RESUMO

The aim of this study was to estimate the size at first sexual maturity (Lm) for 36 species belonging to 24 families from the marine habitat of Balochistan and Sindh in Arabian Sea, Pakistan through maximum length based an empirical and logistic model using commercial catch during June 2020 to May 2021. Individual total length (TL) was noted up to 0.1 cm using measuring broad. The Lm was calculated using two formulae; (i) log (Lm) = - 0.1246 + 0.9924 * log (Lmax) for Elasmobranchs and (ii) log (Lm) = -0.1189 + 0.9157* log (Lmax) for ray-finned fishes. The minimum Lm was recorded as 10.27 cm TL for Caranx malabaricus and 108.38 cm TL for Isurus oxyrinchus, respectively. Around Lm with 58.33% species were ranges from 19.00 cm to 25.00 cm TL. This study was estimated 16 newly Lm which is globally absent and rest 20 Lm are absent in the Arabian Sea (Pakistan coastal habitats). Therefore, the results will be helpful for the sustainable management and conservation of these marine fishes through the establishment of mesh size of trawl nets based on the size at sexual maturity (Lm).

O objetivo deste estudo foi estimar o tamanho na primeira maturidade sexual (Lm) para 36 espécies pertencentes a 24 famílias do hábitat marinho do Baluchistão e Sindh, no Mar Arábico, Paquistão, por meio de modelo empírico e logístico com base no comprimento máximo usando captura comercial, durante junho de 2020 e maio de 2021. O comprimento total individual (TL) foi anotado até 0,1 cm usando medição ampla. O Lm foi calculado por duas fórmulas; (i) log (Lm) = - 0,1246 + 0,9924 * log (Lmax) para elasmobrânquios; e (ii) log (Lm) = - 0,1189 + 0,9157* log (Lmax) para peixes com nadadeiras raiadas. O Lm mínimo foi de 10,27 cm de TL para Caranx malabaricus, e o máximo, de 108,38 cm de TL para Isurus oxyrinchus. Em 58,33% das espécies com Lm foram encontradas faixas de 19,00 cm a 25,00 cm de TL. Este estudo estimou que 16 espécies com Lm estão globalmente ausentes e as 20 espécies restantes com Lm estão ausentes no Mar Arábico (hábitats costeiros do Paquistão). Portanto, os resultados serão úteis para o manejo sustentável e a conservação desses peixes marinhos por meio do estabelecimento da malhagem das redes de arrasto com base no tamanho na primeira maturidade sexual (Lm).

Assuntos

RESUMO

Coastal zones are usually composed of coastlines and coastal wetlands and are among the most productive and dynamic ecosystems. However, the deltas are seldom detected and compared in detail at the continental scale to investigate the spatiotemporal evolution of coastline migration and coastal wetlands. Here we detected and compared the spatiotemporal changes in coastlines, wetlands, and ecosystem services in major deltas in Asia, including the Yellow River Delta (YRD), Yangtze River Delta (YAD), Pearl River Delta (PRD), Red River Delta (RRD), Mekong River Delta (MERD), Chao Phraya River Delta (CPRD), Mahanadi River Delta (MARD), Krishna River Delta (KRD), and Indus River Delta (IRD). We used time series remote sensing images from 1990 to 2019 to derive coastline and wetland information for the nine coastal zones. The ecosystem service value coefficients were applied to explore the ecosystem services characteristics of wetland changes in coastal areas. We found that the coastlines of the deltas in the study area changed less in the bedrock and sandy coasts, while the coastlines in the silty delta coasts changed more from 1990 to 2019. The interannual dynamics of coastal wetland areas in nine major deltas over the nearly 30 years can be divided into three periods: decreasing variability (1990-2005), increasing variability (2005-2015), and increasing volatility (2015-2019). Ecosystem services had an overall downward trend. These findings complement the official database of coastal planning and have substantial guiding implications for adjusting coastal management regulation policies.

Assuntos

RESUMO

Se realizó un estudio de la dinámica espacial de los crustáceos decápodos asociados a céspedes algales en los municipios de Moñitos, Puerto Escondido y Los Córdobas, Caribe colombiano. Se efectuaron cuatro muestreos trimestrales entre agosto de 2006 y julio de 2007 en cinco puntos de muestreo; dos en Moñitos, dos en Puerto Escondido y uno en Los Córdobas. Para la recolección de los especímenes se delimitó un cuadrante de 625 cm² con cinco repeticiones dispuestas al azar en cada punto de muestreo. Las macroalgas fueron separadas desde su disco de fijación al sustrato y conservadas en bolsas plásticas. Los crustáceos decápodos se conservaron en alcohol al 70%. Se identificó un total de 27 especies de crustáceos decápodos asociadas a los céspedes algales, agrupadas en 13 familias y 19 géneros, registrándose por primera vez Hippolyte pleuracanthus para el Caribe colombiano. Con base en el análisis de clasificación (UPGMA), se determinó que la estructura de las poblaciones de decápodos está relacionada con las características del sustrato rocoso y la composición algal, indicando que las diferencias en las poblaciones son consecuencia de una escala espacial. Los resultados indicaron que de las 27 especies identificadas, Epialtus bituberculatus registró el mayor porcentaje de abundancia (65,7%), seguida de Pachygrapsus transversus (6,2%), Eurypanopeus abbreviatus (3,8%), Acanthonyx petiverii (3,6%), Panopeus sp1. (3,6%) y Panopeus sp2. (3,4%). El resto de las especies aportaron una abundancia ≤2,2%.

A spatial scale study of decapods crustacean associated with algal assemblages was conducted at Moñitos, Puerto Escondido and Los Córdobas, Colombian Caribbean. During August of 2006 and July of 2007 were realized four samplings in five station; two in Moñitos, two in Puerto Escondido and one in Los Cordobas. A quarter of 625 cm2 was used to collect the species with five repetitions which were chosen at random, in each station. To separate the macroalgae from hold fast, it was used palette knife. The decapods crustaceans were separate in a plastic recipient, and those were preserved in alcohol at 70%, in bottles of plastic which were carefully named. 27 species of decapods associated with algae assemblages were reported, grouped in 13 families and 19 genera. Hippolyte pleuracanthus was registered for first time for the Colombian Caribbean. According to the classification analyses (UPGMA), it was found that the structure of the decapods crustacean were related with characteristic rocky line and algae assemblages, indicating that the differences in the population were consequences of a spatial patterns. The results indicated that of the 27 species identified, Epialtus bituberculatus recorded the highest percentage of abundance (65.7%), followed by Pachygrapsus transversus (6,2%), Eurypanopeus abbreviatus (3,8%), Acanthonyx petiverii, Panopeus sp1. (3,6%) and Panopeus sp2. (3,4%). The rest of the species provided an abundance ≤ 2.2%.