Southern African Waters Research Articles

Twenty years later: Biodiversity of marine symbiotic Siphonostomatoida (Copepoda) off Southern Africa.

Siphonostomatoida (Copepoda) consists of 40 families of symbionts infecting vertebrates (17 families) and invertebrates (23 families) found mostly in marine habitats. In 2004, a list was compiled of all the reported families, genera and species symbiotic with marine fish in Southern African waters. Since this was done 20 years ago, it is necessary to re-evaluate the progress made in 20 years regarding our knowledge of the diversity of marine siphonostomatoids. To assess the current knowledge, the 2004 list was updated with reports published since 2004 as well as with new host and locality records including species with changes in taxonomy. Additionally, species collected but unreported as well as species previously reported but with new hosts and/or localities were also added. Currently reports include 16 families, 75 genera and 234 species. However, amongst these are reports of only two families (3 species) infecting invertebrates. Even though the report includes 71 additional species it still compares poorly with the about 2 274 accepted species, especially regarding species infecting invertebrates. Considering South Africas wealth in possible marine host species, examination of more hosts (especially marine teleosts and invertebrates) will definitely result in an increase in the current knowledge about the biodiversity of marine siphonostomatoids off Southern Africa.

A new species of Grillotia Guiart, 1927 (Cestoda: Trypanorhyncha) from the spotted skate, Raja straeleni Poll, in South Africa

A new species of Grillotia Guiart, 1927 was recovered from the spotted skate (Raja straeleni Poll) from the south coast of the Western Cape, South Africa. Grillotia sasciae n. sp. is described based on morphological and molecular data. This species most closely resembles species in the subgenus Grillotia (viz., Grillotia borealis Keeney and Campbell, 2001, Grillotia brayi Beveridge and Campbell, 2007, Grillotia dollfusi Carvajal, 1971, Grillotia erinaceus Dollfus, 1969, Grillotia musculara Hart, 1936 and Grillotia patagonica Menoret and Ivanov, 2012) in having four hooks per principal row and intercalary hook rows in the metabasal region of the tentacular armature, a band of hooks on the external tentacular surface, numerous proglottids, and the presence of an uterine pore, a hermaphroditic sac, and internal and external seminal vesicles. The molecular phylogenetic analysis of the partial 28S rDNA gene, confirms the morphological data as it also groups Grillotia sasciae n. sp. within the G. erinaceus species complex. Grillotia sasciae n. sp. is distinctive among all other valid species in the complex by having two enlarged, uncinate hooks in the basal armature, of a different shape and size from the remaining hooks 1(1') in the metabasal armature. In addition, the retractor muscle of Grillotia sasciae n. sp. attaches at the posterior region of the tentacular bulb rather than the middle portion, continuing posteriorly as seen in most congeners (viz., G. erinaceus, G. borealis, G. brayi, G. musculara and G. pantagonica). The new species is the seventh species within the subgenus Grillotia and the first record of a species of Grillotia from southern African waters.

Disentangling species of the genus Limacia O.F. Müller, 1781, from southern Africa and Europe using integrative taxonomical methods, with the description of four new species

Uncertainty surrounding the number and identity of species of genus Limacia O.F. Muller, 1781, in southern African and European coastal waters presents an ongoing conundrum. Limacia clavigera (O.F. Muller, 1776) was previously thought to be the only species of its genus in the eastern Atlantic, with a distribution covering north- to south-eastern Atlantic waters. In the light of more recent molecular and morphological research, several distinct lineages have been uncovered in both Europe and southern Africa. Here, we gathered this information and included additional specimens from the two regions to produce an integrative morphological and molecular framework in which to delineate species. Molecular data of mitochondrial genes cytochrome oxidase subunit I and the large ribosomal subunit (16S rRNA) were amplified to perform molecular phylogenetic- and species-delimitation analyses. Findings led to the discovery and description of one new species from Europe: Limacia inesae sp. nov., three new species from southern Africa: Limacia jellyi sp. nov., Limacia miali sp. nov., and Limacia langavi sp. nov., and the confirmation of the validity of Limacia lucida (Stimpson, 1855) from southern Africa. Species-specific distributional and ecological traits further support species distinctions and historical biogeographical processes behind the inferred evolutionary relationships are further explored.

Redescriptions of two species of Sepia (Cephalopoda: Sepiidae) from South African waters: Sepia robsoni (Massy, 1927) and S. faurei Roeleveld, 1972

Two species of cuttlefish: Sepia robsoni (Massy) and Sepia faurei Roeleveld, are redescribed based on sexually mature males and females of both species. They were previously known only from their holotypes: male and female, respectively. They belong to a distinct group of small-sized sepiids, all near-endemics of southern African waters. The knowledge of the systematics and biology of this group is still limited despite the long time since the first description (1875). This is because, inter alia, of their small size: not larger than 4 cm mantle length at maturity. Twenty-one individuals of S. robsoni described here were scattered from Port Nolloth area to the Tsitsikamma coast (bottom depth <37–449 m). Eight known individuals of S. faurei came from the eastern Agulhas Bank (bottom depth 116–184 m). S. robsoni can be identified by extremely thinly calcified cuttlebone (transparent); smooth skin of dorsal mantle and head; tips of first pair of arms thick, finger-like, devoid of suckers. S. faurei can be distinguished by the following combination of characters: thick, heavily calcified cuttlebone but with flat and fused inner cone; skin of dorsal mantle and head very densely covered by characteristic warts; thin, whip-like tips of first pair of arms devoid of suckers. All described specimens of both species are deposited in the South African Institute of Aquatic Biodiversity (SAIAB) and in Iziko, South African Museum (SAMC).

Clicking throughout the year: sperm whale clicks in relation to environmental conditions off the west coast of South Africa

Knowledge of cetacean occurrence and behaviour in southern African waters is limited, and passive acoustic monitoring has the potential to address this gap efficiently. Seasonal acoustic occurrence and diel-vocalizing patterns of sperm whales in relation to environmental conditions are described here using passive acoustic monitoring data collected off the west coast of South Africa. Four autonomous acoustic recorders (AARs) were deployed on 3 oceanographic moorings from July 2014 to January 2017. Sperm whale clicks were detected year round in most recording sites, with peaks in acoustic occurrence in summer and late winter through spring. Diel-vocalizing patterns were detected in winter, spring and summer. Higher percentages of sperm whale clicks were recorded by AARs deployed at 1100 m water depth compared to those concurrently deployed at 850 and 4500 m, likely inferring that the whales exhibited some preference to water depths around 1100 m. Acoustic propagation modelling suggested a maximum detection range of 83 km in winter for sperm whale clicks produced at 1100 m. Random forest models classified daylight regime, sea surface height anomaly and month of the year as the most important predictors of sperm whale acoustic occurrence. The continuous acoustic occurrence of sperm whales suggests that the study area supports large biomasses of prey to sustain this species’ food requirements year round. This is the first study to describe the seasonal acoustic occurrence and diel-vocalizing patterns of sperm whales off the west coast of South Africa, extending knowledge of the species previously available only through whaling records.

Species distribution modelling of Bryde's whales, humpback whales, southern right whales, and sperm whales in the southern African region to inform their conservation in expanding economies.

In southern African waters, information about species distribution and habitat preferences of many cetacean species is limited, despite the recent economic growth that may affect them. We determined the relative importance of eight environmental variables (bathymetry, distance to shore, slope, chlorophyll-a, salinity, eastwards sea water velocity, northwards sea water velocity and sea surface temperature) as drivers of seasonal habitat preferences of Bryde’s whales (Balaenoptera brydei), humpback whales (Megaptera novaeangliae), southern right whales (Eubalaena australis) and sperm whales (Physeter macrocephalus). Using presence only data from multiple sources, we constructed predictive species distribution models (SDMs) consisting of ensembles of seven algorithms for these species during both summer and winter. Predicted distribution for all cetaceans was high in southern Africa and, in particular, within the South African Exclusive Economic Zone (EEZ). Predictive models indicated a more pronounced seasonal variation for humpback, sperm and southern right whales than for Bryde’s whales. Southern right whales occurred closer to shore during winter, humpback whales were more likely to occur along the east coast in winter and the west coast in summer, and sperm whales were more concentrated off the shelf in winter. Our study shows that ensemble models using historical, incidental and scientific data, in conjunction with modern environmental variables, can provide baseline knowledge on important environmental drivers of cetacean distribution for conservation purposes. Results of this study can further be used to help develop marine spatial plans and identify important marine mammal areas.

Feeding ecology and microplastic ingestion in Chelon richardsonii (Mugilidae) associated with surf diatom Anaulus australis accumulations in a warm temperate South African surf zone

The study aimed to explore ontogenetic dietary changes and microplastic ingestion in Chelon richardsonii associated with diatom Anaulus australis accumulations in a warm temperate South African surf zone. This species is commercially important and forms an important trophic link in southern African coastal waters. Postflexion larvae, juveniles and adults are dominant in surf zones and were used for comparison. Index of Relative Importance (%IRI) results showed an ontogenetic dietary shift, with postflexion larvae ingesting mostly copepods (%IRI = 52.0) and microplastic fibres (%IRI = 30.7); while older developmental stages fed predominantly on diatoms (%IRI ranging from 53.9 to 65.6) and sand (%IRI ranging from 34.2 to 46.0). Microplastic fibres were found in 40% of fish sampled, microplastic fragments in 5%, and both types were recorded across all developmental stages assessed. This study provides the first record of microplastics in C. richardsonii, adding to growing microplastic research in fishes.

Ideogorgia laurae, an uncommon new octocoral species (Alcyonacea: Keroeididae) from a newly established Marine Protected Area at Burdwood Bank, Argentina

A new deep-sea keroeidid octocoral, Ideogorgia laurae, is described from Burdwood Bank, Argentina. It is distinguished from its single congener by the presence of conspicuous calyces, anthocodial sclerites (flattened and warted rods) and large coenenchymal triradiates. This is the deepest and the first record of that genus outside southern African waters. In addition, this is the first new species described for the recently created Marine Protected Area Namuncura II at Burdwood Bank, Argentine Sea. This discovery in a very well-sampled area shows how little we know about that fauna, and also reinforces the importance of creating MPAs to safeguard hotspots of biodiversity in Subantarctic waters. Finally, the new species is an evidence of early connections between deep Subantarctic and shallow South African benthic faunas.

Iconography of Haliotidae of Southern Africa

The five living species of Haliotdae found in Southern African waters are discussed in detail, descriptions are provided, and a series of images illustrate the variability in color and pattern of these species and a differential diagnosis photographic plate is provided.

Historical Biogeography of Delphininae Dolphins and Related Taxa (Artiodactyla: Delphinidae)

Delphinine dolphins arose via a recent, rapid radiation, probably within the last four million years. Although molecular phylogenies are increasingly well resolved, patterns of morphology-ecology-geography are hard to link to phylogeny or to translate into taxonomy. Such problems might be tackled through understanding the drivers of the delphinine radiation. Here, we examine delphinine historical biogeography using the phylogeny of McGowen et al. (Mol Phylogenet Evol 53:891–906, 2009) as our working hypothesis. We used the “Spatial Analysis of Vicariance” method to delimit modern distribution patterns, including disjunctions involving sister nodes in the Delphininae. The analysis identified disjunct sister nodes, allowing some interpretation of Delphininae biogeography. The Central American Seaway was probably an important gateway for early delphinids, but the succeeding “hard” barrier of the Panama Isthmus had little influence. Southern African waters form the Atlantic-Indo-Pacific gateway, which is sometimes considered a “soft” barrier because of the variation in the Benguela and Agulhas currents, in turn driven by tectonic changes and/or Pleistocene glacial and interglacial cycles. The latter cycles probably fragmented coastal habitats, allowing allopatric speciation. Geological patterns of turnover in Southern Ocean diatoms, which link to physical oceanic change, closely match the main cluster of delphinine divergences. The Eastern Pacific Barrier, and perhaps the associated Humboldt Current and equatorial “cold tongue,” affect modern distributions, but cause and effect are poorly understood. Future research should involve molecular-morphological phylogenetics for all species, subspecies, and ecomorphs. Complete distributions must be known for all taxa to understand how vicariance and dispersal shaped the distribution of delphinines.

International Radicalism, Local Solidarities: The 1797 British Naval Mutinies in Southern African Waters

AbstractThis article details the 1797 mutinies in the British Royal Navy in southern African waters at Simon's Bay and Table Bay at the Cape of Good Hope. Drawing attention to the intersections between international protest during the age of revolution and between local, African protest, it shows that the Cape mutinies were part of an empire-wide strike, and were rooted in the organizational traditions of naval sailors. Yet, these mutinies were also of local significance. They signalled the growing confidence, and radicalization, of the popular classes at the Cape, as sailors, KhoiSan labourers, and slaves all experimented with new strategies of rebellion. Realizing the fundamental class bias of custom and law during their struggles for improvements in wages and working conditions and for a more democratic workplace regime, naval sailors also contributed to a broader political dialogue at the Cape concerning the relationship between the imperial state, freedom, and rights.

Fecundity, oogenesis, and ovulation pattern of southern African Lycoteuthis lorigera (Steenstrup, 1875)

Lycoteuthis lorigera is among the most abundant mesopelagic squid on the continental slope of the south Atlantic. It is the dominant prey in some commercially harvested groundfish. Despite its abundance and importance in the mesopelagic foodweb, its general biology is poorly known. In this study, the spawning pattern and fecundity of L. lorigera from southern African waters were investigated. Both histological examination and length frequency analysis of ovaries in various stages of development revealed that the ovulation pattern of L. lorigera is asynchronous, which indicates a spawning strategy where batches of eggs are spawned repeatedly over time. More specifically, ovulation is group synchronous, where distinct batches of 1,200–2,400 eggs ripen in the ovary and accumulate in the oviducts. The potential fecundity was estimated to be 20,000–50,000 in immature females (n = 6) and 8,000–25,000 in mature females (n = 21). The number of ripe eggs in the oviducts suggests that batches of spawned egg masses contain between 1,000 and 4,000 eggs. The reproductive strategy of L. lorigera is discussed and compared to the reproductive strategies of oceanic squid inhabiting the continental slope of southern Africa.

Delineating the fishes of the Clinus superciliosus species complex in southern African waters (Blennioidei: Clinidae: Clinini), with the validation of Clinus arborescens Gilchrist & Thompson, 1908 and Clinus ornatus Gilchrist & Thompson, 1908, and with de

The Clinus superciliosus complex comprises six closely related species. Three of the species were originally recognized by Gilchrist and Thompson as two distinct species, Clinus superciliosus (Linnaeus, 1758) and Clinus ornatus Gilchrist & Thompson, 1908, and a variety, Clinus superciliosus var. arborescens Gilchrist & Thompson, 1908. A number of other authors described various similar species, which subsequently were all synonymized with Clinus superciliosus. A further species, Clinus spatulatus Bennett, 1983, an obligate estuarine dweller, is known only from the Bot, Kleinmond, and Klein river estuaries in the Western Cape, South Africa. Two further species, Clinus musaicus sp. nov. (discovered while searching for C. ornatus specimens) and Clinus exasperatus sp. nov., are herein described: the first is currently known from False Bay and the west coast of the Cape Peninsula, whereas the second species is known from only two specimens just east of False Bay. Clinus ornatus and Clinus arborescens Gilchrist & Thompson, 1908 are recognized as a valid species, and can be distinguished from C. superciliosus and C. spatulatus on the basis of meristic values, form of the orbital cirrus, position of the dorsal-fin crest, taste bud number and pattern, diet, and coloration. All extant types of C. superciliosus are examined as specimens, or photographs and radiographs, and their validity and identification are assessed. Genetic analysis of mitochondrial and nuclear DNA supports species differentiation. A key is provided for the species complex. Furthermore, the variable coloration of four of the species, probably related to the substrate the larvae settle upon, and the increase in the number of vertebrae, and fin-ray and spine number, with decreasing water temperature is discussed. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society 2012, 166, 827–853.

Sightings of killer whales Orcinus orca from longline vessels in South African waters, and consideration of the regional conservation status

Killer whales Orcinus orca are seldom reported from South African nearshore waters but, allowing for the bias of vessel attraction, observations from longline vessels suggest there is a resident offshore population of fish-eating killer whales. We present reports of killer whales made by observers on pelagic longline vessels fishing for tuna Thunnus spp., swordfish Xiphias gladius and sharks off South Africa, and on demersal longline vessels fishing for Patagonian toothfish Dissostichus eleginoides off the Subantarctic Prince Edward Islands. Off South Africa, observers reported 689 occurrences of killer whales during the period January 2002 to December 2006. Observations off South Africa peaked in January and were minimal in April–May. Most killer whale pods comprised 1–4 individuals and few were more than six. Observations were largely over the shelf edge between the Agulhas Bank and Port Elizabeth on the south-east coast of South Africa. In all, 1 843 line sets, using 3.8 million hooks, were monitored and killer whales occurred at an overall rate of 0.18 per 1 000 hooks. Killer whales depredated at an overall rate of 0.5% of the total catch. A small (maximum 12 individuals) population was recorded at longline vessels off the Prince Edward Islands, but observations were limited to August–September, October–November and May–June. We consider the conservation status of killer whales in southern African waters to be 'vulnerable', because the populations are very small and are subject to both short- and long-term impacts from the longline fisheries.

Reproductive system and the spermatophoric reaction of the mesopelagic squid Octopoteuthis sicula (Rüppell 1844) (Cephalopoda: Octopoteuthidae) from southern African waters

Reproductive features of the poorly known oceanic squid Octopoteuthis sicula are described and quantified to gain insight into the reproductive biology of the species. The data are based on 39 complete and partial specimens from southern African waters, collected between 1975 and 2005. The specimens ranged in mantle length from 38 mm to 290 mm and included juveniles and mature females and males. The species shows female-biased sexual size dimorphism. Ovulation is asynchronous, indicating a repeated spawning strategy. Males transfer spermatophores presumably by using their long terminal organ. Spermatangia (discharged spermatophores) were found implanted in several parts of the body in both females and males, including in the anterior dorsal and ventral rugose, semi-gelatinous mantle tissue of maturing and mature females. This modified mantle tissue was only well developed in females. The morphologies of the spermatophore and the spermatangium of O. sicula are described. The spermatophoric reaction is reconstructed, using various stages of discharge, to provide insight into the process of intradermal implantation of spermatangia of this species.

Southern African skate biodiversity and distribution

The skates (Family Rajidae) have 12 genera and possibly 28 species off southern Africa (southern Angola, Namibia, South Africa and Mozambique). The geographic and bathymetric distribution and the taxonomic composition of the southern African skate fauna are analysed and the distribution mapped. The southern African skate fauna is best known off the temperate west coast of South Africa from the intertidal to approximately 1,200 meters, but poorly known below 1,200 m and sketchily known in warm-temperate and tropical parts of the area. Southern African skates of the temperate continental shelves above 100 m are not diverse and regularly include one species of the genus Dipturus, one species of Leucoraja, two species of Raja (including R. straeleni, the most abundant skate in southern African waters) and the giant skate Rostroraja alba. All of these skates are ‘shelf overlap’ species that range onto the outer shelves and uppermost slopes, and none are confined to inshore environments. Skate diversity increases on the outer shelves and upper slopes. At least half of the skate species are endemic to the southern African region; other species also occur off East or West Africa, a few extend to European waters, and records of one species, Amblyraja taaf, appear to be of strays from nearby sub-Antarctic seas. The genus Bathyraja and softnose skate group (Arhynchobatinae) are surprisingly limited (a single species) in deep-water off southern Africa (unlike other regions including the Antarctic), and almost all of southern African skates are members of the Rajinae. Amongst rajines, the tribes Amblyrajini (Amblyraja, two species, Leucoraja, two species, and Rajella, five species) Rajini (Dipturus, six species, Okamejei, one species, Raja, two species, and Rostroraja, one species), and Anacanthobatini (Anacanthobatis, two species, and Cruriraja, three species) predominate, while Gurgesiellini has a species of Neoraja and possibly two of Malacoraja.

Nidamental glands in males of the oceanic squid Ancistrocheirus lesueurii (Cephalopoda: Ancistrocheiridae) – sex change or intersexuality?

AbstractThis is the first record of intersexuality to have been found within the Cephalopoda. Seven out of 16 sexually mature Ancistrocheirus lesueurii males from southern African waters had nidamental glands in the mantle cavity in addition to a normally developed male reproductive system (spermatophoric complex, testis and hectocotylus). The frequency of occurrence suggests that feminization in male A. lesueurii is not a rare phenomenon in the south‐eastern Atlantic. Normal A. lesueurii shows sexual size dimorphism, with females growing larger than males. The intersexual males formed a distinct size group intermediate between normal males and females, and their testis mass and spermatophore length were significantly larger than in normal males. The absence of oocytes and oviducts in intersexual males indicates that feminization represents pseudohermaphroditism. Intersexuality does not seem to affect male functionality and is apparently advantageous in that larger body size is accompanied by larger testis and spermatophores.

Hidden theories, troubled waters: International relations, the ‘territorial trap’, and the Southern African Development Community's transboundary waters

Abstract Much of the literature examining transboundary watercourses employs an implicit international relations framework. This literature, while helpful in understanding aspects of transboundary watercourses, routinely obfuscates many crucial factors. Specifically, such analyses are marked by: (i) a mis-theorization of the hegemonic structures at work, (ii) undue pessimism regarding the propensity for multi-lateral cooperation, (iii) an assumption that conflict and cooperation exist along a progressive continuum, (iv) a tenet that conflict is restricted to state competition, and thus a neglect of state collusion in violence against certain citizens, and (v) a depoliticization of ecological conditions. Bringing a geographical critique to bear on the IR framed literature illuminates such deficiencies and leads to a more grounded and holistic analysis of the politics of shared watercourses. A case study of the management of shared water resources in the Southern African Development Community is used to demonstrate, in a concrete way, what is obfuscated in the implicit IR approach and how a geographical critique is able to provide an analysis that is both more critical, and more insightful.

Reported Siphonostomatoid Copepods Parasitic on Marine Fishes of Southern Africa

Worldwide there are more than 12000 species of copepods known, of which 4224 are symbiotic. Most of the symbiotic species belong to two orders, Poecilostomatoida (1771 species) and Siphonostomatoida (1840 species). The order Siphonostomatoida currently consists of 40 families that are mostly marine and infect invertebrates as well as vertebrates. In a report on the status of the marine biodiversity of South Africa, parasitic invertebrates were highlighted as taxa about which very little is known. A list was compiled of all the records of siphonostomatoids of marine fishes from southern African waters (from northern Angola along the Atlantic Ocean to northern Mozambique along the Indian Ocean, including the west coast of Madagascar and the Mozambique channel). Quite a few controversial reports exist that are discussed. The number of species recorded from southern African waters comprises a mere 9% of the known species.

Some observations on the reproductive biology of The sixgill shark Hexanchus griseus (Bonnaterre, 1788) from southern African waters

Observations are made of the maturation status of 81 male and 88 female sixgill sharks Hexanchus griseus from southern African waters. Males mature at about 310 cm total length (TL) with the calcification of the terminal cartilage elements of the claspers. Determination of maturity for females was problematic, but most were fully mature by at least 420 cm TL. Newborns were captured at the same location over three consecutive summer seasons, indicating the location of a possible pupping ground.