Decapod crustaceans associated with the shrimp fishery of the central-south portion of Veracruz, Mexico

The objective of this study was to analyze the brachyuran crab assemblages associated with shrimp fishing on the central-southern coast of Veracruz. Information was collected using 46 trawls organized within nine fishing quadrants. The total catch shrimp, bycatch, and discard were recorded and standardized (CPUE kg h-1). Value index by species, species richness, diversity using Shannon and Weaver index, and equitability were determined. A total of 3055 individuals were collected, which corresponded to nine families, 13 genera, and 14 species. Achelous spinicarpus species were identified at the greatest relative abundance (77.74%). Four new species records for the zone: Hepatus pudibundus, Iliacantha liodactylus, Leiolambrus punctatissimus, and Platylambrus granulatus. Species richness varied according to fishing quadrant and depth interval assessed. The highest value of species richness was eight, and observed Margalef species richness index values ranged from 0 to 2.23. The diversity values ranged from 0 to 2.41 bits ind-1; this may indicate that a few species share the greatest impact of trawling. The presence of lagoon systems was determined to define a portion of the composition of the assemblage. Understanding assemblage structure is important to improve knowledge on the impact of shrimp trawling activity on the ecosystem.

Pronounced Water Age Partitioning Between Arid Andean Aquifers and Fresh-Saline Lagoon Systems

<p>The challenge of deciphering connections between groundwater systems and surface water bodies and by extension connections to hydroclimate represent major unsolved questions in the hydrology community. Within the UPH framework, under the Interfaces in hydrology theme, this includes aspects of both questions <em>twelve</em> and <em>thirteen</em>. In arid regions, disentangling these processes is an especially difficult challenge due to the large spatial and temporal scales over which these systems are integrated. Yet we must improve our understanding if we are to use water sustainably in these landscapes. In the dry Andes, very deep water tables develop groundwater flow paths with long transit times, often crossing topographic boundaries before emerging at basin floors. These factors combined with the complex evaporite stratigraphy in which surface and groundwaters interact make it quite difficult to close water budgets and quantify groundwater fluxes across hydrological boundaries. As a result, many fundamental questions about connections across these interfaces remain unresolved. This study presents a novel examination of processes controlling fluxes across critical boundaries (groundwater recharge, inter-catchment flow, and riparian/stream/aquifer exchange) by employing a comprehensive set of ~150 <sup>3</sup>H samples from waters across the entire dry Andes paired with a large dataset (>1,500 samples) of <sup>18</sup>O, <sup>2</sup>H in water and dissolved major ions.</p><p>We present an integrated process-based conceptual framework describing the dominant controls on water compartment connections intrinsic to these arid mountain systems. The large range in mean transit times and the persistence of hydrologic features here allow for reliable delineation of multiple distinct source and flow path groupings. Repeat sampling over several years provides further constraints on connections between these compartments and the modern hydroclimate. Our results outline a few novel findings regarding the hydrological attributes of these environments: i) most of the water sustaining both the regional and local hydrological systems is old (0-10 % modern and 100-10000 yrs old) yet modern water (days-10 yrs old) is critical to sustaining many surface water bodies. ii) transit time distributions in specific water compartments (Groundwaters, Springs, Streams, Saline lagoons, and Vegas) are remarkably stable over time and show consistent patterns across the entire plateau; iii) the existence of surface water bodies and their connection to groundwater compartments is regulated by persistent hydrological features (regional flow paths, hydrogeology, fresh-saline interfaces); and iv) sharp divergence in mean residence and transit time of source waters occurs over very short spatial scales (<<1km).  By describing water age distributions and geochemical attributes of these features we define the dominant controls on several discrete water compartments and delineate clear distinctions between long-term average source waters and the decoupling of modern hydroclimate from the hydrologic system as a whole. This analysis represents a significant advancement in our understanding of controls on fluxes across boundaries in arid mountainous regions and freshwater-salt lagoon systems. An improved understanding of the primary controls on water source and transport will allow us to better protect communities and fragile ecosystems from the most damaging potential impacts of water extraction in these environments.</p>

Population Aspects of Graceful Mojarra Eucinostomus gracilis (Perciformes: Gerreidae) in a Coastal Lagoon in the Tropical Eastern Pacific

Graceful mojarra (Eucinostomus gracilis) is an important component of the ichthyic fauna of lagoon systems but knowledge of its population aspects is scarce. Monthly samples in the Magdalena-Almejas Lagoon system (March-August, 2014-2017) were obtained with a trawling net. Abundance was estimated using the swept area method and its spatial variation; and the maturity size was determined using the logistic method. The sex ratio for mature and immature populations, and their length-weight relationship were estimated; FISAT was used to estimate the growth and recruitment parameters. Abundance ranged from 0.6 to 203 ind-Ha-1 with changes for each lagoon system areas and among years. Size at maturity (L50) was 132 mm in total length (TL) for the population, 129 mm TL females, and 135 mm TL males. Considering the population of the total organisms, L50 indicated that 18% were adults and 82% were juveniles. Juvenile dominance indicated that this lagoon system is used for grow-out. The smaller ratio of adult organisms does not allow asserting assertion that the priority of the area is for reproduction. E. gracilis showed moderate growth (K = 0.56 year-1) with longevity of 5.4 years and asymptotic length of L∞ = 195 mm.

Coastal landforms evolution during the Holocene marine transgression: a witness from the past to understand the future

<p>The continental shelves submerged during the last marine transgression could constitute a unique laboratory to analyse how coastal landforms developed and evolved within the framework of a rising sea level. Such features therefore represent precious witnesses in the light of the high rates of sea-level rise predicted for the end of the century. Unfortunately, the majority of the coastal landforms have been wiped away during and soon after their submersion as a consequence of the pervasive wave and tidal action. Therefore, only few examples of well-preserved submerged coastal landforms are available.</p><p>In this study we focused our attention on the Italian side of northern Adriatic Sea, where a wide, low-gradient continental shelf, coupled to a very rapid marine ingression, allowed the partial conservation of the transgressive coastal landforms. Such study was carried out through the analysis of almost 10,000 km of high-resolution geophysical surveys (CHIRP-sonar profiles) and tens of stratigraphic cores carried out in the area during the last 30 years.</p><p>We recognized a series of almost 100 remnants of paleo tidal inlets which formed during the post-LGM transgression that led to the submersion of the Adriatic shelf. Despite paleo tidal inlets are often almost completely erased by the wave ravinement processes, when preserved they represent ideal markers for reconstructing the timing and impact of sea-level rise on the transgressed coastal plain. A wealth of information can be obtained by their analysis, such as the paleo coastlines locations, the dimensions of the paleo lagoon systems and, in particular conditions, the relative paleo sea-level. Such features therefore represent valid means to reconstruct the impact of the transgressive sea on the coastal area.</p><p>In particular, the paleo tidal inlets recognized in the northern Adriatic Sea suggest the recurrent formation followed by rapid overstepping of large lagoon systems during the early Holocene. Moreover, these features can be subdivided into clusters based on the depth of their top, thus allowing to infer the position of a series of paleo coastlines and suggesting the occurrence of periods of stasis of the relative sea-level rise, which allowed the formation of such inlets.</p><p>Although remnants of paleo tidal inlets are common on the northern Adriatic Shelf, they are almost absent in the northernmost portion of the basin (i.e. the Gulf of Trieste), where a series of paleo fluvial systems have been identified, thus providing a direct witness on the evolution of the coastal plain during a transgressive phase and right before its rapid submersion.</p><p>This research provides new insights on two main topics: i) it improves our knowledge on the post-LGM marine transgression, therefore contributing to reconstruct the history of sea-level rise and to constrain the modelling of future behaviour; ii) it contributes to understand the evolution of tidal inlets and lagoon-barrier island systems under the forcing of high rates of sea-level rise.</p>

Nematode parasites in the striped mullet (Mugil cephalus Linnaeus, 1758) in the southern Gulf of California

Coastal lagoons are an important component of the Gulf of California as they are considered natural ecosystems with high productivity and home to species of regional economic interest such as the striped mullet (Mugil cephalus), which, for its eating habits tends to present parasitism. The objective of the present work was to identify and determine the number of nematode parasites in the striped mullet in three lagoon systems (Navachiste, La Reforma, and Ceuta) in coastal areas of the southern Gulf of California. Thirty Mugil cephalus were randomly obtained from each of the lagoon systems. From each fish was obtained the total length, weight and condition factor (FC), next was dissected to be analyzed hepatosomatic index (HSI) and determine by direct count the prevalence, average intensity and average abundance of nematode; nematodes are identified taxonomically and molecularly. The nematode parasites found to belong to the genus Contracaecum of the family Anisakidae in all the fish sampled the parasitic prevalence was 67%. The nematode parasites found by sex indicated that 77% of the striped mullet females analyzed were parasitized, while the males presented 59%. The CF obtained was 1.17- 4.07, and the HSI ranged between 0.85 and 1.45; the average intensity for nematodes was 7.45, and the average abundance was 4.97, demonstrating that Contracaecum multipapillatum is the main nematode parasite present in all lagoon systems the southern Gulf of California.

A Numerical Assessment of Artificial Reef Pass Wave-Induced Currents as a Renewable Energy Source

The present study aims to estimate the potential of artificial reef pass as a renewable source of energy. The overall idea is to mimic the functioning of natural reef–lagoon systems in which the cross-reef pressure gradient induced by wave breaking is able to drive an outward flow through the pass. The objective is to estimate the feasibility of a positive energy breakwater, combining the usual wave-sheltering function of immersed breakwater together with the production of renewable energy by turbines. A series of numerical simulations is performed using a depth-averaged model to understand the effects of each geometrical reef parameter on the reef–lagoon hydrodynamics. A synthetic wave and tide climate is then imposed to estimate the potential power production. An annual production between 50 and 70 MWh is estimated.