Implications of spatial heterogeneity for management of marine protected areas (MPAs): examples from assemblages of rocky coasts in the northwest Mediterranean

Marine protected areas (MPAs) are increasingly used as a management tool to preserve species and habitats. Testing hypotheses about the effectiveness of MPAs is important for their implementation and to identify informative criteria to support management decisions. This study tested the general proposition that MPAs affected assemblages of algae and invertebrates between 0.0 and 0.5 m above the mean low water level of rocky coasts on two islands in the Tuscan Archipelago (northwest Mediterranean). Protection was concentrated mainly on the west coasts of the islands, raising the possibility that neither the full range of assemblages nor the relevant scales of variation were properly represented within MPAs. This motivated the comparison of assemblages on opposite sides of islands (habitats). The effects of MPAs and habitat were assessed with a multifactorial sampling design; hypotheses were tested about differences in structure of assemblages, in mean abundance of common taxa and in univariate and multivariate measures of spatial variation. The design consisted of three replicate shores for each condition of protected and reference areas on the west side of each island and three unprotected shores on the eastern side. Assemblages were sampled independently four times on each island between June 1999 and January 2001. At each time of sampling two sites were selected randomly at each of two tidal heights to represent midshore and lowshore assemblages on each shore. Estimates of abundance were obtained using non-destructive sampling methods from five replicate 20x20 cm quadrats at each site. Results indicated differences among habitats in structure of assemblages, in mean abundance of common taxa and in univariate and multivariate measures of spatial variation at the scale of shores. Most of these patterns were inconsistent with the predicted effect of management through MPAs. The data suggest that designation of MPAs in the Tuscan Archipelago should proceed through management of multiple shores and types of habitat selected to guarantee protection to a representative sample of assemblages and to the processes responsible for maintenance of spatial patchiness at different scales. This study also shows that considerations of spatial heterogeneity are important to underpin management decisions about the number, size and location of MPAs.     

A Middle Devensian woolly rhinoceros (Coelodonta antiquitatis) from Whitemoor Haye Quarry,Staffordshire (UK): palaeoenvironmental context and significance

This paper reports the discovery of a rare partial skeleton of a woolly rhinoceros (Coelodonta antiquitatis Blumenbach, 1799) and associated fauna from a low Pleistocene terrace of the River Tame at Whitemoor Haye, Staffordshire, UK. A study of the sedimentary deposits around the rhino skeleton and associated organic‐rich clasts containing pollen, plant and arthropod remains suggests that the animal was rapidly buried on a braided river floodplain surrounded by a predominantly treeless, herb‐rich grassland. Highlights of the study include the oldest British chironomid record published to date and novel analysis of the palaeoflow regime using caddisfly remains. For the first time, comparative calculations of coleopteran and chironomid palaeotemperatures have been made on the same samples, suggesting a mean July temperature of 8–11 °C and a mean December temperature of between ?22 and ?16 °C. Radiocarbon age estimates on skeletal material, supported by optically stimulated luminescence ages from surrounding sediments, indicate that the rhino lived around 41–43 k cal a BP. The combined geochronological, stratigraphic and palaeoenvironmental evidence places the assemblage firmly within the Middle Devensian (Marine Oxygen Isotope Stage 3). This would agree with other regional evidence for the timing of aggradation for the lowest terrace of the Trent and its tributary systems. Copyright © 2012 John Wiley & Sons, Ltd.     

Geological controls on natural ecosystem recovery on mine waste in southern New Zealand

Slopes of an abandoned waste rock at Wangaloa coal mine, south-east New Zealand, have naturally developed variable vegetation cover over the last 40–60 years. Three distinct areas of revegetation can clearly be identified: dense cover, patchy cover, and largely unvegetated, and the differences in revegetation success are directly related to the physical properties of different rock types making up the waste rock substrate. The colonizing plants have become established in largely unweathered rock with essentially no soil development. Quartz gravel and siltstone waste rock are the two principal rock types forming substrates for revegetation. The quartz gravel has clasts up to 3 cm, and was derived from the coal-bearing sequence. Siltstone was largely derived from a Quaternary loess cap on the coal mine area. These two substrates have similar mineral contents, and this mineral material provides the low level of available nutrients. However, there is little difference in nutrient status or trace element load of the different substrates, and differences in cohesion, moisture content, and proportion of quartz pebbles control revegetation success. Finer grained matrix has been flushed from quartz gravel waste rock by rain water, leaving a dry surface armour layer of quartz pebbles. This surface layer inhibits plant establishment, so quartz gravel waste rock remains largely unvegetated. Erosion creates deep rills, and steep surfaces creep downslope. In contrast, full vegetation cover was established on the siltstone waste rock that was cohesive and did not erode. Patchy revegetation was localized by siltstone in mixed quartz gravel and siltstone substrate. Invertebrate diversity and distribution were closely linked to the spatial patterns of revegetation. The rate of revegetation and ecosystem recovery was primarily dependent on the proportion of siltstone waste rock in the last dumped truck load. A quartz pebble content <15% is optimal for plant establishment.     

Selenium in sediments and biota from estuaries of southwest England

Selenium concentrations have been measured in sediment, fucoid macroalgae and macroinvertebrates from four estuaries of SW England (Yealm, Plym, Looe, Fal). Sediment concentrations ranged from about 0.4 μg g⁻¹ in the Yealm to 1.49 μg g⁻¹ at one site in the Plym. Concentrations in Fucus vesiculosus (0.05–0.31 μg g⁻¹) and F. ceranoides (0.05–0.51 μg g⁻¹) were significantly lower than corresponding concentrations in sediment but there was no correlation between algal and sediment concentrations. Selenium concentrations in Littorina littorea (∼4 μg g⁻¹), Hediste diversicolor (2.82–12.68 μg g⁻¹), Arenicola marina (∼17 μg g⁻¹) and Scrobicularia plana (1.18–6.85 μg g⁻¹) were considerably higher than concentrations in macroalga or sediment, suggesting that Se is effectively accumulated from the diet. Although Se concentrations in some invertebrates exceed toxicity thresholds for the diet of predacious birds and fish, no specific evidence for Se toxicity exists in these estuaries.     

Do abyssal scavengers use phytodetritus as a food resource? Video and biochemical evidence from the Atlantic and Mediterranean

Deep-sea benthic communities derive their energetic requirements from overlying surface water production, which is deposited at the seafloor as phytodetritus. Benthic invertebrates are the primary consumers of this food source, with deep-sea fish at the top of the trophic hierarchy. Recently, we demonstrated with the use of baited cameras that macrourid fish rapidly respond to and feed vigorously on large plant food falls mimicked by spinach (Jeffreys et al., 2010). Since higher plant remains are scarce in the deep-sea, with the exception of canyons, where terrestrial material has been observed, these results led us to ask if a more commonly documented plant material i.e. phytodetritus might form a food source for deep-sea fish and mobile scavenging megafauna. We simulated a phytodetritus dump at the seafloor in two contrasting environments (1) the NE Atlantic where carpets of phytodetritus have been previously observed and (2) the oligotrophic western Mediterranean, where the deposition of phytodetritus at the seafloor is a rare occurrence. We recorded the response of the scavenging fauna using an in situ benthic lander equipped with baited time-lapse cameras. In the NE Atlantic at 3000 m, abyssal macrourids and cusk-eels were observed ingesting the phytodetritus. The phytodetrital patch was significantly diminished within 2 h. Abundance estimates calculated from first arrival times of macrourids at the phytodetrital patch in the Atlantic corresponded with abundance estimates from video-transect indicating that fish were attracted to the scent of phytodetrital bait. In contrast to this, in the western Mediterranean at 2800 m a single macrourid was observed investigating the phytodetrital patch but did not feed from it. The phytodetrital patch was significantly diminished within 6.5 h as a result of mainly invertebrate activity. At 1900 m, Lepidion lepidion was observed near the lander and the bait, but did not feed. The phytodetrital patch remained intact until the end of the experiment. In the deployments in the Mediterranean abundance estimates from first arrival times at the bait, corrected for their body size, were lower than estimates obtained from video-transects and trawl catches. This suggests that the Mediterranean fish were not readily attracted to this food source. In contrast, invertebrates in the Balearic Sea were observed ingesting the phytodetritus bait despite the rare occurrence of phytodetritus dumps in the Mediterranean. Stable isotope values of the fish at both study sites, set within the context of the benthic food web, did not demonstrate a strong trophic link to phytodetritus. Fatty acid profiles of these fish indicated a strong link between their lipid pool and primary producers i.e. phytoplankton, which may be attributed to trophic transfer. The usefulness of fatty acid biomarkers in ascertaining deep-sea fish diets is discussed. Our study suggests that the abyssal grenadier C. armatus on the Atlantic Iberian margin is attracted to phytodetritus. However the exact contribution of this food source to the diet of macrourids in this area remains unresolved.     

Food web structure of the epibenthic and infaunal invertebrates on the Catalan slope (NW Mediterranean): Evidence from ��C and ��N analysis

The food-web structure of the epibenthic and infaunal invertebrates on the continental slope of the Catalan Sea (Balearic basin, NW Mediterranean) was investigated using carbon and nitrogen stable isotopes on a total of 34 species, and HPLC pigment analyses for three key species. Samples were collected close to Barcelona (NE Iberian Peninsula), between 650 and 800 m depth and between February 2007 and February 2008. Mean ??¹³C values ranged from −21.0‰ (small Calocaris macandreae and Amphipholis squamata) to −14.5‰ (Sipunculus norvegicus). Values of ??¹⁵N ranged from 4.0‰ (A. squamata) to 12.1‰ (Molpadia musculus). The stable isotope ratios of benthic fauna displayed a continuum of values (e.g. ??¹⁵N range of 8‰), confirming a wide spectrum of feeding strategies (from active suspension feeders to predators) and complex food webs. According to the available information on diets of benthic fauna, the lowest values were found for surface deposit feeders (small C. macandrae and the two ophiuroids A. squamata and Amphiura chiajei) and active suspension feeders (Abra longicallus and Scalpellum scalpellum) feeding on different sizes of particulate organic matter (POM), among which small particles may exhibit lower ??¹⁵N. High annual mean ??¹⁵N values were found among sub-surface deposit feeders, exploiting refractory or frequently recycled organic matter that is enriched in ??¹⁵N. Carnivorous polychaetes (Nephtys spp., Oenonidae and Polynoidae) and large decapods (Geryon longipes and Paromola cuvieri) also displayed high ??¹⁵N values. ??¹³C ranges were particularly wide among surface deposit feeders (ranging from −21.0‰ to −16.4‰), suggesting exploitation of POM of both terrigenous and oceanic origins. Correlation between ??¹³C and ??¹⁵N was generally weak, indicating multiple carbon sources, likely due to the consumption of different kinds of sinking particles (e.g. marine snow, phytodetritus, etc.), sedimented and frequently recycled POM, together with macrophyte remains. The stronger ??¹³C-??¹⁵N correlations found in February and April suggest that during the period of water column homogeneization (winter-spring), the benthic community was sustained by phytodetritus inputs originating from the peak of surface primary production in February. Conversely, weaker ??¹³C-??¹⁵N correlations were observed during the period of water column stratification (beginning in June-July), suggesting that the benthic community in this period was sustained, with a delay of ca. 2/3 months, by multiple carbon sources including continental inputs from river discharge (with the maxima in April-May). Thus both advective and vertical fluxes seem to be food sources for benthos on the Catalonian slope. Pigments in the guts of key species were generally degraded, and only the active suspension feeder A. longicallus ingested fresh chlorophyll during periods of high primary production at the surface (February and April 2007).     

Empty native and invasive bivalve shells as benthic habitat modifiers in a large river

Bivalves are remarkable ecosystem engineers and their long-lasting shells may provide important physical structures for benthic organisms. In the last decades the Danube River has experienced great changes in the bivalve fauna, i.e. several native species have been declining and several invasive species have been introduced. The invasive Corbicula fluminea and Sinanodonta woodiana are now widespread and produce large amounts of shells. In this study, we investigated empty shells of native (Anodonta anatina, Unio tumidus) and invasive (C. fluminea, S. woodiana) bivalves (including their mixtures) as benthic substrates and compared them to clay granules (control), which mimics the natural hard substrates in the Danube River (Hungary). Macroinvertebrate colonization was compared between (i) empty shells and control substrate; (ii) different bivalve species (native and invasive) and (iii) three scenarios (before invasion, and short and long time after invasion) by using a mix of empty shells (native, native plus invasive, and invasive species). In comparison to control treatments the empty shells facilitated the presence of amphipods, caddis larvae and isopods, which contributed to a shift in the trophic structure by decreasing the proportion of gathering collectors while increasing the presence of shredders and predators. Several shell traits such as size, outer-shell surface roughness, hardness, thickness, 3D shape and chemical composition may be important attributes in the habitat modifying effects; however, this study could not disentangle which contribute most for the differences found. Given the capability of invasive C. fluminea and S. woodiana to accumulate large amounts of empty shells on several sites of the Danube, its habitat modifying effects can be particularly important, especially on the macroinvertebrate community structure. Moreover, these effects may increase in near future due to the predicted more frequent and severe extreme climatic conditions, which have been responsible for massive mortalities in both species.     

Effects on biodiversity,physical conditions and sediment in streams receiving stormwater discharge treated and delayed in wet ponds

The impact of human activities on watercourses has led to increased contamination, eutrophication, erosion and reduced biodiversity in streams and rivers. Increased urbanization is one of the factors that may influence the water quality. Wet stormwater ponds are a commonly used buffer structure to delay and treat the water before it reaches the recipient – often streams as studied in this paper. However, knowledge on how stormwater outlets from wet ponds may affect downstream recipients is still limited. We studied the impact of six outlets from wet stormwater ponds to streams in 2016 and 2017, by measurements in the streams upstream and downstream of the outlet. The aim was to study possible effects on physical conditions, sediment grain size and invertebrate community composition. The Fauna Index showed no significant differences between upstream and downstream stations. However, we found a significant decrease in biodiversity (Shannon-Wiener) and a significantly lower evenness downstream of the stormwater outlets, even though the water was delayed and treated in a pond first. The physical conditions were both positively and negatively affected depending on the specific outlet. Finally, the smallest particle fraction (<63 μm) in the stream sediments was reduced at downstream sites compared to upstream sites at four outlets indicating possible erosion effects. Our study shows that the stormwater outlets have an effect on the recipients, but whether it is measurable depends on the methods utilized.     

The distribution of megabenthic, invertebrate epifauna in the Balearic Basin (western Mediterranean) between 400 and 2300 m: Environmental gradients influencing assemblages composition and biomass trends

The distribution of megabenthic epifauna (invertebrates) in the Balearic Basin (western Mediterranean) has been analyzed at depths between 427 and 2265 m after compiling samplings performed in 1985–1992 and 2007–2008 with an OTSB-14 bottom trawl. 84 epibenthic taxa of invertebrates (excluded decapod crustaceans) were collected. Epibenthic assemblages were organized in five groups (n-MDS analyses) as a function of increasing depth: upper slope assemblage, U, hauls between 427 and 660 m; middle slope assemblages M1 and M2, hauls between 663–876 m and 864–1412 m, respectively; lower slope assemblages L1 and L2, hauls between 1488–1789 m and 1798–2265 m, respectively). We found significant differences in assemblage composition between all depth-adjacent pairs of groups. Trends in the distribution of biomass vs. depth and within assemblages varied when hauls taken over insular were compared to those over mainland slopes. Over insular slopes we found (n-MDS) only four distinct depth assemblages, with significant differences between all depth-adjacent group pairs, except between L1 and L2. Over the mainland slope, two peaks of biomass situated at U (427–660 m) and at L1 (1488–1789 m) were clearly identified, attributable to the echinoid Brissopsis lyrifera and holothurian Molpadia musculus at U and to the synallactid holothurian Mesothuria intestinalis at L1. The distribution of biomass vs. depth on insular slopes did not follow this pattern, showing no significant biomass peak below 1000 m and a total biomass an order of magnitude lower than adjacent to the mainland. After compiling available environmental data over the mainland slope off Barcelona, we found coincidence between the peak biomass of Mesothuria intestinalis and: i) a significant increase of labile OM (%OrgC, C/N, hydrolizable aminoacids–EHAA, and the EHAA/THAA-total hydrolizable aminoacids-ratio) over 1600 m; and ii) an increase of turbidity and T at 1500–1600 m in February 2008. We suggest that such OM inputs must likely be associated to the formation of nepheloid layers close to submarine canyons, probably associated with oceanographic processes in deep water masses in the area. This would explain why aggregations of M. intestinalis were linked to the mainland part of the Balearic basin, with highest densities located south of canyons. If hotspots of biomass as cited here for M. intestinalis are regulated by factors such as river inputs, both natural climatic changes (e.g. changes in rainfall regimes) and human impact (e.g. river damming) may affect deep-Mediterranean communities below 1000 m.