Life-history traits of the false jacopever Sebastes capensis (Scorpaenidae: Sebastinae) in South African waters

Seasonal occurrence, diel‐vocalizing patterns, and call‐types of Antarctic minke whales are described using bio‐acoustic recordings from the west coast of South Africa and the Maud Rise, Antarctica. In Antarctica, minke whale bioduck calls were detected in seven of nine months of hydrophone deployment (peaking in May and September) while downsweeps were only detected in June. Bioduck calls were sporadically detected in South African waters with peak calling in September/October, and no bioducks were detected from March through August. Bioduck call occurrence was high during daytime in Antarctica but there was no diel‐vocalizing pattern in South African waters. We split bioduck B call‐type into two subtypes: B1 with 13 ± 1 pulses (Dominello & Širović, 2016) and B2 with 9 ± 1 pulses (this study). Bioduck B2 was detected both in Antarctic and South African waters, with harmonics up to 2 kHz. Similar bioduck call‐types were detected in Antarctic and South African waters, with bioduck A2 being the most common. Month of the year was the most important predictor of bioduck occurrence both in Antarctic and South African waters. This is the first study to describe the seasonal occurrence, diel‐vocalizing behavior and call‐types of Antarctic minke whales off the South African west coast and eastern Weddell Sea.

Little is known of the movements and seasonal occurrence of humpback whales (Megaptera novaeangliae) of South Africa and the Antarctic, populations once brought to near extinction by historic commercial whaling. We investigated the seasonal occurrence and diel-vocalizing pattern of humpback whale songs off the west coast of South Africa (migration route and opportunistic feeding ground) and the Maud Rise, Antarctica (feeding ground), using passive acoustic monitoring data collected between early 2014 and early 2017. Data were collected using acoustic autonomous recorders deployed 200-300 m below the sea surface in waters 855, 1,118 and 4,400 m deep. Acoustic data were manually analyzed for humpback whale vocalizations. While non-song calls were never identified, humpback whale songs were detected from June through December in South African waters, with a peak in percentage of acoustic occurrence around September/October in the austral spring. In Antarctic waters, songs were detected from March through May and in July (with a peak occurrence in April) where acoustic occurrence of humpback whales was negatively correlated to distance to the sea ice extent. Humpback whales were more vocally active at night than in the day at all recording sites. Detection range modelling indicates that humpback whale vocalizations could be detected as far as 18 and 45 km from recorders in South African and Antarctic waters, respectively. This study provides a multi-year description of the offshore acoustic occurrence of humpback whales off the west coast of South Africa and Maud Rise, Antarctica, regions that should continue to be monitored to understand these recovering populations.

Understanding how thermal tolerance varies in intertidal species is essential for predicting their responses to climate change, including future distribution patterns. This study investigates the upper thermal limits of the patellogastropod, Scutellastra granularis and pulmonate gastropod Siphonaria capensis, two sympatric limpet species from the west and southern coasts of South Africa. Cardiac performance (heart rate) was measured to determine sublethal (Arrhenius Breakpoint Temperature, ABT) and lethal (Flatline Temperature, FLT) thresholds under controlled temperature ramping. Results showed that Siphonaria exhibited higher sublethal (ABT: 40.23±1.96°C) and lethal (FLT: 45.15±2.13°C) thermal limits than Scutellastra (ABT: 35.78±1.58°C, FLT: 40.71±2.08°C), highlighting Siphonaria's greater thermal tolerance. Thermal Safety Margins (TSMs) also varied, with Scutellastra demonstrating site-dependent sensitivity, particularly lower at West Coast National Park (TSM: 3.19±1.41°C). The differences observed are attributed to phylogenetic and habitat adaptations: with Siphonaria's dual respiration system (lungs and gills) supporting a higher thermal tolerance, while Scutellastra's reliance on anaerobic pathways during low tides possibly results in limited thermal tolerance. These findings highlight the greater resilience of Scutellastra to warming, suggesting a greater ability to withstand future climatic conditions, unlike Siphonaria, which faces increasing vulnerability. The study provides a better understanding of the adaptive capacity of intertidal limpets and provides insight into species-specific risks under climate change.

Knowledge of the temporal and spatial characteristics of chokka squid (Loligo vulgaris reynaudii) biology in South African waters is limited, so the possibility of there being a geographically fragmented stock was examined by investigating the distribution of maturity patterns for the species, covering all known spawning areas and using both historical and recent data. Gonadosomatic indices (GSI) varied between year-round consistency and apparent seasonal peaks in both summer and winter; there was no clear spatial pattern. Monthly percentage maturity provided further evidence for two peak reproductive periods each year, although mature squid were present throughout. Sex ratios demonstrated great variability between different areas and life history stages. Male-biased sex ratios were only apparent on the inshore spawning grounds and ranged between 1.118:1 and 4.267:1. Size at sexual maturity was also seasonal, squid maturing smaller in winter/spring than in summer/autumn. Also, squid in the east matured smaller than squid in the west. Although the results from the present study do not provide conclusive evidence of distinct geographic populations, squid likely spawn over a significantly larger area of the Agulhas Bank than previously estimated, and squid on the west coast of South Africa may return to spawn on the western portion of the Agulhas Bank. It remains likely, however, that the east and west coast populations are a single stock and that migration of juveniles to the west coast and their subsequent return as sub-adults is an integral but non-essential and variable part of the life history.

Squalus acutipinnis (previously included in S. megalops) individuals caught off the east, south and west coasts of South Africa were examined for siphonostomatoid copepod infection. Collected siphonostomatoids were fixed and preserved in 70% ethanol and studied under microscopes using both transmitted and incidental light. The copepods were identified and the host-parasite associations estimated by calculating their prevalence, mean intensity and mean abundance. The siphonostomatoids represented four families and six species, and included new host records for Nemesis sp., Lernaeopoda sp. and Eudactylina acanthii, and a new geographical record for E. acanthii. Squalus acutipinnis individuals were infected by relatively low loads of siphonostomatoids. The most commonly found species was Achtheinus pinguis, the only species found off all three coasts. There was no difference in the prevalence of A. pinguis in sharks sampled off the three coasts but the highest mean intensity was found on the East Coast followed by the West Coast. The overall prevalence of A. pinguis was 33.6%, and was an order of magnitude higher than that of the other siphonostomatoids recorded. At such low levels of infection it will thus be necessary to examine a large number of hosts to determine the biodiversity of siphonostomatoids and geographical differences in prevalence in South African waters.

Seasonal occurrence and diel calling behaviour of Antarctic blue whales and fin whales in relation to environmental conditions off the west coast of South Africa

The commercially important chokka squidLoligo reynaudiioccurring in South African waters is currently managed on a single-unit stock hypothesis. We tested this assumption through a spatial comparison of the morphology throughout the distributional range of the species. Forty-three morphometric characters were measured from 1079 chokka collected off the south coast of South Africa, the west coast of South Africa, and southern Angola. While no significant differences were found in the hard body parts, results from classification analysis showed that though all four types of morphometric attributes (soft body parts, beaks, statoliths, sucker rings) resulted in some separation, the most consistent separation of samples from the three regions was based on soft body part morphometric characters. On average, though dependent on the model, the overall correct classification rate ranged from 0.68–0.99 for males and 0.7–0.99 for females in all three regions. Previous DNA analysis had revealed some genetic differences between west coast and south coast samples, suggesting the confluence of the cold Benguela and warm Agulhas current may act as the approximate point of a phenotypic and possible genetic breakpoint. Finer scale genetic analysis of samples collected across the Benguela–Agulhas confluence reported no significant genetic structuring in this area suggesting environmental heterogeneity and not restriction of genetic flow/isolation as the primary driver of the observed phenotypic divergence.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 607:113-127 (2018) - DOI: https://doi.org/10.3354/meps12794 Comparisons of life-history traits of the alien invasive Semimytilus algosus and three other mytilid mussels on the West Coast of South Africa Zannè Zeeman*, George M Branch, Deena Pillay Department of Biological Sciences and Marine Research Institute, University of Cape Town, Rondebosch 7700, South Africa *Corresponding author: zannezeeman@gmail.com ABSTRACT: The invasive mytilid mussel Semimytilus algosus was first recorded on South African shores in 2009 and rapidly spread to occupy 500 km of the West Coast, where it dominates lower portions of the rocky shore. To identify mechanisms underlying the invasive success of S. algosus, the life-history parameters survivorship, reproductive output, recruitment, growth rate and shell and byssus strength were compared among S. algosus and another alien, Mytilus galloprovincialis, and the indigenous mussels Aulacomya atra and Choromytilus meridionalis. To standardise the effects of wave exposure and shore height on life history patterns, all observations and sampling were limited to the low shore at the research site, Bloubergstrand. The 4 mussel species employed very different means of maximising survival and/or space occupancy. S. algosus proved to be a typical r-selected species, with low survival due to its weak shell and byssal strength. Unexpectedly, it grew relatively slowly but had a high reproductive output and exceptionally high recruitment rate that largely account for its invasive success. This study therefore demonstrates how life-history traits influence the invasive success of alien species and allows predictions about their relative impacts on intertidal rocky shores. KEY WORDS: Invasive species · Competition · Rocky shores · Recruitment · Growth · Reproduction Full text in pdf format Supplementary material PreviousNextCite this article as: Zeeman Z, Branch GM, Pillay D (2018) Comparisons of life-history traits of the alien invasive Semimytilus algosus and three other mytilid mussels on the West Coast of South Africa. Mar Ecol Prog Ser 607:113-127. https://doi.org/10.3354/meps12794 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 607. Online publication date: December 06, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

Seasonal acoustic occurrences and diel singing patterns of humpback whale (Megaptera novaeangliae) songs and Antarctic minke (Balaenoptera bonaerensis) whale are described using acoustic recordings from the west coast of South Africa and Maud Rise, Antarctica. Acoustic data were recorded from early 2014 to early 2017. Acoustic occurrences (i.e., presence) of humpback and minke whale sounds were identified through visual scrutiny of spectrograms of recorded data. Environmental conditions associated with humpback whale song occurrences were ranked according to their model-predicted relative importance. In South Africa, humpback whale songs were detected from June to December but peaked in September. In Antarctica, humpback whale songs were detected from March to May (singing peaked in April). Minke whale sounds were only recorded in 2014, between June and September in Antarctica and between September and November in South Africa. Humpback whales were more vocally active at night in all recording sites whereas minke whales were more vocally active during the day. This is the first study to describe the seasonal acoustic occurrences of humpback and minke whales off the west coast of South Africa. Such knowledge could be essential for the conservation and management of these species in both South Africa and Antarctica.


 
 
 No direct palaeoclimatic proxies have been available to indicate the seasonality or amount of rainfall on the west coast of southern Africa during the Early Pliocene. The Benguela Upwelling System (BUS) is today one of the factors responsible for the present-day aridity on the west coast of southern Africa. The initiation of the BUS is frequently linked to the entrenchment of aridity and the establishment of the current winter rainfall pattern on the west coast; however, marine proxies are inconclusive regarding the effects of past fluctuations in the BUS and sea surface temperatures on the rainfall regime. Neither the fossil evidence nor the fact that plants using the C3 photosynthetic pathway predominate at this time, provide direct evidence of winter rainfall at Langebaanweg. We challenge certain assumptions which are commonly made in the literature regarding the timing of inception of a winter rainfall regime on the west coast and the onset of aridity in the Langebaan region, and provide new evidence as to seasonality of rainfall at Langebaanweg in the Early Pliocene. Herein, the identification of frog species from the genus Ptychadena from Langebaanweg provides new and compelling evidence for a summer rainfall regime, or of at least significant summer rainfall, at 5.1 mya in the southwestern Cape of South Africa.
 
 
 
 
 Significance: 
 
 
 
 Advances understanding of the evolution of the winter rainfall zone on the west coast of South Africa
 Assesses evidence for the inception of aridity and a winter rainfall regime on the west coast of South Africa
 Fossil Ptychadenidae from the Early Pliocene site of Langebaanweg provide evidence for a summer rainfall regime at 5.1 mya on the west coast of the southwestern Cape.
 
 
 

Acoustic detectability of whales amidst underwater noise off the west coast of South Africa.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 118:1-12 (1995) - doi:10.3354/meps118001 A suspended migration of humpback whales Megaptera novaeangliae on the west coast of South Africa Best, P. B., Sekiguchi, K., Findlay, K. P. Between 5 October and 19 November 1993, 62 sightings of 155 humpback whales were made from the lighthouse at Cape Columbine, South Africa, in 3 episodes about 9 d apart. For 59 groups tracked by theodolite, the average distance offshore peaked at 2 to 2.5 km. Independent information on offshore distribution was obtained from 1112 km searched by a ski-boat in the vicinity of Cape Columbine, from which the proportions of humpback whale groups in 2 strata (0 to 5 and >5 km) from the shore as seen from the lighthouse did not differ from those expected from the boat data. Net directions of movement for 51 groups were distributed equally to all 4 quadrants of the compass, and those groups showing a concerted directionality of movement were headed equally to the north and to the south. Of the same 51 groups, 70% travelled at net speeds of less than 1.5 km h-1. Migratory indices for individual groups (average speed/net speed) ranged as high as 82, and those with the lowest indices (corresponding to those most likely to be migrating) were distributed equally between northerly and southerly directions. Individual identification photographs taken of 27 humpback whales over 20 d revealed only 10 individuals, 5 of which were resighted on more than 1 occasion and up to 20 d apart. Apparent feeding behaviour by humpback whales was seen on 10 occasions over 38 d, and the production of reddish particulate faeces indicative of recent feeding was seen on 7 occasions, at a defecation rate of 0.22 whale-1 h-1. Faecal samples collected contained euphausiid remains (possibly Euphausia lucens) on 2 occasions and amphipods on another. Overall the data indicated that the southward migration of humpback whales expected at this time of year on the west coast of South Africa had been suspended, probably in response to locally abundant prey. Humpback whale . Migration . Feeding . South Africa Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 118. Publication date: March 09, 1995 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 1995 Inter-Research.

Lernaeopodidae Milne Edwards, 1840, is an ecological and economically important fish parasite family of copepods (Crustacea: Copepoda), consisting of 48 genera with 334 valid species. To date, approximately 17genera have been documented from both teleost and elasmobranch hosts from South African marine waters. As part of parasitological surveys targeting parasites of the endemic intertidal klipfish, Clinus superciliosus (Linnaeus) (Clinidae) along the South African coast, a species of Lernaeopodidae was discovered on the gills of this host. Alella igillimpethu n. sp. is described from Clinussuperciliosus from Langebaan marina on the west coast of South Africa, with a prevalence of 42.1% and mean intensity of 2.9 (ranging from 1-13). Morphological identification was done using light and scanning electron microscopy and the species description was generated with the aid of DEscription Language for TAxonomy (DELTA) software. The mitochondrial cytochrome c oxidase subunit 1 (COI) region, as well as partial 18S and 28S ribosomal RNA genes confirmed the classification within the family Lernaeopodidae. This is the first report of Lernaeopodidae from C.superciliosus, or in fact any member of Clinidae, as well as the first molecular characterisation of any marine lernaeopodid infecting teleost fish from South Africa. This study contributes valuable genetic and morphological data for this copepod family, as well as new host and distribution records.

The west coast of South Africa is well known for its Cenozoic unconsolidated marine and aeolian placer deposits. The gem-quality diamond deposits have been effectively depleted; however, the significant heavy mineral concentrations are actively exploited at Namakwa Sands. This world-class mineral sand has an inferred resource of some 900 million tons at a grade of ~10% total heavy minerals (THMs) from which high-grade concentrates of zircon, rutile and leucoxene are extracted and titanium slag and pig iron are produced. Gangue minerals consist of garnet, pyroxene, kyanite, amphibole, apatite and monazite. Several other resources including satellite deposits proximal and distal to the mine area, extensive diamond mine dumps and present-day beach placers demonstrate the vast heavy mineral potential along the west coast. The increased global demand for the rare-earth elements (REEs) uranium and thorium has initiated interest in the economic potential of gangue minerals from these placer deposits. The present quantitative mineral distribution and mineral chemistry study has shown that monazite, impure zircon, leucoxene and garnet are common constituents that host significant concentrations of the REEs uranium and thorium. The total estimated resources in the Namakwa Sands deposit amount to 250 kt REEs, 4.7 kt uranium and 10.5 kt thorium. Monazite is the most significant contributor to the total thorium and light REE resource, whereas zircon is a heavy REE and U-enriched. Garnet and leucoxene show low concentrations of these elements and make a minor contribution to the total resources. Results from the Namakwa Sands deposit suggest that the west coast of South Africa as a whole presents a vast untapped resource for these elements. Considering the anticipated increasing demand for rare earths and possibly thorium, these resources could be produced as a low-cost by-product from existing and future ilmenite–zircon–rutile producers, thereby increasing the in situ value of the placers and ultimate revenue.

Detrital zircon geochemistry and U–Pb geochronology as an indicator of provenance of the Namakwa Sands heavy mineral deposit, west coast of South Africa