Over het archief
Het OWA, het open archief van het Waterbouwkundig Laboratorium heeft tot doel alle vrij toegankelijke onderzoeksresultaten van dit instituut in digitale vorm aan te bieden. Op die manier wil het de zichtbaarheid, verspreiding en gebruik van deze onderzoeksresultaten, alsook de wetenschappelijke communicatie maximaal bevorderen.
Dit archief wordt uitgebouwd en beheerd volgens de principes van de Open Access Movement, en het daaruit ontstane Open Archives Initiative.
Basisinformatie over ‘Open Access to scholarly information'.
Human exploitation and benthic community structure on a tropical intertidal flat
In: Journal of Sea Research. Elsevier/Netherlands Institute for Sea Research: Amsterdam; Den Burg. ISSN 1385-1101; e-ISSN 1873-1414, meer
|  |
| Trefwoorden |
Aquatic organisms > Marine organisms > Aquatic animals > Marine invertebrates
Interspecific relationships > Predation
Species diversity
Species richness
Marien/Kust |
| Author keywords |
intermediate disturbance; key stone; macrofauna; predation; speciesrichness |
| Auteurs | | Top |
- de Boer, W.F., correspondent, meer
- Prins, H.H.T.
|
|
|
| Abstract |
Human exploitation of intertidal marine invertebrates is known to alter benthic community structure. This study describes the impact that harvesting by women and children has on the intertidal community structure of the mudflats of the Saco on Inhaca Island, Mozambique, by comparing the benthic communities of exploited and unexploited areas. Sampling was done using two different methods: a standard core sampling method with sieving over a 1 mm mesh, and collection by the women of all animals within a 10×10 m quadrat. A number of predictions were tested on the basis of previous studies. Species richness analyses were based on multivariate non-parametric tests. The women collected in total 64 different species per tide period, their mean catch amounting to 30.5 g AFDW (Ash-Free Dry Weight) per person, 69% of which comprised predators. The crab Portunus pelagica was the dominant species in weight. Average harvest was estimated at 0.12 g AFDW m -2 y -1. The benthic community comprised 117 different species, totalling 2200 organisms m -2 or 6.0 g AFDW m -2. No impact of the exploitation could be detected for any of the following macrobenthos parameters: biomass, abundance, density or percentage of target species, predator:prey ratio, target species size, species richness, species-rank abundance, or biomass/abundance ratio. No significant correlation was found between the benthos variables obtained with the core samples and the human predation pressure. The low biomass figures for predators obtained in the Saco could be linked with the human exploitation there. The samples collected in the 10×10 m quadrats comprised <0.1% of the numerical abundance and <5% of the biomass of the core samples. Species composition was also different by this method. Nevertheless, people preferred the areas with the highest abundance, biomass and species richness as judged from these 10×10 m samples. These samples apparently represented better the substrate characteristics from a human-predation perspective, and measured target species availability. The absence of any large exploitation impact is attributed to: the low level of harvest in relation to availability, the high production/biomass ratio of tropical benthos, and the mobility of the crabs. The human impact is also relatively low because of the specific characteristics of the sand-and mudflats, in which animals targeted can hide and escape predation, in contrast to rocky substrates (on which the majority of previous studies have concentrated). No keystone species could be found, and no cascading effects were apparent through the exploitation of predatory crabs. |
IMIS is ontwikkeld en wordt gehost door het VLIZ.
