Abstract. Marine 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 sizeclasses 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.

ABSTRACT1. Maerl beds occur worldwide and are formed by an accumulation of unattached calcareous red algae (Rhodophyta).2. Maerl-forming algae grow in a superficial living layer on sediments within the photic zone. 3. Maerl beds are spatially complex habitats with a high degree of species and trophic group diversity.4. The European Commission's 'Habitats Directive' mandates the conservation management of two of the main European maerl-forming species, Phymatolithon calcareum and Lithothamnion corallioides.5. Mediterranean maerl beds are to be considered for inclusion in national inventories of sites of conservation interest, as required by the SPABIM Protocol of the Barcelona Convention.6. In spite of their importance, and the requirement for their conservation management, European maerl grounds suffer a variety of anthropogenic perturbations including direct exploitation through extraction, fishing impacts and chemical pollution by organic matter and excess nutrients.7. The ecology of northeast Atlantic and Mediterranean maerl beds has received little attention, in contrast to other marine communities (e.g. kelp forests, sea-grass meadows). * Correspondence to: P.G. Moore, University Marine Biological Station Millport, Isle of Cumbrae, KA28 0EG, UK. E-mail: pmoore@udcf.gla.ac.uk y Authorship alphabetical: cite as BIOMAERL team z Coordinator 8. Key conservation and management measures proposed include: the recognition that maerl beds are non-renewable resources and cannot sustain direct exploitation; prohibitions on the use of towed gear on maerl grounds; moratoria on the issue of further permits for the siting of aquaculture units above maerl grounds; monitoring of existing exploited or impacted maerl beds; the designation of 'no-take' reserves; measures to limit the impacts that might affect water quality above maerl beds; a programme of monitoring of the 'health' of European maerl beds; an awareness campaign on the biological importance of maerl beds; a higher conservation status for maerl habitats and maerlforming species in European legislation; and further research on maerl ecosystems.

Forty stations within a 20 km2 Maltese maerl bed were sampled by grab to gather data on sediment granulometry and the percentage mass, sphericity, and morphotype of rhodoliths. Two stations were monitored between July 1996 and April 1998 to study temporal variation in species diversity and abundance of the epi- and endo-benthos. Maerl was commonest at 51–90 m depth with 20–39% live rhodoliths in central parts of the maerl bed, while the peripheral parts had less than 20% live rhodoliths. The most abundant rhodolith morphotypes were branching forms and those with a rugged surface. The maerl bed proved to have high species diversity with 244 animal and 87 algal taxa recorded; molluscs, crustaceans, and annelids were the dominant taxa in the endobenthos, and bryozoans and sponges in the epibenthos. Community composition, rhodolith morphology and sediment characteristics at the two sites were related to differences in the hydrodynamic regime resulting from seabed topographical heterogeneity.peer-reviewe

The conservation of the coastal marine environment requires the possession of information that enables the global quality of the environment to be evaluated reliably and relatively quickly. The use of biological indicators is often an appropriate method. Seagrasses in general, and Posidonia oceanica meadows in particular, are considered to be appropriate for biomonitoring because of their wide distribution, reasonable size, sedentary habit, easy collection and abundance and sensitivity to modifications of littoral zone. Reasoned management, on the scale of the whole Mediterranean basin, requires standardized methods of study, to be applied by both researchers and administrators, enabling comparable results to be obtained. This paper synthesises the existing methods applied to monitor P. oceanica meadows, identifies the most suitable techniques and suggests future research directions. From the results of a questionnaire, distributed to all the identified laboratories working on this topic, a list of the most commonly used descriptors was drawn up, together with the related research techniques (e.g. standardization, interest and limits, valuation of the results). It seems that the techniques used to study meadows are rather similar, but rarely identical, even though the various teams often refer to previously published works. This paper shows the interest of a practical guide that describes, in a standardized way, the most useful techniques enabling P. oceanica meadows to be used as an environmental descriptor. Indeed, it constitutes the first stage in the process.

The present study investigated the levels of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb and Zn in the seagrasses Posidonia oceanica and Cymodocea nodosa, and in the wetland macrophytes Phragmites australis, Arundo donax, Typha domingensis, Apium nodiflorum, and Nasturtium officinale. Results showed that the bioaccumulation capacity from sediments, translocation, total levels in plant tissues, and bioindication of metals in sediments, are generally species-specific. In particular, the patterns of metals in the aquatic plants studied were overall independent of ecology (coasts vs wetlands), biomass, anatomy (rhizomatous vs non rhizomatous plants), and life form (hemicrytophytes vs hydrophytes). However, marine phanerogams and wetland macrophytes shared some characteristics such as high levels of heavy metals in their below-ground organs, similar capacity of element translocation in the rhizosphere, compartmentalization of metals in the different plant organs, and potential as bioindicators of Cu, Mn and Zn levels in the substratum. In particular, the present findings indicate that, despite ecological and morphological similarities, different plant species tend to respond differently to exposure to heavy metals. Furthermore, this seems to result from the species individual ability to accumulate and detoxify the various metals rather than being attributed to differences in their ecological and morpho-anatomical characteristics.