Structuring factors of the spatio-temporal variability of macrozoobenthos assemblages in a southern Mediterranean lagoon: How useful for bioindication is a multi-biotic indices approach? (original) (raw)
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One hundred eighty nine species of benthic macroinvertebrates, belonging to eleven different zoological groups, were collected in the Tunis north lagoon after regular surveys carried out in twenty six stations. Among the collected species, the Bivalves Musculista senhousia and Pinctada radiata, the Nudibranches Spurilla neapolitana, Hypselodoris villafranca, the Opisthobranch Bursatella leachii and the Polychaetes Pariospilus affinis and Paradoneis lyra were found for the first time in this lagoon. The latter polychaete species were recorded for the first time in Tunisian inshore area. This study revealed the persistence of some species that previously constituted stable populations of the lagoon and also the installation of some new species. The pioneer species Ficopomatus enigmaticus disappeared from this water plane. Moreover, we noted the persistence in the whole lagoon of many species that indicate an unbalanced environment, such as Neanthes caudata, Heteromastus filiformis, Cirriformia tentaculata, Capitella capitata, Ruditapes decussatus, Loripes lacteus and Cerastoderma glaucum. The multivariate analyses did not show an increasing biological gradient from marine water input area towards the inner parts of the lagoon. However, they revealed homogeneity of the communities dominated by disturbance-indicating species. The latter observation could be due to the influence of edaphic factors, particularly sediment organic matter content. The area close to the sea is dominated by species of marine affinity. At phyla level, the most significant variations of abundance averages were shown within Cnidaria and Nemertini groups. In spite of the water quality improvement that led to the decrease of the organic matter content several years after management, the Tunis north lagoon is still polluted.
Impact of management on the diversity of macrobenthic communities in Tunis north lagoon: systematics
Cahiers de biologie …, 2008
One hundred eighty nine species of benthic macroinvertebrates, belonging to eleven different zoological groups, were collected in the Tunis north lagoon after regular surveys carried out in twenty six stations. Among the collected species, the Bivalves Musculista senhousia and Pinctada radiata, the Nudibranches Spurilla neapolitana, Hypselodoris villafranca, the Opisthobranch Bursatella leachii and the Polychaetes Pariospilus affinis and Paradoneis lyra were found for the first time in this lagoon. The latter polychaete species were recorded for the first time in Tunisian inshore area. This study revealed the persistence of some species that previously constituted stable populations of the lagoon and also the installation of some new species. The pioneer species Ficopomatus enigmaticus disappeared from this water plane. Moreover, we noted the persistence in the whole lagoon of many species that indicate an unbalanced environment, such as Neanthes caudata, Heteromastus filiformis, Cirriformia tentaculata, Capitella capitata, Ruditapes decussatus, Loripes lacteus and Cerastoderma glaucum. The multivariate analyses did not show an increasing biological gradient from marine water input area towards the inner parts of the lagoon. However, they revealed homogeneity of the communities dominated by disturbance-indicating species. The latter observation could be due to the influence of edaphic factors, particularly sediment organic matter content. The area close to the sea is dominated by species of marine affinity. At phyla level, the most significant variations of abundance averages were shown within Cnidaria and Nemertini groups. In spite of the water quality improvement that led to the decrease of the organic matter content several years after management, the Tunis north lagoon is still polluted.
Journal of the Marine Biological Association of the United Kingdom, 2014
The lagoon of Boughrara is the largest lagoon in Tunisia. For several decades it has been subject to the impact of increasing anthropogenic activities, and also to environmental stressors due to climate change and the low renewal of its waters. The present work is a contribution to the study of the functional organization of the benthic macrofauna of the lagoon of Boughrara 3 years after the extension of the channel ‘El Kantra’ which connects this lagoon to the open sea. In total, 13 stations facing the main prospective sources of disturbance and in areas likely to be more polluted were seasonally sampled during 2009–2010. Seasonal monitoring of the abiotic parameters shows a spatial heterogeneity linked to environmental and anthropogenic factors, including hydrodynamics, sedimentary texture and anthropogenic activities. The community of benthic macrofauna is generally poorly diversified at lagoonal-marine stations undergoing influences of both the marine and lagoon environment. The...
2009
Two Tunisian lagoons and a coast location, diversely subject to anthropogenic activities and differing according to their degree of communication with the sea, were studied seasonally. The principal environmental variables (temperature, salinity and dissolved oxygen) were measured in situ. Jointly, main benthic macrofauna factors and the AZTI Marine Biotic Index (AMBI) were determined and analyzed. Results show that the seasonal fluctuations of the benthic communities structure differ in the three studied sites and are controlled mainly by the pollution and the hydrodynamic flow. In the first almost enclosed area (southern lagoon of Tunis) where measured environmental factors are more fluctuating and anthropogenic activities are important, the benthic community is more affected all year. The total abundance varies from 1279 to 7547 ind./m 2 and the specific richness from 31 to 61 species, however the evenness does not exceed 0.25 all year. In the other almost enclosed area (lagoon o...
Sardá, R., Serrano, L., Labrune, C., Gil, J., March, D., Amouroux, J.M., Taboada, S., Bonifácio, P. and Grémare, A. 2014. Shallow-water polychaete assemblages in the northwestern Mediterranean Sea and its possible use in the evaluation of good environmental state. Memoirs of Museum Victoria 71: 289-301.
Marine Ecology, 2006
Coastal lagoons can be characterised by strong environmental changes along the outer marine-inner brackish gradient, which are reflected in the patterns of distribution of organisms and composition of assemblages. Close to the sea the assemblages are dominated by marine animals, while in the innermost confined areas, there would be estuarine taxa and organisms typical of organicallyenriched areas. During the last decades, human impact has been severe in these habitats and has often profoundly altered the distribution of animals and plants along the gradient. In this study we have analysed the distribution of macrofauna along the outer marine-inner brackish gradient in five Italian lagoons, affected by severe human disturbance on the Adriatic, Tyrrhenian and Sardinian coasts. We aimed to measure changes in the composition of assemblages according to the distance from the sea, consistent among lagoons and time, after the occurrence of eutrophication, repeated distrophic crisis and other human interventions. We considered existing data from campaigns done during 1994, 1995 and 1999. We arranged different datasets according to the available data, in order to measure the spatial distribution of macrofauna genera with distance from the sea and through time. Analyses showed differences among assemblages related to the gradient. Nevertheless, the species characterizing the assemblages were all typical of organically-enriched areas, which testified to an impoverishment of diversity and functioning of all these systems.
CBM - Cahiers de Biologie Marine, 2009
The Bizerte lagoon belongs to a large lagoonal complex increasingly affected by anthropogenic activities during the last years. At the same time, it is influenced by seawater inputs and by the freshwaters coming from Ichkeul Lake and several wadis, this giving rise to greatly fluctuating environmental conditions. To study the functional organization of the benthic macroinvertebrates, 11 stations facing the main important contamination sources were sampled using a 0.1 m² Van Veen grab. Our results showed that the ecosystem presented signs of trophic imbalance and the overall macrobenthic community was very impoverished, despite the apparent satisfactory ecological status showed by biotic indices. In this situation, microbial food web replaced the herbivore one while only some invertebrate species tolerant to environmental fluctuations were able to survive in such conditions.
The macrozoobenthic assemblages of the Orbetello lagoon was studied in 1994. This basin, one of the widest western Mediterranean lagoons, showed, at the end of 1970s, very rich and highly structured communities, mainly due to the heterogeneity of its habitats and also presented large prairies of marine phanerogams. An increase in organic pollution over recent years has progressively brought about change in the environment, eventually leading in 1992 and 1993 to extended spring macrophyte blooms followed by severe dystrophic crises with high fish mortality in most of the lagoon. The aim of this study was to describe the zoobenthic community structure after these crises in order to assess the ecological conditions of the lagoon. A total of 70 species and 15 332 individuals were collected at the 9 stations sampled quarterly (March, June, September, December). The results of ordination and correlation analysis indicated that the oxygen level and organic matter percentage in the sediment mainly influenced horizontal species distribution in the different sites at each sampling date. Furthermore, a clear impoverishment of the communities in comparison to previous researches was also observed. Species reduction affected not only marine taxa but also the so-called opportunistic species (primarily aunelids) which were confined near sea inlets. Such patterns, which were quite unusual and differed from those described in other brackish environments with high organic pollution, gave evidence of a reduced resilience of the community despite a moderate recovery in December. The Orbetello lagoon in 1994 was therefore to be considered as under severe environmental stress and it was difficult to assess when or whether these drastic changes will be reversible.
Journal of Coastal Research
Three Tunisian lagoon and coast locations, diversely subjected to human activities and differing according to their degree of communication with the sea, were studied seasonally. Main environmental parameters and the trophic structure and biodiversity parameters of the benthic macrofauna were determined and analysed. Results show that the sites are quite different and each one has its own seasonal fluctuation linked certainly to environmental and anthropogenic factors. In the almost-enclosed lagoon of Ghar El-Melh with high salinity, selective deposit feeders dominate in spring and summer, and in the other seasons the trophic structure is rather balanced. In the southern lagoon of Tunis where environmental factors are more fluctuating and man-made activities of Tunis City and its suburbs are more important, the community is clearly more enriched because of the strong dominance of leader species. In this site, micrograzers dominate clearly all year, with a slight increase in winter. ...