gradients against a background of relatively stable climate and geology after the mediterranean climate was established there sometime after the beginning of the Pliocene. A local or ecological mode of speciation may have been more important under these conditions than allopatric speciation.     

A new species of Brachysiphon (Penaeaceae) from the Southern Cape, South Africa

A new chasmophitic species of Brachysiphon, B. microphyllum from the dry interior mountain ranges of the Southern Cape is described.     

The Griqua of Campbell, Cape Provice, South Africa.

The Griqua of Campbell in the Cape Province of South Africa are reputed to be descended from an amalgam of Khoi ("Hottentots") with various Caucasoid, Negroid and East Asian elements at the Cape of Good Hope. A stormy history of migration and deprivation has left this small residuum on the edge of the Kalahari Desert. It was hoped that a sero-genetic study of these people, who proudly preserve their identity, might provide further insights into the genetic consitution of their Khoi forebears. Despite the retention of the language of their own, an social mores distinct from of other Mixed populations, they have been shown, however, to have received an appreciable inflow of non-Khoisan genes. This has probably resulted from social factors such as the prestige attaching to Griqua membership and the willingness of the Griqua to assimilate outsiders, combined with the tendency of Campbell Griqua to migrate elsewhere. There are no significant differences between "Griqua" members of the population and those who are not recognized as "Griqua."     

The genus Urera (Urticaceae) in eastern tropical Africa

The species of Urera Gaud. occurring in eastern tropical Africa are revised. Three species are recognized: U. cameroonensis Wedd., occurring from Uganda to the South African Republic (Natal), U. sansibarica Engl., restricted to the coastal zone of Kenya and Tanzania, and U. hypselodendron (Hochst. ex A. Rich.) Wedd., occurring in montane forest from Ethiopia to Malawi. The original material of U. hypselodendron var. flamigniana Hauman (nom. inval.) and var. platyrrhachis Hauman (nom. inval.) is excluded from U. hypselodendron; the same applies to the other material of U. hypselodendron cited from central Zaire in Flore du Congo belge. Distribution maps of the eastern African species are provided. Also included is a preliminary study and discussion of the generic subdivision of Urera , with special reference to the species of this revision.     

Feeding habits of the Alaska greenlingHexagrammos octogrammus in the coastal waters of amurskii bay (sea of Japan)

Feeding habits of the Alaska greenlingHexagrammos octogrammus were studied in the coastal waters of Amurskii Bay in April–October 1997–1998. The greenling is characterized by a wide feeding spectrum of no less then 56 fish and invertebrate species. Decapods predominate in the diets of all fish age groups. The feeding spectrum ofH. octogrammus broadens as the fish grows. From spring to autumn, the stomach filling index of first-year fish rises, while that of the other age groups decreases, reaching minimum values in the spawning period.     

The food and feeding habits of two co-occurring marine catfish Galeichthys feliceps and G. ater (Osteichthyes: Ariidae) along the south-east coast of South Africa

The feeding-associated morphological structures of the two Galeichthys species were found to be similar in all respects. Interspecific competition for food was avoided through habitat separation. Habitat preference, as established by dietary analysis and fishing trials, was based on substratum type. Galeichthys feliceps fed over sandy and muddy substrata in marine and estuarine environments, while G. ater fed exclusively over marine reefs. The two species have different caudal fin structures which are probably evolutionary responses to habitat-associated behavioural requirements in the two different environments.
The diets of the two species were investigated and compared using calorific values of prey items. While both species fed predominantly on benthic crustaceans, polychaetes and molluscs, little dietary overlap occurred at the species level. In the estuarine environment, G. feliceps fed mainly on the anomurans Upogebia africana and Calianassa kraussi , crabs Hymenosoma orbiculare and Cleislosoma edwardsii , and several isopod species. In the marine environment G. feliceps fed mainly on two species of crabs, Thaumastoplax spiralis and Goneplax angulata , the echiurid Ochaetostoma capense and the sedentary polychaete Sternaspsis scutata. A high incidence of teleost scales in the diet of G. feliceps juveniles was found to be a consequence of scavenging rather than a lepidophagous habit. Galeichthys ater fed widely on several reef-associated crabs, isopods, polychaetes and cephalopods.