No abstract

Coastal aquaculture in Bangladesh consists mainly of two shrimp species (Penaeus monodon and Macrobrachium rosenbergii). Currently, there are about 16,237 marine shrimp (P. monodon) farms covering 148,093 ha and 36,109 fresh water shrimp (M. rosenbergii) farms covering 17,638 ha coastal area. More than 0.7 million people are employed in the farmed shrimp sector and in 2005-2006 the export value of shrimp was 403.5 million USD. Thus, coastal aquaculture contributes significantly to rural employment and economy but this is overshadowed by negative social and ecological impacts. This article reviews the key issues, constraints and opportunities of sustainable shrimp farming. In addition we present the results of two case studies from southwestern coastal areas where shrimp farming originated and central coastal areas where shrimp farming, especially M. rosenbergii, began in recent years. Lessons learned from the review and case studies are considered in the context of recommendations to encompass a socially equitable and ecologically sound coastal aquaculture.

The radular teeth of 55 species of Sacoglossa (= Ascoglossa) (Mollusca: Opisthobranchia) with known diets are classified into three basic groups: triangular, blade‐shaped and sabot‐shaped. Cell wall composition of the food plant is the single most important factor influencing radular morphology. The algae eaten by sacoglossans have either xylan, mannan or cellulose as their structural wall component. Sabot‐shaped teeth are associated with diets of Siphonocladales and Cladophorales, which have cellulose cell walls of a ‘crossed fibrillar texture’. Triangular teeth with lateral denticles are associated with diets of Caulerpa or with calcified algae. Most of these have xylan as the major structural polysaccharide. Blade‐shaped teeth occur in a large number of species representing a wide variety of diets. It is proposed that the three types of teeth function in different manners. Tooth denticulation is correlated with functional group of the food plant. The radular teeth of Elysia viridis feeding on Codium are longer, wider and have more curved tips than teeth of E. viridis feeding on Chaetomorpha. The teeth of E. viridis transferred from Codium to Chaelomorpha in the laboratory change in shape as well as size.

No abstract

1. The disproportionately low presence of marine species in the list of invasive alien species (IAS) of Union concern of the European Union (EU) Regulation 1143/2014 does not fully acknowledge the threat they pose to the EU marine environment.2. In this study, the first EU-scale Horizon Scanning (HS) focusing on marine alien species was performed, aiming to deliver a ranked list of species that should be of high priority for risk assessment (Article 5 of the EU IAS Regulation).3. Species absent from or with a limited distribution in EU marine waters were targeted. In total, 363 alien species were initially screened for HS by a panel of experts, including a broad range of taxonomic groups. Species were scored for their likelihood of arrival, establishment, spread, and impact in EU waters. 4.A consensus workshop ranked 267 species, including a subset of 26 prioritized species. These species are considered to be mainly introduced by shipping (fouling and ballast water), via the Suez Canal, and aquaculture activities. The 26 priority species were also scrutinized in terms of feasibility of their management; 18 of them were suggested for performing risk assessments on the basis of the EU IAS Regulation.5. Since biological invasions are dynamic and connected with accelerated globalization and diversified human activities, we recommend HS to be repeated periodically to review the species already listed and assess new ones.

No abstract

No abstract

No abstract