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Weak and monthly variable self-recruitment in the coral reef damselfish Dascyllus aruanus in New Caledonia, Cécile Fauvelot [et al.]

Weak and monthly variable self-recruitment in the coral reef damselfish Dascyllus aruanus in New Caledonia, Cécile Fauvelot [et al.]

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C7/ Larval recruitment in marine

and freshwater fishes: Current issues

and future directions



268



Are mangroves important for reef fish on

the Island of Mayotte in the Indian Ocean?

Rakamaly Madi Moussa

1



∗ 1



Institute for Pacific Coral Reefs (IRCP) – BP 1013 Papetoai 98729 Moorea, Polyn´esie f¸caise Tel :

(689) 40 56 13 45, French Polynesia



Coastal habitats such as mangroves are widely considered important nursery grounds for

various species of juvenile reef fishes. In the Caribbean, mangroves are clearly connected to

coral reef, while the function of Indo-pacific mangroves as nursery habitats for reef fishes has long

been debated. This ecosystem has unfortunately been affected by human activity such as coastal

development, bush clearance, landfill and unsustainable fishing. Due to a lack of studies, the

nursery role of these habitats in this region remains undetermined and it is, therefore, essential

to understand the role played by mangroves for coral reef fish on Mayotte Island. Sampling was

carried out during twelve months from April 2016 to March 2017 in three sites (Bandrele near to

a fringing reef, Dzoumogne close to a river mouth and Malamani in a bay) on the mangrove front

using a fyke net combined to visual census surveys. A total of 28,689 fishes distributed among 75

species were recorded. The catches indicate the abundance of juveniles or sub-adults and smallsized species. At Bandrele’s site, specie richness was more diverse than the two other sites with

more reef fish species, indicating that proximity to the coral reef provide an important habitat

for juveniles reef fishes. Ambassidae, Atherinidae, Mugilidae, Sillaginidae, and Mullidae were

the most abundant families in the mangrove of Dzoumogne whereas Atherinidae, Ambassidae

and Leiognathidae dominated the fish population in Malamani Bay. We assume that the habitat

configuration of the Bandrele site shows a possible effect of habitat connectivity between coral

reef fish and adjacent mangroves. The mangroves of Mayotte also provide an additional foraging

area for adults reef fish species during high tide. The mangroves are important habitats for a

diverse assemblage of fish and also have a nursery function. However the mangrove importance

to Mayotte’s reef fish is limited and its role as a nursery for juvenile reef fish should not be

generalised to the whole mangrove island.







Speaker



269



Artificial Light At Night in the Underwater

World

Jack O’connor



∗ 1



1

2



, Emily Fobert 1 , Marc Besson 2 , Lecchini David



2



University of Melbourne – Melbourne, Australia

CRIOBE – bp 1013 Papetoai, French Polynesia



Anthropogenic light pollution affects organisms in terrestrial ecosystems, with chronic exposure leading to altered behaviours and community structures. Although over 20% of the world’s

populated coastline experiences light pollution from coastal infrastructure and marine vessels, we

know little about its impacts on marine organisms, many of which rely on natural lunar cues to

trigger critical biological functions. We investigated for the first time the effects of artificial light

on coral reef fishes during their early life history . Experiments on habitat choice, endocrinology,

histology, growth and predation showed that individuals were behaviourally and physiologically

sensitive to artificial light exposure from the larval stage through to post-settlement, resulting in higher mortality rates and predation vulnerability. These results suggest that increasing

exposure to coastal lighting may impact coral-reef fish populations.







Speaker



270



Effect of the 2011 Tsunami disaster

accompanying the Great East Japan

Earthquake on the population dynamics of

Japanese tube snout Aulichthys japonicus

Go Katayose

1



∗† 1



, Takashi Asahida‡



1



School of Marine Biosciences, Kitasato University – Kitasato, Sagamihara, Kanagawa 252-0373, Japan



The Japanese tube snout Aulichthys japonicus is a small fish species which lives in shallow

coastal waters, especially in seagrass (Zostera spp.) beds. The fish is known for their unusual

spawning behavior of concealing their eggs in ascidians (Halocynthia roretzi ). We have been

studying the larval and juvenile fish fauna in a seagrass bed in southern Iwate, Japan from 2007,

and observed that the fish is a dominant species in the seagrass bed. On March 11, 2011, the

seagrass bed was washed away by the Tsunami. The Japanese tube snout also decreased after

the Tsunami disaster together with the loss of the seagrass bed which plays an important role

as a nursery ground for various coastal fishes. The seagrass bed has been recovering since 2012,

the number of tube snout has also increased from 0.080 /m2 in 2012 to 0.214 /m2 in 2013.

In contrast, the number decreased to 0.050 /m2 in 2014. We assumed that the increase and

decrease of ascidian individuals affected the number of tube snouts, we counted the number of

individuals of ascidians growing on the seawall adjacent to the seagrass bed. The number of

ascidians increased from 0 /m2 in just after the Tsunami (2011) to 10 /m2 in 2013, however,

they decreased to 8 /m2 in the spring of 2014 due to human activity. In 2015, all of the ascidians

on the seawall were scraped off due to reconstruction, and the tube snout decreased to 0.048

/m2 in 2016 even though the seagrass bed has recovered. We observed some egg masses of the

tube snout in the removed ascidians collected from the sea bed. The results of a statistical

analysis using model selection by AIC suggested the effects of the decrease of ascidians led to

the decrease of the tube snout.







Speaker

Corresponding author: mf13003c@st.kitasato-u.ac.jp



Corresponding author: asahida@kitasato-u.ac.jp





271



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Weak and monthly variable self-recruitment in the coral reef damselfish Dascyllus aruanus in New Caledonia, Cécile Fauvelot [et al.]

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