Factors determining the abundance, distribution and population size–structure of the penshellPinna carnea

2010 ◽  
Vol 91 (3) ◽  
pp. 593-606 ◽  
Author(s):  
S. Aucoin ◽  
J.H. Himmelman
Keyword(s):  
Size Structure ◽  
Mortality Factor ◽  
Seagrass Habitat ◽  
Seagrass Beds ◽  
Seagrass Bed ◽  
Degree Of Protection ◽  
Size Groups ◽  
Hurricane Dennis ◽  
High Predation ◽  
Silt Load

Surveys conducted in the south-western Dominican Republic showed that the penshellPinna carneais a consistent component of seagrass beds and is absent in adjacent sandflats. Population densities were low (0.012–0.076·m−2) and the size–structure skewed towards large individuals. Trials with different types of substrata in caged spat collectors, involving a combination of sand, seagrass blades and roots, and an artificial treatment by itself, indicated no settlement preference for any of the substrata tested. Comparison of additional spat collectors (caged and uncaged) indicated high predation losses (84%) for recently settled penshells. Experiments with penshells measuring 10–30, 50–70 and 90–110 mm (anterior to posterior dorsal tip) transplanted to plots in a seagrass bed and sandflat showed that predation losses decreased with increasing size and were much less in seagrass than in the sandflat. In 10-day trials, survival in the three size-groups was 27-fold greater in the seagrass bed than on the sandflat. During 3-day trials in the sandflat, survival increased from 6% for 50–100 mm penshells to 93% for 150–170 mm penshells. At the end of 100-day trials, during which the study area was subjected to Hurricane Dennis, the only surviving penshells were large individuals (90–110 mm) that had been transplanted to the seagrass bed. All individuals transplanted to the sandflat went missing. Growth measurements showed that small penshells grow rapidly (up to 2.2 mm·d−1), but the growth rate drops markedly at ~150 mm. Rapid juvenile growth may be a strategy for reducing the period of high vulnerability to predators. The high proportion of large individuals in the population likely represents the accumulation of successive recruitments as growth slows in older penshells.Pinna carneais mainly restricted to seagrass beds because they provide more protection from predators than adjacent habitats. Moreover, the consolidation of sediments in seagrass beds by roots and algal rhizoids provides a degree of protection from physical disturbances such as hurricanes. The advantages provided by the seagrass habitat come at a cost because we detected a mortality factor in the seagrass bed (possibly related to the ~3-fold higher silt load) that was absent on the sandflat.

Size-fractionated surface phytoplankton in the Kara and Laptev Seas: environmental control and spatial variability

2021 ◽  
Vol 664 ◽  
pp. 59-77
Author(s):  
AB Demidov ◽  
IN Sukhanova ◽  
TA Belevich ◽  
MV Flint ◽  
VI Gagarin ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Primary Production ◽  
Water Temperature ◽  
Environmental Control ◽  
Size Structure ◽  
Total Carbon ◽  
The Arctic ◽  
Size Groups ◽  
Phytoplankton Size ◽  
Phytoplankton Size Structure

Climate-induced variability of phytoplankton size structure influences primary productivity, marine food web dynamics, biosedimentation and exchange of CO2 between the atmosphere and ocean. Investigation of phytoplankton size structure in the Arctic Ocean is important due to rapid changes in its ecosystems related to increasing temperature and declining sea ice cover. We estimated the contribution of surface micro-, nano- and picophytoplankton to the total carbon biomass, chlorophyll a concentration and primary production in the Kara and Laptev Seas and investigated the relationships of these phytoplankton size groups with environmental factors which determine their spatial variability. Additionally, we compared chlorophyll specific carbon fixation rate, specific growth rate and carbon to chlorophyll ratios among different phytoplankton size groups. The investigation was carried out from August to September 2018. Generally, picophytoplankton was dominant in terms of chlorophyll a and primary production in the whole study area. The spatial variability of phytoplankton size classes was influenced by river discharge and relied mainly on water temperature, salinity and dissolved silicon concentration. Microphytoplankton prevailed across the river runoff region under conditions of low salinity and relatively high water temperature, while picophytoplankton was predominant under conditions of high salinity and low water temperature. Our study is the first to characterize size-fractionated phytoplankton abundance in the Kara and Laptev Seas, and provides a baseline for future assessment of the response of Kara and Laptev Sea ecosystems to climate-induced processes using phytoplankton size structure.

scholarly journals Intra and inter annual variation in a seagrass meadow on the Caribbean coast of Costa Rica: 2009-2015

2018 ◽  
Vol 66 (3) ◽  
pp. 1149 ◽  
Author(s):  
Margarita Loría-Naranjo ◽  
Jimena Samper-Villarreal ◽  
Marylaura Sandoval-Siles ◽  
Jorge Cortés
Keyword(s):  
Costa Rica ◽  
Leaf Area ◽  
Turnover Rate ◽  
Seagrass Meadow ◽  
Seagrass Beds ◽  
Seagrass Bed ◽  
Monitoring Methods ◽  
Caribbean Coast ◽  
Area Index ◽  
The Caribbean

Seagrass beds are an important ecosystem on the Caribbean coast of Costa Rica. At Cahuita National Park (CNP) a seagrass bed at Perezoso has been monitored continually since 1999 within the CARICOMP program. Thalassia testudinum is the dominant seagrass species, in some cases mixed with Syringodium filiforme. The results from the 2009 to 2015 monitoring period are presented here, and contrasted with data before 2009. Total (above and below ground tissue) mean biomass of T. testudinum was higher (1 255.4 ± 146.0 gm-2) than biomass before 2009, with an increasing tendency. However, productivity (1.5±0.59 gm-2d-1) and turnover rate (4.3 ± 1.22 %d-1) were lower than previous monitoring periods. In this period, mean leaf area diminished considerably (4.9 ± 2.30 m2), but leaf area index (LAI) increased (1.9 ± 0.80 m2leafm-2) in comparison to prior monitoring. Productivity, density, turnover rate, LAI and biomass showed intra-annual variations; while mean biomass of T. testudinum did not vary significantly among years. No correlations were found between water salinity, temperature and clarity with seagrass measurements. However, most seagrass parameters were strongly correlated with precipitation. These results highlight the effect of external environmental agents acting on the ecosystem. CNP presents a long-term stable seagrass meadow. However, there are indirect signals, such as high biomass and above-ground biomass proportion, along with low productivity and LAI, which point to a nutrient increment in Perezoso’s seagrass bed. To continue protecting this seagrass bed, it is necessary to improve monitoring methods, and seagrass beds should be included in national conservation policies and monitoring programs.

Decadal biomass and area changes in a multi-species meadow in Singapore: application of multi-resolution satellite imagery

2018 ◽  
Vol 61 (3) ◽  
pp. 289-304
Author(s):  
James F. Bramante ◽  
Suryati M. Ali ◽  
Alan D. Ziegler ◽  
Tsai M. Sin
Keyword(s):  
Spatial Resolution ◽  
Satellite Images ◽  
Average Rate ◽  
Seagrass Habitat ◽  
Seagrass Bed ◽  
Environmental Pressures ◽  
Global Trends ◽  
Very High Spatial Resolution ◽  
Satellite Sensors ◽  
Very High

Abstract Due to the dearth of information regarding current and changing health of seagrass habitat in the Indo-Pacific region, prior research into global trends of seagrass habitat health has included little data from this region, even though it contains the highest abundance and species diversity of seagrass globally. This study evaluates the suitability of four satellite sensors [Worldview-2 (WV2), Advanced Land Imager (ALI), Enhanced Thematic Mapper+ (ETM+), Operational Land Imager (OLI)] for determining trends in seagrass habitat extent over the past decade in Singapore’s largest seagrass meadow, and thus contributes incrementally to the data available for regional or global analyses of seagrass habitat health. Using all four sensors, we find that seagrass bed extent at Pulau Semakau, Singapore, declined 37% from 2001 to 2015 at an average rate of 3.9% year−1. Using very high spatial resolution satellite images, we calculate that, although bed extent decreased 18% from April 2011 to June 2013, median meadow biomass increased, indicating that complex meadow dynamics may be mediating seagrass response to anthropogenic and environmental pressures. From a technological perspective, we find that, despite their lower spatial resolution, freely available satellite images can be used to measure the extent of a narrow, multi-species seagrass bed and to determine decadal trends reliably.

scholarly journals Sponges facilitate primary producers in a Bahamas seagrass system

2021 ◽  
Author(s):  
Stephanie Archer ◽  
Philina English ◽  
Finella Campanino ◽  
Craig Layman
Keyword(s):  
Nutrient Content ◽  
Theoretical Work ◽  
Positive Influence ◽  
Foundation Species ◽  
Seagrass Beds ◽  
Seagrass Bed ◽  
Primary Producers ◽  
The Bahamas ◽  
Facilitative Interactions ◽  
The Impact

Seagrass beds are important coastal ecosystems worldwide that are shaped by facilitative interactions. Recent theoretical work has emphasized the potential for facilitative interactions involving foundation species to be destabilized in the face of anthropogenic change. Consequently, it is important to identify which taxa facilitate seagrasses. In other ecosystems, sponges contribute to the maintenance of diverse and productive systems through their facilitation of foundation species (e.g., mangroves) and the retention and recycling of energy and nutrients. Sponges are common in tropical and subtropical seagrass beds, yet we know little about how their presence impacts these communities. Here, we examine the impact of the sponge Ircinia felix on primary producers in a Thalassia testudinum dominated seagrass bed using a long-term field experiment in The Bahamas. We transplanted live sponges into the center of 5 m x 5 m plots and monitored the response of seagrasses and macroalgae. Sponge presence increased seagrass nutrient content and growth, as well as the abundance of macroalgae and non-dominant seagrass species (Syringodium filiforme and Halodule wrightii). These changes were not seen in the control (unmanipulated) or structure (where we placed a polypropylene sponge replica) plots. We conclude that I. felix facilitates seagrass bed primary producers in oligotrophic systems, likely due to nutrients supplied by the sponge. Our study shows that sponges can have a positive influence on seagrass bed foundation species. Further work is needed to understand how this facilitation impacts the stability of seagrass beds in areas where human activities have increased ambient nutrient levels.

Comparative morphometric study of the invasive pearl oyster Pinctada radiata along the Tunisian coastline

Biologia ◽  
2010 ◽  
Vol 65 (2) ◽  
Author(s):  
Sabiha Tlig-Zouari ◽  
Lotfi Rabaoui ◽  
Ikram Irathni ◽  
Moctar Diawara ◽  
Oum Hassine
Keyword(s):  
Size Structure ◽  
Shell Height ◽  
Maximum Size ◽  
Pearl Oyster ◽  
Morphometric Study ◽  
Distribution Analysis ◽  
Relative Growth ◽  
Size Groups ◽  
Bizerta Lagoon ◽  
Pinctada Radiata

AbstractIn order to study the relative growth of the pearl oyster Pinctada radiata in Tunisia, a total of 330 individuals of this species were collected from six sites along the Tunisian coastline. Quantitative measurements of collected oysters were conducted for shell height, shell length, shell width, hinge length, height and width of the nacreous part and wet weight. The size structure of the sampled populations was described and the relative growth between different morphometric characteristics was estimated as allometric growth lines for the six P. radiata samples. It appeared that the majority of examined samples were dominated by large individuals that exceed a shell height of 42 mm. The maximum size (100.5 mm), recorded in Bizerta lagoon, is bigger than that recorded elsewhere in particular in the Red Sea. Size distribution analysis also showed that the majority of P. radiata samples were dominated by two or more size groups. Differences of allometric regression were found between the examined samples for the tested relationships. Moreover, the Factorial Discriminant Analysis, coupled with Ascending Hierarchic Classification, classified the sub-populations according to geographic locations.

scholarly journals Effects of naturally acidified seawater on seagrass calcareous epibionts

2008 ◽  
Vol 4 (6) ◽  
pp. 689-692 ◽  
Author(s):  
Sophie Martin ◽  
Riccardo Rodolfo-Metalpa ◽  
Emma Ransome ◽  
Sonia Rowley ◽  
Maria-Christina Buia ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Total Mass ◽  
Coralline Algae ◽  
Seagrass Habitat ◽  
Seagrass Beds ◽  
Benthic Organisms ◽  
Short Term ◽  
Seawater Acidification ◽  
Surface Ocean

Surface ocean pH is likely to decrease by up to 0.4 units by 2100 due to the uptake of anthropogenic CO 2 from the atmosphere. Short-term experiments have revealed that this degree of seawater acidification can alter calcification rates in certain planktonic and benthic organisms, although the effects recorded may be shock responses and the long-term ecological effects are unknown. Here, we show the response of calcareous seagrass epibionts to elevated CO 2 partial pressure in aquaria and at a volcanic vent area where seagrass habitat has been exposed to high CO 2 levels for decades. Coralline algae were the dominant contributors to calcium carbonate mass on seagrass blades at normal pH but were absent from the system at mean pH 7.7 and were dissolved in aquaria enriched with CO 2 . In the field, bryozoans were the only calcifiers present on seagrass blades at mean pH 7.7 where the total mass of epiphytic calcium carbonate was 90 per cent lower than that at pH 8.2. These findings suggest that ocean acidification may have dramatic effects on the diversity of seagrass habitats and lead to a shift in the biogeochemical cycling of both carbon and carbonate in coastal ecosystems dominated by seagrass beds.

scholarly journals Biodiversitas ikan padang lamun di perairan Tanjung Tiram, Konawe Selatan, Sulawesi Tenggara

2020 ◽  
Vol 1 (2) ◽  
pp. 1
Author(s):  
Andi Nur Hassanah H ◽  
Abdul Hamid ◽  
Hasnia Arami
Keyword(s):  
Mesh Size ◽  
Seagrass Beds ◽  
Seagrass Bed ◽  
Fish Biodiversity ◽  
Stable Conditions ◽  
The Family ◽  
The Status ◽  
Seagrass Density ◽  
Night Period

Research on fish biodiversit yof seagrass bed has been carried out in Indonesian waters, and the results vary between water locations.  This study aims to determine the biodiversity of fish based on seagrass density in the day and night period. This research was conducted in the waters of Tanjung Tiram, South Konawe from February to March 2018. Fish sampling based on seagrass density in the day and night period using gillnets with mesh size of 0.75, 1.25 and 1.50 inch.  Fish biodiversity found in this study consisted of 42 species from 24 families with an abundance of 1000 individuals. Fish biodiversity in densely seagrass beds was higher than low seagrass beds.Labridae family was the most doimnan fish during the daytime while at night is dominated by the family Plotosidae. The status of  fish biodiversity based on seagrass density was categorized as moderate to high and stable diversity while based on the day-night period was classified as moderate diversity with unstable to stable conditions, and the level of dominance of both was low.

scholarly journals Density-dependent condition of juvenile penaeid shrimps in seagrass-dominated aquatic vegetation beds located at different distance from a tidal inlet

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10496
Author(s):  
Zeferino Blanco-Martínez ◽  
Roberto Pérez-Castañeda ◽  
Jesús Genaro Sánchez-Martínez ◽  
Flaviano Benavides-González ◽  
Jaime Luis Rábago-Castro ◽  
...  
Keyword(s):  
Aquatic Vegetation ◽  
Coastal Lagoons ◽  
Negative Relationship ◽  
Tidal Inlet ◽  
Seagrass Beds ◽  
Seagrass Bed ◽  
Density Dependent ◽  
Nursery Habitats ◽  
Shrimp Density ◽  
Penaeid Shrimps

Seagrasses are critical habitats for the recruitment and growth of juvenile penaeid shrimps within estuaries and coastal lagoons. The location of a seagrass bed within the lagoon can determine the value of a particular bed for shrimp populations. Consequently, differences in the abundance of shrimp can be found in seagrasses depending on their location. As shrimp density increases, density-dependent effects on biological parameters are more likely to occur. However, knowledge about density-dependent processes on shrimp populations in nursery habitats remains limited. The present investigation was undertaken to examine the effects of population density on shrimp condition in two selected seagrass beds, located at different distance from a tidal inlet, one 25 km away (distant) and the other 1 km away (nearby), in a subtropical coastal lagoon. The study was based on monthly samplings during one year in Laguna Madre (Mexico), performing a total of 36 shrimp trawls (100 m2 each one) within each seagrass bed (n = 3 trawls per bed per month for 12 months). Shrimp density was related to the proximity to the tidal inlet (higher density was consistently observed in the nearby seagrass bed), which in turn adversely affected the condition of both species studied (Penaeus aztecus and P. duorarum). In this regard, the present study provides the first evidence of density-dependent effects on shrimp condition inhabiting a nursery habitat. Both shrimp species exhibited a negative relationship between condition and shrimp density. However, this pattern differed depending on the proximity to the tidal inlet, suggesting that shrimp populations inhabiting the nearby seagrass bed are exposed to density-dependent effects on condition; whereas, such effects were not detected in the distant seagrass bed. Shrimp density within the distant seagrass bed was probably below carrying capacity, which is suggested by the better shrimp condition observed in that area of the lagoon. Intra and interspecific competition for food items is surmised to occur, predominantly within seagrass beds near the tidal inlet. However, this hypothesis needs to be tested in future studies.

scholarly journals SEDIMENT DEPOSITION IN A SOUTH SULAWESI SEAGRASS BED

2008 ◽  
Vol 33 (2) ◽  
pp. 221-224
Author(s):  
Mahatma Lanuru ◽  
Ramdina Fitri
Keyword(s):  
Coastal Waters ◽  
Fine Particles ◽  
Sediment Traps ◽  
Primary Objective ◽  
Sediment Deposition ◽  
Sediment Flux ◽  
Seagrass Beds ◽  
Seagrass Bed ◽  
Quantitative Evidence ◽  
South Sulawesi

Deposition of suspended sediment was measured with sediment traps in shallow coastal waters colonized by Thallasia dominated seagrass in Pannikiang Island, South Sulawesi (Indonesia). The primary objective of this study was to compare the amounts of sediment deposition inside seagrass beds and in adjacent unvegetated area. The traps were placed in a seagrass bed (Station I, II, and III) and in an adjacent unvegetated area (Station IV) measuring the sediment flux on the seabed. The sediment fluxes due to deposition were significantly higher at stations I and II (P < 0.05) and station III (P < 0.01) than at station IV (unvegetated area). Results of this study suggest that sediment deposition was promoted by dense shoots of seagrass. The study provides quantitative evidence for the importance of seagrass bed as sites of sedimentation of fine particles.  

scholarly journals Keanekaragaman Gastropoda Pada Habitat Lamun Di Perairan Desa Tayando Yamtel Kecamatan Tayando Tam Kota Tual

2020 ◽  
Vol 9 (2) ◽  
pp. 163
Author(s):  
Liyatin Gea ◽  
A. S. Khouw ◽  
Ch. I. Tupan
Keyword(s):  
Species Diversity ◽  
Food Chain ◽  
Environmental Parameters ◽  
Seagrass Habitat ◽  
Seagrass Beds ◽  
Thalassia Hemprichii ◽  
Ecological Index ◽  
Cymodocea Rotundata ◽  
Index Value ◽  
Cymodocea Serrulata

The gastropod community is an important component in the food chain in seagrass beds, where the gastropods are the detritus feeder. Research on the diversity of gastropods in seagrass habitat in the waters of Tayando Yamtel Village, Tam City, Tual District, was conducted in March-May 2018, using the quadrant linear transect method. The results of measurements of environmental parameters in Tayando Yamtel waters are: an average pH of 8.55; DO 6.59 µg / l; salinity 32.36 ‰; temperature of 29 ° C; TDS 24.7 mg / l; current velocity (0.42 m / sec) is classified as low current; and a depth of 1.5 m. Gastropod research results obtained 862 individuals consisting of 15 families and 30 species of gastropods, while for seagrass obtained 3 species namely Cymodocea rotundata, Cymodocea serrulata and Thalassia hemprichii. The highest value of composition and gastropod density at Station I was dominated by Psedeovertagus aluco species at 62.73% and 3.708 (ind / m2), while at Station II were 28.01% and 0.93 (ind / m2) and Station III were 38.46% and 0.15 (ind / m2) are dominated by Strombus gibberulus species. Based on the gastropod ecological index value, the index value of species diversity and harmony is included in the medium category and the index value of dominance is in the low category. Keywords: Gastropoda, Seagrass, Tayando Yamtel

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