Activities

Introduction

For my professional practice, we focussed on the restoration of Gongolaria barbata (previously known as Cystoseira barbata). They are threatened by multiple human impacts like urbanization, overfishing, coastal pollution, climate change, and sea-urchins.

G. barbata is a canopy-forming brown alga that is ecologically relevant as an ecosystem engineer and plays a key functional role in controlling spatial habitat heterogeneity, productivity, and nutrient cycling in temperate rocky reefs. Cystoseira forests provide refuge and food for many invertebrates and fishes and modulate the structure of the associated benthic community (Falace et al., 2018).

Cystoseira species are listed as of community interest according to the Habitat Directive and are indicators of environmental quality in Mediterranean coastal waters according to the Water Framework Directive. Several species are protected by the Bern Convention, recognized as a priority by the Barcelona Convention, and considered vulnerable by several international organizations (i.e. IUCN, RAC/SPA, MedPan).

In the Conero riviera in Italy the two Cystoseira s.l. species we found most were Cystoseira compressa and G. barbata. you can distinguish G. barbata from C. compressa by the more brownish color and the more refined branches.

There are two main restoration methods

In-situ restoration: in the field

Natural boulders or terracotta tiles are placed around the native population. When nearby adults release their gametes they might fall on the boulders or tiles. Once the recruits are big enough, they get transplanted to a new restoration site. The other method includes putting the boulders or tiles straight at the restoration site and then attach nets containing fertile receptacles on a fixed height above them.

Ex-situ restoration: in the lab

This method includes building the terracotta tiles structure, placing it in aquaria, and attaching nets with fertile receptacles from the donor population at the top of the tank (as seen in the picture left). The growth process is in this case monitored and environmental variables like light, nutrients, temperature etc. can be adjusted as needed.

Fieldwork

Phenology monitoring

Vegetative monitoring

Here we measured the growth of the adult G. barbata in the field with a long ruler to monitor the growth cycle.

Reproductive monitoring

For the Reproductive monitoring. the percentage of fertile branches is calculated and receptacles are collected for labwork.

Measuring juvenile recruits

Juveniles get measured the same way as the adults but instead of a flexible ruler, we use a fixed one of 30cm. They are measured to follow up with the success of restoration and their growth.

Taking biodiversity samples

Scraping the surface

The substrate gets scraped off and collected in a plastic bag that is attached at the end of the structure. The substrate gets scraped off with a metal scraper. This is done to have an initial and future comparison of the associated biodiversity. The biodiversity here is mainly measured based on macro- and meiofauna.

Picture samples

The associated biodiversity of algae surrounding the G. barbata forests are measured by identifying random quadrat pictures around the area.

Transplantation of recruits

First the natural boulders get selected and collected from the site of the native population. Then we move them to the newly selected transplantation site. Spots get selected for the boulders and the surface gets cleaned by scraping. The boulders get attached to the surface with blue epoxy glue. the glue then needs to dry and after that we measure the recruits to have a starting point.

Labwork

Making sections

To assess the maturity in the lab sections are made of the receptacles. Based on the pressence and amount of female and male gametes a score from 1-4 gets assigned to each receptacle and so each tagged algae.

maturity 1

only male gametes are present

maturity 2

small and less female gametes (dark dots)

maturity 3

a lot of big female gametes

maturity 4

female gametes already start to release

Building structures and nets

Below you will see pictures of the different steps of making the structures and the nets. This was all a very new and education experience that shows that science is not only labwork behind a microscope.

Identification of seaweeds

Some labs consisted of identifying seaweeds as far as possible. Below you can see some examples of seaweeds we identified.

Cladophora cf. laetevirens.

Ceramium ciliatum

Antithamnion hubbsii

Identification of meiofauna and macrofauna groups

As part of the biodiversity assessment, samples had to be checked and the fauna had to be identified to be put in different groups

On this picture you can see several species that belong to the amphipods.

A picture of the setup that is used to identify the macro- and meiofauna.

The species pictured above belongs to the pycnogonidae or seaspiders.

Measuring and counting of zygotes and recruits

Before we start measuring the zygotes we count all zygotes present on the slide.

When the zygotes just started growing we measure them flat on the slide through the microscope.

Once the zygotes are big enough, they start to grow vertically. we then flip the slide on it's side to measure them.

The small recruits growing on the tiles get counted as well to have an overview of the success rate of the reproduction.

The small recruits are being counted with a click-counter

Data input and analysis

The data input and analysis (making of graphs) happened in Excel. On the left you can see a graph that show the temperature in 4 different sites that are used for restoration.

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