Bait collecting by subsistence and recreational fishers in Knysna Estuary may impact management and conservation

A closer look at the taxonomic and genetic diversity of endemic South African Marphysa Quatrefages, 1865

The current study investigates the final unresolved cosmopolitan species of Marphysa in South Africa, Marphysa corallina, collected from KwaZulu Natal, Eastern and Western Cape provinces, together with another species collected from northern KwaZulu Natal. Morphological and genetic data prove that M. corallina, originally described from Hawaii, does not occur in South Africa. The curvature of the inner base on maxilla I, the elevated inner base of maxilla II, and the ventral cirrus as a transverse welt with a rounded tip allow us to identify it as a new species of Treadwellphysa, T. izinqa sp. nov. (common name: brown wonderworm). Characteristic traits include the basal reddish and distal golden colour of the subacicular hook, the ear-shaped postchaetal lobe, and tridentate falcigers which is reported for the first time for the genus. This species is harvested as bait on the south coast of SA, although less frequently than the more common blood wonderworm, Marphysa haemasona Quatrefages, 1866, and can be distinguished by its more uniform brown colouration and white-tipped antennae. A second species, Marphysa mzingazia sp. nov., is characterized by red eyes, six branchial filaments extending to the posterior end, the golden aciculae in posterior chaetigers, weakly bidentate yellow/brown subacicular hooks, and the presence of similar sized spinigers along the body. A molecular analysis based on cytochrome oxidase I fragments confirm both taxa as different species. A key for all South African species of Marphysa is included.

An Introduction to Diopatra, the Amazing Ecosystem Engineering Polychaete

The annelid genus Diopatra occurs in all major oceans but is best represented in the shallow depths of warmer waters, where it lives in elaborately decorated tubes. This paper provides an introduction to the animals, discussing their history and diversity. We describe and illustrate its morphology and geographic distribution. While they were thought to be predominantly gonochoristic, recent reproductive studies show that several species are protandric simultaneous hermaphrodites. Development is by broadcast spawning with a brief pelagic stage or direct development in the parental tube or egg mass attached to it. Diopatra is a key ecosystem engineer, altering water flow and deposition and increasing the availability of refugia. We also discuss its harvesting as fishing bait, its role as an alien or introduced species, its capacity to regenerate, its therapeutic potential, and its applications as a bioindicator species for climate change, geographic distribution changes, and dispersal.

Live to Die Another Day: Regeneration in Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae) Collected as Bait in Knysna Estuary, South Africa

Regeneration is critical for survivorship after injury, sublethal predation, and asexual reproduction; it allows individuals to recover, potentially enabling populations of bait species to overcome the effects of bait collection through incidental asexual reproduction. Opportunities for regeneration are created when worms break during collection (which happens more often than not) and are thrown back into the estuary. Additionally, the trade and movement of bait could result in the range expansion of invasive species. This study investigated bait collection habits of local fishermen and the in situ incidence of regeneration in the estuarine moonshine worm, Diopatra aciculata. The evidence shows that this species is capable of anterior and posterior regeneration. The disproportionately small percentage of worms that seem to be recovering from the degree of damage that may be inflicted during bait collection suggests that regeneration may not help worms to withstand the effects of bait collection. However, the continuous movement and discarding of even small numbers of bait in other estuaries can lead to range expansion through incremental build-up, forming new populations, if these fragments are large enough to regenerate.

Reeling them in: taxonomy of marine annelids used as bait by anglers in the Western Cape Province, South Africa

Background

Common names are frequently used inconsistently for marine annelid species used as bait in the peer-reviewed literature, field guides and legislative material. The taxonomy of many such species based on morphology only also ignores cryptic divergences not yet detected. Such inconsistencies hamper effective management of marine annelids, especially as fishing for recreation and subsistence is increasing. This study investigates the scale of the problem by studying the use and names of bait marine annelids in the Western Cape Province of South Africa.

Methods

Fifteen recreational and six subsistence fishers at 12 popular fishing sites in the Western Cape Province donated 194 worms which they identified by common name. Worms were assigned scientific names according to a standard identification key for polychaetes from South Africa, and mitochondrial cytochrome oxidase I (COI) amplified and sequenced.

Results

This study identified 11 nominal species known by 10 common names, in the families Siphonosomatidae, Arenicolidae, Sabellaridae, Lumbrineridae, Eunicidae, Onuphidae and Nereididae. Cryptic diversity was investigated through employing mitochondrial COI sequences and these data will facilitate future identifications among widely distributed species. Several species (Siphonosoma dayi, Abarenicola gilchristi, Scoletoma species, Marphysa corallina, Lysidice natalensis, Heptaceras quinquedens, Perinereis latipalpa) are reported as bait for the first time, and while the names blood- and moonshineworms were consistently applied to members of Arenicolidae and Onuphidae, respectively, coralworm was applied to members of Sabellaridae and Nereididae. Analysis of COI sequences supported morphological investigations that revealed the presence of two taxonomic units each for specimens initially identified as Gunnarea gaimardi and Scoletoma tetraura according to identification keys. Similarly, sequences for Scoletoma species and Lysidice natalensis generated in this study do not match those from specimens in China and India, respectively. Further research is required to resolve the species complexes detected and also to refine the use of names by fishermen over a wider geographic range.

Conservation value of Codium tenue habitat for the endangered Knysna seahorse Hippocampus capensis

We investigated the density and size structure of the endangered Knysna seahorse Hippocampus capensis in the macroalga Codium tenue at three sites in a residential marina estate in the Knysna Estuary, South Africa, over an 18 month period from March 2017 to August 2018. Seahorses were present in C. tenue throughout the year. Average (± SE) densities of 0.33 (± 0.03) and 0.23 (± 0.03) seahorses per kg of C. tenue were found for 2017 and 2018 respectively. Density did not vary across sites but varied significantly across months with a decreasing trend from summer to spring. The average (± SE) adult seahorse height was 75.16 mm (± 0.63 mm) and 69.09 mm (± 0.64 mm) and mass was 2.05 g (± 0.04 g) and 1.65 g (± 0.04 g) for males and females, respectively, and an even sex ratio was observed throughout the sampling period. Height varied across months, with significantly smaller seahorses found in June and August of 2017. Tail length was highly correlated with height and therefore can serve as a potential proxy for determining the height of H. capensis. This study showed that C. tenue is consistently utilised by Knysna seahorse and should therefore be considered an important habitat to protect and facilitate the ongoing conservation of this endangered seahorse species.