Why do juvenile fish utilise mangrove habitats?

Citation
P. Laegdsgaard et C. Johnson, Why do juvenile fish utilise mangrove habitats?, J EXP MAR B, 257(2), 2001, pp. 229-253
Citations number
66
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Aquatic Sciences
Journal title
JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY
ISSN journal
0022-0981 → ACNP
Volume
257
Issue
2
Year of publication
2001
Pages
229 - 253
Database
ISI
SICI code
0022-0981(20010315)257:2<229:WDJFUM>2.0.ZU;2-P
Abstract
Three hypotheses to discern the strong positive association between juvenil e fish and mangrove habitat were tested with field and laboratory experimen ts. Artificial mangrove structure in the field attracted slightly more juve nile fish than areas without structure. Artificial structure left to accumu late fouling algae attracted four-times the total number of juvenile fish t han areas without structure or areas with clean structure. Community compos ition of fish attracted to structure with fouling algae was different when compared with areas with no structure or clean structure; five species were attracted by structure with fouling algae whilst two species were associat ed with structure regardless of fouling algae. Algae were linked to increas ed food availability and it is suggested that this is an important selectio n criteria for some species. Other species were apparently attracted to str ucture for different reasons, and provision of shelter appears to be import ant. Predation pressure influenced habitat choice in small juvenile fish in laboratory experiments. In the absence of predators, small juveniles of fo ur out of five species avoided shelter but when predators were introduced a ll species actively sought shelter. Large fish were apparently less vulnera ble to predators and did not seek shelter when predators were added to thei r tank. Feeding rate was increased in the mangrove habitat for small and me dium-sized fish compared with seagrass beds and mudflats indicating increas ed food availability or foraging efficiency within this habitat. Larger fis h fed more effectively on the mudflats with an increased feeding rate in th is habitat compared with adjacent habitats. The most important aspect of th e mangrove habitat for small juvenile fish is the complex structure that pr ovides maximum food availability and minimises the incidence of predation. As fish grow a shift in habitat from mangroves to mudflat is a response to changes in diet, foraging efficiency and vulnerability to predators. (C) 20 01 Elsevier Science B.V. All rights reserved.