Length-weight relationships for some important forage crustaceans from South Africa

The diet of marine animals is usually determined by stomach content analysis. Although partially digested prey fragments can often be identified to species level, it is difficult to estimate the original mass of the prey organism. This information, however, is essential for calculating both the total food intake as well as the relative contribution of each prey item. In this study we present regression equations that can be used to estimate the original mass of 18 common South African crustaceans from various indigestible fragments such as the carapace (length and width), chelae (length and width of left and right dactylus) and eye (length and width)

Contributions to the taxonomy of South African hermit crabs (Crustacea: Decapoda: Paguroidea) – integrating microCT scanning and barcoding

Hermit crabs form an important component of the marine benthos and globally more than 1,200 species have been described. In the unique bioregion of South Africa, hermit crabs are poorly known, and the last taxonomic revision of the group was that of K. H. Barnard in 1950, who recorded only 32 species. This study combines morphological taxonomy, threedimensional (3D) micro-computed tomography (µCT) visualisations, and molecular barcoding to add to, revise, and provide an updated listing of, the regional fauna. The first section of the thesis comprises four chapters, each giving a detailed account of a species either new to science, or to the region. The pagurid hermit crab Goreopagurus poorei, a new species and genus record to the country, is reported and described from deep sea habitats along the Agulhas Shelf, extending the distribution by >10,000 km across the Indian Ocean. Furthermore, three species are described as new to science, one each from the three most common families. The first of these, a deep-water species from a genus of the family Parapaguridae that was previously unknown to South Africa, Paragiopagurus atkinsonae n. sp., is fully described and illustrated, and compared with two other parapagurids that each play a dominant role in the regional benthic offshore invertebrate community. The other two species new to science, Diogenes n. sp. from the family Diogenidae, and Pagurus n. sp. from the family Paguridae, inhabit coastal reefs in subtidal waters off southern KwaZulu-Natal. For the first time in crustacean taxonomy, species descriptions, particularly the one of Pagurus n. sp., are informed by, or based on, µCT imagery of calcified body parts. Following on this technique, Chapter 6 is a short presentation of the 3D raw dataset of seven µCT scans of types and rare museum specimens used in this thesis, which is made publicly available for download. The taxonomic use of the scanning method, with disseminating volumetric data of hermit crabs, is discussed briefly. The final section investigates the fauna as a whole. In Chapter 7, 194 cytochrome c oxidase subunit I gene segments (COI ‘barcodes’) of 43 nominal species plus 12 additional putative species (n = 55 species-like units) were used to validate morphological identifications. Testing this dataset revealed high barcoding efficacy, with nearly 99% identification success rates, and with the best Kimura 2-parameter distance to safely delimit species of hermit crabs of about 3.5%. Chapter 8 updates the regional fauna and provides taxonomic accounts for 62 nominal species which have either been added subsequent to the previous monographic review, or which have undergone taxonomic revision since that time. Of these, 12 are added for the first time here, increasing the number of known South African hermit crab species to 72, an expansion of 56% since Barnard, and about 20% since a recent species list published by W. Emmerson in 2016. Because colour images are provided for 51 out of 72 species, Chapter 8 can also be used as a preliminary guide. However, this study has shown that the hermit crabs of South Africa are by far more diverse than originally thought, and the summary, which includes only the 72 nominal taxa and none of the additional 10 putative species included in the barcoding dataset, is speculated to be only 60–70% complete. Future taxonomic work, especially in the genera Diogenes and Paguristes, will most likely result in many more species descriptions. Therefore, this current study is to be seen as important step towards a fully illustrated taxonomic catalogue on the South African hermit crabs to be produced in the near future

Characterization of the Demersal Fish Community of a Deep-Sea Radioactive Dump Site (Results of Cruise EPA-7801, R/V ADVANCE II, 21-27 June 1978)

The present report describes the demersal fish fauna collected by otter trawl from RV Advance II on cruise EPA-7801 in the vicinity of a radioactive waste disposal site (R.D.S.) located at a depth of about 3900 m, approximately 200 miles due east of the Virginia coast (Figs. 1, 2). Because the sampling· effort at the R.D.S. was restricted by time and funding, the limited data base accrued from there was analyzed and compared with a much larger data set collected during previous deep-sea trawling studies using the same trawl gear

Descripción de patrones únicos de coloración en vivo como herramienta para la discriminación de especies de cangrejos ermitaños en la península ibérica

The unique colour patterns of the hermit crab species inhabiting the Iberian Peninsula and geographically close areas are studied based on colour patterns observed in live specimens either in the field or live in the laboratory. Live colour patterns are shown to be useful for differentiating species in the Paguroidea from Iberian waters. Colour information has not been frequently documented in previous studies, mainly because of difficulties in accessing live specimens. Up to 51 species are currently recorded within the study area, 45 of which are included in the present work, focusing on the distinctive colour traits for each species that can be observed in the field. A complete key for identifying the species within the study area based on colour patterns is included. This study is the first attempt to put in place this type of tool oriented to field work. Further studies will be required to complete and update this information, especially for species which are scarce or difficult to observe alive.El estudio de los patrones de coloración en ejemplares vivos observados tanto en el campo como en laboratorio, han permitido investigar la existencia de patrones de coloración distintivos para las especies de cangrejos ermitaños que habitan en la península ibérica y zonas geográficamente cercanas. Estos patrones de coloración han demostrado ser de gran utilidad en los Paguroidea de aguas Ibéricas para la identificación de especies. La información relativa al color ha sido frecuentemente obviada en el pasado, principalmente debido a las dificultades para acceder a los ejemplares vivos. En la actualidad existen alrededor de 51 especies registradas en la zona de estudio, 45 de las cuales se incluyen en el presente trabajo, poniendo el foco en los rasgos de color distintivos de cada especie que pueden observarse en el campo. Se incluye una clave completa para la identificación de las especies dentro del área de estudio basada en los patrones de color. Este estudio es el primer intento de implementar este tipo de herramienta orientada al trabajo de campo. Serán necesarios más estudios para completar y actualizar esta información, especialmente para aquellas especies que son escasas o difíciles de observar en vivo

Illustrated keys for the identification of the Pleocyemata (Crustacea: Decapoda) zoeal stages, from the coastal region of south-western Europe

The identification keys of the zoeal stages of Pleocyemata decapod larvae from the coastal region of south-western Europe, based on both new and previously published descriptions and illustrations, are provided. The keys cover 127 taxa, most of them identified to genus and species level. These keys were mainly constructed upon external morphological characters, which are easy to observe under a stereomicroscope. Moreover, the presentation of detailed figures allows a non-specialist to make identifications more easily

Life history and diet of two southern African smoothhound sharks, mustelus mustelus (linnaeus, 1758) And mustelus palumbes smith, 1957

Aspects of the life history and biology of two sympatric coastal shark species (Mustelus mustelus and M. palumbes) off southern Africa are described and compared. Free-swimming male M. mustelus measured390–1 450 mm total length (TL), whereas females were recorded up to 1 650 mm TL. Most specimens of both sexes were found at depths shallower than 100 m. Males mature at 950–1 300 mm TL and females at1 250–1 400 mm TL. Reproduction is seasonal, and each cycle may take one year or longer, if there is a resting period between pregnancies. Litter size was correlated with female size and varied between 2 and 23. Thelargest embryo measured 425 mm TL. The hepatosomatic indices were negatively correlated to embryo length in both species. Prey was dominated by crustaceans, although cephalopods became important in larger M. mustelus. There was a good relationship between prey size and fish size. Free swimming male M. palumbes measured 275–1 008 mm TL, whereas females were recorded up to 1 126 mm TL. M. palumbes males were most often taken from 100–180 m deep and females from 60–140 m. Males mature at 750–850 mm TL and females at 800–100 mm TL. Reproduction appears to be aseasonal in M. palumbes and litters of 3–15 young were recorded, with larger females having larger litters. The largest embryo recorded measured 340 mm TL.The timing of reproductive cycles could not be established, but a high proportion of non-pregnant femalessuggests that there may be a resting period following pregnancy. Crustaceans were the dominant prey type recorded, although larger predators ate a wider variety of prey types than smaller individuals. Although there was overlap in the prey taken by the two shark species, the composition of the diet was strongly influenced by the prey available in different habitats

Intra- and interspecific variability in the distribution patterns and diet of the two most common catsharks caught in demersal trawls off the West and South coasts of South Africa: Evidence for habitat and resource partitioning?

Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol)The objective of this thesis was to elucidate intra- and interspecific variability in the distribution patterns and diet of the two most common demersal catsharks taken as by-catch by the commercial trawling industry targeting the two Cape hake species off the West and South coasts of South Africa. Samples and data were collected during routine demersal hake biomass surveys conducted by DAFF, with distribution data collected from 1994 to 2015 and stomach content and stable isotope data collected from 2014 to 2015. On examination of the distribution data, Holohalaelurus regani was found to be more abundant on the West Coast and Scyliorhinus capensis was found to be more abundant on the South Coast. Both catsharks were observed to display size-based segregations, with catshark size increasing with depth in both species. Differences in the distribution patterns of male and female H. regani were also noted, with female catsharks inhabiting inshore areas and male catsharks inhabiting offshore areas. The two catsharks appeared to display high levels of dietary overlap, with individuals feeding on the most abundant crustaceans and cephalopods caught as by-catch in the trawl on each coast