Relative abundance and size composition of subtidal abalone, Haliotis spp., sea urchin, Strongylocentrotus spp., and abundance of sea stars off Fitzgerald marine reserve, September 1993

Data were collected at twenty-six dive stations at seven discrete latitudes along Fitzgerald Marine Reserve (FMR). Dive stations were targeted at three stratified depth zones: shallow (6.1 m), medium (10.7 m), and deep (16.8 m) in six of the seven locations. Two types of line transects, emergent and invasive, were completed by separate dive teams at each dive station. The area surveyed totalled 1,510 m2 for emergent and 560 m2 for invasive transects. Reef habitat dominated all depth zones, with moveable boulder and cobble increasing at medium and shallow depths. Encrusting coraline and surface algae dominated (49%), followed by turf (37%), sub-canopy (11.2%), and rare canopy (0.2%). Canopy was found only at shallow depths. Turf and sub-canopy decreased with depth. Only two species of abalone, red, Haliotis rufescens, and flat, H. walallensis, were found. Flat abalone were extremely rare with only two found on invasive transects (0.004 abalone m-2). Red abalone densities were low at both emergent (0.02 abalone m-2, s.e.=O.Ol) and invasive (0.07 abalone m-2, s.e.=0.03 ) transects. Red abalone concentrations differed significantly by depth and location. No abalone were found at deep depths and only one sport-legal (178 mm shell length) abalone was found at medium depth. One commercial legal (198 mm shell length) abalone was found on the entire survey. Most sport-legal abalone were located in cryptic habitat in shallow invasive transects (38%), compared to 7% on emergent transects. The only evidence of recruitment was found on invasive transects where three young-of-the-year (<=31 mm shell length) red abalone were found. Evidence from our survey and other sources suggests that sport and commercial fisheries are not sustainable off the San Mateo coast. Red urchin, Stongylocentrotus franciscanus, were more abundant than purple urchin, S. purpuratus, or red abalone. Red urchin densities were lower in emergent (1.08 urchin m-2,s.e.=0.04) than invasive (1.52, s.e.=0.06 m-2) transects. Densities of red urchin at deep stations in areas of lower algal abundance and potentially greater commercial fishing pressure were about one-half the densities at medium and shallow depths. ANOVA showed significant differences by depth and location. Mean Test Diameter (MTD) increased from deep to medium to shallow depths, while juvenile (<=50 mm) MTD showed an inverse relationship with depth. Shallow-depth invasive transects revealed a missing mode of 83 mm red urchin. This size mode was not found in emergent transects, probably due to cryptic habitat. Purple urchin were found at low densities at all three depth strata. Purple urchin densities were comparable in emergent (0.11 urchin m-2, s.e.=0.02 ) and invasive (0.09 urchin m-2,s.e.=0.03) transects. ANOVA showed densities varied significantly by location but not depth. 'Juvenile' purple urchin abundance showed an inverse relation to juvenile red urchin, increasing from deep to shallow depths. Purple urchin MTD of 84 mm (s.d.=23) was larger than reported for intertidal areas off FMR. Sea stars were found in high abundance off FMR. Bat stars, Asterina minata, had the highest densities (0.79 sea stars m-2, s.e.=0.03) followed by Pisaster sp. (0.47 sea stars m-2,s.e.=0.03 ), and sunflower stars, Pycnopodia helianthoides, (0.11 sea stars m-2, s.e.=0.04). Pisaster sp. was the only group of sea stars where differences in density were significant by depth or location. (30pp.

Results of California Department of Fish and Game spot prawn trawl and trap fisheries bycatch observer program 2000-2001

In 1999 trap fishermen and environmental groups testified at a Fish and Game Commission (Commission) meeting that they were concerned about high levels of bycatch in the spot prawn trawl fishery. Environmental representatives requested that the Commission consider adopting regulations that would phase out the spot prawn trawl fishery by 2004 and convert spot prawn trawl permits to spot prawn trap permits. Also in 1999 the Department reported to the Commission the results of six observed spot prawn trawl tows in March 1999, including the ratio of weight of finfish bycatch to weight of spot prawns (7.4 to 1). Based primarily on the above factors, the Commission initially directed the Department to develop, as part of a package of regulatory proposals for the spot prawn trap and trawl fisheries, a proposal to phase out the spot prawn trawl fishery and convert trawl permits to trap permits. Subsequently the Department recommended that, instead of phasing out the spot prawn trawl fishery, information on the relative amount and type of bycatch in the trawl and trap fisheries be determined through an on-board observer program. An observer fee structure was proposed and adopted, and an observer program was in effect for all vessels landing spot prawns from July 14, 2000 to March 31, 2001. Vessels were required to purchase and possess a spot prawn observer fee permit in order to take and land spot prawns. Funds from the program were used to support on board observers and to digitize and analyze the data. Some fishing trips were observed after the requirement for the observer fee had expired. A total of 86 spot prawn trawl tows (71 from northern California-based vessels and 15 from southern California- based vessels) was observed on nine vessels during the period September 26, 2000 to September 19, 2001. Observed vessels fished from the ports of Fort Bragg, San Francisco, Monterey, Morro Bay, and Ventura. For northern California trawl vessels, the top five finfish species observed in the bycatch, in decreasing frequency of occurrence, were Pacific hake (whiting), Dover sole, sablefish, English sole, and splitnose rockfish, comprising 53.9% of all fishes by weight. Twenty-eight species of rockfishes were observed, comprising 28.1% by weight of all fishes. The weight ratio of total finfish bycatch to total spot prawn catch from all tows combined was 7.5 to 1. The ratio of total rockfish bycatch to total spot prawn catch was 2.1 to 1. For southern California trawl vessels, the top five finfish species observed in the bycatch, in decreasing frequency of occurrence, were Pacific sanddab, Pacific hake, slender sole, shortbelly rockfish, and Dover sole, comprising 83.1% of all fishes by weight. Fifteen species of rockfishes were observed, comprising 8.8% by weight of all fishes. The ratio of total finfish bycatch to total spot prawn catch from all tows combined was 17.7 to 1. The ratio of total rockfish bycatch to total spot prawn catch was 1.5 to 1. The ratio of total trawl bycatch, including invertebrates, to spot prawn catch was 8.8 to 1 in northern California and 20.6 to 1 in southern California. The National Marine Fisheries Service has determined the following rockfish species to be overfished and require rebuilding: bocaccio, canary, cowcod, darkblotched, widow, and yelloweye. Bocaccio, cowcod, darkblotched, and widow rockfishes were observed in multiple tows, and yelloweye and canary each were observed in a single tow. In general, the relative abundance of overfished rockfish species was low compared with other finfishes. However, expansions by weight of finfishes from observed tows to all spot prawn tows, based on the ratio of total to observed spot prawn landings, indicated that the estimated total bycatch of overfished rockfishes was significant in terms of allowable catch levels (optimum yields) established by the Pacific Fishery Management Council (Council). Other overfished species observed in the sampled catch including Pacific hake (whiting) and lingcod. Results from these trawl observations relative to bycatch levels were consistent with the few previous studies conducted. That is, the total observed bycatch in the trawl fishery was more than four times that of spot prawns by weight. A total of 27 trap vessels paid the required observer fee, and 23 of these landed spot prawns during the period in which the observer fee was required. Passage was secured on 16 of these 23 vessels for observations of bycatch. An additional vessel that had not paid the fee was sampled after the fee requirement period had expired. A total of 262 spot prawn trap strings (88 from northern California vessels and 174 from southern California vessels) was observed from 16 vessels during the study. Observed vessels fished out of the ports of Monterey, Morro Bay, Channel Islands Harbor, Ventura, Terminal Island, Newport Beach, Dana Point, Oceanside, and San Diego. For northern California trap vessels, the top five finfish species observed in the bycatch, in decreasing frequency of occurrence, were sablefish, rosethorn rockfish, greenblotched rockfish group, spotted cusk eel, and filetail catshark, comprising 77.7% of all fishes by weight. Seventeen species of rockfishes were observed, comprising 25.5% by weight of all fishes. The ratio of total finfish bycatch to total spot prawn catch from all strings combined was 0.15 to 1. The ratio of total rockfish bycatch to total spot prawn catch was 0.04 to 1. For southern California trap vessels, the top five finfish species observed in the bycatch, in decreasing frequency of occurrence, were lingcod, greenblotched rockfish group, threadfin sculpin, sablefish, and swell shark, comprising 66.4% of all fishes by weight. Twenty-two species of rockfishes were observed, comprising 32.5% by weight of all fishes. The ratio of total finfish bycatch to total spot prawn catch from all strings combined was 0.22 to 1. The ratio of total rockfish bycatch to total spot prawn catch was 0.07 to 1. The ratio of total trap bycatch, including invertebrates, to spot prawn catch was 1.0 to 1 in northern California and 2.0 to 1 in southern California. Most invertebrates and many fish species other than rockfishes could be returned to the water alive. Overfished rockfish species were observed infrequently, and expansions of observed bycatch data to all trap strings yielded relatively low total estimated bycatch weights for these species. In northern California, the relative amount of bycatch for all finfishes and rockfishes was 50 and 52 times greater, respectively, in the trawl fishery compared with the trap fishery. In southern California, the relative amount of bycatch for all fishes and rockfishes was 80 and 21 times greater, respectively, in the trawl fishery compared with the trap fishery. (Document has 88 pages

Analysis and Visualization of Atrial Fibrillation Electrograms Using Cross-Correlation

Despite many recent studies into the behavior of the complex fractionated atrial electrograms (CFAEs) that characterize atrial fibrillation, there has been relatively little success in analyzing them to reliably identify and ablate the rotor sources of atrial fibrillation in real time. The objective of this study is to propose a new method of analyzing and displaying CFAE signals to help cardiologists identify likely rotors during ablation procedures. This method uses cross-correlation to compare the electrograms collected at individual electrodes, and calculates the time lead/lag for each electrode compared to a local reference. The results of the analysis are displayed on a 3D color map using coordinate data collected alongside the electrogram data. Atrial fibrillation CFAE data was collected from patients with one of two different types of electrode catheter, and a data set from a patient with atrial flutter was evaluated using the same methods. The cross-correlation method was confirmed to be working as designed when the atrial flutter lead/lag color map matched the one created by the cardiologists who collected the data. Several AF wave fronts were identified in the data as a lead to lag shift. By varying the length of electrogram data used through the analysis, it was determined that CFAEs have irregular timing and cannot easily be compared in large time sections versus smaller time sections. The unstable CFAE timing also led to the conclusion that nonlocal references cannot accurately correlate with the data, which may be due to the unpredictable flow of activation waves in the heart. The irregular timing of many of the electrograms points to regularity of CFAEs in an area as a potential indicator of rotor centers. Collecting the data using unipolar electrodes rather than bipolar electrodes was found to give much better results, with many instances of wave front activity found, as well as better agreement between large and small sections in some cases. With its ability to identify AF wave fronts, this method has potential as a tool to be used to locate and identify likely AF sources in real time.Master of Scienc

A rapid enzymatic method for the isolation of defined kidney tubule fragments from mouse

The increasing number of available genetically manipulated mice makes it necessary to develop tools and techniques for examining the phenotypes of these animals. We have developed a straightforward and rapid method for the isolation of large quantities of single tubule fragments from the mouse kidney. Immunohistochemistry, electron microscopy, and fluorescence microscopy were used to evaluate the viability, functional characteristics, and morphology of proximal tubules (PT), and collecting ducts from cortex (CCD) and inner stripe of the outer medulla (ISOMCD). Tubules were isolated using a modified collagenase digestion technique, and selected under light microscopy for experimentation. Electron microscopy and trypan blue exclusion showed that a large portion of unselected proximal tubules were damaged by the digestion procedure. The selected tubules, however, all excluded trypan blue, indicating that the plasma membrane had remained intact. Immunocytochemistry on isolated CCD showed normal distribution of H+-ATPase, pendrin, and anion exchanger-1 (AE-1) staining. The pH-sensitive dye 2′,7′-bis(2-carboxylethyl)-5(6)-carboxyfluorescein (BCECF) was used to measure Na+-dependent and -independent intracellular pH (pHi) recovery rates in PT, and in single intercalated cells of CCD and ISOMCD fragments. Na+-dependent pHi-recovery was 0.144±0.008 (PT), 0.182±0.013 (CCD), and 0.112±0.010pH units/min. (ISOMCD). Na+-independent pHi recovery was found in all three segments (PT: 0.021±0.002, CCD: 0.037±0.002, ISOMCD: 0.033±0.002pH units/min) and was sensitive to concanamycin. In summary, we have developed a new technique for rapid and straightforward preparation of large quantities of defined tubule fragments from mouse kidney. Using this technique, the first measurements of plasma membrane vacuolar H+-ATPase activities in mouse PT and collecting duct were made. This technique will facilitate further characterization of kidney function in normal and genetically manipulated animal

Identification of Functionally Distinct Na-HCO3 Co-Transporters in Colon

Na-HCO3 cotransport (NBC) regulates intracellular pH (pHi) and HCO3 secretion in rat colon. NBC has been characterized as a 5,5′-diisothiocyanato-2-2′-stilbene (DIDS)-sensitive transporter in several tissues, while the colonic NBC is sensitive to both amiloride and DIDS. In addition, the colonic NBC has been identified as critical for pHi regulation as it is activated by intravesicular acid pH. Molecular studies have identified several characteristically distinct NBC isoforms [i.e. electrogenic (NBCe) and electroneutral (NBCn)] that exhibit tissue specific expression. This study was initiated to establish the molecular identity and specific function of NBC isoforms in rat colon. Northern blot and reverse transcriptase PCR (RT-PCR) analyses revealed that electrogenic NBCe1B or NBCe1C (NBCe1B/C) isoform is predominantly expressed in proximal colon, while electroneutral NBCn1C or NBCn1D (NBCn1C/D) is expressed in both proximal and distal colon. Functional analyses revealed that amiloride-insensitive, electrogenic, pH gradient-dependent NBC activity is present only in basolateral membranes of proximal colon. In contrast, amiloride-sensitive, electroneutral, [H+]-dependent NBC activity is present in both proximal and distal colon. Both electrogenic and electroneutral NBC activities are saturable processes with an apparent Km for Na of 7.3 and 4.3 mM, respectively; and are DIDS-sensitive with apparent Ki of 8.9 and 263.8 µM, respectively. In addition to Na-H exchanger isoform-1 (NHE1), pHi acidification is regulated by a HCO3-dependent mechanism that is HOE694-insensitive in colonic crypt glands. We conclude from these data that electroneutral, amiloride-sensitive NBC is encoded by NBCn1C/D and is present in both proximal and distal colon, while NBCe1B/C encodes electrogenic, amiloride-insensitive Na-HCO3 cotransport in proximal colon. We also conclude that NBCn1C/D regulates HCO3-dependent HOE694-insensitive Na-HCO3 cotransport and plays a critical role in pHi regulation in colonic epithelial cells

An amino acid transporter involved in gastric acid secretion

Gastric acid secretion is regulated by a variety of stimuli, in particular histamine and acetyl choline. In addition, dietary factors such as the acute intake of a protein-rich diet and the subsequent increase in serum amino acids can stimulate gastric acid secretion only through partially characterized pathways. Recently, we described in mouse stomach parietal cells the expression of the system L heteromeric amino acid transporter comprised of the LAT2-4F2hc dimer. Here we address the potential role of the system L amino acid transporter in gastric acid secretion by parietal cells in freshly isolated rat gastric glands. RT-PCR, western blotting and immunohistochemistry confirmed the expression of 4F2-LAT2 amino acid transporters in rat parietal cells. In addition, mRNA was detected for the B0AT1, ASCT2, and ATB(0+) amino acid transporters. Intracellular pH measurements in parietal cells showed histamine-induced and omeprazole-sensitive H+-extrusion which was enhanced by about 50% in the presence of glutamine or cysteine (1mM), two substrates of system L amino acid transporters. BCH, a non-metabolizable substrate and a competitive inhibitor of system L amino acid transport, abolished the stimulation of acid secretion by glutamine or cysteine suggesting that this stimulation required the uptake of amino acids by system L. In the absence of histamine glutamine also stimulated H+-extrusion, whereas glutamate did not. Also, phenylalanine was effective in stimulating H+/K+-ATPase activity. Glutamine did not increase intracellular Ca2+ levels indicating that it did not act via the recently described amino acid modulated Ca2+-sensing receptor. These data suggest a novel role for heterodimeric amino acid transporters and may elucidate a pathway by which protein-rich diets stimulate gastric acid secretio

The Stomach Divalent Ion-sensing Receptor SCAR Is a Modulator of Gastric Acid Secretion

Divalent cation receptors have recently been identified in a wide variety of tissues and organs, yet their exact function remains controversial. We have previously identified a member of this receptor family in the stomach and have demonstrated that it is localized to the parietal cell, the acid secretory cell of the gastric gland. The activation of acid secretion has been classically defined as being regulated by two pathways: a neuronal pathway (mediated by acetylcholine) and an endocrine pathway (mediated by gastrin and histamine). Here, we identified a novel pathway modulating gastric acid secretion through the stomach calcium-sensing receptor (SCAR) located on the basolateral membrane of gastric parietal cells. Activation of SCAR in the intact rat gastric gland by divalent cations (Ca(2+) or Mg(2+)) or by the potent stimulator gadolinium (Gd(3+)) led to an increase in the rate of acid secretion through the apical H+,K+ -ATPase. Gd(3+) was able to activate acid secretion through the omeprazole-sensitive H+,K+ -ATPase even in the absence of the classical stimulator histamine. In contrast, inhibition of SCAR by reduction of extracellular cations abolished the stimulatory effect of histamine on gastric acid secretion, providing evidence for the regulation of the proton secretory transport protein by the receptor. These studies present the first example of a member of the divalent cation receptors modulating a plasma membrane transport protein and may lead to new insights into the regulation of gastric acid secretion

Regulation of the expression of the Cl-/anion exchanger pendrin in mouse kidney by acid-base status

Regulation of the expression of the Cl-/anion exchanger pendrin in mouse kidney by acid-base status.BackgroundPendrin belongs to a superfamily of Cl-/anion exchangers and is expressed in the inner ear, the thyroid gland, and the kidney. In humans, mutations in pendrin cause Pendred syndrome characterized by sensorineural deafness and goiter. Recently pendrin has been localized to the apical side of non-type A intercalated cells of the cortical collecting duct, and reduced bicarbonate secretion was demonstrated in a pendrin knockout mouse model. To investigate a possible role of pendrin in modulating acid-base transport in the cortical collecting duct, we examined the regulation of expression of pendrin by acid-base status in mouse kidney.MethodsMice were treated orally either with an acid or bicarbonate load (0.28 mol/L NH4Cl or NaHCO3) or received a K+-deficient diet for one week. Immunohistochemistry and Western blotting was performed.ResultsAcid-loading caused a reduction in pendrin protein expression levels within one day and decreased expression to 23% of control levels after one week. Concomitantly, pendrin protein was shifted from the apical membrane to the cytosol, and the relative abundance of pendrin positive cells declined. Similarly, in chronic K+-depletion, known to elicit a metabolic alkalosis, pendrin protein levels decreased and pendrin expression was shifted to an intracellular pool with the relative number of pendrin positive cells reduced. In contrast, following oral bicarbonate loading pendrin was found exclusively in the apical membrane and the relative number of pendrin positive cells increased.ConclusionsThese results are in agreement with a potential role of pendrin in bicarbonate secretion and regulation of acid-base transport in the cortical collecting duct

High spatiotemporal variability of methane concentrations challenges estimates of emissions across vegetated coastal ecosystems

Coastal methane (CH4) emissions dominate the global ocean CH4 budget and can offset the "blue carbon" storage capacity of vegetated coastal ecosystems. However, current estimates lack systematic, high-resolution, and long-term data from these intrinsically heterogeneous environments, making coastal budgets sensitive to statistical assumptions and uncertainties. Using continuous CH4 concentrations, delta C-13-CH4 values, and CH4 sea-air fluxes across four seasons in three globally pervasive coastal habitats, we show that the CH4 distribution is spatially patchy over meter-scales and highly variable in time. Areas with mixed vegetation, macroalgae, and their surrounding sediments exhibited a spatiotemporal variability of surface water CH4 concentrations ranging two orders of magnitude (i.e., 6-460 nM CH4) with habitat-specific seasonal and diurnal patterns. We observed (1) delta C-13-CH signatures that revealed habitat-specific CH4 production and consumption pathways, (2) daily peak concentration events that could change >100% within hours across all habitats, and (3) a high thermal sensitivity of the CH4 distribution signified by apparent activation energies of similar to 1 eV that drove seasonal changes. Bootstrapping simulations show that scaling the CH4 distribution from few samples involves large errors, and that similar to 50 concentration samples per day are needed to resolve the scale and drivers of the natural variability and improve the certainty of flux calculations by up to 70%. Finally, we identify northern temperate coastal habitats with mixed vegetation and macroalgae as understudied but seasonally relevant atmospheric CH4 sources (i.e., releasing >= 100 mu mol CH4 m(-2) day(-1) in summer). Due to the large spatial and temporal heterogeneity of coastal environments, high-resolution measurements will improve the reliability of CH4 estimates and confine the habitat-specific contribution to regional and global CH4 budgets.Peer reviewe

Methane emissions offset atmospheric carbon dioxide uptake in coastal macroalgae, mixed vegetation and sediment ecosystems

Publisher Copyright: © 2023, The Author(s).Coastal ecosystems can efficiently remove carbon dioxide (CO2) from the atmosphere and are thus promoted for nature-based climate change mitigation. Natural methane (CH4) emissions from these ecosystems may counterbalance atmospheric CO2 uptake. Still, knowledge of mechanisms sustaining such CH4 emissions and their contribution to net radiative forcing remains scarce for globally prevalent macroalgae, mixed vegetation, and surrounding depositional sediment habitats. Here we show that these habitats emit CH4 in the range of 0.1 – 2.9 mg CH4 m−2 d−1 to the atmosphere, revealing in situ CH4 emissions from macroalgae that were sustained by divergent methanogenic archaea in anoxic microsites. Over an annual cycle, CO2-equivalent CH4 emissions offset 28 and 35% of the carbon sink capacity attributed to atmospheric CO2 uptake in the macroalgae and mixed vegetation habitats, respectively, and augment net CO2 release of unvegetated sediments by 57%. Accounting for CH4 alongside CO2 sea-air fluxes and identifying the mechanisms controlling these emissions is crucial to constrain the potential of coastal ecosystems as net atmospheric carbon sinks and develop informed climate mitigation strategies.Peer reviewe