Browsing by Author "Kochzius, Marc"

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DNA barcoding reveals endangered and protected elasmobranchs in Tanzanian fish markets
(Western Indian Ocean Journal of Marine Science, 2023) Rumisha, Cyrus; Simwanza, Rehema J.; Nehemia, Alex; Mdegela, Robinson H.; Kochzius, Marc
Western Indian Ocean countries have banned elasmobranch finning and enacted legislation to of Marine Science 22(1): 57-65protect endangered elasmobranchs, however finned and morphologically deformed specimens [doi: 10.4314/wiojms.v22i1.6]are still landed and traded on Tanzanian fish markets. Such specimens are difficult to identify Received:morphologically, and it is possible that protected elasmobranchs are among these. This study September 19, 2022used DNA barcoding to uncover protected elasmobranchs in 102 specimens traded on Tan- Accepted:zanian fish markets. The sampled specimens revealed 23 elasmobranch species, 12 of which April 04, 2023(52.1 %) were classified as endangered (EN) or critically endangered (CR) on the IUCN Red List. Published:Three of the identified species (great hammerhead Sphyrna mokarran, oceanic whitetip shark June 16, 2023Carcharhinus longimanus, and pelagic thresher Alopias pelagicus) are protected by Tanzanian laws. Copyright:Hence, it is advised that steps be taken to strengthen law enforcement at landing sites and fish Owned by the journal.markets in the country. Furthermore, the Third Schedule of Fisheries (Amendment) Regula- The articles are open accesstions of 2009 should be updated to include 11 EN and CR elasmobranchs that are not on the list. articles distributed underAdditionally, national and regional elasmobranch conservation plans should be developed to the terms and conditions of the Creative Commons Attribution (CC BY 4.0) licence. prevent the exploitation of endangered elasmobranchs.
DNA barcoding validates new sightings of tridacna elongatissima in Tanzania and Mozambique (Western Indian Ocean)
(Springer, 2022) Velkeneers, Xander; Dissanayake, P. A. K. N.; Huyghe, Filip; Nehemia, Alex; Ratsimbazafy, Hajaniaina Andrianavalonarivo; Kochzius, Marc
There are currently 12 recognised extant species of giant clams (Cardiidae: Tridacninae) inhabiting the tropical waters of the Indo-Pacific. Six species have been newly described or rediscovered since 1982, such as the recently resurrected species Tridacna elongatissima in the Western Indian Ocean. In order to investigate the distri- bution range of this species, 24 specimens have been col- lected and identified by DNA barcoding. This study provides the first record for T. elongatissima in Tanzania and expands both the northern (Zanzibar, Tanzania) and southern (Ponta de Ouro, Mozambique) ranges of this species.
Genetic erosion in the snail littoraria subvittata (reid, 1986) due to mangrove deforestation
(Journal of molluscan studies, 2016) Nehemia, Alex; Huyghe, Filip; Kochzius, Marc
In tropical coastal ecosystems mangrove forests are important as feeding, spawning, breeding and nursery grounds for many marine species. High human population pressure in coastal areas has led to the loss and deterioration of mangrove habitats. Solar salt production can affect these habitats along the East African coast. Littorinid snails live on mangrove trees, forming an important component of the mangrove ecosys- tem and have been used as bioindicators of environmental health and community stress. Littoraria subvittata is the most abundant littorinid species in mangroves along the East African coast. Partial mitochondrial cytochrome oxidase subunit 1 (COI) gene sequences of 298 individuals were used to assess the impact of mangrove deforestation at salt ponds on the genetic diversity and structuring of L. subvittata populations, as well as to infer the demographic history of the species. Nucleotide and haplotype diversities were found to be lower in samples from mangroves at salt ponds than in samples from natural mangroves. The mean nucleotide diversity was 0.049 ± 0.036% and 0.115 ± 0.068% in mangroves at salt ponds and natural mangroves, respectively. The mean haplotype diversity was 0.23 ± 0.14 and 0.50 ± 0.14 in mangroves at salt ponds and natural mangroves, respectively. Analysis of molecular variance (AMOVA) detected a sig- nificant population structure (Ф st = 0.049; P < 0.0001) for the combined populations. Hierarchical AMOVA detected a significant population genetic structure only between populations from mangroves at salt ponds and natural mangroves (Φ ct = 0.022; P < 0.05), but not between any other groupings. Populations from natural mangrove sites showed a significant genetic structure (Ф st = 0.054, P < 0.0001), while populations from sites at salt ponds could not be differentiated (Ф st = −0.0026, P = 0.64). Reduced effective population size was observed in most samples from mangrove sites at salt ponds compared with natural mangrove. The direction of migrants was mostly from salt ponds to natural mangroves. These results show that salt ponds have a negative impact on the genetic diversity of L. subvittata populations and modify the population’s genetic structure.