The Bear Brook Watershed in Maine: Multi-decadal whole-watershed experimental acidification

The Bear Brook Watershed in Maine (BBWM) is a long-term research site established to study the response of forest ecosystem function to environmental disturbances of chronic acidic deposition and ecosystem nitrogen enrichment. Starting in 1989, the West Bear (treated) watershed received bimonthly applications of ammonium sulfate [(NH₄)₂SO₄] fertilizer from above the canopy, whereas East Bear (reference) received ambient deposition. The treatments were stopped in 2016, marking the beginning of the recovery phase. Research at the site has focused on soils, streams, and vegetation. Here, we describe data collected over three decades at the BBWM—input and stream output nutrient fluxes, quantitative soil pits and soil chemistry, and soil temperature and moisture.     

Propagation of the cosmic-ray iron group at intermediate energies

Elemental abundances of the VH group of cosmic radiation have been measured in the energy interval 250–550 MeV nucl^–1 in a balloon exposure at Sioux Falls (South Dakota) of a plastic detector LeXAN stack. The so obtained abundances have been extrapolated to the sources in the frame of the homogeneous model correcting for energy loss. After taking into account solar modulation, the best fit to model values has led to a escape mean free path _e = 5E ^–0.4 g cm^–2, whereE is the energy in GeV nucl^–1, forE>1 GeV nucl^–1, and a constant _e = 5 g cm^–2 forE1 GeV nucl^–1. When turning to the diffusion model, also including an energy loss term, a diffusion coefficientD=3×10²⁸ cm² s^–1 has been estimated.     

The role of schizogenesis in population dynamics of Timarete filigera (Polychaeta: Cirratulidae): 2-years observations in the Port of Bari (South Adriatic Sea)

Different aspects of reproductive biology of the polychaete Timarete filigera (Delle Chiaje) were studied during a period of 2 years (from September 2002 to August 2003 and from September 2004 to August 2005). Timarete filigera specimens were collected monthly in the port of Bari (South Adriatic Sea, Mediterranean Sea). For population analysis, regenerating and entire specimens were separately analyzed, the regenerating individuals were assigned to different categories related to the region of the body from which they derived. Regenerating individuals were present throughout the year. There were three to four times more individuals deriving from the middle part than the anterior and posterior regenerating portions. From the high percentage of regenerating individuals observed in the T. filigera population, it can be supposed that this species reproduces mainly asexually by schizogenesis. However, histological analysis revealed the presence of female gametes in a few individuals. In contrast, males were never collected, probably due to the limited number of reproductive individuals collected. The abundance has shown wide fluctuations during the year, with a decrease from Winter to Spring. The analysis of the size‐frequency histograms has shown a growing phase of whole specimens from Spring to Winter. The life cycle of the investigated species is discussed with the hypothesis that strategies could be linked to the colonized environments, agamic reproduction coupled with sexual reproduction assures the presence and expansion of the population after the colonization by a limited number of larvae.     

SeagrassNet monitoring across the Americas: case studies of seagrass decline

Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land–sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world's oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1–2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action.     

Regional variation in springtime ichthyoplankton assemblages in the northeast Pacific Ocean

The coastal regions of the northeast Pacific support large, economically valuable fishery resources and provide nursery areas for many fish species. Over the last few decades, there have been dramatic shifts in species abundance and composition in this area. In this paper, we examine the springtime spatial patterns in the ichthyoplankton of three oceanographically different regions, the Southeast Bering Sea, the Gulf of Alaska and the U.S. West Coast. The data examined are a subset of a larger database (comprising data from cruises conducted from 1972 to 1997) that is being used to investigate spatial, seasonal and interannual patterns in ichthyoplankton of the northeast Pacific in relation to environmental conditions. Ichthyoplankton were collected during seven cruises using 60-cm bongo nets. Spatial patterns of ichthyoplankton were examined using both classification and ordination techniques. Relative Bray-Curtis dissimilarity coefficients calculated from the log₁₀ (n+1) of abundance data were used as input to the numerical classification of species and stations. Nonmetric multidimensional scaling was also applied to the abundance data to examine geometric patterns in the data. The numerical analyses of the species abundance data sets for each cruise revealed spatial patterns in the ichthyoplankton that suggest the occurrence of geographically distinct assemblages of fish larvae in each region. For all three sampling regions, the assemblage structure is primarily related to bathymetry, and Shelf, Slope, and Deep-Water assemblages are described. This shallow to deep-water gradient in species occurrence and abundance reflects the habitat preference and spawning location of the adult fish. Another degree of complexity is superimposed on this primary assemblage structure in each region and seems to be related to local topography and the prevailing current patterns. The patterns in ichthyoplankton assemblages of the three regions in the northeast Pacific Ocean described here form the basis for future investigations of spatial and temporal patterns in the ichthyoplankton of the subarctic Pacific.Regional Index Terms: Northeast Pacific Ocean, Southeast Bering Sea, Gulf of Alaska, U.S. West Coast.     

Phytoliths as indicators of pedogenesis and paleoenvironmental changes in the Brazilian cerrado

This paper presents the preliminary results of phytolith analyses of a peat located in the cerrado of the Uberaba municipality, State of Minas Gerais, Brazil. The phytolith soil sequence is discussed by comparison with phytolith assemblages extracted from dominant plants (Cyperaceae and Poaceae). Increasing mean age of phytolith assemblages with depth is assumed. Poaceae Cuneiform bulliform cell, Parallelepiped bulliform cell and Elongate smooth long cell types dominate up to 80 cm, rapidly drop to 42% at 80 cm and regularly decrease from 42% to 2% upwards. Cyperaceae Rondel concave type shows the inverse trend, being dominant in the upper part of the profile. This pattern can be assigned to increasing selective dissolution of the Cyperaceae phytolith type with depth, or/and to a decrease of water stress suffered by the grasses, leading to a decrease of bulliform cell silicification. Soil processes and paleo-environmental changes hypotheses are discussed.     

Regional record of a global oceanic anoxic event: OAE1a on the Apulia Platform margin, Gargano Promontory, southern Italy

The Gargano Promontory of southern Italy, located on the eastern margin of the Apulia Platform, represents a peculiar Tethyan area where the transition between carbonate platform and adjacent basins is exposed on land. The Aptian stratigraphic record, represented in shallow-water, slope and deep-water deposits, provides a good opportunity to investigate the regional response to the worldwide documented climatic, biotic and palaeoceanographic changes related to Oceanic Anoxic Event 1a (OAE1a). A synthesis of data previously published (Ischitella and Coppitella sections), together with original data (Val Carbonara and Coppa della Guardia sections), from four stratigraphic sections from different depositional settings (proximal to distal) is provided, using an integrated, high-resolution micropalaeontological (planktonic foraminifera and calcareous nannofossils) and, for one section, geochemical (stable carbon and oxygen isotopes) approach. Organic matter preservation is confined to the more distal areas and consists of two thin intervals of black shales in the Aptian portion of the Marne a Fucoidi Formation. Biostratigraphic data assign the older black shale (5 cm thick) to the Selli Level equivalent (OAE1a, Lower Aptian); this carbon-rich interval is immediately followed by another black shale (7–10 cm thick) of early Late Aptian age.OAE1a is generally interpreted as a high-productivity event during a warming interval, followed by a cooling trend. In the Gargano Promontory, although the oxygen isotope curve indicates the above-mentioned climatic evolution, the micropalaeontological data do not support high fertility of the surface water, whereas micropalaeontological and geochemical data for the younger black shale do record high productivity (radiolarian increase in overall abundance, low nannofossil and foraminiferal species richness, increase in abudance of nannofossil fertility indices) associated with a cooling trend. The carbon and oxygen isotope record is in line with evidence from the curves documented elsewhere, whereas, among the biotic events, only the “nannoconid crisis” preceding OAE1a is revealed to be globally correlable.Environmental models for the two episodes of organic matter preservation are proposed, taking into account both global and local controlling factors.