138 research outputs found
Structure of fish assemblages on coastal rocky shores of the Azores
Bol. Mus. Mun. Funchal, Sup. N.º 6: 127-138, 2001The structure of fish assemblages was investigated from the surface down to 25 m depth on Azorean rocky shores. A total of 57 fish species was recorded by visual censuses, most species (66%) occurring in the whole depth range studied. Fish abundance was dominated by 11 species, mainly sparids, labrids, carangids and pomacentrids, which constituted over 88% of the total number of individuals recorded. The trophic structure of the fish assemblages studied in the Azores was characterized by the dominance of benthic mesocarnivores and high proportions of herbivores and pelagic macrocarnivores.A estrutura das comunidades ictiológicas dos fundos rochosos dos Açores foi estudada desde a superfície até aos 25 m de profundidade. Um total de 57 espécies de peixes foi identificado com recurso a censos visuais. A maioria das espécies (66%) ocorreu em toda a gama de profundidades estudada. A fauna ictiológica era dominada, em termos de abundância, por 11 espécies, principalmente pertencentes às famílias Sparidae, Labridae, Carangidae e Pomacentridae, os quais constituíram mais de 88% do número total de indivíduos observados. A estrutura trófica das comunidades ictiológicas estudadas nos Açores apresentouse dominada por meso-carnívoros bentónicos e proporções elevadas de herbívoros e macro-carnívoros pelágico
Linking benthic biodiversity to the functioning of coastal ecosystems subjected to river runoff (NW Mediterranean)
Continental particulate organic matter (POM) plays a major role in the functioning of coastal marine ecosystems as a disturbance as well as an input of nutrients. Relationships linking continental inputs from the Rhone River to biodiversity of the coastal benthic ecosystem and fishery production were investigated in the Golfe du Lion (NW Mediterranean Sea). Macrobenthic community diversity decreased when continen¬tal inputs of organic matter increased, whereas ecosystem production, measured by common sole (Solea solea) fishery yields in the area, increased. Decreases in macrobenthic diversity were mainly related to an increasing abundance of species with specific functional traits, particularly deposit-feeding polychaetes. The decrease in macrobenthic diversity did not result in a decrease, but an increase in ecosystem production, as it enhanced the transfer of continental POM into marine food webs. The present study showed that it is necessary to consider functional traits of species, direct and indirect links between species, and feedback loops to understand the effects of biodiversity on ecosystem functioning and productivity
Wanted dead or alive : high diversity of macroinvertebrates associated with living and ’dead’ Posidonia oceanica matte
The Mediterranean endemic seagrass Posidonia
oceanica forms beds characterised by a dense leaf canopy
and a thick root-rhizome ‘matte’. Death of P. oceanica
shoots leads to exposure of the underlying matte, which
can persist for many years, and is termed ‘dead’ matte.
Traditionally, dead matte has been regarded as a degraded
habitat. To test whether this assumption was
true, the motile macroinvertebrates of adjacent living
(with shoots) and dead (without shoots) matte of
P. oceanica were sampled in four different plots located
at the same depth (5–6 m) in Mellieha Bay, Malta
(central Mediterranean). The total number of species
and abundance were significantly higher (ANOVA;
P<0.05 and P<0.01, respectively) in the dead matte
than in living P. oceanica matte, despite the presence of
the foliar canopy in the latter. Multivariate analysis
(MDS) clearly showed two main groups of assemblages,
corresponding to the two matte types. The amphipods
Leptocheirus guttatus and Maera grossimana, and the
polychaete Nereis rava contributed most to the dissimilarity
between the two different matte types. Several
unique properties of the dead matte contributing to the
unexpected higher number of species and abundance of
motile macroinvertebrates associated with this habitat
are discussed. The findings have important implications
for the conservation of bare P. oceanica matte, which
has been generally viewed as a habitat of low ecological
value.peer-reviewe
Marine reserves: Fish life history and ecological traits matter
Copyright by the Ecological Society of AmericaMarine reserves are assumed to protect a wide range of species from deleterious effects stemming from exploitation. However, some species, due to their ecological characteristics, may not respond positively to protection. Very little is known about the effects of life history and ecological traits (e.g., mobility, growth, and habitat) on responses of fish species to marine reserves. Using 40 data sets from 12 European marine reserves, we show that there is significant variation in the response of different species of fish to protection and that this heterogeneity can be explained, in part, by differences in their traits. Densities of targeted size-classes of commercial species were greater in protected than unprotected areas. This effect of protection increased as the maximum body size of the targeted species increased, and it was greater for species that were not obligate schoolers. However, contrary to previous theoretical findings, even mobile species with wide home ranges benefited from protection: the effect of protection was at least as strong for mobile species as it was for sedentary ones. Noncommercial bycatch and unexploited species rarely responded to protection, and when they did (in the case of unexploited bentho-pelagic species), they exhibited the opposite response: their densities were lower inside reserves. The use of marine reserves for marine conservation and fisheries management implies that they should ensure protection for a wide range of species with different life-history and ecological traits. Our results suggest this is not the case, and instead that effects vary with economic value, body size, habitat, depth range, and schooling behavior.Publicado
Habitat associations of juvenile versus adult butterflyfishes
Author Posting. © Springer-Verlag, 2008. This is the author's version of the work. It is posted here by permission of Springer-Verlag for personal use, not for redistribution. The definitive version was published in Coral Reefs 27 (2008): 541-551, doi:10.1007/s00338-008-0357-8.Many coral reef fishes exhibit distinct ontogenetic shifts in habitat use while
some species settle directly in adult habitats, but there is not any general explanation to
account for these differences in settlement strategies among coral reef fishes. This study
compared distribution patterns and habitat associations of juvenile (young of the year)
butterflyfishes to those of adult conspecifics. Three species, Chaetodon auriga,
Chaetodon melannotus, and Chaetodon vagabundus, all of which have limited reliance
on coral for food, exhibited marked differences in habitat association of juvenile versus
adult individuals. Juveniles of these species were consistently found in shallow-water
habitats, whereas adult conspecifics were widely distributed throughout a range of
habitats. Juveniles of seven other species (Chaetodon aureofasciatus, Chaetodon
baronessa, Chaetodon citrinellus, Chaetodon lunulatus, Chaetodon plebeius,
Chaetodon rainfordi, and Chaetodon trifascialis), all of which feed predominantly on
live corals, settled directly into habitat occupied by adult conspecifics. Butterflyfishes
with strong reliance on corals appear to be constrained to settle in habitats that provide
access to essential prey resources, precluding their use of distinct juvenile habitats.
More generalist butterflyfishes, however, appear to utilise distinct juvenile habitats and
exhibit marked differences in the distribution of juveniles versus adults.This research was funded by a JCU Program Grant to MSP, while MLB was
supported by an NSF (USA) Graduate Research Fellowship
Rare Species Support Vulnerable Functions in High-Diversity Ecosystems
Around the world, the human-induced collapses of populations and species have triggered a sixth mass extinction crisis, with rare species often being the first to disappear. Although the role of species diversity in the maintenance of ecosystem processes has been widely investigated, the role of rare species remains controversial. A critical issue is whether common species insure against the loss of functions supported by rare species. This issue is even more critical in species-rich ecosystems where high functional redundancy among species is likely and where it is thus often assumed that ecosystem functioning is buffered against species loss. Here, using extensive datasets of species occurrences and functional traits from three highly diverse ecosystems (846 coral reef fishes, 2,979 alpine plants, and 662 tropical trees), we demonstrate that the most distinct combinations of traits are supported predominantly by rare species both in terms of local abundance and regional occupancy. Moreover, species that have low functional redundancy and are likely to support the most vulnerable functions, with no other species carrying similar combinations of traits, are rarer than expected by chance in all three ecosystems. For instance, 63% and 98% of fish species that are likely to support highly vulnerable functions in coral reef ecosystems are locally and regionally rare, respectively. For alpine plants, 32% and 89% of such species are locally and regionally rare, respectively. Remarkably, 47% of fish species and 55% of tropical tree species that are likely to support highly vulnerable functions have only one individual per sample on average. Our results emphasize the importance of rare species conservation, even in highly diverse ecosystems, which are thought to exhibit high functional redundancy. Rare species offer more than aesthetic, cultural, or taxonomic diversity value; they disproportionately increase the potential breadth of functions provided by ecosystems across spatial scales. As such, they are likely to insure against future uncertainty arising from climate change and the ever-increasing anthropogenic pressures on ecosystems. Our results call for a more detailed understanding of the role of rarity and functional vulnerability in ecosystem functioning
The global flood protection savings provided by coral reefs
Coral reefs can provide significant coastal protection benefits to people and property. Here we show that the annual expected damages from flooding would double, and costs from frequent storms would triple without reefs. For 100-year storm events, flood damages would increase by 91% to 400?M for each of these nations. Sea-level rise will increase flood risk, but substantial impacts could happen from reef loss alone without better near-term management. We provide a global, process-based valuation of an ecosystem service across an entire marine biome at (sub)national levels. These spatially explicit benefits inform critical risk and environmental management decisions, and the expected benefits can be directly considered by governments (e.g., national accounts, recovery plans) and businesses (e.g., insurance).We gratefully acknowledge support from the World Bank Wealth Accounting and Valuation of Ecosystems (WAVES) Program, the Lyda Hill Foundation, Science for Nature and People Partnership, Lloyd’s Tercentenary Research Foundation, a Pew Fellowship in Marine Conservation to MWB, the German International Climate Initiative (IKI) of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) and the Spanish Ministry of Economy and Innovation (BIA2014-59718- R)
The great melting pot. Common sole population connectivity assessed by otolith and water fingerprints
Quantifying the scale and importance of individual dispersion between populations and life stages is a key challenge in marine ecology. The common sole (Solea solea), an important commercial flatfish in the North Sea, Atlantic Ocean and the Mediterranean Sea, has a marine pelagic larval stage, a benthic juvenile stage in coastal nurseries (lagoons, estuaries or shallow marine areas) and a benthic adult stage in deeper marine waters on the continental shelf. To date, the ecological connectivity among these life stages has been little assessed in the Mediterranean. Here, such an assessment is provided for the first time for the Gulf of Lions, NW Mediterranean, based on a dataset on otolith microchemistry and stable isotopic composition as indicators of the water masses inhabited by individual fish. Specifically, otolith Ba/Ca and Sr/Ca profiles, and delta C-13 and delta O-18 values of adults collected in four areas of the Gulf of Lions were compared with those of young-of-the-year collected in different coastal nurseries. Results showed that a high proportion of adults (>46%) were influenced by river inputs during their larval stage. Furthermore Sr/Ca ratios and the otolith length at one year of age revealed that most adults (similar to 70%) spent their juvenile stage in nurseries with high salinity, whereas the remainder used brackish environments. In total, data were consistent with the use of six nursery types, three with high salinity (marine areas and two types of highly saline lagoons) and three brackish (coastal areas near river mouths, and two types of brackish environments), all of which contributed to the replenishment of adult populations. These finding implicated panmixia in sole population in the Gulf of Lions and claimed for a habitat integrated management of fisherie
- …