Evidence of Závora Bay as a critical site for reef manta rays, Mobula alfredi, in southern Mozambique.

The largest known reef manta ray (Mobula alfredi) population in Africa has been monitored for more than 20 years at several locations on the coast of the Inhambane Province in southern Mozambique. Nonetheless, before this study, little had been reported on the population dynamics of M. alfredi from Závora, a remote bay in the region. Photographic mark-recapture was used to investigate the size and structure of M. alfredi that aggregate at "Red Sands," a reef cleaning station in Závora Bay. An 11 year photographic data set was used to identify 583 M. alfredi individuals between 2010 and 2021. More than half of M. alfredi individuals were resighted at least once, with most encounters (up to 18 for one individual) occurring during the peak sighting period in July-November each year. An even sex ratio was observed, 44% females and 50% males, with no significant difference in resightings between the sexes. Pollock's robust design population models were used to estimate annual abundance, emigration, annual apparent survival and capture probability at Red Sands from July to November over a 6 year period (2016-2021). Abundance estimates varied year to year, ranging from 35 (95% c.i. [30, 45]) up to 233 (95% c.i. [224, 249]) M. alfredi individuals. Given the seasonal affinity of M. alfredi observed at Red Sands, this study highlights the importance of understanding fine-scale site use within the larger home range of this population to develop local management strategies.

Redescription of a forgotten nudibranch Miamira striata (Eliot, 1904) and review of the taxonomic status of the genus Orodoris (Nudibranchia: Chromodorididae: Miamirinae).

The genus Orodoris Bergh, 1875 is a small genus that together with Miamira Bergh, 1875, was considered as a junior synonym of Ceratosoma A. Adams Reeve, 1850. This decision was based on a morphological phylogenetic study conducted in 1999 that recovered the monophyly of the Ceratosoma. However, in 2012, molecular evidences led to the resurrection of Miamira, while Orodoris was retained as a junior synonym of Miamira with no further details. Here we revise the status of the genus Orodoris in light of the rediscovery of M. striata (syn. Orodoris striata Eliot, 1904). Our phylogenetic analysis revealed a close sister relationship between Miamira striata and Miamira miamirana Bergh, 1875 which nested within the Miamira clade. Therefore, to retain the monophyly of Miamira, the genus Orodoris should be maintained as a junior synonym of the former. This study proposes a neotype for M. striata and underscores the importance of reviewing historical taxonomic changes and investigating ancient descriptions prior to describing new taxa. Our study also confirms that Miamira magnifica Eliot, 1910 from the Indian Ocean and Miamira flavicostata Baba, 1940 from the Pacific Ocean represent two distinct, sister species.

Astonishing diversity revealed: an annotated and illustrated inventory of Nudipleura (Gastropoda: Heterobranchia) from Mozambique.

This paper provides the first comprehensive annotated and illustrated inventory of Nudipleura from Mozambique. A total of 267 species are recorded, including 61 putative new species, documented over a period of seven years from several localities along the coast. At least 20 species need further investigation through molecular and taxomic analysis. Of the 186 confirmed described species, 118 are new records for the Mozambican fauna. Sampling was carried in tidal reefs and depths up to 60m on the subtropical and tropical coast of Mozambique. The most representative families were Chromodorididae (69 species), Discodorididae (30 species), Facelinidae (23 species) and Phyllididae (16 species). Nevertheless, a vast area of Mozambique remains unexplored, thus it is likely that the species documented here represent only a fraction of the true Nudipleura diversity of the country.

Effects of yearling, juvenile and adult survival on reef manta ray (Manta alfredi) demography.

BACKGROUND: The trade in manta ray gill plates has considerably increased over the last two decades. The resulting increases in ray mortality, in addition to mortality caused by by-catch, has caused many ray populations to decrease in size. The aim of this study was to ascertain how yearling and juvenile growth and survival, and adult survival and reproduction affect reef manta ray (Manta alfredi) population change, to increase our understanding of manta ray demography and thereby improve conservation research and measures for these fish. METHODS: We developed a population projection model for reef manta rays, and used published life history data on yearling and juvenile growth and adult reproduction to parameterise the model. Because little is known about reef manta ray yearling and juvenile survival, we conducted our analyses using a range of plausible survival rate values for yearlings, juveniles and adults. RESULTS: The model accurately captured observed variation in population growth rate, lifetime reproductive success and cohort generation time in different reef manta ray populations. Our demographic analyses revealed a range of population consequences in response to variation in demographic rates. For example, an increase in yearling or adult survival rates always elicited greater responses in population growth rate, lifetime reproductive success and cohort generation time than the same increase in juvenile survival rate. The population growth rate increased linearly, but lifetime reproductive success and cohort generation time increased at an accelerating rate with increasing yearling or adult survival rates. Hence, even a small increase in survival rate could increase lifetime reproductive success by one pup, and cohort generation time by several years. Elasticity analyses revealed that, depending on survival rate values of all life stages, the population growth rate is either most sensitive to changes in the rate with which juveniles survive but stay juveniles (i.e., do not mature into adults) or to changes in adult survival rate. However, when assessing these results against estimates on population growth and adult survival rates for populations off the coasts of Mozambique and Japan, we found that the population growth rate is predicted to be always most sensitive to changes in the adult survival rate. DISCUSSION: It is important to gain an in-depth understanding of reef manta ray life histories, particularly of yearling and adult survival rates, as these can influence reef manta ray population dynamics in a variety of ways. For declining populations in particular, it is crucial to know which life stage should be targeted for their conservation. For one such declining population off the coast of Mozambique, adult annual survival rate has the greatest effect on population growth, and by increasing adult survival by protecting adult aggregation sites, this population's decline could be halted or even reversed.